Efeitos antioxidante, antimicrobiano e cicatrizante in vitro do extrato e frações obtidas das pétalas de Delonix regia (Bojer ex Hook) Raffin

Abstract

The species Delonix regia (D. regia) has been described as having antidiabetic, antiinflammatory, antioxidant and antimicrobial properties. However, most studies have been carried out using the leaves, seeds and bark of the species, and further studies are needed with the petals, a part of the plant also used in folk medicine. Thus, the objective of this study is to investigate the antioxidant, antimicrobial and healing properties of the extract and fractions obtained from the petals of D. regia. For this purpose, the hydroalcoholic extract was initially prepared by cold maceration of the petals (EHADr) and then the hexane (FHDr), chloroform (FCDr) and ethyl acetate (FAEDr) fractions. The final residue was called the polar fraction (FPDr). The Folin-Ciocalteu method was used to determine the content of phenolic compounds, and the aluminum chloride assay was used to identify total flavonoids. For the antioxidant effect, the DPPH assay was used. The antimicrobial effect was verified by the minimum inhibitory concentration (MIC). Additionally, in a human keratinocyte cell line (HaCaT), morphology, viability and cell migration were analyzed. Statistical differences were considered significant when p < 0.05 analyzed by one-way ANOVA, with Bonferroni post-test. Among the fractions obtained, FAEDr demonstrated the highest content of phenolic compounds and flavonoids. This trend is reflected in the antioxidant capacity, since FAEDr presented an IC50 of 4.54 µg/mL, similar to quercetin (1.72 µg/mL) and ascorbic acid (1.15 µg/mL), used as control. For antimicrobial activity, it was observed that all fractions and the hydroalcoholic extract presented MIC of 250 µg/mL against S. aureus and E. coli and 500 µg/mL for P. aeruginosa. However, the lowest MIC were observed against C. albicans, in which FAEDr, FCDr and FPDr presented a MIC of 62.5 µg/mL. To observe the effects in cell culture, HaCaT cells were treated for 24 hours of exposure to the treatments; it was observed that treatments with EHADr, FCDr and FAEDr did not present morphological alterations, nor alterations in cell viability by the MTT assay, when compared to the control. Regarding the horizontal migration assay, only FAEDr, at a concentration of 62.5 µg/mL, presented a significant difference in the reduction of the area, when compared to the control group. Thus, the data obtained to date suggest that EHADr and its fractions have potential antioxidant, antimicrobial and healing effects, with further studies being necessary to identify the molecules and mechanisms involved.