The nutraceutical benefits of subfractions of Abelmoschus esculentus in treating type 2 diabetes mellitus

Effects of dried okra extract on lipid profile, renal function and some RAGE-related inflammatory genes expression in patients with diabetic nephropathy: A randomized controlled trial

BACKGROUND

Diabetic nephropathy (DN) is a common complication of type 2 diabetes. Okra (Abelmoschus esculentus L) is reported to have anti-diabetic effects. The present study aimed to investigate the effects of dried okra extract (DOE) supplementation on lipid profile, renal function indices, and expression of inflammatory genes, as well as serum level of soluble Receptor for Advanced glycation end products (sRAGE) in patients with DN.

METHODS

In this triple-blind randomized placebo-controlled clinical trial, 64 eligible patients with DN received either 125 mg of DOE or placebo daily along with DN-related nutritional recommendations for 10 weeks. Changes in kidney indices including proteinuria and estimated glomerular filtration rate (eGFR), lipid profile, serum SRAGE, as well as the expression of RAGE, ICAM-1, and IL-1 genes were measured over 10 weeks.

RESULTS

After adjustment for the potential confounders, between-group analyses showed no significant differences in terms of lipid profile, kidney function indices, sRAGE, and RAGE-related inflammatory genes expression after 10 weeks.

CONCLUSION

Daily 125 mg DOE along with nutritional recommendations on top of usual care did not lead to significant changes in renal function indices, lipid profile, and inflammatory genes expression in patients with DN.

Clinical efficacy and safety of okra (Abelmoschus esculentus (L.) Moench) in type 2 diabetic patients: a randomized, double-blind, placebo-controlled, clinical trial

AIMS

The recent trend toward the use of natural functional and medical supplements has motivated the focus on the search and revival of traditional medicinal plant applications for many years. As a valuable dietary crop, okra fruit (Abelmoschus esculentus (L.) Moench) has been used for thousands of years as a medicinal food. This clinical trial aimed to assess the efficacy and safety of the okra pod capsule as an adjuvant treatment in controlling type 2 diabetes mellitus and provide clinical trial-based evidence about its anti-inflammatory effects.

METHODS

A total of 100 type II diabetic patients, aged between 40 and 60 years, were randomly assigned into two groups of okra and placebo. The first group was administered 1000 mg of powdered okra fruit three times a day for 3 months, while the other group received a placebo capsule with the same dosage. Both groups continued the standard antidiabetic therapy (consisting of metformin and gliclazide, as well as a nutritional regimen). At the start and three months later, various factors were measured, including FBG, insulin, HbA1c, cholesterol, triglycerides, HDL, LDL, CRP, liver and renal function tests, blood pressure, and BMI changes.

RESULTS

According to the results, patients who received okra treatment exhibited a significant decrease in FBG, HbA1c, total cholesterol, and triglyceride levels when compared to both the baseline and the placebo group. Patients in the okra group have lower levels of hs-CRP compared with the placebo group after 3 months of treatment. No liver, kidney, and blood pressure or other side effects were observed in the groups associated with okra treatment.

CONCLUSIONS

The present study demonstrated that adjunctive consumption of okra, in type 2 diabetic patients with 1000 mg three times a day for three months, improves lipid profile, glycemic control, and chronic inflammation without any tangible adverse effects.

CLINICAL TRIAL REGISTRY

IRCT.Ir (IRCT20120112008712N2). https://www.irct.ir/trial/42042 .

Effects of okra (Abelmoschus esculentus (L.) Moench) on glycemic markers in animal models of diabetes: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Okra (Abelmoschus esculentus (L.) Moench) is traditionally used by different populations of Africa, América, Asia, and Europa to control diabetes. Although its action has been evaluated in several preclinical rodent trials, they have not been systematically analyzed.

OBJECTIVE

To evaluate the effectiveness of using okra in the treatment of diabetes in experimental rodent models.

