Biotransformation of bioactive compounds from lentils affected their antihypertensive properties

Lentils are one of the most consumed legumes worldwide, and its consumption has been associated to the reduction of the development of neurodegenerative and cardiovascular diseases. Biotransformation of plant-based foods can be used as an efficient strategy for production of multifunctional compounds, improving their biological properties. The aim of the present study was to investigate the antihypertensive properties of extracts obtained from lentils after fermentation, germination and enzymatic hydrolysis. Solid-state fermentation was carried out using lentils flour as substrate and Aspergillus oryzae as inoculum. For germination, lentil seeds were hydrated and distributed in a tray with filter paper. The material was kept at room temperature in the dark and moistened daily for 96h. Enzymatic hydrolysis of lentils flour was performed using a solution of cellulase (Celluclast® 1.5L) and protease (Flavourzyme® 500L) at 50°C under shaking (100 rpm) for 2h. The extracts containing the antihypertensive compounds were obtained from samples after biotransformation processes and from crude samples using distilled water and acidified (0.1% HCl) methanol solution (70%) as solvents. The antihypertensive activity was determined through angiotensin-converting enzyme (ACE) inhibition. Aqueous extracts from fermented samples promoted up to 90% of ACE inhibition, while non-fermented samples showed 62% of ACE inhibition. Moreover, aqueous extracts from germinated samples increased the capacity of ACE inhibition from 73% (non-germinated samples) to complete ACE inhibition (100%). Enzymatic hydrolysis promoted a slight increase from 95% (non-hydrolyzed) to 100% in the ability to inhibit ACE activity by lentils aqueous extracts. For methanolic extracts, germinated samples showed the highlighted ACE inhibition of 46%, while non-germinated samples allowed 37% of ACE inhibition. In general, fermentation and germination processes, followed by aqueous extraction, promoted a significant increase on the ability to inhibit ACE activity. Thus, this study demonstrated that biotransformation of lentils may be a technological strategy to improve their biological properties.