Study on chemical constituents from cultivated Gynura nepalensis

Taking application of some isolation and purification technologies, such as solvent extraction, preliminary solvent isolation, column chromatographies over silica gel and Sephadex LH-20 gel and preparative HPLC, 10 compounds were obtained from Gynura nepalensis cultivated in the suburban area of Beijing. Their structures were identified by spectroscopic methods and comparison with literature as (3R) -3-hydroxy-β-ionone (1), (3S,5R, 6S, 7E) -5, 6-epoxy-3-hydroxy-7-megastigmen-9-one (2), (+) -boscialin (3), 3, 6-trans-3-hydroxy-α-ionone (4), 3, 6-cis-3-hydroxy-α-ionone (5), 3, 4-cis-3, 4-dihydroxy-β-ionone (6), ethyl caffeate (7), loliolide (8), 1H-indole-3-carbaldehyde (9), and 3-(hydroxyacetyl)indole (10), respectively. All compounds were isolated from the title plant for the first time, and with compounds 1, 2, 4-7, 9 and 10 being isolated from Gynura species for the first time. Structurally, the above compounds 1-6 belong to C13 nor-sesquiterpenoids, sharing the same carbon skeleton of megastigmane. According to this study, they are one of major kinds of chemical constituents of Gynura nepalensis and have important reference value for the investigation on phytotaxonomy of this species.