Structural Determination of a New Cycloartane Glycoside from Asplenium ruprechtii

Abstract We characterized a new cycloartane glycoside, herein known as aspleniumside F (1), along with five known compounds as kaempferol‐3‐O‐[(6‐O‐(E)‐feruloyl)‐β‐D‐glucopyranosyl]‐(1→2)‐β‐D‐galacopyranoside (2), quercetin‐3‐O‐[(6‐O‐(E)‐feruloyl)‐β‐D‐glucopyranosyl]‐(1→2)‐β‐D‐glucopyranoside (3), kaempferol‐3‐O‐[(6‐O‐(E)‐caffeoyl)‐β‐D‐glucopyranosyl]‐(1→2)‐β‐D‐glucopyranoside (4), kaempferol‐3‐O‐[(6‐O‐(E)‐caffeoyl)‐β‐D‐glucopyranosyl]‐(1→2)‐β‐D‐glucopyranosyl‐7‐O‐β‐D‐glucopyranoside (5), and kaempferol‐3‐O‐[(6‐O‐p‐coumaroyl)‐β‐D‐glucopyranosyl]‐(1→2)‐β‐D‐glucopyranosyl‐7‐O‐β‐D‐glucopyranoside (6), from Asplenium ruprechtii Sa. Kurata, a folk medicine widely used to treat Thromboangiitis obliterans in China, Japan, and Korea. Based on spectroscopic, mainly 1D‐, 2D‐NMR and (+)‐HR‐ESI‐MS, analyses as well as through comparisons with previous reports, its chemical structure was determined as 3β,24,30‐tri‐β‐D‐glucopyranosyl‐23,25‐dihydroxycycloartane (= (23R,24R)‐3β,24‐bis‐(β‐D‐glucopyranosyloxy)‐23,25‐dihydroxy‐9β‐9,19‐cyclolanostan‐29‐yl β‐D‐glucopyranoside). According to the 1H coupling constant of anomeric protons and co‐TLC of the acid hydrolysate with D‐glucose, all three glycoside groups in 1 were revealed as β‐D‐glucopyranosyl. Furthermore, SOD‐like antioxidant activity evaluation via IC50 of 12.43, 6.78, 9.12, 6.94 and 4.85 μM revealed that compounds 2–6 had bioactivity.