Urinary metabolites of type 2 diabetes rats fed with palm oil-enriched high fat diet

Deciphering the mechanism of Annona muricata leaf extract in alloxan-nicotinamide-induced diabetic rat model with 1H-NMR-based metabolomics approach

The leaves of Annona muricata Linn. have long been utilized in traditional medicine for diabetes treatment, and there is no study that has employed a metabolomics approach to investigate the plant's effects in managing the disease. We aimed to explore the antidiabetic effects of the standardised A. muricata leaf extract on diabetes-induced rats by alloxan monohydrate (Ax) and nicotinamide (NA) using a proton nuclear magnetic resonance (¹H-NMR)-based metabolomics approach. Absolute quantification was performed on the leaf extract using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Two different doses of the extract were administered orally for four weeks to diabetic rats induced with Ax + NA, and physical evaluations, biochemical analyses, and ¹H-NMR metabolomics of urine and serum were assessed. The results showed that quercetin 3-rutinoside was the most abundant compound in the 80 % ethanolic extract of A. muricata leaf. The induction of type 2 diabetes mellitus (T2DM) in the rat model was confirmed by the clear metabolic distinction between normal rats, diabetic rats, and metformin-treated diabetic rats. The low-dose of A. muricata leaf extract (200 mg/kg) was found to exhibit better results, significantly reducing serum urea levels in diabetic rats, with effects comparable to those of metformin. Additionally, metabolite analysis from ¹H-NMR metabolomics of serum and urine showed a slight shift toward normal metabolic profiles in the treated diabetic rats. Pathway analysis revealed alterations in the tricarboxylic acid cycle (TCA), pyruvate metabolism, and glycolysis/gluconeogenesis pathways in the diabetic rat model, which were improved following treatment with the A. muricata leaf extract. Overall, this study provides scientific support for its traditional use in diabetes management and offers new insights into the underlying molecular mechanisms.

Phloretin and Enalapril co-administration ameliorates hyperglycemia mediated exacerbation of myocardial injury in rats

Hyperglycemia exacerbates myocardial injury by amplifying oxidative stress, inflammation and apoptosis. This study explores the therapeutic potential of phloretin and enalapril co-administration in mitigating hyperglycemia-exacerbated myocardial damage. Using network pharmacology, 47 therapeutic targets and 10 hub genes, including albumin, insulin, prostaglandin endoperoxide synthase 2, matrix metallopeptidase 9, caspase3, tumor protein p53, insulin like growth factor 1, transforming growth factor beta 1, matrix metallopeptidase 2 and glycogen synthase kinase 3, were identified as critical to the drugs' synergistic action. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses highlighted key pathways, such as Interleukin-17 (IL-17), Advanced Glycation End Product-Receptor for Advanced Glycation End Products (AGE-RAGE), Mitogen activated protein kinase (MAPK), Phosphatidylinositol 3-kinase-protein kinase B (PI3K-Akt), Tumor necrosis factor (TNF) and Forkhead box O (FoxO), involved in angiogenesis, glucose metabolism, oxidative stress regulation and inflammation. Molecular docking confirmed strong affinities of phloretin and enalapril for key targets like insulin (INS), matrix metallopeptidase 9 (MMP9), prostaglandin endoperoxide synthase 2 (PTGS2) and insulin like growth factor 1 (IGF1). In-vivo studies using hyperglycemic rats with isoproterenol-induced myocardial ischemia validated the therapeutic efficacy of the combination. Co-treatment significantly enhanced antioxidant enzyme levels, reduced myocardial injury markers and improved histopathological features. These findings demonstrate the synergistic cardioprotective effects of phloretin and enalapril, offering a promising strategy for managing hyperglycemia and cardiac injury. The study provides a foundation for further preclinical and clinical evaluations to optimize the use of this combination in cardiovascular therapies.

Impact of time-restricted feeding on glycemic indices, vascular oxidative stress, and inflammation in an obese prediabetes rat model induced by a high-fat diet and sugar drink

OBJECTIVE

This study aims to investigate the effects of time-restricted feeding (TRF) on glycaemic indices and aortic tissue oxidative stress and inflammation in an obese prediabetes rat model.

METHODS AND PROCEDURES

Male Sprague-Dawley rats were divided into two normal and four obese groups. Obese prediabetes was induced by feeding a high-fat diet and sucrose water (HFSD) for 10 weeks; normal rats were given a standard diet and plain water. For the next 6 weeks, rats were grouped into the normal group (NR), which continued on the standard diet; the normal group was switched to TRF with the standard diet (NR + TRFSD); the prediabetes group (OR) was continued on HFSD; the prediabetes group was switched to TRF of HFSD (OR + TRFHFSD); the prediabetes group was switched to TRF of the standard diet (OR + TRFSD); and the prediabetes group was switched to the standard diet (OR + SD). Rats were then sacrificed, and aortic tissues were isolated and quantified for oxidative stress markers malondialdehyde, antioxidant enzyme superoxide dismutase, and inflammation markers tumor necrosis factor-α, and interleukin 1. Fasting blood glucose (FBG), body weight, Lee's index, serum insulin level, and resistance (Homeostatic Model Assessment of Insulin Resistance) were also measured.

