RESUMO
The aqueous extract of S. cumini or Eugenia jambolana seeds and Psidium guajava leaves showed higher inhibition against the porcine pancreatic alpha-amylase among the medicinal plants studied. The alpha-amylase inhibitors from S. cumini seeds were separated from the extract by preparative thin layer chromatography into fractions with different Rf values. The fraction with Rf value between 0.285 and 0.43, which showed maximum inhibitory activity, was eluted and analyzed through LC-MS. The compounds identified from the seed extract ofS. cumini were betulinic acid and 3,5,7,4'-tetrahydroxy flavanone, which were reported earlier from S. formosanum and other plants. Dixon plot showed that the inhibition was noncompetitive in nature.
RESUMO
alpha-Galactosidase was strongly induced in the white-rot fungus Pleurotus florida by arabinose than its natural substrates and was purified to homogeneity by acetone precipitation, ultrafiltration and DEAE-Sepharose chromatography. The enzyme was a monomeric protein with a molecular mass of approximately equal to 99 kDa, as revealed by native-PAGE and SDS-PAGE. alpha-Galactosidase was optimally active at 55 degrees C for the hydrolysis of p-nitrophenyl-alpha-galactopyranoside (PNPalphaG) and lost its 20% and 50% of original activity in 30 min at 60 degres C and 70 degrees C, respectively. The pH optimum of the enzyme was between 4.6 and 5.0. It was stable in a wide pH range (pH 4.0 to 9.0) at 55 degrees C for 2 h. The Ag+ and Hg2+ strongly inhibited the enzyme activity. Galactose, glucose, maltose and lactose also inhibited the enzyme activity, whereas N-bromosuccinimide treatment resulted in near total loss of acitivity. The Km and Vmax values of the enzyme for PNPalphaG were found to be 1.1 mM, and 77 micromol min(-1) mg(-1), respectively. alpha-Galactosidase immobilized in agar was more effective for the degradation of raffinose than in the sodium alginate. TLC results indicated its potential for the removal of raffinose and stachyose in soymilk.