MATERIAL AND METHODS

Controlled and randomized rodent animal trials with induced diabetes published between January 2000 and January 2021 were searched in the PubMed, Scopus, Scielo, and Web of Science databases. The search strategy included studies comprising the descriptors: animal species, diabetes induction method, intervention time, part of okra fruit used (whole, seeds, or peels), and dose as well as observed effects on biochemical and metabolic parameters. The systematic review was carried out according to the PRISMA statement, Cochrane bias risk tool (SYRCLE's RoB tool), and registered for systematic review protocols (PROSPERO).

RESULTS

A total of 326 articles were identified and after the exclusion of studies with gestational animal models, non-rodent animals, and non-diabetic animals, 11 studies involving 388 rodents were selected for the synthesis of results. The diabetes induction methods included streptozotocin, streptozotocin-nicotinamide, alloxan monohydrate, insulin resistance by high-fat diets or formulation described in AIN - 76, and feeding with high-fat food. Both Wistar albino rats, Sprague-Dawley males, and rats of both sexes of the Long-Evans lineage as well as male albino mice and C57BL females were included in the experiments. Studies showed that extracts of the fruit, the fresh fruit, or its various fractions had positive effects on the following markers: glycated hemoglobin, cholesterol, HOMA-IR, oral glucose tolerance test, and blood glucose, in acute (2 and 24 h), and chronic (up to 4 months) treatment.

CONCLUSION

An important hypoglycemic effect of okra in its various fractions on induced diabetes was observed by different authors. Moreover, okra promoted improvement in metabolic markers such as insulin sensitivity, lipid profile, and bodyweight loss.

Chitosan Nanogel with Mixed Food Plants and Its Relation to Blood Glucose in Type 2 Diabetes: A Systematic and Meta-Analysis Review of Observational Studies

This systematic review with metanalysis evaluated and analyzed the beneficial effects of certain plants food in type 2 diabetes (T2D) when consumed alone or in combination with chitosan. The main objective of the paper was to examine the relation of chitosan nanogel and mixed food plant (MFP) to control T2D. The databases included Medline, Scopus, PubMed, as well as Cochrane available between the month of January 1990 to January 2021. The eligibility criteria for selecting studies were case-controlled studies that included unripe plantain, bitter yam, okra, and chitosan either used-alone or in combination with non-specified food plants (NSFP). Two-fold autonomous critics retrieved the information required and evaluated the risk of bias of involved studies. Random-effect meta-analyses on blood glucose controls, were performed. Results of 18 studies included: seven that examined unripe plantains, one bitter yam, two okras, and eight chitosan, found regarding the decrease in blood glucose level. Meta-analysis of the results found a large proportion of I² values for all studies (98%), meaning heterogeneity. As a consequence, the combined effect sizes were not useful. Instead, prediction interval (PI) was used (mean difference 4.4 mg/dL, 95% PI -6.65 to 15.50 and mean difference 3.4 mg/dL, 95% PI -23.65 to 30.50) rather than the estimate of its confidence interval (CI). These studies were at 50% high risk of bias and 50% low risk of bias and there was judged to be an unclear risk of bias due to the insufficient information from the included study protocol (moderately low). The intervention lasted between three and 84 days, indicating potency and effectiveness of the intervention at both short and long durations. Due to the moderately low quality of the studies, the findings were cautiously interpreted. In conclusion, the current evidence available from the study does support the relation of chitosan with mixed unripe plantain, bitter yam and okra for the management of T2D. Further high-quality case-controlled animal studies are required to substantiate if indeed chitosan nanogel should be cross-linked with the specified food plant (SFP) for the management T2D.

