Comparative vasodilating actions among terpenoids and flavonoids contained in Ginkgo biloba extract.
BACKGROUND
Comparative vasodilating actions of the constituents of Ginkgo biloba extract (GBE), terpenoids (bilobalide, ginkgolides A, B and C) and flavonoids (quercetin and rutin), were examined using rat aorta ring strips.


METHODS
Cumulative administrations of GBE and its constituents were followed with the pretreatment of 5 micromol/l NE.


RESULTS
GBE at 0.03 to 3 mg/ml had a potent concentration-dependent relaxation; by 70 +/- 4.5% (n = 6, P < 0.001) at 3 mg/ml. Terpenoids and flavonoids at 0.1 to 100 micromol/l had potent concentration-dependent relaxation. At 100 micromol/l, bilobalide dilated by 17.6 +/- 3.9% (n = 7, P < 0.05), and ginkgolides A, B and C also caused it to the almost same extent. Quercetin (100 micromol/l) caused a potent vasorelaxation by 49.9 +/- 4.8% (n = 10, P < 0.001). Rutin at 100 micromol/l had weaker vasorelaxation; by 13.7 +/- 3.2% (n = 6, P < 0.01).


CONCLUSIONS
All constituents of GBE have the concentration-dependent vasorelaxtant effect. The potency of GBE's action was not made simply by addition of those of the constituents. Each constituent itself would contribute to the GBE-induced vasodilation, although the constituents have the complicated interactions with each other.
Nishida
Seiichiro
S
Department of Pharmacology, Division of Crude and Herbal Medicine, Nara Medical University, Kashihara, Nara 634-8521, Japan.
Satoh
Hiroyasu
H
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology*; D020441:Ginkgo biloba / Q000737:chemistry*; D066298:In Vitro Techniques; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry; D051381:Rats; D013729:Terpenes / Q000302:isolation & purification / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*
D005419:Flavonoids; D010936:Plant Extracts; D013729:Terpenes