Isolation and Cytotoxicity of Flavonoids from Daphnis Genkwae Flos
JER-HUEI LIN1*, YA-TZE LIN1, YUH-JAN HUANG1, KUO-CHING WEN1, RUEI-MING CHEN2, TZUU-HUEI UENG2 AND CHUN-HENG LIAO1
1. National Laboratories of Foods and Drugs, Department of Health, Executive Yuan 161-2, Kuen Yang Street, Nankang, Taipei, Taiwan, R.O.C.
2. Institute of Toxicology, College of Medicine, National Taiwan University 1, Jen-Ai Road, Section 1, Taipei, Taiwan, R.O.C.
(Received: May 17、2000; Accepted: December 14, 2000)
ABSTRACT
For the purpose of quality analysis, we investigated polar constituents as marker substance for some traditional herbs. From Daphnis Genkwae Flos twelve flavonoids were isolated. They were identified as potassium apigenin 7-O-β-D-glucuronate (1), apigenin 7-O-β-D-glucuronide (2), apigenin 7-O-β-D- methylglucuronate (3), apigenin (4), genkwanin 5-O-β-D-primeveroside (5), genkwanin 5-O-β-D-glucoside (6), genkwanin (7), tiliroside (8), kaempferol (9), luteolin 5-O-β-D-glucoside (10), luteolin (11) and 7-O-methylluteolin (12). Among them, 2, 3, 5, 6, 9 and 10 were known compounds, but were for the first time isolated from this material. Compound 1 was isolated from nature for the first time. The structures of 1-12 were established on the basis of their physical properties and spectroscopic evidence.
Treatments of human hepatoma HepG2 cells with 0.1 mM apigenin (4), luteolin (11), and 7-O-methylluteolin (12) for 48 hr caused 40% reduction on cell viability, whereas potassium apigenin 7-O-β-D-glucuronate (1), luteolin 5-O-β-D-glucoside (10), genkwanin (7), genkwanin 5-O-β-D-primeveroside (5), and tiliroside (8) caused little or no effects on the viability of HepG2 cell. These data suggest a rough structure - activity relationship of flavonoid cytotoxicity.
Key words: Daphne genkwa, flower, Thymelaeaceae, flavonoid, cytotoxicity