Applications of plant-derived products in photodynamic therapy

Photodynamic therapy (PDT) is a promising noninvasive therapy useful in the treatment of different pathologies, including cancer and bacterial infections. The conventional phototoxic mechanism comprises the generation of radical oxygen species or singlet oxygen. Recently, some plant-based photosensitizers (PSs) have been reported for their photoactivity with the advantages of low or no adverse effects compared to synthetic products, comparable efficiency with conventional PS, and improved target selectivity. PDT for cancer treatment evidenced a feasible, safe, and reliable therapy with many advantages compared to conventional therapy. Additionally, various plant-based PSs have been evaluated for antimicrobial PDT for the treatment of dental caries, chronic and inflammatory dental infections, and bacterial skin infections, representing an emerging field in the era of antibiotic resistance. This chapter focuses on the importance of common natural PS such as chlorophylls and chlorophyll metabolites, curcumin, thiophenes, alkaloids, and anthraquinones and on their phototoxic effects in the treatment of cancer and microbial infections.