Hypoglycemic activity of Momordica charantia (bitter melon)

Diabetes mellitus (DM) represents a global health and economical problem. Many patients with DM in Asia, South America, India and East Africa have traditionally used the water extract of unripe fruits of Momordica charantia (bitter melon) as some form of complementary and alternative medicine. Studies of laboratory animals have shown the beneficial blood-glucose lowering and anti-diabetic effects of this remedy. Some oral components that bring lower blood glucose level have been isolated : charantin (sterol glycosides), charantin (polypeptide) and cucurbine-type triterpenes. Part of their actions are related to AMP-activated kinase and repression of the oxidative stress that is increased in DM. Most clinical reports are not fully convincing due to the lack of randomized control studies. The present article reviews the pharmacological and clinical effects of bitter melon with special emphasis on the anti-diabetic effects, and some effects that would require caution in the context of human trials

Inhibitory Effect of Fermented Papaya Preparation on Hydroxyl Radical Generation from Methylguanidine

We have previously shown that extremely high level of guanidino compounds such as methylguanidine (MG), known as a neurotoxin and also a nephrotoxin, generate reactive oxygen species (ROS) using an electron spin resonance (ESR) technique with spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). In this in vitro study, the inhibitory effect of fermented papaya preparation (SAIDO-PS501:PS-501) on hydroxyl radical (·OH) generation from MG was examined using an ESR spectrometry, and it was found that PS-501 suppressed ·OH generation from MG in a dose-dependent manner. The ID50 value of PS-501 was 8 mg/ml. On the contrary, glucose itself did not suppress ·OH generation from MG up to100 mg/ml, whereas PS-501 almost completely suppressed ·OH generation from MG at a dose of 100 mg/ml. These results imply that PS-501 itself may have a beneficial effect of preventing ROS- and MG-related diseases

A Novel Animal Model of Nonalcoholic Steatohepatitis (NASH): Hypoxemia Enhances the Development of NASH

Recent reports described a high incidence of nonalcoholic steatohepatitis (NASH) in patients with obstructive sleep apnea. Accordingly, we hypothesized that recurrent and intermittent hypoxemia plays an important role in the pathogenesis of NASH. Our objective was construction of a practical and accurate experimental model to reproduce the key features of NASH in humans. Chemical hypoxemia through methemoglobinemia was induced by daily intraperitoneal injection of sodium nitrite (40 mg/kg) for 4 weeks in rats with fatty liver. The later was induced by 4-week feeding a choline-deficient high-fat diet (CDHF). Besides, the normal chow diets feeding groups were prepared with in the same manner except for CDHF feeding. The animal experiment was performed in four groups; Normal control, Hypoxemia, CDHF, and CDHF + hypoxemia. Nitrite was given for the later 4 weeks to each rat of Hypoxemia and CDHF + hypoxemia. CDHF + hypoxemia rats were confirmed to develop histological changes that resemble those of patients with NASH, together with biochemical liver dysfunction, while CDHF group was limited in mild steatosis, and Hypoxemia group liver was normal. Present study established a reproducible and useful NASH model resembling the main features of NASH in humans, and showed first that recurrent and intermittent hypoxemia aggravate fatty liver to steatohepatitis and liver fibrosis

Beneficial effects of Vitis coignetiae Pulliat leaves on nonalcoholic steatohepatitis in a rat model

Vitis coignetiae Pulliat (Yamabudo) is used as a health juice and wine based on the abundant polyphenols and anthocyanins in its fruit. However, it is not known whether the leaves of this plant confer similar benefits. This study investigated the hepatoprotective effects of aqueous extracts from Vitis coignetiae Pulliat leaves (VCPL) in an animal model of nonalcoholic steatohepatitis (NASH). Rats were fed a choline-deficient high-fat diet for four weeks to generate fatty livers. NASH was induced by oxidative stress loading. Ten weeks later, blood and liver samples were collected from anesthetized animals and assessed biochemically, histologically, and histochemically to determine the extent of oxidative stress injury and the overall effects of VCPL. Six-week VCPL extract supplementation reduced serum levels of liver enzymes, decreased CYP2E1 induction, increased plasma antioxidant activities and delayed the progression of liver fibrosis. The findings suggested that VCPL has strong radical-scavenging activity and may be beneficial in preventing NASH progression.</p

Water Extract of Vitis coignetiae Pulliat Leaves Attenuates Oxidative Stress and Inflammation in Progressive NASH Rats

