Absolute Stereostructures and Syntheses of Saussureamines A, B, C, D and E, Amino Acid–Sesquiterpene Conjugates with Gastroprotective Effect, from the Roots of Saussurea lappa
amino acid–sesquiterpene conjugates were synthesized using a Michael type addition reaction of amino acid to the α-methylene-γ-lactone moiety of sesquiterpenes. Saussureamines A, B and C, costunolide and dehydrocostus lactone showed a gastroprotective effect on acidified ethanol-induced gastric mucosal lesions in rats. Saussureamines A also exhibited an inhibitory effect on gastric mucosal lesions induced