Effect of curcumin on rats/mice with diabetic nephropathy: a systematic review and meta-analysis of randomized controlled trials

Role of curcumin on beta-amyloid protein, tau protein, and biochemical and oxidative changes in streptozotocin-induced diabetic rats

Diabetes is one of the most common endocrine metabolic diseases and is associated with the accumulation of beta-amyloid plaques in the brain. Amyloid beta (Aβ) and abnormal tau proteins are effective in the development of Alzheimer's disease. The aim of this study is to investigate the therapeutic and protective effects of curcumin on beta-amyloid (Aβ) accumulation and tau protein expression levels, as well as biochemical and oxidative changes in streptozotocin-induced diabetes in rats. The study comprised five groups, each consisting of eight rats: control, diabetic, curcumin, curcumin during diabetic induction, and curcumin post-diabetic induction. Groups 2 and 4 were administered a single dose of 45 mg/kg streptozotocin on day 1, while group 5 received it on day 28. Curcumin was orally administered via gavage at a dose of 100 mg/kg/day for 35 days to the third, fourth, and fifth groups. At the end of the trial (day 35), blood sugar levels and insulin resistance were similar between the control and curcumin-treated groups but significantly higher in the diabetic groups (P < 0.05). The protective effect of curcumin is tested during induction and active diabetes. The results indicated that diabetic rats displayed increased levels of Aβ, tau protein, and total oxidant capacity (TOS) compared to the curcumin-treated groups. Additionally, the total antioxidant capacity (TAS) levels were lower in the diabetic rats (P < 0.05). Aβ protein levels are lower in both the serum and brain of rats with active diabetes and treated with curcumin compared to control rats (P > 0.05). In addition, serum TAS levels were higher in rats treated with curcumin following the induction of diabetes than pre-induction of diabetes (P > 0.05). The TOS levels in the serum were higher in the rats treated with curcumin during active diabetes compared to the rats treated prior to the induction of diabetes (P < 0.05). However, no significant difference was observed in the brain. The above results show that curcumin has an effect on reducing oxidative stress caused by diabetes and increasing antioxidant activity.

Therapeutic Applications of Plant and Nutraceutical-Based Compounds for the Management of Type 2 Diabetes Mellitus: A Narrative Review

Diabetes mellitus is a condition caused by a deficiency in insulin production or sensitivity that is defined by persistent hyperglycemia as well as disturbances in glucose, lipid, and protein metabolism. Uncurbed diabetes or incessant hyperglycemic condition can lead to severe complications, including renal damage, visual impairment, cardiovascular disease, neuropathy, etc., which promotes diabetes-associated morbidity and mortality rates. The therapeutic management of diabetes includes conventional medications and nutraceuticals as complementary therapies. Nutraceuticals are bioactive compounds derived from food sources that have health-promoting properties and are instrumental in the management and treatment of various maladies. Nutraceuticals are clinically exploited to tackle DM pathogenesis, and the clinical evidence suggests that nutraceuticals can modulate biochemical parameters related to diabetes pathogenesis and comorbidities. Hypoglycemic medicines are designed to mitigate DM in traditional medicinal practice. This review intends to emphasize and comment on the various therapeutic strategies available to manage this chronic condition, conventional drugs, and the potential role of nutraceuticals in managing the complexity of the disease and reducing the risk of complications. In contrast to conventional antihyperglycemic drugs, nutraceutical supplements offer a higher efficacy and lesser adverse effects. To substantiate the efficacy and safety of various functional foods in conjunction with conventional hypoglycemic medicines, additional data from clinical studies are required.

Development and Validation of a Green Stability-Indicating HPTLC Method for Estimation of Curcumin, Gallic Acid, and Ursolic Acid From Polyherbal Formulation Jatyadi Taila

BACKGROUND

Jatyadi taila (JT) is a well-known Ayurvedic wound-healing product, comprising 16 different medicinally important plants, including Curcuma longa, Terminalia chebula, and Jasminum officinale.

OBJECTIVE

The proposed work discusses the development and validation of the green and economical stability-indicating HPTLC method for quantification of the key marker phytoconstituents, curcumin (CUR), gallic acid (GA), and ursolic acid (UA), from JT.