This study aimed to investigate the therapeutic effects of the water extract of leaves of Vitis coignetiae Pulliat (VCPL) on nonalcoholic steatohepatitis (NASH) with advanced fibrosis, as our previous study exhibited its preventive effect on NASH. The NASH animal model [PCT/JP2007/52477] was prepared by loading recurrent and intermittent hypoxemia stress to a rat with fatty liver, which resembled the condition occurring in patients with obstructive sleep apnea (OSA) and fatty liver, who have a high incidence of NASH. Intermittent hypoxemia stress is regarded as a condition similar to warm ischemia followed by re-oxygenation, which induces oxidative stress (OS). The daily 100 or 300mg/kg VCPL administrations were performed for 3 weeks perorally beginning at the time of detection of advanced liver fibrosis. The therapeutic efficacy of VCPL on NASH was demonstrated by the reduction of the leakage of hepato-biliary enzymes and the amelioration of liver fibrosis. The OS elevation in NASH rats was measured based on the derivation of reactive oxygen species from liver mitochondrial energy metabolism and on the decrease in plasma SOD-like activity. The aggravation of inflammatory responses was demonstrated by the neutrophil infiltration (elevated myeloperoxidase activity) and the progression of fibrosis in the livers of NASH rats. In addition, the NASH rats without VCPL treatment also exhibited activation of nuclear factor-κB, a key factor in the link between oxidative stress and inflammation. All of these changes were reduced dose-dependently by the VCPL administration. These findings indicate that VCPL may improve hepatic fibrosis or at least suppress the progression of NASH, by breaking the crosstalk between OS and inflammation

Beneficial Effects of Fermented Green Tea Extract in a Rat Model of Non-alcoholic Steatohepatitis

Oxidative stress is frequently considered as a central mechanism of hepatocellular injury in non-alcoholic steatohepatitis (NASH). The aim of this study was to investigate the effects of fermented green tea extracts (FGTE) on NASH. Rats were fed a choline-deficient high-fat diet for 4 weeks to nutritionally generate fatty livers. NASH was induced chemically by oxidative stress using repeated intraperitoneal injections of nitrite. Rats with NASH developed steatohepatitis and liver fibrosis after 6-week of such treatment. At 10 weeks, blood and liver samples were collected from anesthetized animals and assessed for extent of OS injury and effects of FGTE, by biochemical, histological and histochemical analyses. FGTE reduced serum levels of liver enzymes, lipid peroxidation and production of mitochondrial reactive oxygen species. In addition, FGTE showed inhibition of progressions of cirrhosis. Our findings suggest that our FGTE have strong radical scavenging activity and may be beneficial in the prevention of NASH progression

Production of docosahexaenoic acid bounded phospholipids via phospholipase A2 mediated bioconversion

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Hypothalamic GPR40 signaling activated by free long chain fatty acids suppresses CFA-induced inflammatory chronic pain.

GPR40 has been reported to be activated by long-chain fatty acids, such as docosahexaenoic acid (DHA). However, reports studying functional role of GPR40 in the brain are lacking. The present study focused on the relationship between pain regulation and GPR40, investigating the functional roles of hypothalamic GPR40 during chronic pain caused using a complete Freund's adjuvant (CFA)-induced inflammatory chronic pain mouse model. GPR40 protein expression in the hypothalamus was transiently increased at day 7, but not at days 1, 3 and 14, after CFA injection. GPR40 was co-localized with NeuN, a neuron marker, but not with glial fibrillary acidic protein (GFAP), an astrocyte marker. At day 1 after CFA injection, GFAP protein expression was markedly increased in the hypothalamus. These increases were significantly inhibited by the intracerebroventricular injection of flavopiridol (15 nmol), a cyclin-dependent kinase inhibitor, depending on the decreases in both the increment of GPR40 protein expression and the induction of mechanical allodynia and thermal hyperalgesia at day 7 after CFA injection. Furthermore, the level of DHA in the hypothalamus tissue was significantly increased in a flavopiridol reversible manner at day 1, but not at day 7, after CFA injection. The intracerebroventricular injection of DHA (50 µg) and GW9508 (1.0 µg), a GPR40-selective agonist, significantly reduced mechanical allodynia and thermal hyperalgesia at day 7, but not at day 1, after CFA injection. These effects were inhibited by intracerebroventricular pretreatment with GW1100 (10 µg), a GPR40 antagonist. The protein expression of GPR40 was colocalized with that of β-endorphin and proopiomelanocortin, and a single intracerebroventricular injection of GW9508 (1.0 µg) significantly increased the number of neurons double-stained for c-Fos and proopiomelanocortin in the arcuate nucleus of the hypothalamus. Our findings suggest that hypothalamic GPR40 activated by free long chain fatty acids might have an important role in this pain control system