ESSAI OUVERT TESTANT LE BLEU DE MÉTHYLÈNE DANS LE COVID-19

par Dr Laurent Schwartz | Mar 29, 2020 | Bleu de Méthylène, Covid-19

Dr Laurent Schwartz (cancérologue- AP-HP)
Prof Marc Henry (Prof Physico- Chimie, Faculté de Strasbourg)
Prof Mireille Summa ( Statisticienne- Cereremade-Paris-Dauphine) : Frederic Bouillaud (INSERM Institut Cochin Paris)
Dr Catherine Vierling (MBA)

1) Il EXISTE UNE COHORTE INDEMNE DE COVID-19 DANS LE GRAND EST

L’épidémie de coronavirus s’est abattue sur l’Europe, il y a quelques semaines avec son cortège de malades et de morts.

De nombreux cancéreux sont sous bleu de méthylène pour son action anti tumorale.

Nous avons interrogé une base de données de plus de 30 000 personnes pour la plupart sous traitement métabolique (acide lipoique/hydroxycitrate) par le biais des sites internet suivants:
(https://dr-laurentschwartz.com/, https://www.helloasso.com/associations/association-l-espoir-metabolique, https://www.youtube.com/results?search_query=guy+tenenbaum). De cette cohorte informelle nous avons extrait un sous-groupe de 3000 personnes, dont plus de 500 dans le Grand- Est. Il s’agit de patients qui en sus du traitement métabolique ont pris du bleu de Méthylène à la dose de 75 mg trois fois par jour. Ces patients ont été contactés par internet (vidéo et e- mail). Nous avons eu une seule réponse quant à une possible contamination par le Covid-19 (un syndrome grippal modéré). Les limites de ce type d’enquête rétrospective sont évidentes. Mais cela suggère tout de même fortement que le bleu de méthylène puisse protéger contre cette infection-là.

2) LE BLEU DE MÉTHYLÈNE : UN TRAITEMENT SANS DANGER MAJEUR

            Le bleu de Méthylène est le premier médicament de synthèse datant de 1878. Le bleu de méthylène a été utilisé successivement et avec succès dans le traitement de la malaria (1), de la lèpre (2) puis plus récemment dans le traitement des maladies neurodégénératives (3). Il est approuvé dans le traitement de la méthémoglobinémie (4) et l’empoisonnement au cyanure (5). C’est un complément largement utilisé dans l’industrie alimentaire.

            L’efficacité du bleu de méthylène a été moins étudié dans les maladies virales. Un traitement de l’organe par le bleu diminue le risque de transmission lors de la greffe (6). Le bleu de méthylène a été utilisé seul ou en conjonction avec la photothérapie pour inactiver les virus présents dans le sang (7).Le Bleu de méthylène a été proposé dans le traitement des maladies virales. Un brevet a été posé en ce sens :
https://patents.google.com/patent/US6346529B1/en?q=methylene+blue+virus+treatment&oq=methylene+blue+virus+treatment

Le Bleu de Méthylène a été utilisé avec succès pour le traitement des chocs infectieux (8,9).

La toxicité du bleu de méthylène est faible. Ce médicament inscrit à la liste des médicaments essentiels de l’OMS n’a que peu d’effets secondaires :

• coloration en bleu des urines
• sensation de brûlures urinaires
• des syndromes psychiatriques lors de prise jointe d’inhibiteur de la sérotonine (11,12).

Le bleu de méthylène sous forme injectable fait partie des traitements de base dans les services des urgences.

Dans le dictionnaire Vidal le seul effet secondaire noté pour la forme intra veineuse vendu par la société pharmaceutique marseillaise Provepharm est : Son utilisation en chirurgie de la parathyroïde (non indiquée) a induit des effets indésirables sur le système nerveux central, lorsque l’administration était concomitante à celle de médicaments sérotoninergiques.

3) BLEU DE MÉTHYLÈNE ET COVID-19

Une équipe française vient de publier très récemment une étude très encourageante montrant que l’on pouvait lutter de manière efficace contre le virus SARS-Cov-2 en combinant un médicament anti-paludisme, l’hydroxychloroquine (HCQ), et un antibiotique l’azithromycine (figure 1).

 L’antibiotique est juste là pour lutter contre une éventuelle surinfection bactérienne des poumons qui ont été fortement affaiblis par l’attaque virale. Le médicament anti-paludisme HCQ est quant-à-lui le principe actif dont le mécanisme d’action a été étudié [13].

Il ressort que la chloroquine (CQ) et l’hydroxychloroquine (HCQ) ont la caractéristique chimique d’être des bases faibles (figure 2) qui peuvent élever le pH intracellulaire des organelles acides comme les endosomes ou les lysosomes qui sont indispensables pour que fusion membranaire ait lieu. Comme cette acidification est cruciale pour la maturation et le fonctionnement des endosomes, CQ et HCQ aptes à élever le pH du lysosome de 4,5 à 6,5 à une concentration de 100 µM bloquerait la maturation de l’endosome à une étape intermédiaire de l’endocytose. Ceci aurait pour conséquence l’impossibilité de transporter les virions en milieu intracellulaire. On sait aussi que CQ pourrait également inhiber l’entrée du SARS-CoV dans la cellule en modifiant la glycolysation des récepteurs ACE2 (Angiotensin Converting Enzyme 2) ou des protubérances protéiques. Les récepteurs ACE2 qui s’expriment dans certaines cellules du cœur et des reins sont en fait les points d’entrée dans les cellules humaines de certains coronavirus comme le SARS-CoV-2, ce qui explique la très forte mortalité observée chez les personnes faisant de l’hypertension ou ayant une fragilité cardiaque et/ou rénale. On sait aussi que des fortes concentrations de cytokines sont détectées dans le plasma de malades très gravement atteints. C’est très probablement cette avalanche de cytokines qui aggrave considérablement l’infection virale. Comme l’HCQ est un agent anti-inflammatoire efficace qui a été abondamment utilisé dans le traitement des maladies auto-immunes, cette molécule est donc capable de faire décroître de manière significative la production de cytokines et des facteurs pro-inflammatoires. Le problème de la chloroquine est que, de part son effet sur les récepteurs ACE2, elle peut entraîner des problèmes cardiaques et rénaux. D’où la nécessité de pouvoir disposer d’un autre traitement moins toxique et surtout très peu onéreux pour tous ceux qui ne supporteraient pas les effets secondaires de la chloroquine.

