The Pharmacological Characterization of Herbal Medicines

This project involves the pharmacological characterization of medicinal herbs used to treat hypertension. I am performing the project in collaboration with Dr. Rosita Arvigo (a naturopathic physician who is studying and practicing with natural medicines used in the Mayan culture in Belize) and Michael Balick (an ethnobotanist at the New York Botanical Garden). These herbal medicines are unknown in western medicine and are being tested for their effect on the relaxation of vascular smooth muscle (rat aorta) in a perfused, in vitro model. The purpose of the study is to identify novel substances for the treatment of hypertension.

Initial studies involved screening 90 plant samples derived from 63 different species to determine their vasoactivity. These samples were collected by Drs. Balick and Arvigo and sent blind to my lab for determination of vasoactivity. Vasoactive samples were defined as those that produced 50% relaxation of endothelium denuded tissues pre-contracted with norepinephrine (NE). After the samples were tested, they were divided into two groups: plants gathered by random sampling (Dr. Balick) and plants identitfied by ethno-directed means (Dr. Arvigo). None of the 45 randomly collected samples produced a significant response in the tissues. Six of the ethnodirected samples (from four different species) produced significant relaxation of the tissues. These results showed that ethno-directed sampling is a more efficient means of discovering new vasoactive substances than random screening. (Slish, D.F., Ueda, h., Arvigo, R., and Balick, M.J. (1999) Ethnobotany in the search for vasoactive herbal medicines, J. Ethnopharm. 66:159-165.)

Current studies in the lab involve two different aspects of the characterization of the four plant species that were found to be vasoactive. Pharmacological studies are being performed to determine the mechanism of action of the vasorelaxation produced by the plants. An extract from Alseis yucatanensis produces only relaxation in the tissue and it is being studied to determine the mechanism by which it produces this effect.

An extract from Licaria peckii has been shown to produce relaxation in NE contracted tissues and contraction when added to tissues at equilibrium. This has prompted the second aspect of the project, the separation of an extract into its vasoactive components. Column chromatography is being used to separate vasorelaxant constituents from vasoconstrictive constituents.

If you have questions please send me an Email message.

Back to Home Page.