The isomer of fucosterol, isofucosterol, has been identified as a minor constituent of marine sponge, Gynostemma pentafillum, oat seeds and a few other plants. Isofucosterol of marine sponge is believed to be the biosynthetic precursors of the antiviral orthoesterols and weinbersterols found in the same sponge. Isofucosterol exhibits lipase inhibitory effect, suggesting that it has potential as anti-obesity agent.