4) Biochimie du bleu de méthylène (MB^⊕)

            Le bleu de méthylène (figure 3) est une molécule synthétisée pour la première fois en 1876 par le chimiste allemand Heinrich Caro, par oxydation du diméthyl-4-phenylène-diamine par le chlorure ferrique en présence d’H₂S. Sa structure chimique sera établie en 1884. En 1887, le pathologiste polonais Czeslaw Checinski, appliqua une combinaison de bleu de méthylène et d’éosine sur des frottis sanguins et découvrit ainsi l’existence des parasites Plasmodium malariae en forme de pâquerette et Plasmodium falciparum en forme de faucille [14].

Suite à cette découverte, le médecin Paul Ehrlich (1854-1915) développa un mélange de bleu de méthylène et de fuschsine pour distinguer entre les différents types de globules blancs. Il constata alors que certains colorants pouvaient être des médicaments redoutablement efficaces aptes à tuer de manière spécifique certains organismes tout en laissant d’autres tissus intacts. C’est ainsi que le bleu de méthylène fut surnommé dès 1891, « le boulet magique » dans la lutte contre la malaria, en remplacement de la quinine, substance naturelle dont la production était très limitée. Puis ce fut le tour de la quinacrine en 1931, suivie de la chloroquine en 1934 afin d’éviter la coloration bleue de la peau et du blanc de l’œil. Il existe donc une filiation chimique et biologique évidente en le bleu de méthylène et la chloroquine ou l’hydroxychloroquine. Le tableau 1, montre d’ailleurs un classement par ordre d’efficacité de différents médicaments anti-malaria [15]. On voit que le bleu de méthylène y figure en très bonne place.
https://patents.google.com/patent/US6346529B1/en?q=methylene+blue+virus+treatment&oq=methylene+blue+virus+treatment. On notera aussi qu’une publication récente démontre que les parasites responsables de la malaria peuvent aussi transmettre des virus à ARN [16], ce qui vient renforcer l’idée que les médicaments anti-paludisme puissent être d’un précieux secours dans la lutte contre les coronavirus qui font partie de la famille des virus à ARN. Le fait, que le bleu de méthylène purifié soit plus actif que la chloroquine dans la lutte contre la malaria, et ce avec beaucoup moins d’effets secondaires, démontre a priori tout l’intérêt de tester cette molécule très peu onéreuse dans la lutte contre le COVID-19.  Mais, l’intérêt pour le bleu de méthylène se trouve aussi renforcé pour bien d’autres raisons.

i) Cette molécule est connue depuis 1876 et a donc été étudiée sous toutes les coutures au niveau de ses propriétés acido-basiques ou oxydo-réductrices. La figure 4 montre ainsi toutes les espèces chimiques susceptibles d’exister en solution aqueuse. Donc, lorsqu’on administre du bleu de méthylène, ce n’est pas une molécule que l’on administre mais tout un ensemble de molécules, ce qui explique l’extrême polyvalence de ce médicament, actif dans beaucoup de pathologies allant de la microbiologie à la psychiatrie. Ainsi, le bleu de méthylène est actif dans la thérapie de la méthémoglobinémie, du choc septique, de l’encéphalopathie et de l’ischémie. Comme indiqué plus haut, le bleu de méthylène peut être considéré comme un précurseur des agents anti-malaria comme la quinacrine et la chloroquine, des antihistaminiques de type phénothiazine inhibiteur des récepteurs H1 sous forme de prométhazine. C’est aussi la première drogue antipsychotique sous la forme de chlorpromazine (lobotomie chimique) et il pourrait s’avérer être un médicament majeur dans la lutte contre le cancer. Concernant plus particulièrement les infections virales, on notera que bleu de méthylène lorsqu’il capte un électron forme un radical MB relativement stable puisque susceptible d’être délocalisé sur plusieurs formes mésomères. Surtout ce radical possède un pK_a voisin de 9, ce qui le rend sur le plan acido-basique très proche de la chloroquine. On devrait donc avoir la même inhibition de la fusion membranaire par alcalinisation des endosomes qu’avec la chloroquine.

ii) Pour de faibles concentrations in vivo, le bleu de méthylène et sa forme leuco réduite et incolore sont en équilibre. Par conséquent, le bleu de méthylène, en plus d’être l’ancêtre de la chloroquine, forme un couple d’oxydo-réduction réversible qui peut servir de donneur d’électrons artificiel à la chaine de transport des électrons présente dans les mitochondries [19]. On rappelle ici que plusieurs protéines enchâssées dans la membrane interne des mitochondries sont aptes à transférer des électrons et pomper des protons contre un gradient de concentration dans l’espace intermembranaire (pour générer un gradient de protons nécessaire à la synthèse d’ATP).

Ces complexes peuvent recevoir des électrons depuis des espèces réduites comme NADH ou FADH₂ pour les amener au dioxygène afin de le réduire, via des transporteurs CoQ (complexes I, II et III) ou cytochromes-c (complexes III et IV). Le bleu de méthylène peut donner ses électrons soit à CoQ, soit à Cyt-c, ce qui permet d’augmenter la l’activité du complexe IV (figure 5). Le bleu de méthylène a aussi une action hormétique puisqu’à faible dose il peut interagir directement avec le dioxygène et réduire la quantité de radicaux superoxyde produits de manière secondaire par la phosphorylation oxydative et protéger ainsi la mitochondrie de l’oxydation. Pour des doses plus élevées, il peut capter les électrons de la chaîne respiratoire et ainsi réduire l’activité de ces complexes. Des études in vitro ont montré que l’activité maximale du complexe IV était atteinte pour une dose de 0,5 µM de bleu de méthylène, tandis qu’au-delà de 5 µM, l’activité du complexe IV commence à être inhibée et ce d’autant plus que la concentration augmente. Des études in vivo sur des rats ont montré une activité locomotrice maximale à une dose de 4 mg/kg tandis qu’aucun effet n’est observé en dessous de 1 mg/kg ou au-dessus de 10 mg/kg. Enfin au-delà d’une dose de 50 mg/kg on observe une diminution de l’activité locomotrice au lieu d’une activation.

iii) En plus d’être utile dans tous les cas d’insuffisance respiratoire, en forçant la réduction du dioxygène en eau dans les mitochondries, le bleu de méthylène est aussi un agent facilitant l’oxydation du NADPH avec formation d’eau oxygénée (figure 6).

Par cette génération d’eau oxygénée, le bleu de méthylène est aussi un agent modulateur du système immunitaire, ce qui peut s’avérer très utile en cas d’emballement de ce dernier comme on le voit avec les avalanches de cytokines chez les cas graves de COV-19.

iv) On sait enfin que le bleu de méthylène, pour des raisons qui restent encore à élucider, aide à lutter contre le vieillissement cellulaire et les maladies neurodégénératives. Or, on a pu constater que les enfants qui ont un organisme et un système nerveux en plein développement semblent être des porteurs sains. On pourrait donc penser que les personnes deviennent sensibles au SARS-CoV-2 dès que leur croissance corporelle ou neuronale ralentit de manière conséquente, ce qui expliquerait que les enfants soient naturellement « immunisés ». Ici aussi, le bleu de méthylène a probablement un rôle à jouer.

