[Effect of tea-leaf saponin on blood pressure of spontaneously hypertensive rats].
The antihypertensive effect of tea-leaf saponin (the saponin mixture isolated from leaves of Camellia sinensis var. sinensis) was examined in spontaneously hypertensive rats (SHR). Tea-leaf saponin reduced a time-dependent increase in blood pressure dose-dependently when it was administered orally to young SHR (7 weeks old) for 5 d. Oral administration of tea-leaf saponin to elder SHR (15 weeks old) for 5 d decreased the mean blood pressure by 29.2 mmHg at the dose of 100mg/kg compared to the control group. Single administration of tea-leaf saponin at 50mg/kg, p.o. showed a long-lasting hypotensive effect and this effect was as potent as that of enalapril maleate at the dose of 3 mg/kg, p.o. Tea-leaf saponin inhibited angiotensin I-induced contraction of the isolated guinea pig ileum in a dose dependent manner but little depressed angiotensin II-induced contraction. On the other hand, in in vitro experiment using a synthetic peptide as a substrate, tea-leaf saponin showed almost no inhibitory activity against the angiotensin I converting enzyme (ACE) (IC50 > 10 mg/ml).
Sagesaka-Mitane
Y
Y
Central Research Institute, Ito-en Co. Ltd., Shizuoka, Japan.
Sugiura
T
T
Miwa
Y
Y
Yamaguchi
K
K
Kyuki
K
K
D000803:Angiotensin I / Q000037:antagonists & inhibitors; D000806:Angiotensin-Converting Enzyme Inhibitors; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D051381:Rats; D011918:Rats, Inbred SHR; D012503:Saponins / Q000008:administration & dosage / Q000494:pharmacology*; D013662:Tea
D000806:Angiotensin-Converting Enzyme Inhibitors; D012503:Saponins; D013662:Tea; D000803:Angiotensin I