Estudo químico e avaliação das propriedades biológicas de Calycophyllum multiflorum - Rubiaceae

Abstract

The objective of the present work was to analyze the chemical composition and evaluate the biological activities of the extracts and phases of Calycophyllum multiflorum. The plant material (leaves and stem) was crushed separately and subjected to extraction by maceration (257.9 g of leaves and 1.5 kg of stem), using ethanol, for ten days, obtaining 21 g (leaves) and 49g (stem) of ethanol extract. The extracts had their chemical profiles analyzed by HPLC-DAD-ESI-EM/MS and were evaluated for antimicrobial activity and synergistic effect, where the most active in the synergistic effect, from the leaves, was subjected to liquid-liquid extraction, obtaining the hexane (2 g) and ethyl acetate (14 g) phases. The ethyl acetate phase of the leaves, with better yield, had its chemical profile analyzed by HPLC-DAD-ESI-MS/MS and, later, it was subjected to fractionation using chromatographic techniques aiming at the isolation of chemical constituents. Promising results of antimicrobial activity were observed for the leaf extract, which showed synergism in combination with the antibiotic ampicillin, leading to a significant decrease in the minimum inhibitory concentration of the drug against gram-positive multidrug-resistant clinical bacteria (Staphylococcus aureus, S. intermedius and Enterococcus faecium) and gram-negative (Acinetobacter baumannii and Pseudomonas aeruginosa), isolated at the University Hospital-UFMS, and considered a top priority for the development of new treatments according to the WHO. The chemical profile revealed a diversity of compounds, and through chromatographic techniques it was possible to isolate and identify, by NMR and mass spectrometry, 14 compounds, being one iridoid: loganin; seven glycosylated secoiridoids: secoxyloganin, α-morroniside and β-morroniside, sweroside, 7-O-α-ethyl-morroniside, 7-O-β-ethyl-morroniside and (E)-aldosecologanin; a phenylpropanoid: chlorogenic acid; four glycosylated flavonoids: rutin, quercetin 3-O-[β-D-xylopyranosyl(1→2)]-β-D-galactopyranoside, quercitrin and afzelin; and a proanthocyanidin: kandelin A-2. Of the substances isolated, only two had already been reported in Calycophyllum, and five are being described for the first time in Rubiaceae. These results expand chemical knowledge about Rubiaceae and reinforce the importance and potential of natural products as therapeutic alternatives in the fight against AMR.