Investigation of some medicinal plants from Tunisia for antimicrobial activities

Twenty-three selected plants belonging to 12 families were collected from different localities of Tunisia and dried and extracted with the solvents petroleum ether or hexane, ethyl acetate or acetone, and methanol to yield 72 extracts. The extracts were tested for their antimicrobial activity against 14 Gram-positive and Gram-negative bacteria using agar diffusion and microdilution methods. The antimicrobial profiles varied considerably. Fifty-six (77.78%) extracts showed some degree of activity against one or more of the bacterial strains. Antibacterial activity was demonstrated especially against Gram-positive bacteria. The greatest activity was exhibited by all Cistus monspeliensis L. (Cistaceae) leaves and flowers extracts, Inula viscosa (L.) Ait. (Asteraceae) and Juniperus phoenicea L. (Cupresaceae), by the acetone and methanol extracts of Arbutus unedo L. (Ericaceae) and Polygonum aviculare L. Var. Bellardi (All.) Duby (Polygonaceae), by the hexane and acetone extracts of Hypericum crispum L. (Hypericaceae), by the methanol extract of Satureia nervosa Desf. (Labiateae), and by the ethyl acetate extract of Atriplex parvifolia Lowe Var. ifiniensis (caball) Maire (Chenopodiaceae). The observation that each extract showed a distinctive permutation of target organisms suggested that different bioactive phytochemicals were present in each species.