Capsaicin combined with dietary fiber prevents high-fat diet associated aberrant lipid metabolism by improving the structure of intestinal flora

Capsaicin (CAP) and dietary fibers are natural active ingredients that given separately do positively affect obesity and metabolic diseases. However, it was unknown whether their combined administration might further improve blood lipids and gut flora composition. To test this hypothesis we administered capsaicin plus dietary fibers (CAP + DFs) to male rats on a high-fat diet and analyzed any changes in the intestinal microbiota make up, metabolites, and blood indexes. Our results showed that combining CAP with dietary fibers more intensely reduced total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). CAP + DFs also increased gut bacteria variety, and the abundance of several beneficial bacterial strains, including Allobaculum and Akkermansia, while reducing harmful strains such as Desulfovibrio. Additionally, CAP + DFs significantly increased arginine levels and caused short-chain fatty acids accumulation in the contents of the cecal portion of rats' gut. In conclusion, notwithstanding the rats were kept on a high-fat diet, adding CAP + DFs to the chow further improved, as compared with CAP alone, the lipidemia and increased the gut beneficial bacterial strains, while reducing the harmful ones.

Capsaicin regulates lipid metabolism through modulation of bile acid/gut microbiota metabolism in high-fat-fed SD rats

Capsaicin (CAP) is one of the active ingredients found in chili peppers and has been shown to reduce fat. This study aimed to explore the mechanisms of CAP activity by investigating intestinal microorganisms and bile acids (BAs). This study utilized 16S RNA sequencing to detect gut microbiota in cecal contents, and BAs in Sprague Dawley (SD) rats were also investigated. The results showed that 1) CAP increased the levels of chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), β-muricholic acid (β-MCA), and tauro-β-muricholic acid sodium salt (T-β-MCA), which can regulate farnesoid X receptor (FXR) to inhibit Fgf15, increased CYP7A1 expression to lower triglycerides (TG) and total cholesterol (TC); 2) CAP decreased the abundance of Firmicutes and promoted the presence of specific fermentative bacterial populations, like Akkermansia; meanwhile, less optimal dose can reduce Desulfovibrio; 3) CAP decreased inflammatory factors IL-6 and IL-1β, and increased transient receptor potential channel of vanilloid subtype 1 (TRPV1) to regulate lipid metabolism, fasting plasma glucose and insulin resistance. In conclusion, CAP can reduce fat accumulation by regulating BAs, microorganisms, and short-chain fatty acids.

Abelmoschus esculentus subfractions ameliorate hepatic lipogenesis and lipid uptake via regulating dipeptidyl peptidase-4—With improving insulin resistance

Nonalcoholic fatty liver disease (NAFLD) is recognized as the liver component of metabolic syndrome. The regulation of hepatic lipid should be emphasized to prevent accompanying illness. As AMP-activated protein kinase (AMPK) and sterol regulatory element binding protein (SREBP) regulate lipid metabolism, CD36 and fatty acid synthase (FAS) promote lipid uptake and lipogenesis respectively, while acetyl-CoA carboxylase (ACC) is an indicator of negative feedback. The increase of IRS-1 phosphorylation at the residue ser307 (p-ser307-IRS-1) and decrease of p-ser473-Akt (p-Akt) are viewed as the insulin resistance markers, and our previous reports suggested dipeptidyl peptidase-4 (DPP-4) mediates insulin resistance, the crucial factor of metabolic syndrome. Abelmoschus esculentus (AE) fruit is well-known for its antidiabetic utility. We had isolated several AE subfractions by successive steps, and found that F1 and F2 were especially valid in suppressing DPP-4 signaling. Since little is known if AE works on NAFLD, now we first attempt to investigate whether AE is useful to attenuate hepatic lipogenesis and lipid uptake in liver cells, along with improving the metabolic targets. We demonstrated that AE subfractions attenuated the hepatic lipid accumulation induced by free fatty acids. Treatment of AE alleviated FAS and returned the level of p-ser79-ACC (p-ACC). Although F1 was more effective on AMPK, F2 seemed more stable to attenuate SREBP-1. Moreover, as fatty acids stimulated the expression of CD36, F2 showed a superior effect to down-regulate the lipid uptake. Both AE subfractions reduced the generation of ROS, decreased the level of p-ser307-IRS-1, and restored the expression of p-Akt. Moreover, treatment of DPP-4 inhibitor linagliptin revealed that, AE could prevent the hepatic lipogenesis, oxidative burden, and the related insulin resistance via downregulating DPP-4. In conclusion, the present investigation revealed that AE, especially F2, is potential to be developed as adjuvant to prevent NAFLD.

