Anti-inflammatory, antioxidant and antimicrobial activities of aqueous and organic extracts from Dictyopteris membranacea

Aqueous and organic extracts from Dictyopteris membranacea collected from the Tunisian Mediterranean coast were studied for their anti-inflammatory, antioxidant and antimicrobial activities. All extracts had high anti-inflammatory activity in carrageenan-induced rat paw edema assays in Wistar rats, and their effects are comparable to acetylsalicylate lysine (300 mg kg(-1), applied intraperitoneally) used as a reference drug. Dictyopteris membranacea extracts had inhibition percentages in the third hour of the assay of 65% at a dose of 100 mg kg(-1), 51% at a dose of 50 mg kg(-1), and 49% at a dose of 100 mg kg(-1) in aqueous, chloroform and ethyl acetate extracts, respectively. Chloroform and ethyl acetate extracts exhibited 2,2-diphenyl-1-picrylhydrazyl radical scavenging with IC50 values (0.089 +/- 0.01 and 0.11 +/- 0.02 mg ml(-1), respectively) equivalent to the activity of a powerful antioxidant standard, Trolox (IC50=0.09 +/- 0.02 mg ml(-1)). These extracts (chloroform and ethyl acetate) had reducing activity, and the total phenol contents were: 84.96 and 60.96 mg gallic acid equivalent per gram dried sample, respectively. Organic extracts had moderate antimicrobial activity (using the disc diffusion method) against three bacteria: Staphylococcus aureus, Staphylococcus epidermidis and Micrococcus luteus, and four species of a fungal genus: Candida albicans, C. krusei, C. dubliniensis and C. kefyr at 10 mg per disc, whereas the aqueous extract exhibited significant antibacterial activity against only Staphylococcus aureus and Listeria monocytogenes.