Mature coconut water exhibits antidiabetic and antithrombotic potential via L-arginine-nitric oxide pathway in alloxan induced diabetic rats.

BACKGROUND: The aims of the present study were to assess whether the antidiabetic activity of mature coconut water (MCW) is mediated through L-arginine-nitric oxide pathway in diabetic rats, and to study the effects of MCW on blood coagulation. METHODS: Diabetes was induced in male Sprague-Dawley rats by injecting them with alloxan (150 mg/kg body weight). MCW (4 mL/100 g body weight) and L-arginine (7.5 mg/100 g body weight) was given orally for 45 days. L-NAME was given at a dose of 0.5 mg/kg body weight. Concentrations of blood glucose, plasma insulin, glycosylated hemoglobin (HbA1c), L-arginine, urine volume and urinary creatinine levels, activity of nitric oxide synthase (NOS), and arginase as well as the abnormalities in hemostasis and thrombosis were measured in all the experimental groups. RESULTS: Treatment with MCW and L-arginine reduced the concentration of blood glucose and HbA1c in diabetic rats. MCW and L-arginine treatment exhibited significant antithrombotic activity in diabetic rats, which was evident from the reduced levels of WBC, platelets, fibrin, and fibrinogen. MCW and L-arginine treatment prolonged the prothrombin time in diabetic rats and reduced the activity of Factor V. In addition to this, the activity of nitric oxide synthase, liver and plasma arginine content, and urinary nitrite were higher in MCW-treated diabetic rats whereas L-NAME treatment inhibited the beneficial effects induced by MCW and arginine. CONCLUSIONS: The results clearly indicate that L-arginine is a major factor responsible for the antidiabetic and antithrombotic potential of coconut water, and is mediated through the L-arginine-nitric oxide pathway.

Influence of virgin coconut oil-enriched diet on the transcriptional regulation of fatty acid synthesis and oxidation in rats - a comparative study.

The present study was carried out to evaluate the effects of virgin coconut oil (VCO) compared with copra oil, olive oil and sunflower-seed oil on the synthesis and oxidation of fatty acids and the molecular regulation of fatty acid metabolism in normal rats. Male Sprague-Dawley rats were fed the test oils at 8 % for 45 d along with a synthetic diet. Dietary supplementation of VCO decreased tissue lipid levels and reduced the activity of the enzymes involved in lipogenesis, namely acyl CoA carboxylase and fatty acid synthase (FAS) (P< 0·05). Moreover, VCO significantly (P< 0·05) reduced the de novo synthesis of fatty acids by down-regulating the mRNA expression of FAS and its transcription factor, sterol regulatory element-binding protein-1c, compared with the other oils. VCO significantly (P< 0·05) increased the mitochondrial and peroxisomal ß-oxidation of fatty acids, which was evident from the increased activities of carnitine palmitoyl transferase I, acyl CoA oxidase and the enzymes involved in mitochondrial ß-oxidation; this was accomplished by up-regulating the mRNA expression of PPARα and its target genes involved in fatty acid oxidation. In conclusion, the present results confirmed that supplementation of VCO has beneficial effects on lipid parameters by reducing lipogenesis and enhancing the rate of fatty acid catabolism; this effect was mediated at least in part via PPARα-dependent pathways. Thus, dietary VCO reduces the risk for CHD by beneficially modulating the synthesis and degradation of fatty acids.

Coconut kernel-derived proteins enhance hypolipidemic and antioxidant activity in alloxan-induced diabetic rats.

Impaired lipid levels and oxidative stress are indicative of malfunction of endogenous antioxidant capacity. The aim of this study was to determine the effect of coconut kernel protein (CKP) on the lipid peroxides and antioxidant enzyme activities in diabetic rats. Diabetes was induced prior to feeding by injecting a single dose of alloxan (150 mg/kg body weight) intraperitoneally. CKP (8% w/w) was administered to these rats along with a semi-synthetic diet for 45 days. After the experimental period, peroxide products and antioxidant enzyme activities were determined. Results show that CKP maintained the antioxidant enzyme activities and levels of peroxides to the normal levels in treated group compared to diabetic rats. This study clearly show that CKP has potential effect in lowering oxidative stress associated with diabetes. This beneficial effect of CKP may be due to the high amount of biologically potent arginine present in it.

Protective and curative effects of Cocos nucifera inflorescence on alloxan-induced pancreatic cytotoxicity in rats.

