Antitumor agents, 129. Tannins and related compounds as selective cytotoxic agents

Fifty-seven tannins and related compounds, including gallotannins, ellagitannins, and condensed and complex tannins, were evaluated for their cytotoxicities against human tumor cell lines, including malignant melanoma, lung carcinoma, ileocecal adenocarcinoma, epidermoid carcinoma, malignant melanoma, and medulloblastoma cell lines. Among them, chebulagic acid [1], geraniin [2], sanguiin H-11 [3], 4,5-di-O-galloylquinic acid [12], 1,3,4,5-tetra-O-galloylquinic acid [15], 1(beta)-O-galloylpedunculagin [24], furosin [29], castalagin [38], sanguiin H-2 [34], vescalagin [39], grandinin [40], phyllyraeoidin A [42], (-)-epicatechin 3-O-gallate [50], cinnamtannin B2 [55], and acutissimin A [56] exhibited moderate selective cytotoxicity against PRMI-7951 melanoma cells with ED50 values in the range of 0.1-0.8 microgram/ml. Selective cytotoxicities against the melanoma cells were also observed for strictinin [22], pedunculagin [23], eugeniin [25], elaeocarpusin [28], punicacortein C [37], casuarinin [41], sanguiin H-6 [43], procyanidin B-2 3,3'-di-O-gallate [51], procyanidin C-1 3,3',3"-tri-O-gallate [52], and cinnamtannin B1 [54] with ED50 values of 1-4 micrograms/ml. All of the tannins were found to be inactive (greater than 10 micrograms/ml) against lung carcinoma (A-549), ileocecal adenocarcinoma (HCT-8), epidermoid carcinoma of nasopharnyx (KB), and medulloblastoma (TE-671) tumor cells.