Natural products derived from plants as potential drugs for the photodynamic destruction of tumor cells

Chlorophyll and some of its synthetically produced derivatives are important sensitizers in photodynamic cancer therapy, Other natural products from plants with light dependent activity include quinones like hypericin and fagopyrin. These compounds have extended pi-electron systems which upon photoexcitation with visible light are responsible for singlet oxygen production. Other plant constituents which show UV light induced photosensitizing activity are furanocumarins like psoralen and angelicin, aflatoxins and alkaloids, as well as thiophene derivatives, terthienyl and several polyacetylenes. The photodynamic properties of a chelidonium alkaloid derivative and data for its potential clinical applicability are given.