New stilbene carboxylic acid from Convolvulus hystrix

Convolvulus hystrix Vahl. (family Convolvulaceae) is a common wild plant gr owing in the kingdom of Saudi Arabia. It is used in traditional medicine. O ur study resulted in the isolation and structural elucidation of ten natura l products from which a stilbene carboxylic acid was isolated for the first time as a new natural product. The isolated products are mainly shikimates in addition to two sterols; beta -sitosterol and stigmasterol, as well as one triterpenoid, oleanolic acid. The shikimate products are vanillin, vani llic acid, syringic acid, ferulic acid, isoferulic acid, isoscopoletin and the new stilbene derivative. The structures were elucidated on the basis of spectral data from 400 MHz H-1 NMR, MS, IR and UV. The biogenesis of the n ew stilbene is discussed.