Variabilidade da composição química e atividades biológicas de Secondatia floribunda A. DC. em função da sazonalidade e em diferentes fases fenológicas

Abstract

Plants are one of the most important sources of new substances used directly as medicinal agents and chemical ecology has shown promise in the search medicinal species with priority for chemical and pharmacological investigations. Secondatia floribunda A. DC. (Apocynaceae) stands out as medicinal, but does not present its chemical composition and proven medicinal attributions. The present study aimed to establish the Secondatia floribunda chemical profile to analyze the variability in its chemical components with the influence of seasonality and different phenological phases, in addition to verifying the variation in its bioactivity. Three individuals were selected where stalk sap and core samples were used to firstly evaluate their chemical composition. To analyze the chemical constituent variability of the species during two years, quarterly collections were performed, including both rainy and dry seasons, as well as vegetative and reproductive phases. The ethanolic extracts were prepared and were performed phytochemical triage and total phenol and flavonoid content quantifications. Phenolic composition was determined and quantified by High Performance Liquid Chromatography (HPLC-DAD). Infrared Spectroscopy was performed using the Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) measure. Antibacterial assays were performed to determine the Minimum Inhibitory Concentration (MIC) and aminoglycoside modification. Antioxidant potential was determined by the 1-diphenyl-2-picrylhydrazyl (DPPH•) radical inhibition assays, 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS•+) radical scavenging, iron reducing antioxidant power (FRAP) and iron ion (Fe2+) chelating activity. The extracts proved to be a source of several classes of phenolic and flavonoid compounds. The infrared spectra presented similar characteristics, having among their main bands the hydroxyl group (HO). The antibacterial activity presented clinically significant results against the tested strains. For antibiotic modulation, synergistic and antagonistic effects were observed for both extracts. For the phenolic composition variability, the extract yields presented the highest quantities in the rainy season, during low levels of precipitation where during the two years changes in the levels in all the collections and between the vegetal parts were observed, responding both quantitatively and qualitatively to seasonality and phenology. In the antioxidant activity assays the extracts showed better results during the dry period for the DPPH and ABTS tests, and during the rainy period for FRAP and chelating assays. This study, as the first to report on the chemical and biological knowledge regarding Secondatia floribunda, suggests that it is a clinically relevant source in antibacterial and antioxidant therapy due to the presence of considerable levels of compounds with previously recognized activity. Thus, the present results may also be useful for widening knowledge regarding the species and favoring the development of collection patterns to obtain higher concentrations of the compounds identified herein which are intended for therapeutic use.