<i>Bacillus subtilis</i> 7A Enhances the Nutritional Quality of Velvet Bean ( <i>Mucuna pruriens</i> Linn.) Seeds and Potentiates Its Role in the Management of Type II Diabetes Mellitus

Abstract

Velvet bean seed (VBS) is a tropical underutilized legume, though, rich in bioactive nutrients; nonetheless, limited scientific information exists as regards the health benefits, especially when fermented. Hence, the impact of Bacillus subtilis strain 7A on the nutritional composition and antidiabetic efficacy of fermented VBS (FVBS) at 45°C was investigated. Proximate analyses, gas chromatography-mass spectrometry-flame ionization detector (GC-MS-FID) profiling of phytochemicals, and in vitro antioxidants potentials of VBS and FVBS were determined using established protocols. Diabetes was induced via intraperitoneal injection of a single dose of streptozotocin (STZ) (35 mg/kg) in Wistar rats, and animals with blood glucose ≥200 mg/dL, which were diabetic, were treated with high-fat diet (HFD) containing varied proportions of FVBS (5%, 10%, 15%, and 20%) and HFD+ metformin (100 mg/kg) for 21 days. Hematological, lipid profiling, and enzymatic analyses were evaluated in pancreas, small intestine, liver, lungs, and kidneys of the animals. B. subtilis 7A significantly improved proximate contents of VBS by increasing crude protein (23.31%) and total lipid (2.38%) and reducing carbohydrate (18.77%) and calorific value (778.87 kJ/100 g), among others. Furthermore, GC-MS-FID characterization revealed that FVBS has 14 more bioactive compounds, when compared with VBS. Moreover, FVBS showed comparable antioxidant capacities with VBS; however, in FVBS, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and Fe³⁺ reducing potential were 23.03 µmol TEAC/g and 20.45 mg AAE/g, respectively, higher than VBS. Animals feed with FVBS revealed appreciable improvements in their hematological indices and inhibition of α-amylase, α-glucosidase, lipase, 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-COA) reductase, and angiotensin-converting enzyme (ACE) activities across the experimental groups compared to STZ group. This, therefore, suggests that FVBS could serve as functional food with enhanced nutritional capabilities having anti-TIIDM potentials. PRACTICAL APPLICATIONS: This study investigated the fermentative roles of Bacillus subtilis 7A on velvet bean seeds (VBSs) to enhance their nutritional qualities and targeted at addressing Type II diabetes mellitus (TIIDM). Fermented VBS (FVBS) could be employed towards management of TIIDM by serving as a food product or incorporated into other food products like confectionaries and milk, or as a base for fermentation and production of other nutraceuticals. VBS is highly economical when compared to other expensive commonly consumed legumes, like cowpeas; hence, more research attention to underutilized legumes is encouraged to gear up their consumption, medicinal applications, and consequently their cultivation.