A novel porphyrin photosensitizer from bamboo leaves that induces apoptosis in cancer cell lines.

BACKGROUND

In the screening of new anticancer agents, we found that a methanol extract of bamboo leaves induced rapid apoptosis in the human leukemia CMK-7 cell line.

MATERIALS AND METHODS

The active compounds in the extract were isolated by chromatographic methods and their structures were determined by NMR and mass spectroscopy. Apoptosis by the compounds were evaluated in CMK-7 and human colon adenocarcinoma Colo320 DM cells by monitoring the caspase-3 activation and DNA cleavage.

RESULTS

The active compounds are 201-hydroxypurpurin-7 delta-lactone ethyl methyl diester (1) and the corresponding methyl phytyl diester (2). The apoptosis by compound 1 (0.3 to 0.1 microM for CMK-7 cells) was enhanced when the culture was briefly irradiated with a fluorescent lamp. This photodynamic induction of apoptosis by compound 1 was much stronger than that by a known photosensitizer, pyropheophorbidemethyl. Compound 2 was a weaker inducer of apoptosis than compound 1, but the apoptosis occurred after light irradiation.

CONCLUSION

The 201-hydroxypurpurin-7 delta-lactone esters are promising lead compounds as photosensitizers for photodynamic therapy of cancer.