Exploring the application of herbal photosensitizers in antimicrobial photodynamic therapy against Mycobacterium Tuberculosis.

Abstract

Tuberculosis (TB) is one of the leading causes of death in the world, despite being a preventable and curable disease. Irrespective of tremendous advancements in early detection and treatment, this disease still has high mortality rates. This is due to the development of antibiotic resistance, which significantly reduced the efficacy of antibiotics, rendering them useless against this bacterial infection. This, in turn, causes immune system evasion, antibiotic treatment failures, and recurrence of disease in patients. Regarding this, photodynamic inactivation (PDI) may serve as a useful substitute for antibiotic therapy against drug-resistant mycobacteria. This century-old therapy is already being used in cancer treatment, dentistry, and skeletal and cardiovascular diseases, but it is not yet used in tuberculosis treatment. Researchers have previously used PDI to eradicate other members of the genus Mycobacteria in both in vitro and in vivo settings. This suggests PDI can be explored against M. tuberculosis too. The one limitation associated with PDI is the use of chemical photosensitizers, which are fatal to normal tissues and induce side effects. Recent studies suggest herbal photosensitizers are equally potent as chemically synthesized ones. Therefore, herbal photosensitizers could be used to solve the problem because of their less toxicity to healthy tissues and decreased frequency of side effects. This review emphasizes the importance of herbal photosensitizers and their role as anti-tuberculosis drugs in PDI therapy and also presents five potential herbal photosensitizers-curcumin, quercetin, resveratrol, aloe emodin, and phloretin that could be utilized in the clinical development of PDT-mediated tuberculosis therapies.