Zizimauritic acids A-C, three novel nortriterpenes from Ziziphus mauritiana

Zizimauritic acids A-C (1-3), three novel nortriterpenes with a unique A-nor-E-seco spiro-lactone ceanothane-type triterpene skeleton, together with 3 known Triterpenes ceanothenic acid (4), betulinic acid (5), and ceanothic acid (6), were isolated from the roots of Ziziphus mauritiana. Compounds 1-4 showed cytotoxicities with the IC(50) values ranging from 5.05 to 11.94 μg/ml, and compounds 1 and 3 showed an inhibitory effect on the growth of Staphylococcus aureus with the IC(50) values 2.17 and 12.79 μg/ml. A plausible biosynthetic pathway of compounds 1-3 was proposed.