OBJECTIVES: This study was planned to investigate the effects of pre and post-treatment of young inflorescence of Cocos nucifera (CnI) on alloxan-induced diabetic rats. MATERIALS AND METHODS: Male albino Sprague Dawely rats were divided into five groups of six animals each. Group I was normal control, Group II was diabetic control, Cocos nucifera Inflorescence (CnI) was fed along with diet [20% (w/w)] orally (Group III) for a period of 11 days prior to alloxan injection (150 mg/kg i.p.). The curative effect of CnI was evaluated at the same feeding levels in alloxan-induced diabetic rats (Group IV) for a period of 30 days. The effects of both pretreatment and post-treatment (Group V) were also evaluated. Biochemical parameters such serum glucose, hepatic glycogen, and enzymes involving carbohydrate metabolism (hexokinase, phosphoglucomutase, pyruvate kinase, glucose-6-phosphatase, fructose 1, 6-diphosphatase, glucose-6 phosphate dehydrogenase, and glycogen phosphorylase) were assayed along with pancreatic histopathology. Data were analyzed using one-way analysis of variance followed by Duncan's post hoc multiple variance test. P < 0.05 was considered statistical significant. RESULTS: Diabetic control rats showed significant increase in serum glucose (P < 0.05) and decrease in hepatic glycogen levels (P < 0.05) compared to normal rats, which was reversed to near normal in both CnI pretreated and post-treated rats. Treatment with CnI resulted in significant decrease (P < 0.05) in activities of gluconeogenic enzymes in Group III and IV on compared to the diabetic control group, while glycolytic enzyme activities were improved in these groups. The cytotoxicity of pancreatic islets also ameliorated by treatment with CnI on histopathological examination. CONCLUSION: The results obtained in the study indicate the protective and curative effects of CnI on alloxan-induced pancreatic cytotoxicity, which is mediated through the regulation of carbohydrate metabolic enzyme activities and islets cell repair.

Arginine-rich coconut kernel diet influences nitric oxide synthase activity in alloxandiabetic rats.

BACKGROUND: Coconut kernel protein (CKP) has been reported to contain significant amounts of L-arginine. Its potential effect on glucose homeostasis, possibly through the nitric oxide synthase (NO) pathway, was therefore investigated in alloxan-induced diabetic rats. Diabetes was induced by a single intraperitoneal dose of alloxan (150 mg kg⁻¹ body weight). Experimental rats were grouped as follows: Group I, normal control; Group II, diabetic control; Group III, diabetic + CKP; Group IV, diabetic + L-arginine; Group V, diabetic + L-arginine + L-N(G)-Nitroarginine methyl ester (L-NAME). Purified CKP isolated from dried coconut kernel and L-arginine was administered to rats along with a semi-synthetic diet for 45 days. L-NAME (0.5 mg kg⁻¹ body weight) was given to Group V animals. After the experimental period, serum glucose, insulin, activities of liver nitric oxide synthase and arginase, liver glycogen levels and histopathology of the pancreas were evaluated. RESULTS: Serum glucose, insulin and antioxidant enzyme activities and liver glycogen levels were found to be restored to basal levels in CKP-fed rats. Decreased arginase and increased nitric oxide synthase (NOS) activities were found in CKP- and arginine-fed rats. L-NAME treatment showed a partial effect on these parameters. Histopathology revealed that CKP and L-arginine feeding reduced the diabetes-related pancreatic damage in treated rats compared to the diabetic control. CONCLUSION: The results observed in this study indicate that the potential antidiabetic activity of CKP may be through an arginine-NO pathway leading to pancreatic beta cell regeneration.

Wet and dry extraction of coconut oil: impact on lipid metabolic and antioxidant status in cholesterol coadministered rats.

Because coconut oil extracted by wet process (virgin coconut oil, VCO) is gaining popularity among consumers, this study was conducted to evaluate VCO compared with coconut oil extracted by dry process (copra oil, CO) for their influence on lipid parameters, lipid peroxidation, and antioxidant status in rats coadministered with cholesterol. VCO, CO, and cholesterol were fed in a semi-synthetic diet to 24 male Sprague-Dawley rats for 45 days. After the experimental period, lipid and lipid peroxide levels and antioxidant enzyme activities were observed. Chemical composition and antioxidant properties of the polyphenolic fraction from VCO and CO were also analyzed. The results showed that lipid and lipid peroxide levels were lower in VCO-fed animals than in animals fed either CO or cholesterol alone. Antioxidant enzyme activities in VCO-fed animals were comparable with those in control animals. Although the fatty acid profiles of both oils were similar, a significantly higher level of unsaponifiable components was observed in VCO. Polyphenols from VCO also showed significant radical-scavenging activity compared with those from CO. This study clearly indicates the potential benefits of VCO over CO in maintaining lipid metabolism and antioxidant status. These effects may be attributed in part to the presence of biologically active minor unsaponifiable components.