Moderate cytotoxicity of proanthocyanidins to human tumour cell lines

In the present study the cytotoxicity of 16 proanthocyanidins was evaluated in GLC4, a human small cell lung carcinoma cell line, and in COLO 320, a human colorectal cancer cell line, using the microculture tetrazolium (MTT) assay. With IC50 values ranging from 18 to >200 μM following continuous incubation, the proanthocyanidins examined possess only moderate to low cytotoxicity. The highest cytotoxicity was found in a series of galloylated proanthocyanidins. An increase in the number of galloyl substituents increased cytotoxicity. Simple proanthocyanidins possess low cytotoxicity, that was independent of the stereochemistry. Compounds with doubly linked units had negligible cytotoxic effects, even at 200 μM, the highest concentration tested.