Pour toutes ces raisons, il semble impératif que la piste du bleu de méthylène soit sérieusement étudiée dans la lutte contre l’épidémie de COVID-19, surtout afin d’éviter aux personnes gravement atteintes, le passage par le respirateur artificiel, dont le nombre est forcément très restreint sur le territoire en raison du coût et de la très haute technicité de l’appareillage et les conséquences de fibrose pulmonaire séquellaire à moyen terme. Le bleu de méthylène, lui ne coûte quasiment rien, n’est pas toxique à faible dose et possède comme seul inconvénient de colorer en vert ou en bleu les urines des malades.

5) ESSAI CLINIQUE OUVERT PROSPECTIF

Essai monocentrique testant l’apport du bleu de méthylène à la dose de 75 mg matin midi et soir chez des patients atteints de Covid-19

Critères d’inclusion

• Patients atteints de Covid-19 : diagnostic clinique (céphalées, fièvre, arthralgie, dyspnée…) si possible prouvé par PCR
• Plus de 18 ans

Critères d’exclusion

• Karnovsky inférieur à 70
• Prise de médicaments anti sérotoninergique

LES DESCRIPTEURS A RENSEIGNER PAR PATIENT SUIVI POUR LE COVID-19

Voici une liste de descripteurs que nous suggérons pour le suivi d’un patient qui est en contact avec l’hôpital,

• soit parce qu’il y est hospitalisé,
• soit parce qu’il est à domicile mais est passé par les urgences et fait l’objet d’une surveillance médicale.
• soit qu’il est suivi par un médecin de ville

Il s’agit de mesures pour la plupart faciles à faire qui donnent des informations indirectes sur la charge virale du malade.  Ces mesures n’incluent pas celle de la charge virale qui serait certes pertinente mais il n’y pas à ce jour suffisamment de tests disponibles et l’on a donc proposé des variables de substitution pour suivre l’évolution de la virulence de la maladie.

Variables signalétiques 

• sexe
• âge
• tabagisme (nombre de cigarettes par jour)
• consommation d’alcool
• prise de thiazolidinediones (antidiabétiques)
• prise d’ibuprofène
• prise d’ inhibiteurs de ACE
• antécédents maladies du parenchyme pulmonaire et d’infarctus

Variables à mesurer tous les jours

• un indicateur auto renseigné par le patient quant à l’évolution de son état aux différentes dates,
• la température au matin et soir
• la Tension Artérielle
• Dyspnée à quantifier si possible
• pH urinaire matin et soir
• État général selon échelle de Karnovsky

Références

1. Coulibaly, B., Zoungrana, A., Mockenhaupt, F. P., Schirmer, R. H., Klose, C., Mansmann, U., Müller, O. (2009). Strong gametocytocidal effect of methylene blue-based combination therapy against falciparum malaria: a randomised controlled trial. PloS one, 4(5).
2. DE ALMEIDA, A. O. (1938). Treatment of leprosy by oxygen under high pressure associated with methylene blue.
3. Yang, S. H., Li, W., Sumien, N., Forster, M., Simpkins, J. W., & Liu, R. (2017). Alternative mitochondrial electron transfer for the treatment of neurodegenerative diseases and cancers: Methylene blue connects the dots. Progress in neurobiology, 157, 273-291.
4. Brent, J., Burkhart, K., Dargan, P., Hatten, B., Megarbane, B., Palmer, R., & White, J. (Eds.). (2017). Critical care toxicology: diagnosis and management of the critically poisoned patient.
5. Hanzlik, P. J. (4 February 1933). « Methylene Blue As Antidote for Cyanide Poisoning ». 100 (5): 357.
6. Helfritz, F. A., Bojkova, D., Wanders, V., Kuklinski, N., Westhaus, S., von Horn, C., Swoboda, S. (2018). Methylene blue treatment of grafts during cold ischemia time reduces the risk of hepatitis c virus transmission. The Journal of infectious diseases, 218(11), 1711-1721.
7. Friedman, L. I., Stromberg, R. R. (1993). Viral inactivation and reduction in cellular blood products. Revue française de transfusion et d’hémobiologie, 36(1), 83-91.
8. Preiser, J. C., Lejeune, P., Roman, A., Carlier, E., De Backer, D., Leeman, M., … & Vincent, J. L. (1995). Methylene blue administration in septic shock: a clinical trial. Critical care medicine, 23(2), 259-264
9. Kanter, M., Sahin, S. H., Basaran, U. N., Ayvaz, S., Aksu, B., Erboga, M., & Colak, A. (2015). The effect of methylene blue treatment on aspiration pneumonia. journal of surgical research, 193(2), 909-919.
10. Kwok, E. S., & Howes, D. (2006). Use of methylene blue in sepsis: a systematic review. Journal of intensive care medicine, 21(6), 359-363.
11. Ramsay, R. R., Dunford, C., & Gillman, P. K. (2007). Methylene blue and serotonin toxicity: inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction. British journal of pharmacology, 152(6), 946-951.
12. Gillman, P. K. (2006). Methylene blue implicated in potentially fatal serotonin toxicity. Anaesthesia, 61(10), 1013-1014.
13. Liu et al., « Hydroxychloroquine, a less toxic derivative of chloroquine, is effective in inhibiting SRAS-CoV-2 infection in vitro », Cell Discovery (2020), 6 : 16. DOI : https://doi.org/10.1038/s41421-020-0156-0.
14. Krafts, E. Hempelmann, A. Skorska-Stania, « From methylene blue to chloroquine : a breif review of the development of an antimalarial therapy ». Parasitol. Res. (2012) 111 : 1-6.
15. [3] B. Fall et al., « Plasmodium falciparum susceptibility to standard and potential anti-malarial drugs in Dakar, Senegal, during the 2013-2014 malaria season », Malaria Journal (2015) 14 (60), 10.1186/s12936-015- 0589-3 . hal-01220028.
16. Charon., « Novel RNA viruses associated with Plasmodium vivax in human malaria and Leucocytozoon parasites in avian disease », PLoS Pathog. (2019), 15(12) :e1008216, https://doi.org/10.1371/journal.ppat.1008216
17. Impert, A. Katafias, P. Kita, A. Mills, A. Pietkiewicz-Graczyk, G. Wrzeszcz, « Kinetics and mechanism of a fast leuco-Methylene Blue oxidation by copper(II)–halide species in acidic aqueous media », Dalton Trans. (2003) 348-353.
18. Contineanu, C. Bercu, I. Contineanu, A. Neacsu, « A chemical and photochemical study of radical species formes in methylene blue acidic and basic aqueous solutions, Analele Universităţii din Bucureşti – Chimie (serie nouă), (2009), vol 18 no. 2, 29 – 37.
19. K. Bruchey and F. Gonzalez-Lima, « Behavioral, Physiological and Biochemical Hormetic Responses to the Autoxidizable Dye Methylene Blue », Am J Pharmacol Toxicol. 2008 January 1; 3(1): 72–79.