METHOD

Quality standard parameters for JT were determined following standard procedures. The marker constituents CUR, GA, and UA were resolved from JT using toluene-ethyl acetate-formic acid (6:2:1, v/v/v) as the mobile phase and subsequently derivatized to estimate UA. The developed plates were subjected to HPTLC-MS analysis. All constituents were subjected to forced degradation to determine the proposed technique's stability-indicating property and the accelerated stability studies of marketed formulation and marker constituents. Greenness evaluation of the method was aided by the AGREE methodology.

RESULTS

The Rf values of CUR, GA, and UA were found to be 0.60 and 0.60; 0.27 and 0.28; and 0.74 and 0.77 from reference standard and oil samples respectively, when analyzed at 366 nm, 290 nm, and 366 nm, respectively. HPTLC-MS was carried out to verify the active constituents present in JT. The constituents followed first-order degradation kinetics. The quantity of CUR, GA, and UA in JT was reduced at the end of accelerated stability studies. The developed approach was validated in compliance with the International Conference on Harmonization (ICH) Q2 (R2) guideline.

CONCLUSIONS

Among the chosen key markers, GA was highly unstable during forced degradation. JT should be stored at a controlled temperature using more protective packaging material to ensure its quality and efficacy.

HIGHLIGHTS

The developed method can be used as a quality control tool for JT as it can be used to determine the stability of the key marker compounds the herbal formulation.

Insights into the Uses of Traditional Plants for Diabetes Nephropathy: A Review

Diabetic nephropathy (DN) is a serious kidney illness characterized by proteinuria, glomerular enlargement, reduced glomerular filtration, and renal fibrosis. DN is the most common cause of end-stage kidney disease, accounting for nearly one-third of all cases of diabetes worldwide. Hyperglycemia is a major factor in the onset and progression of diabetic nephropathy. Many contemporary medicines are derived from plants since they have therapeutic properties and are relatively free of adverse effects. Glycosides, alkaloids, terpenoids, and flavonoids are among the few chemical compounds found in plants that are utilized to treat diabetic nephropathy. The purpose of this review was to consolidate information on the clinical and pharmacological evidence supporting the use of a variety of medicinal plants to treat diabetic nephropathy.

Mitochondrial Pathophysiology on Chronic Kidney Disease

In healthy kidneys, interstitial fibroblasts are responsible for the maintenance of renal architecture. Progressive interstitial fibrosis is thought to be a common pathway for chronic kidney diseases (CKD). Diabetes is one of the boosters of CKD. There is no effective treatment to improve kidney function in CKD patients. The kidney is a highly demanding organ, rich in redox reactions occurring in mitochondria, making it particularly vulnerable to oxidative stress (OS). A dysregulation in OS leads to an impairment of the Electron transport chain (ETC). Gene deficiencies in the ETC are closely related to the development of kidney disease, providing evidence that mitochondria integrity is a key player in the early detection of CKD. The development of novel CKD therapies is needed since current methods of treatment are ineffective. Antioxidant targeted therapies and metabolic approaches revealed promising results to delay the progression of some markers associated with kidney disease. Herein, we discuss the role and possible origin of fibroblasts and the possible potentiators of CKD. We will focus on the important features of mitochondria in renal cell function and discuss their role in kidney disease progression. We also discuss the potential of antioxidants and pharmacologic agents to delay kidney disease progression.

Salvia spinosa L. Protects against Diabetes-Induced Nephropathy by Attenuation of Mitochondrial Oxidative Damage in Mice

