No abstract

Geraniin, a hydrolysable polyphenol derived from Nephelium lappaceum L. fruit rind, has been shown to possess significant antioxidant activity in vitro and recently been recognized for its therapeutic potential in metabolic syndrome. This study investigated its antioxidative strength and protective effects on organs in high-fat diet (HFD)-induced rodents. Rats were fed HFD for 6 weeks to induce obesity, followed by 10 and 50 mg/kg of geraniin supplementation for 4 weeks to assess its protective potential. The control groups were maintained on standard rat chows and HFD for the same period. At the 10th week, oxidative status was assessed and the pancreas, liver, heart and aorta, kidney, and brain of the Sprague Dawley rats were harvested and subjected to pathological studies. HFD rats demonstrated changes in redox balance; increased protein carbonyl content, decreased levels of superoxide dismutase, glutathione peroxidase, and glutathione reductase with a reduction in the non-enzymatic antioxidant mechanisms and total antioxidant capacity, indicating a higher oxidative stress (OS) index. In addition, HFD rats demonstrated significant diet-induced changes particularly in the pancreas. Four-week oral geraniin supplementation, restored the OS observed in the HFD rats. It was able to restore OS biomarkers, serum antioxidants, and the glutathione redox balance (reduced glutathione/oxidized glutathione ratio) to levels comparable with that of the control group, particularly at dosage of 50 mg geraniin. Geraniin was not toxic to the HFD rats but exhibited protection against glucotoxicity and lipotoxicity particularly in the pancreas of the obese rodents. It is suggested that geraniin has the pharmaceutical potential to be developed as a supplement to primary drugs in the treatment of obesity and its pathophysiological sequels.

Obesity is a disease growing at an alarming rate and numerous preclinical studies have proven the role of polyphenols in managing this disease. This systematic review explores the prebiotic effect of polyphenols in the management of obesity among animals fed on a high-fat diet. A literature search was carried out in PubMed, Scopus, CINAHL, Web of Science, and Embase databases following the PRISMA guidelines. Forty-four studies reported a significant reduction in obesity-related parameters. Most notably, 83% of the studies showed a decrease in either body weight/visceral adiposity/plasma triacylglyceride. Furthermore, 42 studies reported a significant improvement in gut microbiota (GM), significantly affecting the genera Akkermansia, Bacteroides, Blautia, Roseburia, Bifidobacteria, Lactobacillus, Alistipes, and Desulfovibrio. Polyphenols’ anti-obesity, anti-hyperglycaemic, and anti-inflammatory properties were associated with their ability to modulate GM. This review supports the notion of polyphenols as effective prebiotics in ameliorating HFD-induced metabolic derangements in animal models.

Despite the lack of its toxicity evaluation, traditional herbal products are being widely used for various health indications. Geraniin, an ellagitannin, is a bioactive compound found in many traditional herbal medicines. In spite its numerous health benefits ranging from anti-inflammatory, anti-hyperglycaemic, hepatoprotective, anti-cancer and anti-microbial, no toxicity data on geraniin is available. The objective of this study is to evaluate the acute oral toxicity of geraniin and an enriched geraniin-extract of Nephelium lappaceum L rind. This study followed the guidelines of the OECD 423 acute oral toxicity test. Subsequent to a single oral administration of the test compounds, the rats were observed for 14 days for signs of toxicity and mortality. Following euthanasia, full blood count, biochemistry of blood and histopathology assessment of organs were carried out. All parameters analysed indicated insignificant difference compared to control. The LD 50 cut-off values for both geraniin and geraniin-enriched extract was established to be 2000 mg/kg b. w., following a single oral dose. It was however observed that the hepatocytes of three geraniin-administered rats exhibited a ‘foamy appearance’. As such, the no-observed-adverse-effect level of geraniin is below 2000 mg/kg, while that of geraniin-enriched extract is up to 2000 mg/kg. Further detailed toxicity studies are required to establish geraniin or its enriched extract from Nephelium lappaceum L rind safe for human consumption.

Geraniin, an ellagitannin, has ameliorative properties against high-fat diet (HFD)-induced metabolic syndrome. Since geraniin has poor bioavailability, we hypothesised the interaction of this compound with gut microbiota as the main mechanism for improving metabolic aberrations. Male Sprague Dawley rats were divided into normal diet (ND)- and HFD-fed animals and treated with geraniin and an enriched extract of geraniin (GEE). We observed that 5 mg geraniin and 115 mg GEE supplementation significantly attenuated glucose intolerance, lipopolysaccharide-binding protein, total cholesterol, triacylglyceride, and low-density lipoprotein; improved insulin sensitivity; and significantly increased adiponectin and hepatic PPARα expression. Although geraniin and GEE did not significantly alter the gut microbial composition, we found an increment in the relative abundance of a few butyrate producers such as Alloprevotella, Blautia, Lachnospiraceae NK4A136 group, and Clostridium sensu stricto 1. Geraniin and its enriched extract’s ability to ameliorate metabolic syndrome parameters while positively affecting the growth of butyrate-producing bacteria suggests its potential prebiotic role.