Walnut Polyphenols Inhibit Pancreatic Lipase Activity in Vitro and Have Hypolipidemic Effect on High-Fat Diet-Induced Obese Mice

Abstract

This study was aimed at the chemical composition and inhibitory effects of walnut polyphenols (WP) in vitro lipase activity and on obesity in obese mice models. More than 20 individual phenolics such as gallotannins, ellagitannins, flavonoids and phenolic acids were identified in WP. Studying the interactions between porcine pancreatic lipase (PL) and WP were based on fluorescence quenching and an enzymatic assay. The addition of WP to lipase caused a reduction of protein fluorescence intensity at 310 K. In addtion, we found that the effect of WP on PL was dependent on reaction medium and substrate used and the half maximal inhibitory concentration of WP was determined to be 163 μg/mL. At the beginning of the experiment, mice were divided into 3 groups, one of them served as normal control group (NCG), the second as hyperlipidemia control group (HCG), the last as walnut polyphenol-treated group (WTG). After 8 weeks of treatment, we investigated the effects of WP on weight gain, food intake and biochemical indexes in obese mice. The results showed that WP could significantly decrease body weight in obese mice (-13.52%, P < 0.05). However, there was no remarkable difference in food intake among three groups (1760.2-1823.3 g). In addition, WP could significantly decrease the TG, TC and LDL-cholesterol (LDL-C) concentrations and increase the HDL-cholesterol (HDL-C) concentration when compared to the HCG (-36.12%,-31.27%,-73.3%, and +59.72%, respectively, P < 0.01). The levels of hepatic TG and TC were significantly decrease in WTG when compared to the HCG (-27.72% and-48.43%, respectively, P < 0.01). In conclusion, these results suggest that WP could be a potentially therapeutic alternative in the treatment of obesity caused by a high-fat diet.

Walnut (Juglans regia L.) Septum: Assessment of Bioactive Molecules and In Vitro Biological Effects

“…Our results reveal that the WSE, at the concentration of 1 mg/mL, has a relative inhibition capacity of 50.79% from that of orlistat, the positive control. Based on previous findings that phenol compounds from walnut kernels inhibited lipase activity in vitro [ 29 ], we argue that the phenolic acids and flavonoids identified in WSE could be part of the lipase inhibition mechanism.…”

A Comparative Review on the Extraction, Antioxidant Content and Antioxidant Potential of Different Parts of Walnut (Juglans regia L.) Fruit and Tree

“…In both types of research, phenolic extracts were prepared using a mixture of ethanol and water. Additionally, it has been observed that pancreatic lipase activity was inhibited by 50% ethanolic extract of walnut seed in vitro, and it showed the hypolipidemic effect on high fat diet-induced obese Mice [157]. To evaluate the effect of skin removal on the solubility of protein fractions from walnut flour, Labuckas, et al [154] extracted the phenolic fraction from the skin and walnut flour and examined their antioxidant capacity.…”

A Comprehensive Review on the Chemical Constituents and Functional Uses of Walnut (Juglans spp.) Husk

“…Similarly, in an investigation by Gunduc and El [102], they demonstrated that the kernel of J. regia L. contains the highest content of total phenolic compounds and antioxidant activity among 25 types of commonly consumed foods. It has been reported that the regular and adequate consumption of the walnut seed is associated with the reduction of the risk of some diseases such as cancer [20,103], cardiovascular symptoms [104,105,106,107,108,109,110,111,112,113,114,115,116], diabetes [117], and degenerative disorders [118,119]. Different parts of the walnut tree and its fruit, including the green husk as epicarp or mesocarp, hard shell of the nut (endocarp), dividing membranes of the kernel (pellicle), flower, root, trunk (bark and wood), branch, and leaf are comprehensively considered in order to use for different purposes.…”