Avaliação da atividade antimicrobiana e antioxidante de plantas presentes no estado de Mato Grosso

Abstract

The association of excessive production of reactive species with different chronic illnesses and the rise in microbial resistance, because of the adaptation of the bacterial and fungal cell to exposure to antibiotics, makes the search for compounds with antioxidant and antimicrobial potential relevant. The objective of this work was to evaluate the antimicrobial and antioxidant activity of flowers, leaves, husks and branches of plant species Tabebuia aurea (paratudo), Cordia glabrata (louro branco), Vochysia divergens (cambará) and Fusaea longifolia (envira). The plant matter was collected in different regions of the state of Mato Grosso, and subjected to drying, stabilization and grinding, and later extracted by steeping in hexane (Hex), ethyl acetate (AE), 70% ethanol (ET 70%) and/or methanol (Me). The raw extracts with the most relevant results were subjected to fragmentation. The evaluation of antimicrobial activity was carried out using the broth microdilution technique, and the determination of antioxidant potential using the DPPH technique. The results revealed that none of the extracts showed expressive activity for negative Gram bacteria. The polar (Et 70% and Me) and intermediate-polar extracts (AE) showed better results against the positive Gram strain, Staphylococcus aureus, especially the AE of F. longifolia branches and the Et of C. glabrata leaves, both with a minimum inhibitory concentration (CIM) of 125 μg/mL. The fragmentation of the AE extract of F. longifolia branches revealed a fragment known as 9, shows promising activity against S. aureus, presenting CIM = 31,25 μg/mL. The preliminary phytochemical profile for this fragment revealed the presence of flavonoids, and complementary tests are being carried out to confirm the presence or absence of alkaloids. An enriched alkaloidal fragment (FAC), obtained from the envira branches, also showed high potential against the positive Gram bacteria (CIM = 62,5 μg/mL). In the antifungal activity evaluation against Candida parapsilosis, the AE extracts of leaves and branches of F. longifolia showed the best results, with CIM of 500 and 250 μg/mL respectively. The 9 fragment revealed CIM = 250 μg/mL for C. albicans, and the FAC presented CIM = 250 μg/mL for both types of yeasts. In this work, the fragmenting of a hydroalcoholic extract of V. divergens flowers was also realized, seeing that the same extract showed an inhibition of almost 90% in the growth of C. parapsilosis at the concentration of 1000 μg/mL The methanolic fragment (Me 5) revealed moderate activity for C. parapsilosis (CIM = 500 μg/mL), having detected the presence of flavonoids and terpenes in its phytochemical profile. In the antioxidant evaluation of the plant species, the polar and intermediate-polar extracts, as expected, presented a sequestrant capacity of the DPPH radical superior to the one obtained for apolar (hexanoic) extracts. Of all the extracts, the ones which showed the best capacity of DPPH reduction were the Me leaf and branch and AE branch extracts of F. longifolia, showing efficient concentration (CE50) values of 20,0 μg/mL, 25,1 μg/mL and 18,2 μg/mL respectively. The hydroalcoholic extract of the V. divergens flowers also showed significant antioxidant potential revealing a CE50 of 23,5 μg/mL, and its Me 5 fragment a CE50 of 23,5 μg/mL. The presence of certain metabolites, especially phenolic compounds like flavonoids, can justify the antioxidant potential observed for species F. longifolia and V. divergens. This work contributed to the increased understanding of the antioxidant and antimicrobial in vitro activity of extracts and/or fragments of leaves, flowers, husks and branches of plant species found in the state of Mato Grosso.