A cohort of cancer patients with no reported cases of SARS-CoV-2 infection : the possible preventive role of Methylene Blue

par Dr Laurent Schwartz | Mar 28, 2020 | Bleu de Méthylène, Covid-19

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La cohorte de patients, gérée par les différentes associations et traitée par Bleu de méthylène semble indemne de syndromes grippaux et de Covid 19. Ceci peut être le simple fait du hasard ou plus probablement lié au Bleu de méthylène.

Nous avons soumis l’article ci-dessous à la revue « Substantia » de l’université de Florence. Ce papier a été accepté le jour même. Nous avons aussi rédigé un protocole en français pour tester l’efficacité de cette démarche.
La Chloroquine a été synthétisée en 1934 à base de Bleu de Méthylène  dont on reconnait clairement deux des trois cycles.

Traduire en français

Marc Henry^1*, Mireille Summa², Louis Patrick³, Laurent Schwartz⁴

1 Université de Strasbourg, Chimie Moléculaire du Solide, Institut Le Bel, Strasbourg.
2 Ceremade, Université Paris Dauphine
3 Association Espoir Métabolique
4 Assistance Publique des Hôpitaux de Paris, Paris, France.

Abstract

We report the case of a cohort of 2500 French patients treated among others with methylene blue for cancer care. During the COVID-19 epidemics none of them developed influenza-like illness. Albeit this lack of infection might be by chance alone, it is possible that methylene blue might have a preventive effect for COVID-19 infection. This is in line with the antiviral activity of Chloroquine, a Methylene blue derivative.

Both Chloroquine and Methylene blue have strong antiviral and anti- inflammatory properties probably linked to the change in intracellular pH and redox state.

Keywords: COVID-19, cancer, methylene blue, metabolic treatment

Introduction

Europe has been recently been hit by an epidemic of COVID-19. We report a cohort of patients treated for cancer in France. This cohort is managed by an association (Espoir Metabolique) and is a cancer support group. There are 2500 patients all at high risk for sepsis because of concomitant chemotherapy. One of us has interviewed (by telephone and by e mail) these patients to register the cases of COVID-19. As of March 27^th, 2020, there were no cases of registered COVID-19 or of flu–like syndroms. These patients were treated by a combination of standard therapy and α-lipoic acid (800 mg twice a day), hydroxycitrate (500 mg three times a day) and methylene blue (75 mg three times a day) as well as a low carb diet.

There were 52% women against 48% men. The most prevalent cancer type were breast cancer (40 %), lung (20%), prostate (10%), uterine (10%), colon (8%), liver (6%) miscellaneous (6%). Albeit this lack of influenza-like illness might be by chance alone, it is possible that one of these molecule might have prevented viral infection. Herein, we present a short scientific survey of what is currently known about the SARS-Cov-2 virus, hydroxychloroquine treatment as well as biochemical properties of methylene blue that was called once upon a time a “magic bullet” for healing a wide range of diseases.

Background

Coronaviruses (CoVs) are quite common viruses that are generally related in humans to the upper respiratory tract family of disorders. They may trigger asthma in children and adults and severe respiratory disease in the elderly. They could also be responsible of pneumonia end bronchiolitis infections in the infant and child population. The first human coronaviruses was discovered in 1965 and named B814.¹ Shortly after this discovery, other coronaviruses were described that caused disease in multiple animal species, including, rats, mice, chickens, turkeys, calves, dogs, cats, rabbits and pigs.² In the late 1960s, two major human strains were studied HCoV-OC43 (“OC” meaning that they could be grown in organ cultures such as mouse brain) and HCoV-229E (“E” meaning that such viruses were ether-sensitive suggesting that they required a lipid-containing coat for infectivity), a strain that could be grown in tissue culture directly from clinical samples. Epidemiologic studies found that coronaviruses were endemic in humans, being responsible for 5-10% of all upper and lower respiratory tract infections associated to a quite low pathogenicity. But the situation changed in 2002-2003 after the discovery in Southern Asia of a new respiratory illness, termed Severe Acute Respiratory Syndrome (SARS), which was able to spread quickly in 29 countries of America, Asia and Europe causing 774 fatalities and resulting in a mortality rate of 9%.³ This SARS-CoV was responsible for a loss of $40 billions in economic activity. Phylogenetic studies seemed suggesting a bat origin for this new SARS-CoV virus with an entry in the human population probably relayed by Himalayan palm civets. The strange thing was that 40% of wild animal traders and 20% of individuals, who slaughter animals were seropositive for SARS, without manifestation of any symptoms, meaning that the real causes of the disease remain still nowadays quite unclear. Infection control policies were able to halt the epidemics in 2004.

But the same year, a new strain named HCoV-NL63 was identified in the Netherlands from an infant with bronchiolitis, followed by a new strain HCoV-HKU1 in 2005 from a patient with pneumonia in Hong Kong. These new strains were however not able to trigger new epidemics in the human population. This was however not the case of the MERS-CoV (Middle East Respiratory Syndrome Coronavirus) isolated in 2012 from a patient with pneumonia in Saudi-Arabia that was able to spread in 21 countries with almost 600 related deaths and a mortality rate of ≈ 40%. Again, bats were suspected of being at the origin of the virus, but with a new intermediate that were dromedary camels as natural hosts. It is worth noticing that since 1965, HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1 and MERS-CoV are commonly circulating in the human population causing general respiratory illness and cold symptoms during winter and spring months in healthy individuals and more severe disorders in the immuno-compromised and the elderly. We are now facing a new terrible challenge, with the emergence in late November 2019 of a new strain names SARS-CoV-2 in Wuhan, Hubei province, China. Concerning the origin of the virus, genomic studies have shown that Malayan pangolins (Manis javanica) illegally imported into Guangdong province contain coronaviruses similar to SARS-CoV-2 with as usual bats serving a reservoir hosts.⁴ Another possibility could be natural selection in humans following zoonotic transfer. But, genetic data irrefutably show that SARS-CoV-2 is not derived from any previously known virus backbone, meaning that it is improbable that it emerged after laboratory manipulation of a related SARS-CoV-like coronavirus. Nowadays, CoVs belong to the Nidovirales order split into two subfamilies (Coronavirinae et Torovirinae) and further subdivided into four groups: α-CoVs (HCoV-229E and HCoV-NL63), β-CoVs (OC43, HKU1, SARS, MERS), γ-CoVs and δ-CoVs.

