Ginkgo biloba L. (Ginkgoaceae) is a famous medicinal plant. The biological activity of Ginkgo extracts
is associated with the sesquiterpenoid bilobalide, diterpenoid lactones – ginkgolides
A, B, C and J, and flavonoids – quercetin and kaempferol glycosides [1]. Extracts
of G. biloba leaves are widely used for the treatment of cerebrovascular diseases [2,3]. It was
shown that ginkgolides A, B, C can inhibit the platelet-activating factor (PAF) and
G.biloba drugs are natural PAF antagonists [4]. The aim of the present work was to compare
concentrations of major biologically active compounds in G. biloba leaf tea from tea-bags and drugs with standardized dry extract.
Terpenes were analyzed by HPTLC with densitometry, flavonoids – by RP-HPLC with UV-detection.
Ginkgolide A (Ga), ginkgolide B (Gb), ginkgolide C (Gc), bilobalide (B), rutin, quercetin
(QU), and kaempferol (KF) were used as reference substances (Sigma, Germany). Analytical
methods were developed and validated. Infusions of tea-bags of G. biloba leaves (St-Medipharm, Russia) and capsules Bilobil (KRKA, Slovenia) as reference
drugs were investigated. The contents of the main components were compared. The main
data are presented in the table.
Table: The results of qualitative-quantitative analysis of major Ginkgo compounds
|
Sample
|
Ga
|
Gb
|
Gc
|
B
|
Total terpens
|
QU
|
KF
|
Total flavonoids
|
|
Tea from tea-bag (mg/100ml)
|
0.55±0.10
|
0.40±0.08
|
0.80±0.20
|
0.25±0.05
|
2.0±0.4
|
2.5±0.2
|
2.2±0.2
|
12.0±0.9
|
|
Bilobil
(mg/1capsule)
|
0.69±0.14
|
0.46±0.09
|
0.58±0.12
|
0.91±0.18
|
2.6±0.5
|
2.0±0.1
|
1.8±0.1
|
9.8±0.7
|
It was shown that 100ml of tea obtained from one tea-bag of G. biloba and one Bilobil capsule have similar concentrations of ginkgolides, bilobalide and
flavonoids. Tea making procedure during 5–7min is enough for the extraction of terpenoids
and flavonoids. Thus, application of freshly prepared tea from tea-bags is similar
to administration of drugs with a dry extract of G. biloba leaves.
References: [1] Van Beek T.A. (2002) J. Chromat. 967: 21–55. [2] Kressmann S. et al. (2002) J.
Pharm. Pharmacol. 54: 661–669. [3] Sierpina V. et al. (2003) American Family Physician.
68: 923–926. [4] Smith P.F. et al. (1996) J. Ethnopharmacol. 50: 131–139.
