Fermentation of ascorbic acid-elicited alfalfa sprouts further enhances their metabolite profile, antioxidant, and anti-obesity effects

Abstract

Germination, elicitation, and fermentation are biotechnological methods that could be applied to improve phytochemical profile and functional quality of edible seeds. This research investigated the combined effects of elicitation, germination, and fermentation on the anti-obesity activities of alfalfa seeds. Alfalfa seeds were germinated at 25–27 °C for 3 days while spraying with tap water (control) or 1% of different plant elicitors (sodium chloride, citric acid, or ascorbic acid) solution. Ascorbic acid was the most suitable elicitor to improve phytochemical quality, support growth, and maximize the health-promoting properties of alfalfa sprouts. Treatment with 1% ascorbic acid solution improved lipase (74.57% vs. 41.32%), DPPH (76.58% vs. 57.21%), and ABTS (71.63% vs. 46.5%) inhibitory activities of alfalfa sprouts compared to control. Fermentation of the ascorbic acid-elicited sprouts further enhanced the anti-obesity activities in vitro by improving their inhibitory potential against digestive enzymes, alpha-glucosidase (67.84% vs. 81.39%) and pancreatic lipase (74.57% vs. 82.07%). The fermented sprout extracts prolonged the lifespan and decreased fat accumulation in the glucose-induced obese Caenorhabditis elegans via mechanisms including suppression of genes involved in fat synthesis and changing the worms' metabolite profiles. Specifically, the extract down-regulated genes involved in fat synthesis (fat-4, fat-6 and fat-7), up-regulated genes for fat lipolysis (hosl-1) and lifespan gene (daf-16), while enhancing amino acids profiles in C. elegans. These findings demonstrate that alfalfa sprouts produced through a combination of ascorbic acid treatment and fermentations could be an effective functional ingredient targeting obesity.