Characterization of the chemical profile and the effects of ethanolic extracts of Maytenus ilicifolia Mart. ex Reissek on glucose metabolism in normal hyperglycemic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Maytenus ilicifolia Mart. ex Reissek, Celastraceae, is popularly known as "espinheira-santa" and used to treat pathologies related to the stomach. However, in popular culture, this species has also been used to treat other disorders such as diabetes, but without scientific evidence, requiring more phytochemical and pharmacological studies on the plant.

AIM OF THE STUDY

This work aims to investigate the anti-hyperglycemic potential of ethanolic extracts obtained from leaves from two different accessions of Maytenus ilicifolia (MIA and MIB) in normal hyperglycemic rats.

MATERIALS AND METHODS

The animals were divided into different experimental groups: normal hyperglycemic (negative control); MIA (treatment of Maytenus ilicifolia extract from access 116); MIB (treatment with Maytenus ilicifolia extract from access 122; and glipizide (positive control). At 30 min after treatment, all animals received glucose overload orally. Blood collection occurred at different periods for the assessment of blood glucose (0, 60, 90 and 210 min after treatment) and at the end of the experiment blood was collected through cardiac puncture and the liver, muscle, pancreas and intestine were dissected for further analysis.

RESULTS

Chromatographic analysis identified oleic and palmitic acid as the most common constituents, and both extracts of Maytenus ilicifolia caused a reduction in blood glucose levels within 60 min after administration of glucose overload when compared to the normal hyperglycemic group. No significant changes were observed in hepatic and muscular glycogen levels, plasma insulin concentration and disaccharidases activity with none of the extracts in the model employed. However, hyperglycemic rats treated with the extracts showed a marked increase in triglyceride and HDL cholesterol levels.

CONCLUSIONS

Our data suggest that Maytenus ilicifolia extracts from different locations showed differences in chemical composition which did not reflect significant differences in the results of biological tests. In addition, it was possible to conclude that the treatment with Maytenus ilicifolia had a discreet anti-hyperglycemic effect; however, it was not possible to identify the responsible mechanism, being necessary, therefore, new studies using different technologies in order to determine the possible mechanisms of action of the extract.

Pressurized Hot Water Extraction of Okra Seeds Reveals Antioxidant, Antidiabetic and Vasoprotective Activities

Abelmoschus esculentus L. Moench (okra) is a commonly consumed vegetable that consists of the seeds and peel component which are rich in polyphenolic compounds. The aim of this study is to utilize pressurized hot water extraction (PHWE) for the extraction of bioactive phytochemicals from different parts of okra. A single step PHWE was performed at various temperatures (60 °C, 80 °C, 100 °C and 120 °C) to determine which extraction temperature exhibits the optimum phytochemical profile, antioxidant and antidiabetic activities. The optimum temperature for PHWE extraction was determined at 80 °C and the biological activities of the different parts of okra (Inner Skin, Outer Skin and Seeds) were characterized using antioxidant (DPPH and ABTS), α-glucosidase and vasoprotective assays. Using PHWE, the different parts of okra displayed distinct phytochemical profiles, which consist of primarily polyphenolic compounds. The okra Seeds were shown to have the most antioxidant capacity and antidiabetic effects compared to other okra parts, likely to be attributed to their higher levels of polyphenolic compounds. Similarly, okra Seeds also reduced vascular inflammation by downregulating TNFα-stimulated VCAM-1 and SELE expression. Furthermore, metabolite profiling by LC/MS also provided evidence of the cytoprotective effect of okra Seeds in endothelial cells. Therefore, the use of PHWE may be an alternative approach for the environmentally friendly extraction and evaluation of plant extracts for functional food applications.