Mitochondrial oxidative damage is a crucial factor in the pathogenesis of diabetic nephropathy (DN), which is among the most prevalent problems of diabetes, and there hasn't been an effective treatment for DN yet. This study planned to investigate the effects of Salvia spinosa L. on mitochondrial function along with its protection against streptozotocin-induced nephropathy in diabetic mice. After the injection of streptozotocin (STZ) and verification of the establishment of diabetes, mice (n = 30) were randomly divided into the following groups: control group, diabetic-control, S. spinosa-treated diabetic (50, 100, and 200 mg/kg), and metformin-treated diabetic group (500 mg/kg). After four weeks of treatment, the mice were weighed. Blood and kidney tissues were examined for biochemical and histological evaluation. Hematoxylin and eosin staining was used for evaluating renal pathologic damage. Oxidative damage in the kidney was assessed by the evaluation of lipid peroxidation and glutathione oxidation. Furthermore, differential centrifugation was used to obtain the isolated mitochondria, and mitochondrial toxicity endpoints (mitochondrial function and mitochondrial oxidative markers) were determined in them. S. spinosa remarkably reduced the blood urea and creatinine concentrations, and also normalized kidney weight/body weight coefficient in the diabetic mice. S. spinosa ameliorated the incidence of glomerular and tubular pathological changes in histological analyses. Moreover, the oxidative and mitochondrial damages were notably attenuated in renal tissues of S. spinosa-treated mice. These results indicate that the methanolic extract of S. spinosa modulates the nephropathy in the diabetic mice by the amelioration of oxidatively induced mitochondrial damage and provides a reliable scientific base, suggesting S. spinosa as a promising alternative remedy against DN.

Effect of Curcumin on Diabetic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Clinical Trials

Background

Curcumin, a polyphenolic constituent from Curcuma longa, possesses antioxidant, hypolipidemic, and antidiabetic properties and has been reported to protect against diabetic kidney disease (DKD); however, the effect is inconsistent.

Objective

This systematic review and meta-analysis aimed to investigate the effect of curcumin supplementation on renal function, lipid profile, blood pressure, and glycemic control in DKD.

Methods

A systematic and comprehensive literature search of interrelated randomized controlled trials (RCTs) was conducted in PubMed, Embase, Cochrane Library, Web of Science, Scopus, and ClinicalTrials.gov from inception to July 30, 2021. Two investigators independently extracted data and assessed the risk of bias. Weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated to describe the effect sizes using a fixed-effect model. Statistical analysis was performed using STATA 14.0 and RevMan 5.3.

Results

Five RCTs involving 290 participants with DKD were included. Curcumin supplementation significantly improved the serum creatinine (WMD: −0.16 mg/dL, 95% CI: −0.3 to −0.02, P = 0.029, I² = 0%, moderate certainty), total cholesterol (WMD: −10.13 mg/dL, 95% CI: −17.84 to −2.14, P = 0.01, I² = 0%, moderate certainty), systolic blood pressure (WMD: 3.94 mmHg, 95% CI: 1.86 to 6.01, P < 0.01, I² = 33.5%, moderate certainty), and fasting blood glucose (WMD: −8.29 mg/dL, 95% CI: −15.19 to −1.39, P = 0.019, I² = 43.7%, moderate certainty) levels; however, it had no significant effects on blood urea nitrogen, proteinuria, triglyceride, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and diastolic blood pressure levels.

Conclusions

Curcumin may provide great potential effects against DKD. More large-scale and high-quality RCTs are required to confirm these findings.

Baicalin improves podocyte injury in rats with diabetic nephropathy by inhibiting PI3K/Akt/mTOR signaling pathway

Objective

To investigate the effect of baicalin on diabetic nephropathy (DN) rats and podocytes and its mechanism.

Methods

The rat models with DN were established by high-fat and high-sugar diet and intraperitoneal injection of streptozotocin. The fasting blood glucose (FBG) and weight of rats in each group were measured at 0, 1, 2, 3, and 4 weeks. Their biochemical indicators, expression of inflammatory, and antioxidant factors were measured using an automatic biochemical analyzer together with ELISA. Hematoxylin-eosin staining and periodic acid-schiff staining were used to observe the morphological changes in the kidneys of rats in each group. Finally, the expressions of related molecules and PI3K/Akt/mTOR signaling pathway proteins in renal tissues and podocytes were examined by qRT-PCR and Western blot.

Results

Compared with the DN group, the FBG and weight, serum creatinine, blood urea nitrogen, total cholesterol, triacylglycerol, microalbumin, and albumin/creatinine ratio were all significantly decreased in the Baicalin treatment groups in a concentration-dependent manner. The levels of inflammatory factors in kidney tissue and podocytes were decreased. In addition, the activities of lactate dehydrogenase and malondialdehyde in tissue were decreased, while the superoxide dismutase was increased. The pathological sections showed that glomerular atrophy and glomerular basement membrane thickening caused by hyperglycemia were improved in the Baicalin treatment groups. Meanwhile, baicalin inhibited the downregulation of Nephrin and Podocin expressions and upregulation of Desmin expression caused by DN, and inhibited the expressions of p-PI3K, p-Akt, and p-mTOR proteins.

