Investigation of the antitumor activity of podocarpic acid derivatives.

As a class, octahydrophenanthrene lactones, podolactones , and related podocarpic acid derivatives have been reported to possess a wide variety of biological activities, including antileukemic activity, inhibition of plant cell growth, and hormonal and anti-inflammatory properties. In the present study, a series of synthetic intermediates derived from podocarpic acid have been prepared and evaluated with respect to their ability to inhibit human epidermoid carcinoma of the nasopharynx in vitro. The significant cytotoxicity demonstrated by methyl 6 alpha-bromo-7-oxo-O- methylpodocarpate (50% inhibition of cells at 8.85 X 10(-9) M) was markedly higher than that of the other derivatives examined. Further evaluation against L1210 and P388 lymphoid leukemias in mice failed to demonstrate significant antitumor activity.