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J Photochem Photobiol B ; 227: 112378, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-1654818


In a recent study, we showed that pulsed blue light (PBL) inactivates as much as 52.3% of human beta coronavirus HCoV-OC43, a surrogate of SARS-CoV-2, and one of the major strains of viruses responsible for the annual epidemic of the common cold. Since curcumin and saliva are similarly antiviral and curcumin acts as blue light photosensitizer, we used Qubit fluorometry and WarmStart RT-LAMP assays to study the effect of combining 405 nm, 410 nm, 425 nm or 450 nm wavelengths of PBL with curcumin, saliva or a combination of curcumin and saliva against human beta coronavirus HCoV-OC43. The results showed that PBL, curcumin and saliva independently and collectively inactivate HCoV-OC43. Without saliva or curcumin supplementation 21.6 J/cm2 PBL reduced HCoV-OC43 RNA concentration a maximum of 32.8% (log10 = 2.13). Saliva supplementation alone inactivated the virus, reducing its RNA concentration by 61% (log10 = 2.23); with irradiation the reduction was as much as 79.1%. Curcumin supplementation alone decreased viral RNA 71.1%, and a maximum of 87.8% with irradiation. The combination of saliva and curcumin reduced viral RNA to 83.1% and decreased the RNA up to 90.2% with irradiation. The reduced levels could not be detected with qPCR. These findings show that PBL in the range of 405 nm to 450 nm wavelength is antiviral against human coronavirus HCoV-OC43, a surrogate of the COVID-19 virus. Further, it shows that with curcumin as a photosensitizer, it is possible to photodynamically inactivate the virus beyond qPCR detectable level using PBL. Since HCoV-OC43 is of the same beta coronavirus family as SARS-CoV-2, has the same genomic size, and is often used as its surrogate, these findings heighten the prospect of similarly inactivating novel coronavirus SARS-CoV-2, the virus responsible for COVID-19 pandemic.

Antiviral Agents/pharmacology , COVID-19/therapy , Curcumin/pharmacology , Photosensitizing Agents/pharmacology , SARS-CoV-2/drug effects , Saliva/chemistry , Combined Modality Therapy , Coronavirus OC43, Human , Humans , Light , Photochemical Processes , Photochemotherapy , RNA, Viral
Journal of Photochemistry and Photobiology ; : 100064, 2021.
Article in English | ScienceDirect | ID: covidwho-1401645


Photo-eradication of microorganisms with UV and blue light has been around since the 1870s. Research to further the development and deployment of germicidal UV and violet-blue light has been on the rise since COVID-19 pandemic. This paper traces the evolution of UV and violet-blue light, presents suggested ways to exploit two leading germicidal light technologies—far UV and pulsed blue light (PBL)—in the ongoing quest to effectively stem the spread of pandemic diseases. An effective way to overcome or minimize the spread of disease is to inactivate and reduce the number of viral particles both in the environment and in accessible parts of patients. This can be achieved by irradiating spaces, infected air, and the general environment with PBL or far UV, and by similarly disinfecting supplies, tools, and equipment. Irradiating the oronasal cavity of infected patients with PBL could clear the virus and kill oral opportunistic bacteria that worsen coronavirus infections. The advantages and disadvantages of the two-leading photo-disinfection light technologies are discussed.

J Photochem Photobiol B ; 222: 112282, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1347724


Emerging evidence suggests that blue light has the potential to inactivate viruses. Therefore, we investigated the effect of 405 nm, 410 nm, 425 nm and 450 nm pulsed blue light (PBL) on human alpha coronavirus HCoV-229 E and human beta coronavirus HCoV-OC43, using Qubit fluorometry and RT-LAMP to quantitate the amount of nucleic acid in irradiated and control samples. Like SARS-CoV-2, HCoV-229E and HCoV-OC43 are single stranded RNA viruses transmitted by air and direct contact; they have similar genomic sizes as SARS-CoV-2, and are used as surrogates for SARS-CoV-2. Irradiation was carried out either at 32.4 J cm-2 using 3 mW cm-2 irradiance or at 130 J cm-2 using 12 mW cm-2 irradiance. Results: (1) At each wavelength tested, PBL was antiviral against both coronaviruses. (2) 405 nm light gave the best result, yielding 52.3% (2.37 log10) inactivation against HCoV-OC43 (p < .0001), and a significant 1.46 log 10 (44%) inactivation of HCoV-229E (p < .01). HCoV-OC43, which like SARS-CoV-2 is a beta coronavirus, was more susceptible to PBL irradiation than alpha coronavirus HCoV-229E. The latter finding suggests that PBL is potentially antiviral against multiple coronavirus strains, and that, while its potency may vary from one virus to another, it seems more antiviral against beta coronaviruses, such as HCoV-OC43. (3) Further, the antiviral effect of PBL was better at a higher irradiance than a lower irradiance, and this indicates that with further refinement, a protocol capable of yielding 100% inactivation of viruses is attainable.

Coronavirus 229E, Human/radiation effects , Coronavirus OC43, Human/radiation effects , Low-Level Light Therapy/methods , SARS-CoV-2/radiation effects , Coronavirus 229E, Human/physiology , Coronavirus OC43, Human/physiology , Dose-Response Relationship, Radiation , Humans , SARS-CoV-2/physiology