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

Abstract

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-β-D-glucopyranoside (32) and 25-acetoxy-2-β-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 μM, with no cytotoxicity being observed at the effective concentrations. Furthermore, acylated phenylethanoid glycosides, calceolarioside A (19, IC50 = 69.2 μM), plantamajoside (20, 51.8 μM), isoplantamajoside (21, 76.8 μM), and scroside E (23, 65.5 μM), exhibited collagenase inhibitory activity equivalent to that of positive agents caffeic acid (75.6 μM) and epigallocatechin 3-O-gallate (75.4 μM).