RESUMEN
The antihyperglicemic activity of crude extract from Moringa oleifera leaves and isolation of phenolic compounds with antioxidant activity using bioguided assay were employed by the first time in leaves cultivated in Brazil. The hydroalcoholic extract (HE) was produced by using ethanol:water (80:20 v/v) and purified by solid-liquid procedure using solvents in ascending order of polarity. The ethyl acetate fraction (Fr-EtOAc) presented high antioxidant potential and it was purified using chromatographic techniques rendering isolated compounds that were identified from the spectral data. The HE extract (500 mg kg-1) was adimistrated in diabetic rats induced by streptozotocin and chemical markers and lipid peroxidation in liver and kidney were evaluated. The Fr-EtOAc showed high antioxidant potential by FRAP reduction method (1678 µmol Fe2+ g-1), DPPH and ABTS scavenging methods (526.7 and 671.5 µmol TEAC g-1 respectively) and ORAC assay (3560.6 µmol TEAC g-1). Therefore, the Fr-EtOAc was purified and yielded three bioactive subfractions (S-12, S-13 abd S-15) that were rechromatoghaphed in HPLC-SemiPrep. After that, two main bioactive glycosylated flavonoids (isoquercitrin and astragalin) and phenolic acid (3-O-caffeoylquinic acid) were obtained. Additionally, the HE extract provided protection against oxidative damage in liver and kidney of diabetic rats ameliorating endogenous antioxidant defenses by increase catalase (CAT), glutathione S-transferase (GST) and non-protein thiol groups (NPSH) levels as well as decreased the lipid peroxidation in these tissues. Our results indicate that three phenolic compounds with high antioxidant activity were isolated and, the chemical composition of HE crude extract, rich in flavonoids glycosylated could be intimately related to antihyperglycemic action. So, it is possible to suggest that these compounds may be used as chemical biomarkers for this plant in Brazil, ensuring quality and supporting the use of aerial parts in tradicional medicine.
Asunto(s)
Diabetes Mellitus Experimental , Moringa oleifera , Animales , Antioxidantes/farmacología , Brasil , Diabetes Mellitus Experimental/tratamiento farmacológico , Hipoglucemiantes/farmacología , Extractos Vegetales/farmacología , Hojas de la Planta , RatasRESUMEN
Moringa oleifera leaves are used in Brazilian folk medicine for their hypoglycemic and nutritional properties. In this context, the chemical and biological characteristics were determined. Conventional successive solid-liquid extraction with simultaneous bioguided purification using solvents with different polarities was performed with M. oleifera leaves, yielding six fractions and extracts. The fractions showed better results for antioxidant activity than the extracts. All of them were evaluated by scavenging of synthetic free radicals and reactive oxygen species, and Fr-Ace and Fr-EtOAc showed >100â¯mg GAE g-1 of phenolic content, while for FRAP and ORAC assays the values were higher than 1600⯵mol Fe2+ g-1 and 3500â¯mmol TEAC g-1 respectively. The UPLC-ESI-QTOF-MS analysis of hydroalcoholic extract (HE) allowed identifying 24 compounds, with flavonoid derivatives being the most abundant group. Furthermore, the alkaloid trigonelline and sesquiterpenoid abscisic acid were identified for the first time in M. oleifera leaves. Finally, gallic acid, caffeic acid, rutin and quercetin were found in concentrations of 16.5, 2129, 477.4 and 127.5⯵gâ¯g-1 respectively in HE, all of which were higher in fractions and extracts. These results suggest that bioguided extraction is an important technique, due to its ability to concentrate active compounds in a logical and rational way. In addition, M. oleifera leaves grown in Brazil are an important source of phenolic compounds with antioxidant activity that can be used in food, nutraceutical and pharmaceutical products.