Crude plant extracts application in photodynamic therapy: making a case for Ficus carica L.

Photodynamic therapy (PDT) exploits the cellular effects of reactive oxygen species (ROS) generated by light-induced photosensitisers. Ficus carica leaf latex causes severe photodermatitis in the sunlight, indicating the presence of natural photoactive compounds. This project investigated whether crude extracts of F. carica may be suitable for simple and cheap PDT applications. UV/Vis spectrophotometry of the leaves’ acetone extract revealed three main absorption peaks (330, 410, 666 nm) and two minor ones (538 and 612 nm). Assays for ROS showed a light-dependent synthesis of singlet oxygen and hydroxyl radicals. With microscopic methods, intracellular accumulation of fluorescence was visible within 2 – 4 hours of exposure of 4T1 and MRC-5 cells to the extract. Further in vitro studies in these cell lines indicated a strong reduction of viability after application of white light (10 minutes, 32 mW/cm²) together with an exposure to the extract at concentrations that were harmless in the dark. Preliminary results of FAM-FLICA assays indicated apoptosis may not be the main mode of cell death, while Seahorse XFe96 Mito Stress tests provided evidence for profound changes in mitochondrial respiration due to the treatment.

In conclusion, F. carica leaves may contain photosensitisers with promising profiles for safe and efficient PDT. Our observation that a simple extraction in acetone suffices to achieve a product with the desired PDT activity opens up new avenues for the development of simple therapeutic interventions in remote areas and impoverished settings. Ongoing studies are investigating the potential of this crude extract to combat wound infections.

Publication History

Article published online:
16 November 2023