Antimicrobial, antioxidant, and antiviral activities of Retama raetam (Forssk.) Webb flowers growing in Tunisia

Abstract

Antimicrobial, antioxidant, and antiviral activities of flower extracts of Retama raetam Forssk. Webb (Fabaceae) were screened both from standard and isolated Gram-positive and Gram-negative bacteria by solid medium technique. Oxa- cillin, Amoxicillin, Ticarcillin, Cefotaxim, and Amphotericin were used as the control agents. The antiviral activity was evaluated against human cytomegalovirus (HCMV) strain AD- 169 (ATCC Ref. VR 538) and coxsackie B virus type 3 (CoxB- 3) using a cytopathic effect (CPE) reduction assay. The anti- oxidant activity was evaluated using two tests: 1,1-diphenyl-2- picrylhydrazyl (DPPH) free-radical scavenging and the ammonium thiocyanate methods. All extracts were character- ized quantitatively for the presence of polyphenols, flavonoids, and tannins. Of the extracts tested, butanol and ethyl acetate extracts showed important antibacterial activity against Gram- positive and Gram-negative bacteria but only moderate antifungal activity. Methanol extract exhibited moderate anti- viral activity against HCMV with IC50 of 250 lg/ml. Ethyl acetate, chloroform, and methanol fractions were found to cause significant free-radical-scavenging effects in both assays. These results may suggest that R. raetam flowers could be used as a natural preservative ingredient in the food and/or phar- maceutical industries.