Green synthesis and in vitro photodynamic efficacy of hypericin: Cytotoxicity assessment on MCF-7 breast cancer cells

Photodynamic therapy (PDT) is a minimally invasive therapy for treating cancers, infectious diseases and several other conditions. It uses light as an activator and component called photosensitizer. Hypericin is a natural photosensitizer which garnered a lot of attention due to its potential use in PDT for cancer treatment. Historically, hypericin has been used for millennia in herbal therapy because of its antiviral and antidepressant properties. However, the traditional synthesis of hypericin requires certain chemicals that are harmful to the environment and human health. To overcome this problem, scientists have been working towards the developing a green synthesis approach for producing hypericin. This study focuses on the green synthesis and assessment of the photosensitizer hypericin from the dried leaves of Hypericum perforatum (St. John's Wort) and its photodynamic efficacy were evaluated in vitro using MCF7 breast cells. An eco-friendly method was employed for extracting and purifying the hypericin.. This green synthesis approach uses fewer chemicals and solvents that minimize the hazard to the environment and health. The formation of hypericin was characterized using FTIR and UV-Vis-NIR spectrophotometers and the morphology was analyzed by HRTEM. The FTIR spectrum confirmed the presence of hydroxyl and carbonyl groups and the UV-Vis-NIR peaks exhibited the characterstic absorption peak at 589 nm. The spherical shaped morphology was seen in HRTEM. As hypericin is hydrophobic in nature, polyvinylpyrrolidone (PVP), a biodegradable, non-toxic material makes the former hydrophilic by producing hypericin-PVP compound. MTT assay and AO-EB staining assay established that hypericin exhibited the highest cell death in MCF7 cancer cells via apoptosis. The results demonstrate hypericin's efficacy in inducing cancer cell death through apoptosis and oxidative stress. Thus, hypericin proved its potential to be a promising natural photosensitizer in the future.