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.
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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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Keywords
Medicinal Plants ; Acokanthera schimperi