Isolation of lactic acid bacteria and yeasts from fermented corn gruels with angiotensin-converting enzyme (ACE) and hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase-inhibitory activities

Introduction: This study was designed to investigate the HMG-CoA reductase and ACE-inhibitory activities of lactic acid bacteria (LAB) and yeasts isolated from fermented corn gruels for the production of functional foods/nutraceuticals. The use of “statins” and “prils” as inhibitors of HMG-CoA reductase and ACE for the treatments of hyperlipidemia and hypertension are usually accompanied by adverse side effects. Hence, the need for alternative sources of HMG-CoA reductase and ACE inhibitors from food-grade micro-organisms arises.

Methods: LAB and yeasts were isolated and characterized from fermented maize gruels using standard methods. The HMG-CoA reductase and ACE inhibitory activities of the LAB and yeast cultures were also carried out using established protocols.

Results: The screening of LAB with HMG-CoA reductase and ACE-inhibitory activities revealed that at concentrations (mg/ml) of 3,6, 12 and 24, Lactobacillus helveticus MZL12 showed the highest HMG-CoA reductase-inhibitory activities of 5.96, 9.63, 12.84 and 15.14, with corresponding ACE-inhibitory activities of 8.41, 16.60, 19.47 and 25.00, respectively, when compared with other isolates. In addition, at concentrations (mg/ml) of 6, 12, 24 and 48, the yeast isolate Cryptococcus sp. MZY13 showed the highest HMG-CoA reductase-inhibitory activities of 8.72, 11.92, 19.72 and 22.48, with corresponding ACE-inhibitory activities of 13.93, 35.11, 41.41 and 57.63, respectively. L. helveticus MZL12 also showed the lowest HMG-CoA reductase half maximal concentration inhibitory (IC₅₀) value of 84.84 µg/mL, with an ACE IC₅₀ value of 46.09 µg/mL, while Cryptococcus sp. MZY13 had the lowest IC₅₀ values of 108.38 µg/mL and 49.93 µg/mL for HMG-CoA reductase and ACE inhibition, respectively.

Conclusions: Used together, L. helveticus MZL12 and Cryptococcus sp. MZY13 can be employed as potential starter cultures with HMG-CoA reductase and ACE-inhibitory activities that can be used for the fermentation of functional foods targeted against hyperlipidemia and hypertension.