Rarely Occurring Natural Products Isolated from Vincetoxicum stocksii

Silica gel column chromatography of the ethyl acetate fraction of methanol extract of Vincetoxicum stocksii resulted in the separation of three new rarely occurring natural products; [4-(4-(methoxycarbonyl)benzyl)phenyl] carbamic acid (1), bis[di-p-phenylmethane]ethyl carbamate (2), methyl 2-hydroxy-3-(2-hydroxy-5-(3-methylbut-2-enyl)phenyl)-2-(4-hydroxyphenyl) propanoate, stocksiloate(3), along with five known compounds; 1 -(4-hydroxy-3-methoxyphenyl)-1,2,3 ,-propanetriol (4), feruloyl-6-O-beta-D-glucopyranoside (5), 4-hydroxy-3,5-dimethoxybenzoic acid (6), apocynin (7) and vincetomine (8). The structures of compounds 1 and 2 were established with help of 1D, 2D-NMR techniques and high resolution mass spectrometry, whereas, compound 3 could only be characterized tentatively by 1D, 2D-NMR techniques. Compounds 1 is new compound while 2 is synthetically known but never been reported from natural source. The known compounds were identified due to 1D NMR analysis and in comparison with the literature values. Compounds 1-3 were found inactive in an anti-urease assay.