Conclusion

Baicalin slows down podocyte injury caused by DN by inhibiting the activity of PI3K/Akt/mTOR signaling pathway.

Therapeutic application of nutraceuticals in diabetic nephropathy: Current evidence and future implications

Diabetes mellitus (DM) is a common metabolic disease which may cause several complications, such as diabetic nephropathy (DN). The routine medical treatments used for DM are not effective enough and have many undesirable side effects. Moreover, the global increased prevalence of DM makes researchers try to explore potential complementary or alternative treatments. Nutraceuticals, as natural products with pharmaceutical agents, have a wide range of therapeutic properties in various pathologic conditions such as DN. However, the exact underlying mechanisms have not been fully understood. The purpose of this review is to summarize recent findings on the effect of nutraceuticals on DN.

The protective effect of curcumin on the diabetic rat kidney: A stereological, electron microscopic and immunohistochemical study

The prevalence of diabetes in the world is increasing rapidly. Kidney diseases are among the most common medical disorders. The aim of this study was to investigate the effect of curcumin on the diabetic kidney. Thirty-five female Wistar albino rats were divided into seven groups. No procedure was performed on the Cont group. The Sham group received corn oil via gavage for 14 days. The curcumin (Curc) group received 30-mg/kg curcumin for 14 days, while the diabetes mellitus (DM) group received 50-mg/kg streptozotocin (STZ) in a single dose intraperitoneally. The DM + curcumin 1 (DC1) group received 30 mg/kg curcumin for 14 days, seven days after the application of STZ, while the DM + curcumin 2 (DC2) received 30 mg/kg curcumin for 14 days, 21 days after the application of STZ, and the DM + curcumin 3 (DC3) group received single-dose STZ at the same time as the application of 30 mg/kg curcumin for 14 days. Medulla, cortex, tubule, and glomerulus volume ratios were calculated using stereological techniques. Cortex volumes in the Sham and DM groups were significantly lower than in the Cont group (p < 0.05). The cortex volume in the DC3 group was also significantly lower than in the Curc group (p < 0.05). Medullary volume was significantly higher in the DC3 group compared to the DM group (p < 0.05). Curcumin was determined to exhibit a protective effect on the diabetic kidney since the glomerulus in the curcumin-exposed group exhibited a well-protected structure following experimentally induced diabetes based on light and electron microscopic analysis findings. These findings suggest that curcumin used following experimentally induced diabetes exhibits protective effects on the diabetic kidney.

Protective effects of pharmacological agents against aminoglycoside-induced nephrotoxicity: A systematic review

Introduction: Aminoglycosides have been long used for antibacterial treatment and are still commonly used in clinical practice. Despite their extensive application and positive effects, drug-related toxicity is considered as the main obstacle for aminoglycosides. Aminoglycosides induce nephrotoxicity through the endocytosis and accumulation of the antibiotics in the epithelial cells of proximal tubule. Most importantly, however, a number of pharmacological agents were demonstrated to have protective activities against nephrotoxicity in experimental animals.Areas covered: In the present systematic review, the authors provide and discuss the mechanisms and epidemiological features of aminoglycoside-induced nephrotoxicity, and focus mainly on recent discoveries and key features of pharmacological interventions. In total, 39 articles were included in this review.Expert opinion: The majority of studies investigated gentamicin-induced nephrotoxicity in animal models. Antioxidants, chemicals, synthetic drugs, hormones, vitamins, and minerals showed potential values to prevent gentamicin-induced nephrotoxicity. Indicators used to evaluate the effectiveness of nephroprotection included antioxidative indexes, inflammatory responses, and apoptotic markers. Among the nephroprotective agents studied, herbs and natural antioxidant agents showed excellent potential to provide a protective strategy against gentamicin-induced nephrotoxicity.

