UNAMBIGUOUS ASSIGNMENTS OF THE H-1 AND C-13 CHEMICAL-SHIFTS OF THE MAJOR BITTER PRINCIPLE OF SWERTIA-CHIRATA BY 2D NMR-STUDY AND CHARACTERIZATION OF OTHER CONSTITUENTS

A methanol extract of Swertia chirata, with the aid of HPLC, gave as i ts major bitter principle sweroside 2'-O-3 '',3''',5 ''-trihydroxy-bip henyl-2 ''-carboxylic acid ester (1A)(.) along with sweroside (1A'), a maroswerin (1B'), oleanolic acid (1C) and beta-sitosterol-3 beta-D-glu coside (in). A complete assignments of H-1 and C-13 NMR spectra of 1A were accomplished wi th the a id of concerted 1D and 2D high field NMR study. All quaternary carbons were unambiguously assigned by means of C-13 detected correlation using long range couplings (COLOC). Structu re of In was already reported [10] but for a compound with completely different chemical and incomplete spectral data. Other compounds were identified on the basis of their spectral and chemical data.