Preparation of horsegram protein concentrate with improved protein quality, in vitro digestibility and available lysine.

Horsegram (Macrotyloma uniflorum or Dolichos biflorus), an inexpensive pulse crop with high lysine and iron contents, is underutilized due to the presence of antinutrients like lectin and trypsin inhibitors, which limit protein digestibility and availability. Horsegram protein concentrate (HGPC) was prepared, which had 80.4 ± 3.5% protein and 94.2 ± 1.4% in vitro protein digestibility compared to dehulled horsegram flour (22.8 ± 0.8% and 82.3 ± 1.2%, respectively). Available lysine content in concentrate was increased by 64% compared to dehulled horsegram flour. The trypsin inhibitory activity in the protein concentrate decreased by 51% from 36.6 ± 3.5 TIU/mg in horsegram flour to 17.6 ± 2.5 TIU/mg in HGPC. Nutritional indices, including PDCAAS values for different age groups, were calculated and found to be slightly lower due to the loss of methionine and tryptophan in the concentrate. However, branched amino acids and lysine contents were higher. Thus, a vegetarian source with high protein digestibility and available lysine content could be prepared as a protein ingredient for the food industry.

Anti-hyperglycemic activity of myricetin, through inhibition of DPP-4 and enhanced GLP-1 levels, is attenuated by co-ingestion with lectin-rich protein.

Dipeptidyl peptidase-4 (DPP-4) is a proteolytic enzyme responsible for the rapid degradation of Glucagon-like peptide 1 (GLP-1) that is required for the secretion of insulin. DPP-4 also influences activation of node like receptor family, pyrin domain containing 3 (NLRP3) inflammasome under diabetic conditions. Although several polyphenols are reported for various bioactivities, they are consumed as part of the food matrix and not in isolation. Horsegram (Macrotyloma uniflorum) is a rich source of myricetin (Myr) (35 µg/g flour), reported for its anti-hyperglycemic effect. In this investigation, we aimed to study the effect of Myr, singly, and in the presence of co-nutrient horsegram protein (HP) on DPP-4 activity and its consequential impact on GLP-1, insulin, and NLRP3 inflammasome in high-fat diet and single low dose streptozotocin (STZ)-induced diabetic male Wistar rats. In diabetic control (DC), the activity of DPP-4 and its expression were higher compared to treated groups. The consequential decrease in the circulating GLP-1 levels in the DC group, but not treated groups, further indicated the effectiveness of our test molecules under diabetic conditions. Specifically, Myr decreased DPP-4 activity and its expression levels with enhanced circulating GLP-1 and insulin levels. Myr administration also resulted in a lessening of diabetes-induced NLRP3 inflammasome activation and enhanced antioxidant enzyme activities. HP also proved to be efficient in reducing elevated blood glucose levels and enhancing antioxidant enzyme activities. However, Myr, in the presence of HP as a co-nutrient, had diminished capacity to inhibit DPP-4 and, consequently, reduced potential in ameliorating diabetic conditions. Myr proved to be a potent inhibitor of DPP-4 in vitro and in vivo, resulting in enhanced circulating GLP-1 and insulin levels, thereby improving diabetic conditions. Though Myr and HP, individually ameliorate diabetic conditions, their dietary combination had reduced efficiency.