ATIVIDADE ANTIMICROBIANA, ANTIOXIDANTE E PROSPECÇÃO FITOQUÍMICA DOS EXTRATOS DE EQUISETUM PYRAMIDALE, POUTERIA RAMIFLORA, POROPHYLLUM RUDERALE, TAPIRIRA OBTUSA E SMILAX FLUMINENSIS.

Abstract

Infectious diseases, for decades, have been one of the most relevant public health problems. Antimicrobial resistance is a serious threat to treatment efficacy and responsible for high morbidity and mortality rates. There are bacteria resistant to all classes of antimicrobials available and the number of antifungal resistances is also on the rise. However, the production of new drugs by the pharmaceutical industry does not occur at the same speed. The objective of this work was to evaluate the antimicrobial and antioxidant activity, as well as the phytochemical composition of the extracts of Equisetum pyramidale, Pouteria ramiflora, Porophyllum ruderale, Tapirira obtusa and Smilax fluminensis extracts. Ethanol extracts from leaves and/or aerial parts of each botanical material were prepared. The classes of secondary metabolites were determined from a phytochemical screening. The contents of phenolic compounds and flavonoids were obtained by UV-visible. To determine the antimicrobial activity of extracts from these plants, susceptibility tests were performed using the disk diffusion method and microdilution in broth against resistant multidrug clinical isolates of Staphylococcus aureus and Klebsiella pneumoniae and against ATCC strains of Candida. From the extracts that inhibited microbial growth, the minimum bactericidal concentration and the minimum fungicidal concentration were determined. The total antioxidant activity of the extracts was determined by the DPPH free radical scavenging method (2.2-diphenyl-1-picrylhydrazyl). Phytochemical analysis showed the presence of some classes of secondary metabolites in common: phenolic compounds, flavonoids, steroids, tannins and saponins. The contents of phenolic compounds and flavonoids were significant, being higher in S. fluminensis (CF= 230,34 ± 1,20 mg/g (mg Catechin/g extract) e Flav.= 155,77 ± 0,99 (quercetin/g extract)), followed by E. pyramidale (CF= 205,4 ± 0,70 mg/g (mg Catechin/g extract) e Flav.= 150,9 ± 0,25 mg/g mg (quercetin/g extract)). The extract of S. fluminensis showed fungicidal activity on C. glabrata (ATCC 2001) (MIC=500 μg/mL). Bactericidal activity on MRSA (MIC=1000 μg/mL) was demonstrated by the extract of T. obtusa. All plant extracts tested showed antioxidant activity above 50% of DPPH free radical scavenging, the most significant being T. obtusa (82.36 ± 0.44 %) and S. fluminensis (69.89 ± 1.06 %). The S. fluminensis extract showed promising antifungal and antioxidant properties. Tapirira obtusa demonstrated antibacterial activity against a resistant pathogen and can be considered for further research, in addition to representing a potential natural antioxidant. Porophyllum ruderale, E. pyramidale, and P. ramiflora have antioxidant potential.

Keywords: medicinal plants; antimicrobial activity; Klebsiella pneumonie; Staphylococcus aureus; Candida.