Antibacterial, Antioxidant, and Anticholinesterase Activities of Plant Seed Extracts from Brazilian Semiarid Region

Abstract

The antimicrobial, antioxidant, and anticholinesterase activities of ethanolic seed extracts of twenty-one plant species from Brazilian semiarid region were investigated. The extracts were tested for antimicrobial activity against six bacteria strains and three yeasts. Six extracts presented activity against the Gram (−) organismSalmonella choleraesuisand the Gram (+) organismsStaphylococcus aureusandBacillus subtilis. The MIC values ranged from 4.96 to 37.32 mg/mL. TheTriplaris gardnerianaextract presented activity against the three species, with MIC values 18.8, 13.76, and 11.15 mg/mL, respectively. Five extracts presented antioxidant activity, with EC50values ranging from 69.73 μg/mL (T. gardneriana) to 487.51 μg/mL (Licania rigida). For the anticholinesterase activity, eleven extracts were capable of inhibiting the enzyme activity. From those,T. gardneriana,Parkia platycephalaandConnarus detersuspresented the best activities, with inhibition values of 76.7, 71.5, and 91.9%, respectively. The extracts that presented antimicrobial activity were tested for hemolytic assay against human A, B, and O blood types and rabbit blood. From those, only theMyracrodruon urundeuvaextract presented activity (about 20% of hemolysis at the lowest tested concentration, 1.9 µg/mL). Infrared spectroscopy of six representative extracts attested the presence of tannins, polyphenols, and flavonoids, which was confirmed by a qualitative phytochemical assay.