RESULTS

Mean FBG and body weight in obese groups were higher compared to the normal groups after 10 weeks of HFDSD. Both obese-prediabetes groups that underwent TRF had reduced levels of tumor necrosis factor-α, interleukin 1, body weight, Lee's index, FBG, and insulin resistance. Furthermore, obese prediabetes on TRF with SD also reduced levels of lipid peroxidation (malondialdehyde), insulin levels and increased levels of the antioxidant enzyme (superoxide dismutase).

CONCLUSION

TRF reduced weight, improved glycaemic indices, vascular oxidative stress, and inflammation in obese-prediabetic rats.

Revealing metabolic and biochemical variations via 1H NMR metabolomics in streptozotocin-nicotinamide-induced diabetic rats treated with metformin

The increasing prevalence of lean diabetes has prompted the generation of animal models that mimic metabolic disease in humans. This study aimed to determine the optimum streptozotocin-nicotinamide (STZ-NA) dosage ratio to elicit lean diabetic features in a rat model. It also used a proton nuclear magnetic resonance (1H NMR) urinary metabolomics approach to identify the metabolic effect of metformin treatment on this novel rat model. Three different STZ-NA dosage regimens (by body weight: Group A: 110 mg/kg NA and 45 mg/kg STZ; Group B: 180 mg/kg NA and 65 mg/kg STZ and Group C: 120 mg/kg NA and 60 mg/kg STZ) were administered to Sprague-Dawley rats along with oral metformin. Group A diabetic rats (A-DC) showed favorable serum biochemical analyses and a more positive response toward oral metformin administration relative to the other STZ-NA dosage ratio groups. Orthogonal partial least squares-discriminant analysis (OPLS-DA) revealed that glucose, citrate, pyruvate, hippurate, and methylnicotinamide differentiating the OPLS-DA of A-MTF rats (Group A diabetic rats treated with metformin) and A-DC model rats. Subsequent metabolic pathway analyses revealed that metformin treatment was associated with improvement in dysfunctions caused by STZ-NA induction, including carbohydrate metabolism, cofactor metabolism, and vitamin and amino acid metabolism. In conclusion, our results identify the best STZ-NA dosage ratio for a rat model to exhibit lean type 2 diabetic features with optimum sensitivity to metformin treatment. The data presented here could be informative to improve our understanding of non-obese diabetes in humans through the identification of possible activated metabolic pathways in the STZ-NA-induced diabetic rats model.

Antidiabetic effect of Ardisia elliptica extract and its mechanisms of action in STZ-NA-induced diabetic rat model via 1H-NMR-based metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Ardisia elliptica Thunb. (AE) (Primulaceae) is a medicinal plant found in the Malay Peninsula and has been traditionally used to treat diabetes. However, limited studies to date in providing scientific evidence to support the antidiabetic efficacy of this plant by in-vitro and in-vivo models.

AIM OF THE STUDY

To investigate the anti-hyperglycemic potential of AE through in-vitro enzymatic activities and streptozotocin-nicotinamide (STZ-NA) induced diabetic rat models using proton-nuclear magnetic resonance (1H-NMR)-based metabolomics approach.

MATERIALS AND METHODS

Anti-α-amylase and anti-α-glucosidase activities of the hydroethanolic extracts of AE were evaluated. The absolute quantification of bioactive constituents, using ultra-high performance liquid chromatography (UHPLC) was performed for the most active extract. Three different dosage levels of the AE extract were orally administered for 4 weeks consecutively in STZ-NA induced diabetic rats. Physical assessments, biochemical analysis, and an untargeted 1H-NMR-based metabolomics analysis of the urine and serum were carried out on the animal model.

RESULTS

Type 2 diabetes mellitus (T2DM) rat model was successfully developed based on the clear separation observed between the STZ-NA induced diabetic and normal non-diabetic groups. Discriminating biomarkers included glucose, citrate, succinate, allantoin, hippurate, 2-oxoglutarate, and 3-hydroxybutyrate, as determined through an orthogonal partial least squares-discriminant analysis (OPLS-DA) model. A treatment dosage of 250 mg/kg body weight (BW) of standardized 70% ethanolic AE extract mitigated increase in serum glucose, creatinine, and urea levels, providing treatment levels comparable to that obtained using metformin, with flavonoids primarily contribute to the anti-hyperglycemic activities. Urinary metabolomics disclosed that the following disturbed metabolism pathways: the citrate cycle (TCA cycle), butanoate metabolism, glycolysis and gluconeogenesis, pyruvate metabolism, and synthesis and degradation of ketone bodies, were ameliorated after treatment with the standardized AE extract.

CONCLUSIONS

This study demonstrated the first attempt at revealing the therapeutic effect of oral treatment with 250 mg/kg BW of standardized AE extract on chemically induced T2DM rats. The present study provides scientific evidence supporting the ethnomedicinal use of Ardisia elliptica and further advances the understanding of the fundamental molecular mechanisms affected by this herbal antidote.