Effects of coconut water on carbohydrate metabolism and pancreatic pathology of alloxan induced diabetic rats

Coconut (Cocos nucifera (L.)) Water Improves Glucose Uptake with Concomitant Modulation of Antioxidant and Purinergic Activities in Isolated Rat Psoas Muscles

The present study investigated the effect of coconut water on glucose uptake and utilization, and metabolic activities linked to hyperglycemia in isolated rat psoas muscles. Coconut water was subjected to in vitro antioxidant and antidiabetic assays, which cover 2,2'-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP), and inhibition of α-glucosidase and α-amylase activities. Psoas muscles were isolated from male Sprague Dawley rats and incubated with coconut water in the presence of glucose. Control consisted of muscles incubated with glucose only, while normal control consisted of muscles not incubated in coconut water and/or glucose. The standard antidiabetic drug was metformin. Incubation with coconut water led to a significant increase in muscle glucose uptake, with concomitant exacerbation of glutathione level, and SOD and catalase activities, while suppressing malondialdehyde level, and ATPase and E-NTDase activities. Coconut water showed significant scavenging activity against DPPH, and significantly inhibited α-glucosidase and α-amylase activities. LC-MS analysis of coconut water revealed the presence of ellagic acid, butin, quercetin, protocatechuic acid, baicalin, and silibinin. Molecular docking analysis revealed potent molecular interactions between the LC-MS-identified compounds, and AKT-2 serine and PI-3 kinase. These results indicate the potential of coconut water to enhance glucose uptake, while concomitantly improving antioxidative and purinergic activities. They also indicate the potential of coconut water to suppress postprandial hyperglycemia. These activities may be attributed to the synergistic effects of the LC-MS-identified compounds.

Anti-cataract effects of coconut water in vivo and in vitro

OBJECTIVE

To determine the anti-cataract effects of coconut water (CW) in vivo and in vitro, and to explore the potential pathogenic mechanism.

METHODS

In this study, 48 male Sprague-Dawley rats were randomly divided into 4 groups: control (CO), diabetic (DM), diabetic treated with CW (DM + CW), and diabetic treated with Glibenclamide (DM + Gli). Except for the CO group, in the other three groups, intraperitoneal injection of STZ (60 mg/kg) was conducted to establish diabetic models. The experiment was conducted for 20 weeks. The slit-lamp examination was undertaken during the period of experiment (20 weeks), and then, all rats were sacrificed. The levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in the left lens were measured by using biochemical assays. The right lens was used for pathological analysis. The rat lens epithelial cells (LECs) were cultured in vitro and the subcultured cell were divided into four groups, namely the normal glucose group (5 mmol /L glucose, Group I), the high glucose group (40 mmol/L glucose, Group II), high glucose +5% CW group (Group III), and high glucose +10% CW group (Group IV). LECs were cultured under the conditions as described above for 48 h. Cell proliferation and the morphological changes were observed with interted phase contrast microscope.The level of cell apoptosis was determined by flow cytometry. the level of SOD, MDA and GSH-Px were also detected.

RESULTS

The lens opacity index decreased in diabetic rats, and LECs apoptosis ratio also decreased in high glucose environments that received CW. Under treatment with CW, reduced MDA level and elevated activities of SOD and GSH-Px were detected, both in vivo and in vitro experiments. The increased severity of cataract and LECs apoptosis were noted in diabetic rats that received normal water, while CW markedly mitigated the enhanced cataract severity and the reduction of LECs induced by diabetes mellitus.

CONCLUSION

CW is a functional food that can protect the lens from diabetic cataract. The possible underlying mechanism may be partly explained via the decreased oxidative stress in lens. However, further research needs to be conducted to indicate the pathogenic mechanism of anti-diabetic effects of CW.

Effects of coconut water on blood sugar and retina of rats with diabetes

Background

This study aimed to evaluate the effects of coconut water on the general condition (fasting blood sugar and body weight) and retina of diabetic rats.

Methods

Forty-eight Sprague-Dawley male rats were divided into normal controls (NC), diabetes mellitus (DM), diabetes+coconut water (DM+CW), and diabetes+glibenclamide (DM+Gli) groups. After 4 weeks of normal feeding, coconut water was given to group III-DM+CW and 0.6 mg/kg glibenclamide to group IV-DM+Gli. The blood sugar, body weight, total retinal thickness, pathological changes, and VEGF expression in the retina were analyzed at different time points.

Results

The fasting blood sugar was 4-6 mmol/L in group I-NC and continuously increased in group II-DM, whereas gradually decreased after the 4th experiment week in the remaining two groups. The rats, except in group I-NC, have lost weight. In group II-DM, the total retinal thickness was significantly increased after the 8th and 12th experiment week, and the pathological changes in retina were observed. VEGF was almost fully expressed in the ganglion cell layer and inner granular layer and partially expressed in the outer granular layer in group II-DM, and mainly expressed in the ganglion cell layer and inner layer in group I-NC, with a lighter color. Group III-DM + CW and group IV-DM + Gli demonstrated similar VEGF expression as in group I-NC.

Conclusions

Coconut water has the potential to reduce blood sugar and diabetic retinal damage, serving as a candidate drug or nutrient for treating diabetes and its complications.

