5,6-Didehydro-20(S)-ginsenoside Rg3, a novel triterpenoid saponin from flower buds of Panax ginseng / 中草药

Objective: To study the chemical constituents of ginsenosides from the flower buds of Panax ginseng. Methods: The compounds were isolated and purified by Diaion HP-20, MCI gel, silica gel, and semi-preparative HPLC. The structures were elucidated based on NMR and MS data. Results: Four compounds were isolated from the extract of P. ginseng flower buds, and identified as 6’-acetyl-ginsenoside F1 (1), 12α-hydroxyl-ginsneoside Rd (2), 20(S)-ginsenoside Rg3 (3), and 5,6-didehydro-20(S)- ginsenoside Rg3 (4). Conclusion: Compound 4 is a novel ginsenoside, compounds 1 and 2 are new natural products.