Prospecção química e avaliação do potencial antimicrobiano e antidiabético de espécies dos gêneros Cassia e Senna (Fabaceae) por CLUE-ESI-EM/EM

Abstract

The Cerrado and the Atlantic Forest are Brazilian biomes rich in biodiversity, harboring a variety of medicinal plant species. Among them, species of Cassia and Senna have stood out for their medicinal properties and have aroused scientific interest due to the presence of special metabolites with biological potential. In this study, six species of these genera were collected (C. fistula, C. grandis, C. javanica, S. multijuga, S. rugosa, and S. velutina), and nine leaf and flower extracts were prepared and subjected to liquid-liquid extraction to obtain the organic fractions. The obtained extracts were analyzed by UPLC- IES-MS/MS, in negative and positive modes. In this process, flavonoids, an anthraquinone, and proanthocyanidins, along with other classes of compounds, were identified. In the antibacterial activity assay, using cariogenic bacteria, the EE demonstrated moderate activity, with minimum inhibitory concentration (MIC) values ranging from 100 to 400 μg mL–1, the exception being the EE from S. velutina leaves, which exhibited an MIC of 25 μg mL–1 for Streptococcus mitis and 50 μg mL–1 for Porphyromonas gingivalis. In the assay using anaerobic bacteria, the ethyl acetate fraction of S. velutina flowers exhibited a MIC of 50 μg mL–1 against S. mitis. In the assay using aerobic bacteria, the hexane fractions of S. rugosa (flowers) and C. javanica (leaves and flowers) showed antibacterial activity with MIC values ranging from 6.25 to 25 μg mL–1 against P. gingivalis and Actinomyces naeslundii. In the assay to evaluate antifungal activity using yeasts of the genus Candida, the most promising EE were those of S. rugosa and C. javanica flowers, as well as S. velutina leaves and flowers, exhibiting MIC values between 5.86 and 11.72 μg mL–1 against C. glabrata. The most polar fractions of S. rugosa leaves and flowers and C. javanica flowers showed MICs between 2.93 and 23.4 μg mL–1 against C. albicans and C. glabrata. A very promising result was obtained from the ethyl acetate fraction of S. velutina flowers, exhibiting an MIC of 1.46 μg mL–1 against C. glabrata. This fraction was selected for chemical study based on analysis by UPLC-ESI-MS/MS, which revealed the presence of proanthocyanidins, from which the compounds (ent)-cassiaflavan-gallocatechin (A), (ent)-cassiaflavan-(ent)-cassiaflavan- catechin (D), and a mixture of (ent)-cassiaflavan-(4→8)-(epi)-catechin B and C were isolated. The anti-Candida potential of these compounds was evaluated against strains of C. albicans, C. glabrata, and C. tropicalis, and they showed selectivity against C. glabrata with MICs between 1.95 and 15.69 μg mL–1. C. javanica, a species used in folk medicine for the treatment of diabetes, was selected for chemical and antidiabetic study. The dichloromethane fraction of C. javanica flowers was one of the most active in the enzymatic assay against α-amylase and α-glucosidase, and in anti-glycation assays. Chemical analysis of this fraction isolated kaempferol (E), rhein (F), elegentin (G), and afzelin (H), which were also subjected to α-glucosidase and anti-glycation assays. Compound E was one of the most active, particularly in inhibiting α-amylase with an IC50 of 0.04 ± 0.003 μg mL⁻¹ (positive control triticum, 0.2 ± 0.00 μg mL⁻¹). The results of the biological assays highlight the relevance of chemical and pharmacological investigation of Cassia and Senna species, which are still underexplored when it comes to investigating natural products with antimicrobial and antidiabetic potential.