Genome and structure

SARS coronaviruses are medium-sized RNA viruses, holding inside an oily shell a 30 kilobases long single stranded RNA-genome, positive in sense, with a 5’ cap structure ending with a 3’ poly-adenylated tail. The virions appear to spherical in shape with a diameter of about 125 nm with several club-shape spike projections emanating from the oily surface and conferring to the virus its corona-like aspect (figure 1).

            The overall packing of the coronavirus genome is 5’ – leader – UTR – Replicase (ORF1ab) – S (Spike) – E (Envelope) – M (Membrane) – N (Nucleocapsid) – 3’UTR – poly (A) tail with accessory genes interspersed within the structural genes at the 3’ end. UTR corresponds to untranslated regions. The replicase gene occupying two-thirds of the genome encodes for nonstructural proteins (Nsps) through two polyproteins (pps) 1a (coding for nsps1-11) and 1ab (coding for nsps1-16) with the following identified functions:⁴

– Gene nsp1 promotes cellular mRNA degradation and blocks host cell translation resulting in blockage of innate immune response.
– Gene nsp2 have currently no known function.
– Gene nsp3 encodes for a large multi-domain trans-membrane protein with ubiquitin-like and acidic domains that interacts with N-protein, ADP-ribose-1’’-phosphatase (ADRP) activity that promotes cytokine expression, papain-like protease  (PLPro) with deubiquitinase domain is responsible for cleavage at nsp1/2, nsp2/3 and nsp3/4 boundaries and blocks host innate immune response.

– A potential trans-membrane scaffold protein playing an important role for proper structure of double-membrane vesicles (DMVs) in encoded in gene nsp4.
– A serine type main protease (Mpro) in nsps5 gene is responsible for all cleavage events not mediated by PLPro.
– Genes (nsp7, nsp8) encodes for two hexadecameric complexes that may act as processivity clamp for RNA polymerase.
– A RNA binding protein is encoded in gene nsp9.
– Gene nsp10 encodes for a cofactor that forms heterodimer with nsp16 and nsp14 for stimulating activity of the corresponding proteins.
– Gene nsp11 from pp1a extended into pp1b becomes nsp12 encoding the RNA-dependent RNA polymerase (RdRp) that duplicates viral RNA. The recombination ability of coronaviruses during viral evolution is tied to the switching ability of RdRp during replication.
– A RNA helicase with RNA 5’-triphosphatase activity insures unpackage of the viral genome (gene nsp13).
– Gene nsp14 encodes an Exoribonuclease (ExoN) that insures replication fidelity (proofreading of the viral genome) with N7-methyltransferase (N7-MTase) activity for adding 5’ cap to viral RNAs.
– A viral endoribonuclease (NendoU) with unclear function is encoded in gene nsp15 and is a genetic marker (together with nsp14-ExoN) for the order Nidovirales.
– Finally, gene nsp16 encodes for a 2’-O-methyltransferase (2’-O-MT) that shields viral RNA from MDA5 (melanoma differentiation associated protein 5) recognition.

Once cleaved, genes behave as mRNA for the ribosomal units of the infected cell for producing the set of Nsps that are able to self-assemble into a replicase-transcriptase complex (RTC) providing a suitable environment for producing both genomic and sub-genomics RNAs. The role of sub-genomic RNAs is to serve as mRNAs for the structural and accessory genes which resides downstream of the replicase polyproteins. Following replication and sub-genomic RNA synthesis, the viral structural proteins S, E and M are translated and inserted into the endoplasmic reticulum (ER) for further processing by the endoplasmic reticulum-Golgi intermediate compartment (ERGIC). After encapsidation of the viral genome by the N-proteins in the ERGIC, budding with viral structural proteins (first with M and E, then with S later on) leads to mature virions. Following assembly, virions are transported to the cell surface in vesicles for further release by exocytosis.

If some S-proteins remain outside the virions, they may also transit towards the surface for mediating cell-cell fusion between infected cells and adjacent uninfected cells, leading to giant multinucleated cells, responsible for virus spreading without detection or neutralization by virus-specific antibodies. Accordingly, the primary determinant for infection of a cell by coronaviruses is the attachment of the virion through non-covalent interactions of protein-S with a suitable receptor. For human coronaviruses it is known that HCoV-OC43 binds to N-acetyl-9-O-acetylneuraminic acid, HCoV-HKU1 binds to O-acetylated sialic acids, while HCoV-NL63 and SARS-CoV bind to heparin sulfate proteoglycans.⁵ After binding to the cell, coronaviruses use a broad variety of fusion receptors: aminopeptidase N (APN) for HCoV-229E, human leucocyte antigen molecule (HLA class I) or sialic acids for HCoV-OC43, angiotensin-converting enzyme 2 (ACE2) for HCoV-NL63 and SARS-CoVs and dipeptyl-peptidase (DPP4) for MERS-CoV. The binding receptor of HCoV-HKU1 remains unknown. ACE2 receptors are expressed by epithelial cells of the lung, intestine, kidney and blood vessels, with a substantial upregulation in patients with type 1 or 2 diabetes or hypertension, who are treated by ACE inhibitors and angiotensin II type-I receptor blockers (ARBs).⁶ Increased expression of ACE2 is also observed by thiazolinidiones and ibuprofen. It has thus been inferred that people using ACE2-stimulating drugs may have a higher risk of developing severe and fatal COVID-19. 

