Isolation and characterization of the chemical constituents from Gynura bicolor and G. divaricata

Two Gynura species, G. bicolor and G. divaricata , are used in folk recipes for the treatment of diabetes mellitus in south China. Our previous pharmacological study proved that both plants showed significant hypoglycemic activity on normal and alloxan-diabetic mice. Sixteen chemical constituents were isolated from the CH 2 Cl 2 and EtOAc extracts of the aerial parts of G. bicolor . Their structures were determined spectroscopically as hydroxymethylfurfural, benzoic acid, 4-hydroxybenzoic acid, protocatechuic acid, vanillic acid, 4-hydroxybenzaldehyde, kaempferol, 3,3'-di-O-methylellagic acid-4-O-β-D-xylopyranoside, loliolide, ficusic acid, vomifoliol, dehydrovomifoliol, boscialin, (6S,9S)-roseoside, benzyl-β-D-glucopyranoside, and 2-phenylethyl-β-D-glucopyranoside. Fractionation and isolation of the EtOAc extract of aerial parts of G. divaricata yielded six compounds [succinic acid, ethyl methyl succinate, salicylic acid, isovanillic acid, 4-hydroxycinnamic acid, esculetin]. All compounds, except 4-hydroxybenzoic acid and kaempferol, were isolated for the first time from these two plant sources.