A Comparison Between the Photodynamic Action of “Hypocrellin A” and “Pheophorbide A” Against Bacteria and SARS-CoV-2 Virus --- A MiniReview

Hypocrellin A and Pheophorbide a are well-known organic chemicals that may be contained in herbal products. They can act as photosensitizers and have a strong photodynamic effect on bacteria. In any case, are these photosensitizers appropriate for photodynamic treatment against the SARS-CoV-2 infection? The principles of photodynamic therapy are the same regardless of the target. It causes selective cytotoxicity at the site of infection through activation of photosensitizer under light irradiation to generate cytotoxic reactive oxygen species (ROS), leading to the death of infected cells. Is antimicrobial photodynamic therapy a good choice against the SARS-CoV-2 virus? Nine electronic databases were searched, including WanFang Data, PubMed, Science Direct, Scopus, Web of Science, Springer Link, SciFinder, and China National Knowledge Infrastructure (CNKI), regardless of term, and language restrictions. All eligible studies were analyzed and summarized in this review. “Hypocrellin A” and “Pheophorbide a” were effective for bacterial and SARS-CoV-2 in photodynamic therapy. 99.98 % of S. aureus was killed when incubated with the 10-3 M Hypocrellin A and illuminated a 490 nm in 30 mW/cm2 for 120 min. The difference was Pheophorbide a could also inhibit gram-negative bacteria, such as P. aeruginosa with a concentration of 1 µg/ml for 2 hr irradiated of a 671 nm laser in 0.3 W of 1 J, and a nearly 100 % suppression rate. “Hypocrellin A” and “Pheophorbide a” with antiviral activity, and virucidal effects for preventing and treating the infection. Based on previous studies, “Hypocrellin A” and “Pheophorbide a” are photosensitizers used for photodynamic therapy against bacteria or SARS-CoV-2, however, much more works need to be done in the future including the development of a better way for systematic infectious disease, and its correlated infections for the application of photodynamic therapy.