Chloroquine and hydroxychloroquine

            Quite recently, a French team led by Pr. Didier Raoult in Marseille, has reported that is was possible healing in less than a week COVID-19 patients after administration of an anti-malaria drug, hydroxychloroquine (HCQ) and an antibiotic, azithromycin (figure 2).⁷ It is worth noticing that antibiotics are generally of no use against viruses, but could be nevertheless useful in order to prevent severe respiratory tract infections in patients suffering from viral infection. Such results are obviously very promising as the mean duration of viral shedding in patients suffering from COVID-19 in China was at least 20 days and up to 37 days.⁸ In vitro studies has suggested that a possible mechanism of action of chloroquine (CQ) and HCQ could be the augmentation of the intracellular pH in acidic organelles such as endosomes and lysosomes, owing to the fact that both molecules are weak bases.⁹ Accordingly, it is known that acidic media (pH < 5) are mandatory for endosome maturation and function. CQ was thus reported to elevate the pH of lysosome form about 4.5 to 6.5 at 100 µM. Consequently, it could be surmised that endosome maturation might be blocked at intermediate stages of endocytosis, resulting in failure of further import of virions into the cytosol. Another possibility could be inhibition of SARS-CoV entry by CD or HCQ through their ability of changing the glycosylation state of ACE2 receptors and S-proteins. Accordingly, it has been checked using immunofluorescence analysis (IFA) and confocal microscopy that the transport of SARS-CoV-2 from early endosomes (EEs) to endolyosomes (ELs) required for the release of the viral genome, was blocked (in vitro) by CQ and HCQ.⁹ Another point concerns the high concentration of cytokines (IL1B, IFNγ, IP10, MCP1, MIP1A, TNFα) in the plasma of critically ill patients infected by SARS-CoV-2. As HCQ is a successful anti-inflammatory agent that has been extensively used in autoimmune diseases, one may anticipate its ability to decrease the production of cytokines and pro-inflammatory factors. It is also worth noting that if HCQ is less toxic than CQ, prolonged and/or overdose usage of both molecules may lead to poisoning with cardiovascular and renal complications. There is thus an obvious need of finding other much less toxic molecules. Another constraint should be the low price and the large-scale availability of theses molecules as on Friday March 27, the COVID-19 has affected 175 countries, with more than 535’000 confirmed cases and about 24’000 deaths worldwide.¹⁰

Methylene blue (MB^⊕)

            Cancer is another kind of disease able to lead to cytokines storms and one may expect a large number of deaths from COVID-19 in such patients. However, our survey among our database of patients treated with a combination of α-lipoic acid, hydroxycitrate and methylene blue suggests that this treatment prevents from severe infection from COVID-19. It may thus be anticipated, but yet not proved, that MB^⊕ could be of considerable help for fighting against the COVID-19 epidemics. Here, we give a survey of the very interesting properties of this molecule with emphasis on chemistry, clinical trials being currently under investigation. Moreover, it is worth noting that methylene blue is the ancestor of modern anti-malaria drugs such as chloroquine and is associated to a lesser toxicity, the only drawback being a green-blue coloring of urine.

            Methylene blue chloride is an old compound synthesized in 1876 by the German chemist Heinrich Caro, through oxidation of a mixture of dimethyl-4-phenylene-diamine Me₂N-Ph-NH₂ and hydrogen sulfide by ferric chloride:¹¹

2 C₈H₁₂N₂ + H₂S + 6 FeCl₃ = C₁₆H₁₈N₃SCl + 6 FeCl₂ + 4 HCl + NH₄Cl

The sulfur atom bridges two molecules of the p-phenylene-diamine backbone (figure 3), forming a phenothiazine heterocyclic molecule displaying a formally positive thionium ion in one mesomeric form. Through aromatic resonance among the three fused rings, this formal positive charge may be delocalized over the two nitrogen atoms of the right and left dimethyl-amino groups leading a characteristic absorption at λ = 663 nm (ε = 75 mM^-1·cm^-1) for the un-protonated cation and undergoing a red-shift at λ = 740 nm for HMB^2⊕ after protonation.¹² Owing to strong absorption of the red part of the visible spectrum, cationic forms of methylene blue are deep-blue colored, a property used in 1882 by Robert Koch for staining the tubercle bacilli and extensively used by Paul Ehrlich (1854-1915) for differentiation between the different types of white blood cell.^13,14 The chemical structure of methylene blue was established in 1884 and it was used in 1887 in combination with eosin by the Polish pathologist Czeslaw Checinski for evidencing presence of daisy-like (Plasmodium malariae) and sickle-shape (Plasmodium falciprum) parasites in blood smears. In 1891, Ehrlich discovered that methylene blue fell in the category of “magic bullets” drugs for its ability to target the malarial organism. Replacement of quinine, a natural substance derived from the cinchona tree of South America with very limited supply, by methylene blue, a costless synthetic dye has allowed large-scale production of antimalarial therapy. Subsequent developments of what has been called at that time “chemotherapy” has led to the synthesis in 1831 of the very successful drug quinacrine, marketed by Bayer under the names of mecaprine and atrabine. Atrabine was further modified in 1934 by the German chemist Hans Andersag by replacing the acridine ring with a quinolone ring, giving access to a product named “resochin” upon reaction of oxaloacetic acid diethylester with m-chloroaniline. But, the product was found to be too toxic for practical use in humans and in order to minimize toxicity; the compound 3-methylresochin, named “sontochin” was synthesized and patented in November 1939, after testing over 1’100 patients with malaria. In November 1945, E. K. Marshall rediscovered resochin giving to the compound its definitive name “chloroquin”, becoming the first-line antimalarial therapy for about 20 years, saving countless lives. Later on, hydroxychloroquine was developed and reported to be half as toxic as chloroquine.¹⁵

            It follows that methylene blue may be considered as a template for the synthesis of substitutes of quinine in the cure of malaria. As shown in table 1, methylene blue is in fact in the top-five drugs against 18 stains of Plasmodium palcifarum.¹⁶ Moreover, a recent paper has evidenced that parasites responsible for malaria may also be hosts of yet unidentified RNA viruses,¹⁷ reinforcing the idea that it may exist a strong link between RNA viruses and anti-malaria drugs. There is also recent evidence that methylene blue activated with visible light effectively reduce Ebola Virus (EBOV), MERS-CoV, SARS-CoV, Crimean–Congo hemorrhagic fever virus (CCHFV) and Nipah virus (NiV) infectivity in platelets and plasma, respectively.^18,19 It follows that methylene blue used in conjunction with light may open a quite novel route of anti-viral therapy by mixing biochemistry with photo-physics. The need for large-scale testing of methylene blue against COVID-19 is again reinforced.

Methylene blue in non-viral pathologies

Methylene blue is in fact what may be called a BONARIA drug.²⁰ Here the three letters “BON” means that it is a safe and efficacious remedy while the last letters indicates that it is also affordable (A), registered (R) and internationally accessible (IA). This comes from the quite peculiar chemical properties of this substance. As shown in figure 4, the behavior of methylene blue as a function of pH, redox potential and irradiation is quite diversified and fascinating.^12,21 Upon assimilation, it is not a single molecule that enters blood circulation, but a full set of molecules, explaining the extreme versatility in a large number of pathologies ranging from microbiology to psychiatry. Concerning viral infections, it is worth noticing that when methylene blue undergoes a one-electron reduction, it becomes a neutral lipophilic MB^• radical with good stability insured by its delocalization over several mesomeric forms. Moreover, such a radical acts as a weak base (pK_a ≈ 9) favoring, as with chloroquine, transient alkalinization of cytosolic spaces.

