Triterpenos, esteroides e fenólicos isolados dos extratos de Minquartia guianensis Aubl. (Coulacea) e atividade antibacteriana

Abstract

Minquartia guianensis is a plant species belonging to the Coulaceae family, which, according to the literature, produces biotechnologically interesting substances such as terpenes and phenolic compounds. These metabolites are considered essential therapeutic resources for the benefit of human health, particularly in the treatment of infectious diseases caused by pathogenic and multi-resistant bacteria. Over the years, efforts have been focused on the prospecting of plants that produce bioactive substances. However, even presenting biotechnological potential to produce new chemical substances, research with plants still constitutes a line of investigation lacking in research. Thus, this work aimed to carry out the chemical study of the extracts from the branches and leaves of Minquartia guianensis (Coulaceae) and to evaluate their antibacterial potential. The collection of plant material was carried out in the Ducke Reserve, Manaus, Amazonas. The plant material was dried, ground, and extracted with hexane (Hex) and methanol (MeOH). The obtained extracts were subjected to chromatographic analyses and presented mainly terpenes and phenolics. From the fractionation of the MeOH extract of the branches, it was possible to isolate and identify the mixture of steroids: β-sitosterol (1) and stigmasterol (2); and triterpenes: lupeol (3) and β-amyrin (4); lupenone (5) and β-amyrone (6), in addition to a phenolic derivative: methyl gallate (7), and a depsidone: hypoprotocetraric acid (8). From the fractionation of the MeOH extract of the leaves, the mixture of triterpenes: taraxerol (9) and lupeol (3) was isolated. These same methanolic extracts were active against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Aeromonas hydrophila and Pseudomonas fluorescens, with inhibition percentages of 63 to 70%. In conclusion, the study of Minquartia guianensis has unveiled its potential as a source of biotechnologically valuable compounds with significant antibacterial properties. The chemical analysis of extracts from both branches and leaves has provided insights into the diverse range of metabolites present within this plant, including some substances previously unreported within the Coulaceae family like β-amyrin, β-amyrone, methyl gallate, and hypoprotocetraric acid. The demonstrated antibacterial activity against a spectrum of bacteria, including multi-resistant strains, underscores the therapeutic promise of these metabolites. This research not only offers prospects for the development of novel antibiotics but also highlights the importance of preserving and exploring the Amazon rainforest's biodiversity for potential medical applications.