The Effect Of Alkaloids Isolated From Kopsia sp. On The Synthesis Of The Catecholamines In Rat Brain

Author

Perumal, R*., Malini, M.*, Yoganathan, K., Kam, T.S., Kwan, T.K.* Departments of Biochemistry* and Chemistry, University of Malaya, 59100 Kuala Lumpur.

Proceeding

Trends in Traditional Medicine Research, Proceedings of the International Conference on the Use of Traditional Medicine & Other Natural Products in Health Care

Date

8/6/1993

Keyword

Kopsia sp., alkaloids, catecholamines, synthesis, brain.

Abstract

A method for the simultaneous determination of the catecholamines and their metabolites in a single preparation, using reversed-phase ion pair high performance liquid chromatography (HPLC) coupled with electrochemical detection has been developed. By optimising the ionic strength, pH, methanol and octane sulfonic acid (the ion pairing reagent) concentrations in the mobile phase, the simultaneous separation of 3,4-Dihydroxyphenyl acetic acid (DOPAC), Noradrenaline (NA), Adrenaline (AD) and Dopamine (DA) was achieved. Dihydroxy benzylamine (DHBA) was used as the internal standard. The method was then applied to the determination of catecholamines in rat brain samples. Rats were treated with Kopsia alkaloids equivalent to dosages of 4.3 x 10-2 M, 4.3 x 10 -3M and 4.3 x 10-4M via intraperitoneal injections. The effect of these alkaloids on brain catecholamines in vivo was then monitored. Synaptosomes isolated from the rat brain by means of a discontinuous Ficoll-sucrose gradient were incubated with the catecholamine precursor, tritiated tyrosine and two different alkaloids, one isolated from Kopsia teoi and the other, from Kopsia fruticosa. The effect of these alkaloids on the uptake of tritiated tyrosine by synaptosomes and its subsequent incorporation into catecholamines were monitored. A simple and rapid procedure involving pre-activated alumina was used for the extraction of catecholamines, prior to their separation and determination by HPLC. Behavioural studies were also carried out on the two alkaloids. These studies provide a simple and useful new approach in biochemical pharmacology.