Methylene blue also possesses antibacterial activity and is secreted in urine, explaining why it was heavily used for treating infections and painful disorder of the urinary tract in multi-ingredient prescriptions (polypharmacy).²² A quite useful combination was 5.4 mg of MB, 0.03 mg of atropine sulfate and 0.03 mg hyoscyamine (for pain relief of smooth muscle spasms), 40.8 mg of methamine (condensation product of formaldehyde with ammonia, breaking down in acidic urines), 5.4 mg of benzoic acid and 18.1 mg of phenyl salicylate (salol, an antiseptic). The mechanism of action of methylene blue against parasites has been partially elucidated involving homodimeric flavoenzymes of the glutathione (GR) reductase family that are present both in malarial parasite and the mammalian host cell.²⁰ The first affected enzyme is glutathione reductase (GR) allowing reducing glutathione disulfide (GSSG) to the sulfhydryl form glutathione (GSH):

GR                   NADPH + H₃O^⊕ + GSSG = NADP^⊕ + 2 GSH + H₂O

The second enzyme is thioredoxin reductase (TrxR) allowing reduction of thioredoxins (Trx) that are proteins facilitating the reduction of other proteins by cysteine thiol-disulfide exchange:

TrxR               NADPH + H₃O^⊕ + TrxS₂ = NADP^⊕ + 2 Trx(SH)₂ + H₂O

The role of GR and TrxR is to keep GSH and redoxins in the reduced state in order to maintain cytosolic spaces under reduced conditions. The key point is that methylene blue could be a substrate for TrxR with production of the reduced neutral and colorless form (leuco-methylene blue or LMBH) absorbing in the UV-part of the electromagnetic spectrum (λ = 340 nm, ε = 3.3 mM^-1·cm^-1 and λ = 258 nm, ε = 17.4 mM^-1·cm^-1):

TrxR               NADPH + MB^⊕ = NADP^⊕ + LMBH

 It follows that methylene acts as an inhibitor of the natural reactions of TrxR. It is worth noticing that methylene blue is unable to inhibit the enzyme dihydrolipoamide dehydrogenase (LipDH), another flavoprotein enzyme that oxidizes dihydrolipoamide to lipoamide (functional form of α-lipoic acid):

LipDH             NAD^⊕ + H₂O + dihydrolipoamide(SH)₂ = NADH + H₃O^⊕ + lipoamideS₂

However, the reduced form LMBH is unstable in presence of micromolar concentrations of molecular oxygen and auto-oxidizes readily under such conditions as shown in figure 5. The antioxidant thiol-producing enzymes guarding the reducing milieu of cytosolic spaces are thus turned in contact with methylene blue into pro-oxidant H₂O₂-producing enzymes challenging the reducing milieu that they are meant to protect. It follows that methylene blue is both an inhibitor and a subversive substrate allowing concomitant production of reactive oxygen species (ROS). Under such conditions, NADP(H) and molecular oxygen that are needed for the pathogen’s metabolism are irreversibly consumed by methylene blue. In addition, there is less GSH available in the parasite as a substrate of GSH S-transferase for the detoxification of hemes and other lipophilic compounds. The anti-bacterial effect of methylene blue then lies in the fact human GR reacts more slowly with methylene blue than parasites GR and that human TrxR is not present in erythrocytes. Accordingly, when parasitized red blood cells and normal erythrocytes are incubated together in MB-containing solution, the drug becomes concentrated selectively in the parasitized erythrocytes. A possible reason is that as LMBH bears no electrical charge, it easily permeates the membrane of digestive vesicles and is then auto-oxidized back to MB^⊕, thus remaining trapped in the vesicles. It is finally worth noticing that synergistic effects have been found against P. falciparum in culture when using methylene blue in combination with artemisinin derivatives.²⁰

          In the 1920s methylene blue proved to be a dramatic antidote for carbon monoxide or cyanide poisoning.²³ Consequently, methylene blue could be very efficient since 1940 for treatment of methemoglobinemia, a pathology where the ferrous ion of hemoglobin becomes oxidized into ferric ion, impairing attachment of dioxygen and thus reducing the oxygen-carrying capacity of the blood.²² Upon IV-injection methylene blue (1-2 mg·kg^-1 or 1% sterile solution) transforms in contact with reductases in the erythrocytes into the colorless leuco-methylene blue (LMBH) able to reduce methemoglobin back to normal hemoglobin. It follows that if used as such rather low concentrations, methylene blue functions as an alternative electron carrier in mitochondria, which accepts electrons from NADH or FADH₂ and transfers them to CoQ or cytochrome c and bypassing any complex I/III blockage (figure 6).²⁴ It is worth noting than in this case, an harmless product, water, in produced instead of hydrogen peroxide (cf. figure 5).

As a side effect, methylene blue is also able to scavenge any leakage in superoxide anion O₂^•⊝ from the ETC according to the reaction:

O₂^•⊝ + MB^⊕ = O₂ + MB^•

2 MB^• = MB^⊕ + LMB^⊝

Methylene blue is thus a potent antioxidant able stopping the oxidative cascade at its very beginning. It may thus also be considered as pyromaniac firefighter able to increase oxidative stress by accelerating ATP production and also able to eliminate the same oxidative stress thus generated. Associated to these well-known antioxidant properties is the ability of methylene blue for attenuating any ischemia/reperfusion injury through inhibition of superoxide generation by xanthine oxidase.²⁵ The ability of methylene blue for minimization of free radical production in the mitochondrial ETC explains why it has positive effects under metabolically stressed conditions, such as ischemic brain injury, where excess free radicals may lead to cellular damage and cell death. Accordingly, in vivo studies have shown that methylene blue reaches its maximum concentration in blood by 5 min after intravenous administration in humans.²⁶ The half-life of MB in blood after intravenous administration is 5.25 h in humans. No significant effects on vascular reactivity were observed using functional magnetic resonance imagery (fMRI) but a preferential potentiation of regions with a higher metabolic demand has been evidenced. Consequently, methylene blue concentrates in cortical regions with the largest metabolic energy demands in an activation task such as forelimb stimulation, boosting intellectual tasks.

