Antimicrobial and Anti-inflammatory Activities of Extracts of Four Medicinal Plants Traditionally Used in Ethiopia for Skin Disorder

Abstract

Hydroalcoholic extracts of four different plant species [Artimesia absinthum L. (Asteraceae), Asparagus
africanus Lam. (Liliaceae), Datura stramonium L. (Solanaceae) and Nigella sativa L. (Ranunculaceae)]
commonly used in traditional medicine in Ethiopia for the treatment of skin disorders were evaluated for
their potential antimicrobial activities against pathogenic bacteria (Escherhia coli, Pseudomonas aeruginosa,
Staphylococcus aureus, and Streptococcus pyogenes) and fungi (Candida albicans, Epidermophyton floccosum,
Microsporum canis, Trichophyton verrucosum, and Trichophyton violaceum) using agar diffusion method. All
the extracts showed antibacterial activities against one or more test organisms. The extract of N. sativa seeds
exhibited the highest antibacterial activity against all the bacterial species tested. The minimum inhibitory
concentrations (MICs) of the methanolic extract of N. sativa seeds were 0.156 and 2.5 mg/ml on standard
strains of S. aureus and C. albicans, respectively. Successive extraction of the seeds of N. sativa with
petroleum ether, chloroform, acetone and methanol revealed that the chloroform extract exhibited larger
diameter of zone of inhibitions against the test organisms. Phytochemical screening of the total extract of N.
sativa powdered seeds revealed the presence of flavonoids, polyphenols, terpenoids, and steroids which are
thought to be responsible for the activity of the extracts of N. sativa seeds. Of the various, topical
formulations of the crude extract of N. sativa seeds, the O/W emulsion based formulation showed larger
diameter of zone of inhibition. In mice paw oedema induced by carrageenan, the crude extract of N. sativa at
a dose of 300 mg/kg showed the strongest anti-inflammatory activity (64.2%) followed by A. Africanus
(50.1%).

Keywords: skin disorders, plant extracts, antimicrobial activity, anti-inflammatory activity, minimum inhibitory
concentration