Abelmoschus esculentus subfractions attenuate Aβ and tau by regulating DPP-4 and insulin resistance signals

Background

Insulin resistance could be associated with the development of Alzheimer disease (AD). The neuropathological hallmarks of AD are beta amyloid (Aβ) produced from sequential cleavage initiated by β-secretase and degraded by insulin degradation enzyme (IDE), as well as hyperphosphorylation of tau (p-tau). Insulin action involves the cascades of insulin receptor substrates (IRS) and phosphatidylinositol 3-kinase (PI3K), while phosphorylation of IRS-1 at ser307 (p-^ser307IRS-1) hinders the response. Our previous report suggested dipeptidyl peptidase-4 (DPP-4) is crucial to insulin resistance, and the subfractions of Abelmoschus esculentus (AE), F1 and F2, attenuate the signaling. Here we aim to investigate whether AE works to reduce Aβ generation via regulating DPP4 and insulin resistance.

Methods

The subfractions F1 and F2 were prepared according to a succession of procedures. F1 was composed by quercetin glycosides and triterpene ester, and F2 contained a large amount of polysaccharides. The in vitro insulin resistance model was established by SK-N-MC cell line treated with palmitate. MTT was used to define the dose range, and thereby Western blot, ELISA, and the activity assay were used to detect the putative markers. One-way ANOVA was performed for the statistical analysis.

Results

Treatment of palmitate induced the level of p-^ser307IRS-1. Both F1 and F2 effectively decrease p-^ser307IRS-1, and recover the expression of p-PI3K. However, the expression of total IRS plunged with 25 μg/mL of F1, while descended steadily with 5 μg/mL of F2. As palmitate increased the levels of Aβ40 and Aβ42, both AE subfractions were effective to reduce Aβ generation of and β-secretase activity, but IDE was not altered in any treatment conditions. The expression of DPP4 was also accompanied with insulin resistance signals. Inhibition of DPP4 attenuated the activity of β-secretase and production of Aβ. Moreover, the present data revealed that both AE subfractions significantly decrease the level of p-Tau.

Conclusions

In conclusion, we demonstrated that AE would be a potential adjuvant to prevent insulin resistance and the associated pathogenesis of AD, and F2 seems more feasible to be developed.

Structural Properties, Bioactivities, and Applications of Polysaccharides from Okra [Abelmoschus esculentus (L.) Moench]: A Review

Okra [Abelmoschus esculentus (L.) Moench], as a kind of nutritive vegetable, is rich in flavonoids, polyphenols, polysaccharides, amino acids, and other bioactive substances and has various biological activities. As one of main bioactive components, okra polysaccharides (OPs), mainly comprising pectic polysaccharides, have various biological activities. OPs have been extensively investigated in recent years. Many studies characterized structures of OPs obtained by different extraction methods, which were confirmed to be rhamnogalacturonan-I-type polysaccharides in most cases. OPs have a thick and slimy texture, suggesting that they can be a promising source of texture modifiers for complex food matrices. They have various biological activities, such as antioxidant activity, immunomodulatory activity, hypoglycaemic activity, and improving intestinal function. Therefore, OPs may potentially serve as novel immunomodulators or an adjuvant for diabetic nephropathy. Up to now, there is no specific summary on the research progress of OPs. In this paper, the latest research progress on the extraction, purification, characterization, rheological properties, biological activities, and applications of OPs is reviewed, to provide the reference for the processing and comprehensive utilization of OPs in the future.

