PHYTOCHEMICAL CHARACTERIZATION, EVALUATION OF PROTEIN CONTENT AND BIOPROSPECTION OF LECTINS AND TRYSTIN INHIBITORS IN EXTRACT OF Sesbania virgata (Cav.) Poir SEEDS

Fabaceae presents 145 subclades and 737 genera. Among them, the genus Sesbania, with about of 500 species, such as Sesbania virgata, whose seeds present high protein content. The present study aimed to characterize phytochemically, evaluate the protein content and bioprospecting lectins and trypsin inhibitors in the protein extract of Sesbania virgata seeds. Seed meal was used to obtain Total Protein Extract (TPE) in Glycine-NaOH 0.1 mol.L^-1 pH 9.0 NaCl 0.15 mol.L^-1 (1:15, w/v). After 22 hours of magnetic stirring, the extract was centrifuged (10000 x g, 30 min, and 4 °C) and the supernatant collected and named TPE. In this, it was determined the total protein content using the bovine serum albumin standard curve; bioprospecting lectins by hemagglutination assays in rabbit erythrocytes (CEUA/UFPB n°.178/2015), and trypsin inhibitors by enzyme assays using the enzyme bovine trypsin; and phytochemical characterization was given by different qualitative tests. TPE presented as protein content 7.13 mgP/mL and 106.96 mgP/gF; hemagglutination titers were 32 UH/mL, with 480 UH/gFa and 4.4887 UH/mgP; not precipitated trypsin inhibitors; and in phytochemical tests, reacted positively to saponins, catechins, flavones, flavonols, xanthones, anthocyanins, anthocyanidins and flavonoids, but reacted negatively to pyrogallic and catechin tannins, leucoantocyanidins, steroids and triterpenes. In other assays performed by our group (data not shown) in which an extract was obtained from buffer Glycine-HCl 0.1 mol.L^-1 pH 9.0 NaCl 0.15 mol.L^-1, under the same conditions, it was found that this extraction method was not able of bioprospecting lectins, but favored the precipitation of protease inhibitors. It is understood, thus, that the extraction method influences the obtaining of TPE, the demarcation of considerable protein content and numerous phytochemical compounds, besides the hemagglutination assays suggest the presence of lectins. Together, all these constituents make TPE a versatile biotechnological tool, to check various biological activities.