“Yacón roots inhibit hepatic lipid accumulation by activating AMP-Activated Protein Kinase”

ALEMAN M. N, HONORÉ SM, TERRITORIALE ERIKA, GENTA SB, SANCHEZ SS

Rosario, Santa Fé

Congreso; XI Simposio Argentino XIV Simposio Latinoamericano de Farmacobotánica; 2013

Non-alcoholic fatty liver disease, a further expression of metabolic syndrome, strictly linked to obesity and diabetes mellitus, is characterized by insulin resistance, elevated serum levels of free fatty acids and liver fatty infiltration, which is known as hepatic steatosis. The purpose of the present study was to determine whether yacon roots have a beneficial effect against hepatic steatosis induced by a high-fructose-diet (HF-diet) and to elucidate its underlying molecular mechanisms in rats. Male Wistar rats maintained with a rat standard chow were randomly separated into a control group (water ad libitum) and a HF-group (fructose 10% w/v, p.o., ad libitum, HF). After 12 weeks, rats with a HF-diet were randomly distributed in two groups: HF-diet and HF-diet supplemented with yacon flour (340mgFOS/kg twice a day, HF+Y) during 8 weeks. The supplementation of yacon flour significantly lowered plasma triglycerides (HF: 171.8±18.6mg/dl vs. HF+Y: 117.0±17.3mg/dl) and free fatty acids (HF: 1.06±0.05mmol/l vs. HF+Y:0.89±0.12mmol/l) but elevated the ratio of HDL-C/total-C (HF: 0.27±0.02 vs. HF+Y: 0.32±0.05) and adiponectin levels (HF: 2.52±0.14µg/ml vs. HF+Y: 7.03±1.43µg/ml). Yacon flour reduced hepatic weight (HF: 12.9±0.6g vs. HF+Y: 9.5±1.1g), hepatic triglyceride content (HF: 9.31±1.38mg/g vs. HF+Y: 6.88±1.42 mg/g) and ameliorated the hepatocyte degeneration and decreased the inflammatory cell infiltration in the livers induced by HF-diet. Additionally, yacon roots significantly reversed the HF-induced decreases in the AMP-activated protein kinase (AMPK) expressions at protein levels and restored the HF-induced inhibitions in the AMPK phosphorylation. Both processes are related to fatty acid beta-oxidation, in the hepatic tissue. Dietary supplementation with yacon roots also reversed the HF-induced down-regulation of the peroxisome proliferator-activated receptor alpha (PPARα) and decreased the expression of the lipogenic genes fatty acid synthase (FAS), glycerol-phosphate acyltransferases (GPAT) and HMG-CoA reductase (HMGR). These results suggested that yacon roots improve liver fatty degeneration regulating lipid metabolism through an elevated AMPK protein expression and phosphorylation in the liver.