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.
METHODS AND RESULTS: Here, we showed that three di-O-caffeoylquinic acids suppressed hepatic glucose production in H4IIE rat hepatoma cells by reducing expression of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), two key enzymes that regulate hepatic gluconeogenesis. Direct comparisons between CQAs and their metabolites (3-caffeoylquinic, caffeic, and quinic acids) revealed the caffeic acid moiety alone was responsible for the observed effects. Further analysis suggested the activation of PI3K and MAPK pathways as a method of controlling gene expression was shared between caffeoylquinic and caffeic acids. These compounds promoted increased mitochondrial respiration and cellular metabolism, in part by inducing oxidative phosphorylation and proton leak.
CONCLUSION: We concluded that the caffeic acid moiety was important for suppression of hepatic gluconeogenesis and hyperglycemia, ultimately strengthening the link between dietary interventions based on caffeic acid-containing plant foods and healthy glucose metabolism.
METHODS: The ethanol extract and its subfractions, and isolated compounds from T. indica stems were subjected to cytotoxicity test using MTT viability assay on 3T3-L1 pre-adipocytes. Then, the test groups were subjected to the in vitro antidiabetic investigation using 3T3-L1 pre-adipocytes and differentiated adipocytes to determine the insulin-like and insulin sensitizing activities. Rosiglitazone was used as a standard antidiabetic agent. All compounds were also subjected to fluorescence glucose (2-NBDG) uptake test on differentiated adipocytes. Test solutions were introduced to the cells in different safe concentrations as well as in different adipogenic cocktails, which were modified by the addition of compounds to be investigated and in the presence or absence of insulin. Isolation of bioactive compounds from the most effective subfraction (ethyl acetate) was performed through repeated silica gel and sephadex LH-20 column chromatographies and their structures were elucidated through (1)H-and (13)C-NMR spectroscopy.
RESULTS: Four monoflavonoids, namely, wogonin, norwogonin, quercetin and techtochrysin were isolated from the T. indica stems ethanol extract. Wogonin, norwogonin and techtochrysin induced significant (P
METHODS: Subjects (n = 121) received oral repaglinide (4 mg). Blood samples were taken at 0, 30, 60, 120, 180 and 240 min and serum concentrations of repaglinide were determined using high-performance liquid chromatography. Subjects were also genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for CYP3A4*4, *5 and*18 and by an allele-specific multiplex PCR for CYP2C8*2, *3, *4 and *5 alleles.
RESULTS: The allele frequencies of CYP2C8*1, *2, *3, *4 and *5 were 95.04, 0.40, 0.40, 0 and 4.13%, respectively. The frequencies of the CYP3A4*1, *4, *5 and *18 alleles were 97.93, 0, 0 and 2.07%, respectively. CYP2C8 and CYP3A4 genotypes were not significantly associated with repaglinide's blood glucose-lowering effect. However, the CYP3A4 genotype significantly influenced some of repaglinide's pharmacokinetics, where the mean elimination rate constant was 44.0% lower (p = 0.04) and the mean half-life was 33.8% higher (p = 0.04) in subjects with the CYP3A4*1/*18 genotype as compared to those with the normal CYP3A4*1/*1 genotype. This result confirms that CYP3A4 plays a large role in metabolizing repaglinide.
CONCLUSION: Genetic polymorphisms of CYP3A4, specifically CYP3A4*18, play a major role in contributing to the interindividual variability in repaglinide's pharmacokinetics.