Polyphenol-rich Rutgers Scarlet Lettuce improves glucose metabolism and liver lipid accumulation in diet-induced obese C57BL/6 mice

Abstract

Objective The aims of the following experiments were to characterize anti-diabetic in vitro and in vivo activity of the polyphenol-rich aqueous extract of Rutgers Scarlet Lettuce. Materials / Methods Rutgers Scarlet Lettuce (RSL) extract (RSLE) and isolated compounds were evaluated for inhibitory effects on glucose production as well as tumor necrosis factor alpha (TNFα)-dependent inhibition of insulin activity in H4IIE rat hepatoma cells. Additionally, high fat diet-induced obese mice were treated with RSLE (100 or 300 mg/kg), Metformin (250 mg/kg) or vehicle (water) for 28 days by oral administration and insulin and oral glucose tolerance tests were conducted. Tissues were harvested at the end of the study and evaluated for biochemical and physiological improvements in metabolic syndrome conditions. Results A polyphenol-rich RSLE, containing chlorogenic acid, cyanidin malonyl-glucoside and quercetin malonyl-glucoside, was produced by simple boiling water extraction at pH 2. In vitro, RSLE and chlorogenic acid demonstrated dose-dependent inhibition of glucose production. In vivo, RSLE treatment improved glucose metabolism measured by oral glucose tolerance tests, but not insulin tolerance tests. RSLE treated groups had a lower ratio of liver weight to body weight as well as decreased total liver lipids compared to control group after 28 days of treatment. No significant differences in plasma glucose, insulin, cholesterol, and triglycerides were observed with RSLE treated groups compared to vehicle control. Conclusion RSLE demonstrated anti-diabetic effects in vitro and in vivo and may improve metabolic syndrome conditions of fatty liver and glucose metabolism.

Extraction Technology Can Impose Influences on Peanut Oil Functional Quality: A Study to Investigate the Lipid Metabolism by Sprague–Dawley Rat Model

“…Furthermore, the hepatocytes size in CPO group was smaller than HPO and EAO groups and those in EAO group was bigger than HPO group. Previous studies have shown that squalene, tocopherols, and polyphenols could improve hepatic steatosis and correct atherosclerosis (Chang, Peng, Yeh, Kao, & Wang, ; Cheng et al., ; Daugherty, Tall, Mjap, Falk, & Fishe, ; Eun‐Young et al., ; Lavine et al., ). These indicated that bioactive compounds in CPO, HPO, and EAO may answer for these results.…”

High phenolics Rutgers Scarlet Lettuce improves glucose metabolism in high fat diet‐induced obese mice

“…RSL looseleaf variety NFR, was provided by Shamrock Seed Co. (Salinas, CA) and green leaf lettuce (GL) variety Crispa (Andy Boy, Salinas, CA) were purchased from the grocery store (Stop and Shop, Highland Park, NJ). NFR plant and seed vouchers were made and deposited at the Chrysler Herbarium and ATCC . Outer leaves and tops of RSL lettuce heads were used as they have the highest levels of phenolics.…”

“…Trunk blood was into tubes containing EDTA (BD, Franklin Lakes, NJ) centrifuged for 10 min at 1000 × g (within the first 30 min) and plasma was collected and stored at ≤ −20°C. Plasma was sent to Pennington Biomedical Research Center (PBRC, Baton Rouge, LA) for biochemical analysis of glucose, insulin, triglycerides, free fatty acids, and lipopolysaccharide (LPS) concentrations, as previously described .…”

“…Oral administration of dehydrated RSL powder for eight days acutely reduced hyperglycemia and improved insulin sensitivity in very high fat diet (VHFD)‐fed mice compared to vehicle control . Oral administration of an aqueous extract of RSL for 28 days improved oral glucose tolerance and decreased total hepatic lipids compared to VHFD‐fed control mice .…”

Ferulic acid lowers body weight and visceral fat accumulation via modulation of enzymatic, hormonal and inflammatory changes in a mouse model of high-fat diet-induced obesity

“…Several studies have focused on prevention and treatment of obesity and its associated health risks using plant-derived phenolic compounds. The nutritional effects of phenolic compounds have been well established in their role in modulating specific physiological functions in rodents and human beings (5,6). Ferulic acid (FA) (Figure 1) belongs to the family of phenolic acids and is very abundant in fruits, vegetables and grains, such as rice bran, oats, wheat, barley, roasted coffee, tomatoes, asparagus, berries, vegetables, citrus fruits and leaves of most plants.…”