Curcumin alleviates diabetic nephropathy via inhibiting podocyte mesenchymal transdifferentiation and inducing autophagy in rats and MPC5 cells

Context: Curcumin could ameliorate diabetic nephropathy (DN), but the mechanism remains unclear.Objective: The efficacy of curcumin on epithelial-to-mesenchymal transition (EMT) of podocyte and autophagy in vivo and in vitro was explored.Materials and methods: Thirty male Sprague-Dawley rats were divided into the normal, model and curcumin (300 mg/kg/d, i.g., for 8 weeks) groups. Rats received streptozotocin (50 mg/kg, i.p.) and high-fat-sugar diet to induce DN. Biochemical indicators and histomorphology of renal tissues were observed. In addition, cultured mouse podocytes (MPC5) was induced to EMT with serum from DN rats, and then exposed to curcumin (40 µM) with or without fumonisin B1, an Akt specific activator or 3BDO, the mTOR inducer. Western blot analysed the levels of EMT and autophagy associated proteins.Results: Administration of curcumin obviously reduced the levels of blood glucose, serum creatinine, urea nitrogen and urine albumen (by 28.4, 37.6, 33.5 and 22.4%, respectively), and attenuated renal histomorphological changes in DN rats. Podocytes were partially fused and autophagic vacuoles were increased in curcumin-treated rats. Furthermore, curcumin upregulated the expression of E-cadherin and LC3 proteins and downregulated the vimentin, TWIST1, p62, p-mTOR, p-Akt and P13K levels in DN rats and MPC5 cells. However, fumonisin B1 or 3BDO reversed the effects of curcumin on the expression of these proteins in cells.Discussion and conclusions: The protection against development of DN by curcumin treatment involved changes in inducing autophagy and alleviating podocyte EMT, through the PI3k/Akt/mTOR pathway, providing the scientific basis for further research and clinical applications of curcumin.

Natural phenolic compounds potentiate hypoglycemia via inhibition of Dipeptidyl peptidase IV

Dipeptidyl peptidase IV (DPP IV) is a surface glycoprotein that can degrade glucagon like pepetide-1 (GLP-1) by decreasing blood sugar. Herbal medicines for diabetic therapy are widely used with acceptable efficacy but unsatisfied in advances. DPP IV was chosen as a template to employ molecular docking via Discovery Studio to search for natural phenolic compounds whether they have the inhibitory function of DPP IV. Then, docking candidates were validated and further performed signal pathway via Caco-2, C2C12, and AR42J cells. Lastly, a diet-induced diabetes in mice were applied to examine the efficacy and toxicity of hit natural phenolic products in long-term use (in vivo). After screening, curcumin, syringic acid, and resveratrol were found in high affinity with DPP IV enzymes. In enzymatic tests, curcumin and resveratrol showed potential inhibition of DPP IV. In vitro assays, curcumin inhibited of DPP IV activity in Caco-2 cells and ERK phosphorylation in C2C12 cells. Additionally, curcumin attenuated blood sugar in S961-treated C57BL/6 mice and in diet-induced diabetic ICR mice and long-term regulate HbA1c in diabetic mice. Curcumin targeted to DPP IV for reducing blood glucose, it possesses potential and alternative substitution of synthetic clinical drugs for the medication of diabetes.

Efficacy of curcumin on prevention of drug-induced nephrotoxicity: A review of animal studies

Drug-induced nephrotoxicity is a frequent serious adverse effect, contributing to morbidity and increased healthcare utilization. Prevention or reversal is key. Curcumin has useful biological features that include antioxidant, anti-inflammatory, and anticancer properties. This review covers aspects of curcumin in relation to prevention of drug-induced nephrotoxicity: dosage and schedule, effect on kidney biomarkers and histological changes, and mechanisms of curcumin's protective effects. Despite success in some animal models, human studies and clinical administration of curcumin for nephroprotection remains limited due to difficulty in achieving therapeutic levels following oral administration and in determining the optimal dosing schedule. Lack of sufficient evidence from animal studies, coupled with low systemic bioavailability, continues to limit the utilization of curcumin in addressing and controlling drug-induced nephrotoxicity. Therefore, human studies are required to fully assess and validate the therapeutic potential of curcumin.

