Juliana Teixeira de Magalhães

Purification, partial characterization and antimicrobial activity of Lectin from Chenopodium Quinoa seeds

A novel lectin was isolated from the seeds of Chenopodium quinoa. To achieve this end, the crude extract from the quinoa was submitted to two purification steps, Sephadex G50 and Mono Q. The hemagglutinating activity showed that this lectin agglutinates human erythrocytes. Its activity is inhibited by glucose and mannose, and remained stable under a wide range of pH levels and temperatures. The quinoa lectin was found to be a heterodimeric lectin of approximately 60 kDa, consisting of two subunits of approximately 25 kDa and 35 kDa. This lectin had its antimicrobial activity tested against several bacteria strains and effectively inhibited three strains. These strains were all Gram-negative, making this lectin a promising antimicrobial tool.

Antibacterial and cytotoxic antibacterial potential of ethanol extract and fractions from Aristolochia galeata Mart. ex Zucc

The aim of this investigation was to evaluate the phytochemical, antibacterial and cytotoxic activities of ethanol extract and hexane, dichlorometane, ethyl acetate and hydroethanolic fractions from Aristolochia galeata’s rhizomes. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were evaluated by the broth microdilution assay to investigate the antibacterial activity of various extracts and fractions of A. galeata against Gram-positive and Gram-negative bacteria. The cytotoxicity of plant samples was evaluated in human cervix carcinoma cell line (HeLa) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. The phytochemical study showed the presence of main secondary metabolites, steroids, flavonoids, coumarins and alkaloids. The ethanol extract and their fractions presented antimicrobial activity against Gram-positive bacteria, and Staphylococcus aureus was regarded the most sensitive strain with MIC of 250 µg/ml for the ethanol extract. The dichlorometane fraction showed bactericidal activity with the value of 1250 µg/ml and moderate cytotoxicity in front of the HeLa cell line tested (CC50 = 90 µg/ml). The results showed that A. galeata had effective antibacterial activity against Gram-positive bacteria and compounds extracted from A. galeata Mart. ex Zucc could be used as possible antimicrobials. The good antimicrobial activity and the low cytotoxicity presented by the hexane fraction can be promised for the new molecules with antibiotic activity.