Abstract
We hypothesized that a mixture of blackberry fruit and leaf extracts may alleviate non-alcoholic fatty liver disease (NAFLD). Rats with diet-induced NAFLD were used to test the hypothesis and explore possible mechanisms. Male Sprague–Dawley rats were orally administered diets 51% of energy from fat and 450 mg dextrin/kg bw (NAFLD-control), 50% ethanol blackberry leaf extract (450 mg/kg bw; BL), 50% ethanol blackberry fruit extract (450 mg/kg bw; BF), the mixture of blackberry leaf and fruit extracts (2:1; 150 mg/kg bw; BLF), and milk thistle extracts (150 mg/kg bw; positive-control) for 12 weeks. Normal-control rats were fed low-fat diets with 450 mg dextrin/kg bw (20 En% fat diet) Body weight, visceral fat mass, liver triglycerides, serum cholesterol, triglyceride, non-esterified fatty acid, and insulin resistance were all elevated in rats in the NAFLD-control group compared to the normal-controls. Rats in the NAFLD-control group exhibited liver damage accompanied by increased oxidative stress and inflammation compared to the rats in the normal-control group. BL and BLF protected the NAFLD rats against the triglyceride and lipid peroxide accumulation, improved insulin sensitivity and dyslipidemia, and increased the antioxidant enzymes, SOD, and GSH-Px, to levels similar to the normal-control group. Further, BL and BLF ameliorated inflammation and hepatocyte damage compared to the NAFLD-controls, and they suppressed mRNA expressions of genes involved in triglyceride synthesis (FAS and SREBP-1c). BLF also modulated the gut microbiota by elevating Lactobacillus and Akkermansia in the feces from the cecum compared to the NAFLD-control group. The integrity of intestinal tissues was improved, and the number of goblet cells was elevated by BLF. In conclusion, BL and BLF prevented high-fat diet-induced liver damage by protecting against oxidation and inflammation-induced injury. BLF (human equivalent 1.3 g/day) might, therefore, be used as a therapeutic agent for NAFLD.
Impact statement
NAFLD is a diet-related metabolic disease with no good drug treatments. Therefore, dietary interventions are needed to alleviate NAFLD. This paper demonstrated that feeding a blackberry leaf and fruit mixture extract can alleviate diet-induced NAFLD in rats. Specifically, the blackberry extract, rich in flavonoids and anthocyanins decreased hepatic triglycerides and lipid peroxides, increased genes related to beta oxidation, decreased those involved fatty acid biosynthesis, alleviated oxidative stress, and suppressed pro-inflammatory cytokine release. The blackberry extract also alleviated gut dysbiosis that was associated with NAFLD by increasing the amount of Lactobacillus and Akkermansia in the feces. This research demonstrated that the extract of a common and inexpensive fruit can help alleviate NAFLD and associated intestinal dysbiosis at a dose equivalent to 1.3 g/day in humans. If this work can be duplicated in humans, it would provide a safe and inexpensive intervention to help alleviate NAFLD.
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