Comparative effects of some naturally-occurring aspidofractinine-type alkaloids on the blood pressure in spontaneously hypertensive rats

Choo Y.M., . and Kok L.K., . and Lim T.M., . and Mok S.L., . and Subramaniam G., . and Kam T.S., . (2000) Comparative effects of some naturally-occurring aspidofractinine-type alkaloids on the blood pressure in spontaneously hypertensive rats. [Proceedings Paper]

The effect of saveral aspidofractinine-type alkaloids derived from the genus kopsia Apocynacea on the mean arterial blood pressure MABP were examined in anaesthetised male spontaneously hypertensive rats SHR of the japanese strain. The alkaloids investigated are kopsingine kopsaporine and kopsidine A from K teoi kopsamine and methyl 11 12- methylenedioxychanofruiticosinate from K. dasyrachis. Intravenous i.v injections of 0.2-10.0mg/kg of kopsingine kopsaporine kopsamine and methyl 11 12-methyleneddioxychanofruiticosinate produced liner dose- related decreases in MABP. After attaining a peak within the initial 10 to 30 s the values returned to predrug levels during the following 3 to 5 min. and these were accompanied by bradycardia in all the rats tested. In contrast kopsidine A 0.2 to 10.0mg/kg produced a small dose-related increase in MABP and decrease in heart rate HR after i.v injection pretreatment with atropine 2 mg/kg phentolamine 3mg/kg and hexamethonium 20 mg/kg on the cardiovasscular effects of 10 mg/kg of i.v. injection of these alkaloids were also studied. Atropine was ineffective in antagonising the cardiovascular responses to kopsigine and kopsamine in SHR. The depressor actions of kopsingine were significantly attenuated by hexamethonium but completely reversed to pressor actions by phentolamine. Both the depressor and bradycardic effects of kopsamine were significantly reduced by phentolamine. Our results show that only the indole alkaloids devoid of the 3-to17 oxo-bridge in the aspidofractinine molecular skeleton could effectively lower the arterial pressure. The antihypertensive effects of kopsingine and its congeners along with the pressor effect produced by kopsidine A could be ascribed to central as well as peripheral actions.

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Abstract

The effect of saveral aspidofractinine-type alkaloids derived from the genus kopsia Apocynacea on the mean arterial blood pressure MABP were examined in anaesthetised male spontaneously hypertensive rats SHR of the japanese strain. The alkaloids investigated are kopsingine kopsaporine and kopsidine A from K teoi kopsamine and methyl 11 12- methylenedioxychanofruiticosinate from K. dasyrachis. Intravenous i.v injections of 0.2-10.0mg/kg of kopsingine kopsaporine kopsamine and methyl 11 12-methyleneddioxychanofruiticosinate produced liner dose- related decreases in MABP. After attaining a peak within the initial 10 to 30 s the values returned to predrug levels during the following 3 to 5 min. and these were accompanied by bradycardia in all the rats tested. In contrast kopsidine A 0.2 to 10.0mg/kg produced a small dose-related increase in MABP and decrease in heart rate HR after i.v injection pretreatment with atropine 2 mg/kg phentolamine 3mg/kg and hexamethonium 20 mg/kg on the cardiovasscular effects of 10 mg/kg of i.v. injection of these alkaloids were also studied. Atropine was ineffective in antagonising the cardiovascular responses to kopsigine and kopsamine in SHR. The depressor actions of kopsingine were significantly attenuated by hexamethonium but completely reversed to pressor actions by phentolamine. Both the depressor and bradycardic effects of kopsamine were significantly reduced by phentolamine. Our results show that only the indole alkaloids devoid of the 3-to17 oxo-bridge in the aspidofractinine molecular skeleton could effectively lower the arterial pressure. The antihypertensive effects of kopsingine and its congeners along with the pressor effect produced by kopsidine A could be ascribed to central as well as peripheral actions.

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Item Type:	Proceedings Paper
Additional Information:	Available at Perpustakaan Sultan Abdul Samad Universiti Putra Malaysia 43400 UPM Serdang Selangor Malaysia. mal QK99 A1S471 2000 Call Number.
AGROVOC Term:	DRUG PLANTS
AGROVOC Term:	BLOOD PRESSURE
AGROVOC Term:	HEART RATE
AGROVOC Term:	RATS
AGROVOC Term:	ALKALOIDS
AGROVOC Term:	MALAYSIA
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:13
URI:	http://webagris.upm.edu.my/id/eprint/11289

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