Photocytotoxic Pheophorbide-Related Compounds from Aglaonema simplex

In our screening program for new photosensitizers from the Malaysian biodiversity, we found five pheophorbide‐related compounds from the leaves and stems of Aglaonema simplex. Detailed spectroscopic analyses showed that compounds 1–3 and 5 are pheophorbide and hydroxy pheophorbide derivatives of chlorophyll a and b. Compound 4, identified as 151‐hydroxypurpurin‐7‐lactone ethyl methyl diester, was isolated for the first time from the Araceae family. An MTT‐based short‐term survival assay showed that all five compounds exhibit moderate‐to‐strong photocytotoxic activities towards human leukemia (HL60) and two oral squamous carcinoma cell lines (HSC‐2 and HSC‐3). Compounds 4 and 5 showed the strongest photocytotoxicities, with IC50 values of 0.30–0.41 μM (Table 2). Compounds 1–3 with Et chains at C(173) were less photocytotoxic than the parent pheophorbide a (5).