Using methylene blue in patients with septicemia, leads to positive results owing to a direct inhibition of nitric oxide synthases (NOS), both constitutive and inducible. It inhibits guanylyl cyclase (GC) by binding to the heme group of the enzyme and blocks the catalytic functions of NO synthase by oxidation of the enzyme-bound ferrous iron.²⁷ An additional effect on soluble guanylyl cyclase, which normally leads to the formation of cyclic guanosine monophosphate (cGMP) as the second messenger of NO^•, adds to the inhibition of the NO–cGMP pathway. Methylene blue may be a more specific and potent inhibitor of NO synthase than guanylyl cyclase, because direct NO-donating compounds in the presence of methylene blue can still partially activate cGMP-signaling pathways. Methylene blue also inhibits platelet activation, adhesion, and aggregation synergistically with an inhibition of platelet thromboxane A2 and endothelial prostacyclin I2 production.²⁷

A very important point is that if methylene blue is able to increase complex-IV activity by about 30%, it also has a marked hormetic action by capturing electrons of the ETC at high dose (> 10 mg/kg) and through interaction with nitrogen oxide synthase (NOS) may produces cardio-vascular effects.²⁶ Studies performed in vitro has evidenced that complex-IV achieves a maximum activity for a 0.5 µM concentration. Above 5 µM, complex-IV activity is inhibited, and the larger the concentration, the stronger the inhibition.²⁸ On the other hand, studies performed in vivo on rats has shown that a maximal locomotion activity was reached at a dose of 4 mg·kg^-1, no effects being observed below 1 mg·kg^-1 or above 10 mg·kg^-1. Finally, above 50 mg·kg^-1, locomotion activity becomes to be reduced.

Summing together all these properties explains why methylene blue could be of considerable use in neurodegenerative diseases²⁹, ageing³⁰, cancer³¹ or for healing psychic disorders.³² Figure 7 shows for instance how methylene blue may act on key enzymes involved in Alzheimer disease (AD). Beneficial effects of methylene blue against AD has been demonstrated in clinical studies and comes from the non-polar character of the reduced LMBH form allowing it to cross easily the blood-brain barrier, for hitting multiple molecular targets. Concerning the inhibition of Tau protein aggregation by methylene blue, an in vitro target seems to be the microtubule affinity-regulating kinase (MARK4) at Ser262, through stabilization of its dimeric form following cysteine oxidation. But, as shown in figure 7, this is just one of the mode of action, the other ones being the down-regulation of cholinesterase activity for preventing acetylcholine (ACh) degradation and the ability of scavenging superoxide. But research in this field is progressing quite rapidly. For instance, it was recently shown that methylene blue reverses Caspase-6-induced cognitive deficits by inhibiting Caspase-6, and Caspase-6-mediated neurodegeneration (inhibition of the cleavage of the amyloid precursor protein APP) and neuroinflammation.³² As Caspase-6-mediated damage seems to be reversible months after the onset of cognitive deficits suggesting that methylene blue could benefit Alzheimer disease patients by reversing Caspase-6-mediated cognitive decline.

            As shown in figure 7, methylene blue is also an inhibitor of monoamine oxidases (MAOs), a biochemical fact that has been known for many decades.³² Figure 8 gives more details about the antipsychotic effects of methylene blue that have been exploited for more than a century. Accordingly, many studies have confirmed that methylene blue influences neuronal communication by altering cholinergic, monoaminergic, and glutamatergic synaptic neurotransmission both in the central and the peripheral nervous systems. First, methylene blue is able to induce neuronal membrane depolarization with inhibition of Ca^2⊕-activated K^⊕ channels, activation of Ca^2⊕ channels, and facilitation of Na^⊕ channel inactivation.³² It also modulates the functions of various integral membrane proteins involved in transports of solutes such as glucose and ions such as Na^⊕, K^⊕, and H^⊕. It was demonstrated that the cGMP pathway does not mediate the actions of methylene, reported in the majority of these studies.

Both glutamate and dopamine have been implicated in the pathogenesis of psychoses and methylene blue has been the lead compound for the development of classical antipsychotics. Thus, promethazine was made in the 1940s by a team of scientists from Rhône-Poulenc laboratories and shares with LMBH the same phenothiazine backbone and was the first-generation antihistaminic. It was used to treat allergies, trouble sleeping, and nausea and may help with some symptoms associated with the common cold. As it may also be used for sedating people who are agitated or anxious, it has led to the development of chlorpromazine that was first experimented in the early 1950s by the French military surgeon Henri Laborit in the hope of discovering a more effective anesthetic. While the drug did not cause his patients to lose consciousness, it did induce a remarkable calmness. This discovery was the very beginning of the “chemical lobotomy” revolution for the treatment of both acute and chronic psychoses, including schizophrenia and the manic phase of bipolar disorder, as well as amphetamine-induced psychosis. Considering the similarities in the chemical structures of methylene blue and antipsychotics of, it is likely that methylene blue modulates the activity of dopamine receptors. And owing to its antioxidant properties, it could also be of considerable help in the prevention of Li-toxicity in bipolar disorder patients.

             Among other interesting properties, methylene blue has been shown to modulate the physiological actions of hormones involved in the hypothalamo-pituitary-peripheral axis, increasing thyroid peroxidase activity and enhancing the iodination of thyronines, with subsequent increases in the synthesis of thyroxine.³² Moreover, when exposed to light, MB becomes photosensitized, leading to the release of cytotoxic, highly active, and short-lived oxygen-derived species such as singlet oxygen ¹O₂. It has also been shown that photons in the red-to-near-infrared frequency range of approximately 620–1150 nm penetrate to the brain and intersect with the absorption spectrum of cytochrome oxidase.³⁴ While low-dose methylene blue and low-level near-infrared light may produce different pleiotropic cellular effects, both interventions cause a similar up-regulation of mitochondrial respiration with similar benefits to protect nerve cells against degeneration. These human studies suggest that low-dose methylene blue may have potential therapeutic applications in neurology as a neuroprotective agent, and in psychiatry and clinical psychology to facilitate psychotherapeutic interventions. Similarly, low-level near-infrared light improved human neurological outcome after ischemic stroke,³⁵ and could help in conjunction with methylene blue to enhance emotional and neurocognitive functions such as sustained attention and working memory in humans.

Conclusion

With the current COVID-19 outbreak, the world is facing a challenge and every possibility of helping people should be considered. Our preliminary data suggest but do not prove that Methylene blue might be a good treatment for influenza- like illnesses. Both Methylene blue and its derivatives such as chloroquine may share similar mechanism of action. Time is ripe for a prospective randomized clinical trial for the treatment of this dreadful disease.

Old drugs which have been tested for other indications ( such as Methylene blue or Chloroquine) have a well-defined safety profile. They are often more effective than new drugs from the High Tech. The Covid 19 epidemics like cancer has a solution. Reporpusing of known molecules will help cure these deadly diseases.

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