Aqueous extract of fresh leaves from Alternanthera brasiliana (L.) Kuntze: chemical evaluation and antimycobacterial and anticandidal activities

The focus of this study was to evaluate the presence and type of carbohydrates and phenolic molecules inaqueous extract (Aq-E) ofAlternanthera brasilianafresh leaves and its antioxidant and antimicrobial activities and cytotoxicity in vitro. The amount and types of the carbohydrates were measured by colorimetric and TLC methods. Phenolic compounds was detected by colorimetric assay and analysed by HPLC profiles. The antioxidant activity was evaluated by ABTS and Phosphomolybdenum methods. Antimicrobial activity was tested by microdilution method using microorganism models and antibiotic as positive control, the cytotoxicity in vitro was tested usingArtemia salina. The results showed the presence of high amount of total sugars and uronic acids. TLC chromatograms showed mainly D-glucose, D-fructose, oligosaccharides and uronic acids in the Aq-E and a sugar alcohol in the methanolic extract. The colorimetric determination showed high concentration of phenolic compounds, which were visualised on the HPLC profiles, such as chemical markers of the Amaranthaceae family and several phenolic acids and flavonoids. The Aq-E demonstrated optimal antioxidant activities. The most important results were the excellent antibacterial and bactericidal activities againstMycobacterium megmatis(MIC = 15.6 mu g/mL and MBC = 1000 mu g/mL) and antimicrobial activity againstCandida albicans(MIC = 31.2 mu g/mL) and low cytotoxicity. Further possibilities for this plant extract will be to improve the pharmacological potential for developing new herbal medicines and possibly to study its association to allopathic antibiotics for prevention or treatment of infection diseases.