The effect of okra (Abelmoschus esculentus) on lipid profiles and glycemic indices in Type 2 diabetic adults: Randomized double blinded trials

The aim of the present study was to investigate the effect of okra consumption on serum levels of lipid profiles and glycemic indices in Type 2 diabetic (T2D) patients. The present study was a randomized, double-blinded clinical trial, carried out in Kerman, Iran. Sixty T2D patients were randomized into intervention and control groups and received 10 g okra powder blended in 150 g conventional yogurt or conventional yogurt alone, along with dinner and lunch, for 8 weeks. Glycemic markers and lipid profile were assessed, as well as anthropometric measures, at the beginning and end of study. The findings showed that 8 weeks okra consumption resulted in a significant decrease in fasting plasma glucose (-15.61 ± 19.44 vs. -3.40 ± 24.78; p = .02), homeostatic model of assessment for insulin resistance (-1.17 ± 1.61 vs. -0.14 ± 1.64; p = .01), quantitative insulin sensitivity check index (0.01 ± 0.007 vs. 0.00 ± 0.01; p = .004), triacylglycerol (-22.30 ± 32.46 vs. -3.86 ± 30.57; p = .001), total cholesterol (-10.23 ± 10.36 vs. -2.03 ± 13.94; p = .004), low-density lipoprotein cholesterol (LDL-C; -8.15 ± 10.01 vs. -2.31 ± 9.37; p = .02), and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio (-0.28 ± 0.37 vs. -0.08 ± 0.24; p = .01). No significant difference was observed between groups in HDL-C, glycated hemoglobin, fasting insulin levels, and anthropometric measures. The present study suggests that okra consumption can elicit improvements in lipid profile, as well as glycemic markers, among T2D patients.

High fat-induced inflammation in vascular endothelium can be improved by Abelmoschus esculentus and metformin via increasing the expressions of miR-146a and miR-155

Background

Obesity is associated with chronic inflammation, which contributes to cardiovascular diseases. MicroRNAs (miRNAs) are reported to be involved in vascular inflammation and atherosclerosis. Abelmoschus esculentus (AE) and metformin have been suggested to improve inflammation in vascular system. The aim of this study is to evaluate whether miRNAs are involved in high fat induced endothelial inflammation, and whether AE and metformin improve endothelial inflammation by regulating miRNAs.

Methods

We established high fat treated rats and human aortic endothelial cells (HAECs). AE and metformin were added to explore their effects on endothelial inflammation induced by high fat and the possible mechanism.

Results

The vascular inflammatory genes were increased in rats treated with high fat diet. The decreased miR-146a and miR-155 were involved in endothelial inflammation induced by high fat through targeting IL-1 receptor-associated kinase 1 (IRAK1), TNF receptor-associated factor 6 (TRAF6) and nuclear factor-κB p65 (NF-κB p65), respectively. While AE and metformin could ameliorate the endothelial inflammation by increasing miR-146a and miR-155.

Conclusions

These results indicate that miR-146a and miR-155 play roles in the high fat induced endothelial inflammation, which could be potential therapeutic targets. AE and metformin can attenuate endothelial inflammation through regulating miR-146a and miR-155.

Quercetin and Isoquercitrin Inhibiting Hepatic Gluconeogenesis Through LKB1-AMPKα Pathway

Objective

To observe the impact of quercetin and isoquercitrin on gluconeogenesis in hepatocytes.

Methods

Mouse primary hepatocytes were cultured with lactic acid and pyruvic acid. After treatment with quercetin and isoquercitrin for 24 hours, the glucose concentration in the culture supernatant was determined. RT-PCR was used to detect the mRNAs of PEPCK, G6Pase, LKB1, and AMPKα. Protein levels of LKB1, AMPKα, and Thr172 phosphorylation were evaluated by Western blot.

Results

The glucose concentration in the gluconeogenesis group (GN) was significantly higher than in the control group (C), but the glucose concentrations in the high level quercetin(group 80Q) and high level isoquercitrin (group 80I) were significantly lower than in the group GN, P<0.01. In the group 80Q, and group 80I, the mRNA levels of PEPCK and LKB1were significantly lower than in the group GN (P<0.01), and the G6Pase mRNA were significantly lower than in the group GN (P<0.05). The protein levels of LKB1 and the phosphorylation of AMPKα Thr172 in the group 80Q, group 40I, and group 80I were higher than in the group GN. The effects of quercetin and isoquercitrin on LKB1 and AMPKα were similar to those of metformin.

