IDENTIFICATION OF α-GLUCOSIDASE INHIBITORY ACTIVITY FROM COLD PRESSED ALMOND CAKE AFTER ENZYME-ASSISTED EXTRACTION

The almond cake is a residue generated after cold pressing oil extraction from almond seeds, that presents high protein content and residual oil. Enzyme-assisted aqueous extraction (EAEP) is an environmental-friendly approach that simultaneously extracts oil and protein from oilseeds. Besides the extraction, the hydrolysis of proteins by EAEP can generate peptide sequences that exhibit bioactive properties. Bioactive peptides are encrypted within the primary structure of food proteins and may be released by proteolysis. These peptides may act as inhibitors of metabolic enzymes and present potential use as therapeutic agents against specific diseases. Antidiabetic peptides are α-glucosidase inhibitors that act in the digestive tract and may help in controlling diabetes. The objective of this study was to evaluate the inhibitory effect of the protein-rich fraction extracted by EAEP against α-glucosidase. For EAEP, the almond cake was crushed and was dispersed into water. Extractions were performed at pH 9.0, 50 °C, for 60 min under constant stirring and 0.85% enzyme was added in the reaction slurry. For the α-glucosidase inhibitory assay, 50 μL of the freeze-dried sample (2 mg/mL) or ultrapure water (control), was incubated with 25 μL of 0.5 U/mL α-glucosidase at 37°C for 60 min. After that, 25 μL of pNPG solution was added, and the mixture was further incubated for 30 min. The absorbance of the released p-nitrophenol was measured at 405 nm at a microplate reader. The peptides obtained from EAEP showed 97.8% α-glucosidase inhibition. Enzymatic kinetics was performed, and the values found for Vmax and Km can be interpreted as resulting from an uncompetitive type inhibition. These results evidence that peptides generated by EAEP show potential to serve as a possible component of nutraceuticals aiming to reduce the efficiency of starch digestion in the gut.