Nortriterpenoids and lignans from Schisandra sphenanthera

Nortriterpenoids, sphenadilactone C (1) and sphenasin A (2), together with four known lignans (3-6), were isolated from the leaves and stems of Schisandra sphenanthera. Compound 1 characterized with a partial enol moiety and an acetamide group in its structure. Compound 2 featured a biosynthetically modified seven-membered lactone ring.