Conclusions

Quercetin and isoquercitrin inhibit gluconeogenesis in hepatocytes, which may be related to the LKB1 upregulation and phosphorylation of AMPKα.

Abelmoschus esculentus subfractions attenuate beta amyloid-induced neuron apoptosis by regulating DPP-4 with improving insulin resistance signals

The association of Alzheimer disease (AD) and Diabetes (DM) is less clear. Accumulation of beta amyloid (Aβ) and presence of hyperphosphorylated tau (p-tau) are hallmarks of AD, spreading in the region where insulin receptors are also found. Aβ exerts neuron toxicity, and could disturb insulin signaling of phosphatidylinositol 3-kinase (PI3K), glycogen synthase kinase (GSK)-3β and AMP-activated protein kinase (AMPK), but increase IRS-1-Ser307 phosphorylation which is viewed as insulin resistance marker. Previously we reported dipeptidyl peptidase-4 (DPP-4) mediate insulin resistance signals, and Abelmoschus esculentus (AE) subfractions F1 (rich in quercetin glucosides and triterpene ester) and F2 (containing large amount of polysaccharides) attenuate DPP-4-mediated apoptosis. In the present study, we aim to investigate if Aβ induce neuron death by regulating DPP-4 and insulin resistance signals, and the putative effect of F1 and F2. By MTT, microscopy, and Western blotting, we demonstrate treatment of appropriate doses of AE subfractions prevent Aβ-induced neuron apoptosis. F1 attenuate Aβ-induced caspase 3 expression especially at 25 μg/mL, while F2 attenuate caspase 3 activation even at the low dose of 1 μg/mL. Both AE subfractions decrease Aβ-enhanced DPP-4, but increase Aβ-reduced p-AMPK and p-PI3K. The activity analysis reveals that F2 is more valid than F1 to reduce DPP-4 activity. The inhibition of DPP-4 demonstrates it plays the pivotal role in Aβ-induced neuron apoptosis. Moreover, although both F1 and F2 are effective to inhibit p-IRS-1-Ser307, F2 takes advantage to reduce p-Tau while F1 is superior to enhance p-GSK-3β. This implies AE subfractions act on different targets, and could be developed respectively. In conclusion, we demonstrate AE is potential to prevent Aβ-induced neuron damage by regulating DPP-4 and the insulin resistance cascades. AE could be an adjuvant to protect neuron degenerative disease related to Aβ and insulin resistance.

Abelmoschus esculentus subfractions improved nephropathy with regulating dipeptidyl peptidase-4 and type 1 glucagon-like peptide receptor in type 2 diabetic rats

Abelmoschus esculentus (AE) has been used in traditional medicine to ameliorate hyperglycemia, but its mucilage increased bioassay difficulties. We have obtained a series of AE subfractions. Among them F1 and F2 regulated dipeptidyl peptidase-4 (DPP-4) and type 1 glucagon-like peptide receptor (GLP-1R), the treatment targets for type 2 diabetes. F1, F2 and fraction residues (FR) showed advantage on different aspects, which attenuates insulin resistance and metabolic disorder in vivo, and prevents renal-tubular change in vitro. In the present study, using type 2 diabetes model induced by high fat diet (HFD) and streptozotocin (STZ), we aim to investigate whether AE prevent diabetic nephropathy by regulating the putative markers. The results showed that all the subfractions ameliorated albuminuria and renal hyperfiltration (measured by creatinine clearance rate; CCr) accompanied with diabetes, while F2 acted most promptly and consistently. Histologically AE reduced renal tubular change, fibrosis and fat deposition. F2 and FR exerted significant effects to decrease DPP-4 while increase GLP-1R. Although all the subfractions were effective to reduce oxidative stress, only F2 acted on kidneys specifically. In conclusion, we have demonstrated AE has benefits to regulate DPP-4 and GLP-1R, to reduce oxidative stress and renal fibrosis, with resultant to improve renal function and prevent diabetic renal damage. Taken together, F2 could be more promising to be developed as adjuvant for diabetic nephropathy.