Cardiovascular Protective Effects Of Standardized Extracts And Isolated Compounds Of Selected Medicinal Plants From The Tropical Rainforest

Compounds with diverse chemical structures including phenols, xanthones, prenylflavonoids, benzophenones, alkaloids and triterpenoids, isolated from several Malaysian plants, were investigated to discover leads for development of new cardiovascular protective agents. The compounds were tested for their ability to inhibit platelet aggregation in human whole blood using an electrical impedance method and their ability to inhibit human LDL oxidation using thiobarbituric acid reactive substances assay. Standardized extracts of several plants were evaluated for their cardiovascular protective effects against isoproterenol-induced myocardial infarction (MI) in rats and effects on serum lipid profiles of rats fed with high cholesterol diet (HCD) and their platelet-mediated antithrombotic effects. Among the compounds tested, xanthones from Guttiferae species showed strong inhibitory activities against platelet aggregation and LDL peroxidation. 2-(3-Methylbut-2-enyl)-1,3,5,-trihydroxyxanthone and 2-(3-methylbut-2-enyl)-1,3,5,6-tetrahydroxyxanthone showed strong inhibition on platelet aggregation induced by arachidonic acid (AA), macluraxanthone and 1, 7 dihydroxyxanthone showed significant and selective inhibitory activity against ADP-induced aggregation while rubraxanthone showed inhibitory activity against aggregation caused by all three inducers [1]. Recently we reported the isolation of a new xanthone, 1, 3, 6-trihydroxy-5-methoxy-7-(3′-methyl-2′-oxo-but-3′-enyl) xanthone and 1, 3, 5, 7-tetrahydroxyxanthone from Garcinia cantleyana var. cantleyana, with strong ability to inhibit LDL oxidation [2]. The standardized extracts of Zingiber officinale, Curcuma domestica and Labisia pumila var alata significantly (p < 0.05) reduced the total cholesterol, triglycerides, and LDL levels and helped in improving high density lipoprotein (HDL) and oxidase enzymes levels on HCD rats in a dose-dependent way. The extracts also exhibited protective effects on biochemical and histopathological alterations of the cardiac muscle cells in Isoproterenol-induced MI rats [3, 4].

Acknowledgements: Financial support was received from the Ministry of Science, Technology and Innovation (grant no: 02 – 01 – 02-SF0012) and Ministry of Agriculture (grant no. NH0811S003) are greatly acknowledged.

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