Collagen synthesis-promoting and collagenase inhibitory activities of constituents isolated from the rhizomes of Picrorhiza kurroa Royle ex Benth.

Three new acylated phenylethanoid glycosides, kurroaosides A (14), B (15), and C (16), and a new acylated cucurbitane-type triterpene glycoside, kurroaoside D (17), were isolated from a methanol extract of the rhizomes of Picrorhiza kurroa Royle ex Benth. (Plantaginaceae) along with 29 known isolates including 10 acylated phenylethanoid glycosides (18-27), three cucurbitane-type triterpene glycosides (32-34), and a nortriterpene glycoside (35). The structures of these new compounds (14-17), including their stereochemistry, were determined based on chemical and physicochemical evidence derived from NMR and MS analysis. Among the isolates, acylated iridoid glycosides, picrosides I (8), II (9), III (10), and IV (11) and 6-feruloylcatalpol (12), phenylethanoid glycosides (14-16), triterpene glycosides, cucurbitacin B 2-O-beta-D-glucopyranoside (32) and 25-acetoxy-2-beta-D-glucopyranosyloxy-3,16,20-trihydroxy-9-methyl-19-norlanosta-5 -en-22-one (35), and an acetophenone glycoside, picein (36), significantly promoted collagen synthesis at 10-30 muM, with no cytotoxicity being observed at the effective concentrations. Furthermore, acylated phenylethanoid glycosides, calceolarioside A (19, IC50 = 69.2 muM), plantamajoside (20, 51.8 muM), isoplantamajoside (21, 76.8 muM), and scroside E (23, 65.5 muM), exhibited collagenase inhibitory activity equivalent to that of positive agents caffeic acid (75.6 muM) and epigallocatechin 3-O-gallate (75.4 muM).