Studies on chemical constituents of saponins from Panax ginseng flower buds

Abstract

This project is to investigate the chemical constituents of ginsenosides from the flower buds of Panax ginseng. The compounds were isolated by using a variety of chromatographic methods including Diaion HP-20,silica gel,MCI gel and semi-preparative HPLC chromatography. Their structures were identified by NMR,and MS data. As a result,32 compounds were isolated from the extract of P. ginseng flower buds,and identified as ginsenoside Rk_3( 1),ginsenoside Rh_4( 2),ginsenoside Rh_8( 3),pseudoginsenoside Rc_1( 4),ginsenoside Rc( 5),ginsenoside Rb_2( 6),ginsenoside Rg_6( 7),20( E)-ginsenoside F_4( 8),ginsenoside Rb_1( 9),vinaginsenoside R_(16)( 10),ginsenoside Rh_6( 11),vinaginsenoside R_3( 12),5,6-didehydro-ginsenoside Rd( 13),vinaginsenoside R_4( 14),vinaginsenoside R_8( 15),ginsenoside Rf( 16),notoginsenoside E( 17),ginsenoside Ⅲ( 18),3-O-β-D-glucopyranosyl-3β,7β,12β,20 S-tetrahydroxydammar-5( 6),24-diene-20-O-β-D-glucopyranoside( 19),20( S)-ginsenoside Rg_2( 20),20( R)-ginsenoside Rg_2( 21),notoginsenoside R_2( 22),ginsenoside F_2( 23),quinquenoside I( 24),ginsenoside M_1( 25),quinquenoside L_(10)( 26),ginsenoside Rh_5( 27),ginsenoside Rg_5( 28),ginsenoside Rk_1( 29),20( R)-ginsenoside Rg_3( 30),oleanolic acid 3-O-β-D-glucopyranosyl-( 1→2)-β-D-( 6'-methyl ester)-glucuronopyranoside( 31) and ginsenoside MC( 32). Among them,compounds 10,12,13,15,19,22,24,31 and 32 were isolated from P. ginseng for the first time,and compound 19 was a genuine ginsenoside firstly obtained by separation and identification,with NMR data that were also reported. Compounds 1-3,7,8,23,25-30 were isolated from P. ginseng flower buds for the first time.