Solarium paludosum extracts obtained by maceration (SP-EtOH(CRUDE) and SP-EtOH(MARC)) and supercritical fluid extraction (SP-SFE(CO2)) were evaluated. Three extracts with distinct chromatographic profiles were obtained: SP-EtOH(CRUDE), with a complex phenolic composition; SP-SFE(C02), containing methoxylated flavonoids; and SP-EtOH(MARC), which bears mainly polar polyphenols. All extracts were strong antioxidants, as measured using the diphenylpicrylhydrazyl (DPPH(center dot)) method, xanthine/xanthine oxidase/luminol and iron-induced lipid peroxidation systems. Extracts were also evaluated as modifiers of antibiotic activity in strains of Staphylococcus aureus expressing fluoroquinolone, macrolide and tetracycline efflux proteins. Despite their lack of antibacterial activity, all extracts were able to potentiate antibiotics activities by as much as eight fold. Both the maceration and supercritical fluid extraction processes were adequate to obtain extracts with different biological activities according to their patterns of phenolic compounds. The data suggest that S. paludosum could be a valuable source of antioxidants and putative efflux pumps inhibitors. (C) 2011 Elsevier B.V. All rights reserved.