Curcumin as a natural photosensitizer in photodynamic therapy: efficacy against metastatic melanoma cells.

Abstract

Malignant melanoma is one of the most aggressive and lethal forms of skin cancer, posing a significant global health challenge. Despite therapeutic advances, current treatment strategies remain limited in efficacy, highlighting the need for alternative approaches. Photodynamic therapy (PDT) is a minimally invasive treatment that uses a photosensitizer activated by specific light wavelengths to generate reactive oxygen species (ROS), leading to targeted destruction of cancer cells. Curcumin, a natural phenolic compound derived from Curcuma longa, possesses diverse pharmacological properties, including anticancer activity, and has emerged as a potential photosensitizer. This study aimed to evaluate the in vitro efficacy of curcumin-mediated PDT in inducing cytotoxic effects in metastatic melanoma (A375) cells. A375 cells were treated with curcumin followed by irradiation using a 405 nm laser at fluence levels of 5 and 15 J/cm². Post-irradiation incubation was conducted for 24 and 48 h. Cellular responses were assessed via ROS detection assays, nuclear damage evaluation (using nuclear staining), apoptosis assays, morphological observation, and cell viability tests. Curcumin-PDT treatment induced a fluence- and time-dependent increase in intracellular ROS levels. Treated cells exhibited marked nuclear fragmentation, reduced viability, morphological alterations, and significant apoptosis compared to control groups. The extent of these effects correlated with both laser fluence and incubation time. These findings confirm that curcumin, upon photoactivation, induces oxidative stress and apoptosis in melanoma cells, thereby reducing cell survival. These results support the potential of curcumin as a natural photosensitizer in PDT and suggest its promising application in nanobioconjugate delivery systems for melanoma therapy.