Evaluation of Dose-Dependent Obesity and Diabetes-Related Complications of Water Chestnut (Fruit of Trapa japonica) Extracts in Type II Obese Diabetic Mice Induced by 45% Kcal High-Fat Diet

Hydrolyzed Polyphenols from Water Chestnut (Trapa japonica) Suppress Lipase Activity in vitro and Blood Triacylglycerols in Mice

Water chestnut (Trapa japonica) is a thorny aquatic floating plant that contains hydrolyzable polyphenols (WCPs) such as eugeniin, 1,2,3,6-tetra-O-galloyl-β-d-glucopyranose (TGG), and trapain. Previous studies have revealed that WCPs have antioxidant properties and can suppress postprandial blood glucose elevation in mice and human participants. However, the functionality of WCPs in treating obesity and metabolic syndrome, which have become significant issues in recent years, remains unclear. Here, we aimed to determine the effects of WCPs on lipid metabolism. We initially investigated the effects of WCPs on pancreatic lipase in vitro. Among WCPs, eugeniin and trapain, which contain a hexahydroxybiphenyl group, particularly inhibited lipase activity. We also found that WCPs suppressed fat accumulation in mouse adipose progenitor 3T3-L1 cells. We compared the effects of WCPs on lipid metabolism among groups of mice (n=7 each) fed for four weeks without (standard control and high-fat (HF) diet controls) or with HFWP 0.5 or HFWP 1 supplemented with 0.5 and 1% WCPs, respectively. Subsequently, we examined lipid-related parameters in adipose tissue, liver, and blood. We found significantly lower plasma triacylglycerol content in the HFWP1 than in the HF group. These findings suggest that WCPs may help prevent the onset of obesity and metabolic syndrome.

Alterations in Glutathione Redox Homeostasis in Metabolic Dysfunction-Associated Fatty Liver Disease: A Systematic Review

Low molecular weight (LMW) thiols, particularly glutathione, play pathogenic roles in various multiorgan diseases. The liver is central for the production and systemic distribution of LMW thiols; thus, it is particularly susceptible to the imbalance of redox status that may determine increased oxidative stress and trigger the liver damage observed in metabolic dysfunction-associated steatotic liver disease (MASLD) models and humans. Indeed, increased LMW thiols at the cellular and extracellular levels may be associated with the severity of MASLD. Here, we present a systematic literature review of recent studies assessing the levels of LMW thiols in MASLD in in vivo and in vitro models and human subjects. Based on the PRISMA 2020 criteria, a search was conducted using PubMed and Scopus by applying inclusion/exclusion filters. The initial search returned 1012 documents, from which 165 eligible studies were selected, further described, and qualitatively analysed. Of these studies, most focused on animal and cellular models, while a minority used human fluids. The analysis of these studies revealed heterogeneity in the methods of sample processing and measurement of LMW thiol levels, which hinder cut-off values for diagnostic use. Standardisation of the analysis and measure of LMW thiol is necessary to facilitate future studies.

Validating the Health Benefits of Coffee Berry Pulp Extracts in Mice with High-Fat Diet-Induced Obesity and Diabetes

The effects of coffee (Coffea arabica L.) berry pulp extracts (CBP extracts) on the improvement of diabetes, obesity, and non-alcoholic fatty liver disease (NAFLD) were evaluated using various in vitro antioxidant activity assays and through a high-fat diet-induced mild diabetic obese mouse model. After an 84-day oral administration of CBP extracts (400-100 mg/kg), bioactivities were evaluated. The in vitro analysis showed the highest DPPH● scavenging activity of 73.10 ± 4.27%, ABTS● scavenging activity of 41.18 ± 1.14%, and SOD activity of 56.24 ± 2.81%, at a CBP extract concentration of 1000 µg/mL. The in vivo analysis of the CBP extracts showed favorable and dose-dependent anti-obesity, anti-diabetic, NAFLD, nephropathy, and hyperlipidemia refinement effects through hepatic glucose enzyme activity, 5'-AMP-activated protein kinase (AMPK) up-regulation, antioxidant activity, lipid metabolism-related gene expression, and pancreatic lipid digestion enzyme modulatory activities. This study shows that an appropriate oral dosage of CBP extracts could function as a potent herbal formulation for a refinement agent or medicinal food ingredient to control type 2 diabetes and related complications.

Identification of Antioxidative Hydrolyzable Tannins in Water Chestnut

Despite the various biological activities exhibited by water chestnut (the fruit of the Trapa genus), the phenolic compounds present in its extract require comprehensive characterization. Accordingly, we analyzed a 80% methanol extract of commercially available water chestnut and identified a new hydrolyzable tannin dimer termed trapadin A. Additionally, 22 known compounds, including 10 hydrolyzable tannin monomers and 2 dimers, were also detected in the extract. Spectroscopic and chemical methods were used to elucidate the structure of trapadin A, revealing it to be a hydrolyzable tannin dimer formed from units of tellimagrandin II and 1,2,3,6-tetra-O-galloyl-β-d-glucose. Moreover, the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity assay used to determine the half-maximal effective concentration values for the 23 compounds isolated from water chestnut indicated significant radical scavenging activity associated with hydrolyzable tannins. Notably, trapadin A, the new hydrolyzable tannin dimer, exhibited the highest activity value among the tested compounds.

Efficacy Confirmation Test of Black Cumin (Nigella sativa L.) Seeds Extract Using a High-Fat Diet Mouse Model

To deal with the adverse effects associated with the use of currently available treatments for metabolic disorders, such as type 2 diabetes, there is a need to find an alternative drug compound. In the present study, we investigated the therapeutic potential of black cumin (Nigella sativa L.) seeds extract (BCS extract) for type 2 diabetes using a 45% Kcal-fed obese mouse model. The BCS extract at different doses (400–100 mg/kg) showed a dose-dependent improvement tendency in high-fat diet (HFD)-induced obesity, non-alcoholic fatty liver disease (NAFLD), hyperlipidemia, and diabetic nephropathy compared to the metformin (250 mg/kg). In particular, BCS extract at a dose of 200 mg/kg significantly inhibited the HFD-induced metabolic conditions. The oral administration of BCS extract (200 mg/kg) significantly inhibited the oxidative stress through lipid peroxidation, normalized the activity of sugar metabolism-related enzymes and the expression of genes involved in fat metabolism, and inhibited insulin resistance through glucose and fat metabolism by regulating the 5’-AMP-activated protein kinase (AMPK) expression. Furthermore, BCS extract (200 mg/kg) showed renal damage improvement effects compared to the metformin (250 mg/kg). The results clearly show that BCS aqueous extract at an appropriate concentration could help in the treatment of metabolic disorders, and BCS aqueous extract can be used as a functional food for various diabetic complications, such as obesity, diabetes, and NAFLD.