Antioxidant activity of diterpenes and polyphenols from Ophryosporus heptanthus.

The antioxidant activity of 14 compounds (1-14) isolated from the ether and butanolic extracts of the aerial parts of Ophryosporus heptanthus has been assayed using a beta-carotene bleaching method and the DPPH technique. Compounds 1 and 13 showed the most potent antioxidant activity. Their structures have been established by spectroscopic techniques (mainly NMR). Compounds 7 and 12 are new natural products, and their structures have been confirmed by chemical synthesis.