Effects of Coconut Water on Retina in Diabetic Rats

Coconut water (CW) is a natural aseptic nutritious beverage, containing several biologically active compounds. This study aimed to determine the antiretinopathy effects of CW on diabetic Sprague Dawley (SD) rats using streptozotocin (STZ) and explore its potential mechanism. After allowing the rats to acclimatize for 7 days, 48 healthy adult male SD rats were selected and randomly divided into 4 groups, involving control (Ctrl), diabetic rats (DM), diabetic rats treated with CW (DM-CW), and diabetic rats treated with glibenclamide (DM-Gli). The diabetic models were established by an intraperitoneal injection of STZ (60 mg/kg). The Ctrl group was injected with an equal volume of sodium citrate solution. The experiment was totally conducted during 20 weeks, and then, all rats were sacrificed. The serum levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) were measured; additionally, the activities of interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) in the retina were investigated using biochemical assays. Hematoxylin and eosin (H&E) staining was performed to observe pathological changes of retinal tissues. In presence of treatment with CW, serum level of MDA was decreased, while serum levels of SOD and GSH-Px were increased; besides, the activities of IL-6 and ICAM-1 in the retina were reduced compared with the DM group. The antiretinopathy feature of CW was confirmed by the increased number of neurons in the ganglion cell layer (GCL), total retina thickness (TRT), and thickness of the retinal nuclear layer (RNL) in diabetic rats. CW can be protective against diabetic retinopathy (DR), and its effects are comparable to Gli. The possible underlying mechanism may be partly explained by decreasing oxidative stress and anti-inflammatory activities in the retina. However, further research should be conducted to reveal the exact mechanism.

Phytochemical Profiling, GC-MS Analysis and α-Amylase Inhibitory Potential of Ethanolic Extract of Cocos nucifera Linn. Endocarp

BACKGROUND

Drugs with post-prandial action constitute one of the main courses of treatments for diabetes.

OBJECTIVE

In the present investigation, we have explored the α-amylase inhibitory potential of ethanolic extract of Cocos nucifera endocarp.

METHODS

DNS based assay was done to assess the α-amylase inhibition potential of ethanolic extract. Phytochemical screening and GC-MS analysis were done in order to assess the chemical profiling of extract. In silico docking studies were done using VLife MDS 4.6 software and the probable molecules, predicted after GC-MS analysis, were docked with the co-crystallized (acarbose) tracked active site and rest all cavities of porcine pancreatic α-amylase (1OSE). ADMET analysis was done using StarDrop 6.4, Derek Nexus and P450 Modules from Optibrium Ltd. and LHASA Ltd.

RESULTS

DNS based α-amylase assay indicated that the IC50 value of extract lies in the range of 63- 126 µg/ml and at higher doses, i.e. above 250 µg/ml, it has better α-amylase inhibition than the standard drug, acarbose. Phytochemical screening indicated that ethanolic extract is rich in alkaloids, tannins, flavonoids, saponins, triterpenes, glycosides, carbohydrates, terpenoids, quinones and lactones. Further, GC-MS analysis (where Similarity Index was > 90) predicted that the probable phytoconstituents present in the ethanolic extract are myristic acid, syringaldehyde, eugenol, vanillin, 2,4-di-tert-butylphenol, lauric acid, palmitic acid methyl ester and γ-sitosterol. γ-Sitosterol showed the strong affinity towards the active site which was tracked by a co-crystallized ligand along with cavity 1 and 2 while significant interactions were observed in case of co-crystallized tracked active site as well as cavity 4 of 1OSE. Ethanolic extract of C. nucifera has no hemolytic effect.

CONCLUSION

Its ability to effectively inhibit α-amylase may be attributed to the presence of the above probable molecules, which will be explored further.

The effect of a plant extract enriched in stigmasterol and β-sitosterol on glycaemic status and glucose metabolism in alloxan-induced diabetic rats

Banana is an extensively cultivated plant worldwide, mainly for its fruit, while its ancillary product, the banana pseudostem, is consumed as a vegetable and is highly recommended for diabetics in the traditional Indian medicine system. The present study was aimed at elucidating the mechanism of antihyperglycaemia exerted by the ethanol extract of banana pseudostem (EE) and its isolated compounds viz., stigmasterol (C1) and β-sitosterol (C2), in an alloxan-induced diabetic rat model. Diabetic rats which were administered with C1, C2 and EE (100 and 200 mg per kg b. wt.) for 4 weeks showed reduced levels of fasting blood glucose and reversal of abnormalities in serum/urine protein, urea and creatinine in diabetic rats compared to the diabetic control group of rats. Diabetic symptoms such as polyphagia, polydipsia, polyuria, urine glucose and reduced body weight were ameliorated in the diabetic group of rats fed with EE, C1 and C2 (100 mg per kg b. wt., once daily) for 28 days. The levels of insulin and Hb were also increased, while the HbA1c level was reduced. The altered activities of hepatic marker enzymes viz., aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP); glycolytic enzyme (hexokinase); shunt enzyme (glucose-6-phosphate dehydrogenase); gluconeogenic enzymes (glucose-6-phosphatase, fructose-1,6-bisphosphatase and lactate dehydrogenase) and pyruvate kinase were significantly reverted to normal levels by the administration of EE, C1 and C2. In addition, increased levels of hepatic glycogen and glycogen synthase and the corresponding decrease of glycogen phosphorylase activity in diabetic rats illustrated the antihyperglycaemic potential of EE and its components. The histological observations revealed a marked regeneration of the β-cells in the drug treated diabetic rats. These findings suggest that EE might exert its antidiabetic potential in the presence of C1 and C2, attributable to the enhanced glycolytic activity, besides increasing the hepatic glucose utilization in diabetic rats by stimulating insulin secretion from the remnant β-cells.

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.