Phytopharmaceutical Studies of Some Selected Medicinal Plants Locally Used In the Treatment of Skin Disorders

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Date

2004-01

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Addis Ababa University

Abstract

In this study, eight species of traditionally used medicinal plants namely Acokanthera schimperi (Apocynaceae), Calpurnia aurea (Fabaceae, Leguminosae), Kalanchoe petitiana (Crassulaceae), Lippia adoensis (Verbenaceae), Malva parviflora (Malvaceae) Olinia rochetiana (Oliniaceae), Phytolacca dodecandra (Phytolaccaceae) and Verbascum sinaiticum (Scrophulariaceae), were screened for antimicrobial activity against different strains of bacteria and fungi which are known to cause various types of skin infections. Among these plants, L. adoensis and O. rochetiana, which showed better antimicrobial activity in the initial screening test, were selected for further investigations. Fractionation and antimicrobial activity tests of the fractions, anti-inflammatory activity tests, phytochemical screening, evaluation of topical formulations, and preliminary standardization studies were carried out on the two species of plants. The results of the initial antimicrobial screening test indicated the potential of these herbal drugs in treating bacterial and fungal infections of the skin. Almost all species of plants were found to have activity on at least one strain of bacteria and/or fungi. This might justify their claimed uses in the treatment of various skin disorders the majority of which are of infectious origin. Among the different fractions (petroleum ether, chloroform, acetone and methanol) tested for antimicrobial activity, the non-polar fractions were found to be more active than the polar fractions. The phytochemical screening tests carried out on L. adoensis and O. rochetiana indicated the presence of tannins, flavonoids and saponins in both species of plants. The antiinflammatory activity test results however have indicated that the two species of plants do not have demonstrable anti-inflammatory activity. xii Performance evaluation of topical formulations of the crude extracts in different vehicles revealed that extracts incorporated into creams (especially the hydrophilic ones) are superior in performance than those incorporated in to ointments. In addition, crude extracts formulated into water soluble ointment (PEG ointment) demonstrated higher performance compared to lipophilic ointments. The most lipophilic formulation of the crude extracts, petrolatum ointment, was found to be devoid of any activity against all the tested strains of bacteria and fungi indicating that the active compound(s) could not be released from this vehicle. Although evaluation of the quality of the two herbal drugs was not possible due to absence of published data for comparison, the most commonly employed standardization/quality control parameters including ash values, solvent extractable matters, loss on drying and TLC fingerprints were determined for the two herbal drugs in an attempt to provide such base line data as an indication of their quality attributes.

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Medicinal Plants ; Acokanthera schimperi

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