Zerumbone Ameliorates High Glucose-Induced Reduction in AMP-Activated Protein Kinase Phosphorylation in Tubular Kidney Cells

AMP-activated protein kinase (AMPK) plays an important role in pathophysiology of diabetes and its complications. In recent years, its role in kidney as a therapeutic target in ameliorating diabetic kidney damage is receiving renewed attention. Efforts on identifying AMPK modulators from dietary sources have gained prominence because of the tremendous potential it harbors. We therefore, examined the effect of a few bioactives on AMPK phosphorylation in kidney tubular cells. AMPK phosphorylation at Thr¹⁷² was reduced (0.42 ± 0.05-fold change compared to the control; p < 0.01 vs control) after treatment with high glucose (30 mM) for 48 h and restored by zerumbone (1.59 ± 0.20; p < 0.01 vs high glucose) but not by other tested modulators. Zerumbone also increased the phosphorylation of downstream target of AMPK, the acetyl-CoA carboxylase (ACC) without affecting the mitochondrial membrane potential and ADP/ATP ratio. Thus, zerumbone could potentially be explored as a therapeutic agent in bringing about energy homeostasis in diabetes where high glucose suppresses the AMPK pathway.

Effect of curcumin on glycerol-induced acute kidney injury in rats

The aim of this study was to investigate the protective role and underlying mechanisms of curcumin on glycerol-induced acute kidney injury (AKI) in rats. Glycerol (10 ml/kg BW, 50% v/v in sterile saline, i.m.) was used to induce AKI, followed by curcumin (200 mg/kg/day, p.o.) administration for 3 days. To confirm renal damage and the effects of curcumin on AKI, serum BUN, Scr, and CK as well as renal SOD, MDA, GSH-Px were measured. Additionally, morphological changes were identified by H&E staining and transmission electron microscopy. The expression of several factors including chemotactic factor MCP-1, proinflammatory cytokines including TNF-α and IL-6, as well as the kidney injury markers, as Kim-1 and Lipocalin-2 were also assessed using q-PCR. Finally, cell apoptosis in renal tissue was detected using in situ TUNEL apoptosis fluorescence staining and expression of proteins associated with apoptotic, oxidative stress and lipid oxidative related signaling pathways were detected using immunohistochemical staining and western blot. The results showed that curcumin exerts renoprotective effects by inhibiting oxidative stress in rhabdomyolysis-induced AKI through regulation of the AMPK and Nrf2/HO-1 signaling pathways, and also ameliorated RM-associated renal injury and cell apoptosis by activating the PI3K/Akt pathway.

Curcumin inhibits cell proliferation and promotes apoptosis of laryngeal cancer cells through Bcl-2 and PI3K/Akt, and by upregulating miR-15a

Curcumin is a natural compound extracted from the dried rhizomes of Curcuma (curcuma root or zedoary) that exhibits extensive pharmacological effects and low toxicity. The aim of the present study was to investigate whether curcumin inhibits cell proliferation and promotes apoptosis of laryngeal cancer through Bcl-2 and phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), and by upregulating microRNA-15a (miR-15a). It was demonstrated that curcumin inhibits cell proliferation, and promotes apoptosis and increased caspase-3 activity of human laryngeal cancer cells. Furthermore, curcumin decreased Bcl-2 and PI3K protein expression, and decreased the phospho (p)-Akt protein expression of human laryngeal cancer cells. Furthermore, curcumin activated miR-15a expression by human laryngeal cancer cells. Suppression of miR-15a expression reversed the anticancer effect of curcumin on cell proliferation of human laryngeal cancer cells and increased Bcl-2 and PI3K/Akt protein expression in AMC-HN-8 cells treated with 40 µM of curcumin. The results of the present study suggest that curcumin inhibits cell proliferation and promotes apoptosis of laryngeal cancer cells through Bcl-2 and PI3K/Akt, and by upregulating miR-15a.

Natural antioxidants in the treatment and prevention of diabetic nephropathy; a potential approach that warrants clinical trials

Diabetic nephropathy is the major cause of end-stage renal disease and effective and new therapeutic approaches are needed in diabetic nephropathy and chronic kidney diseases. Oxidative stress and inflammatory process are important factors contributing to kidney damage by increasing production of oxidants. KEAP1/Nrf2/ARE pathway regulates the transcription of many antioxidant genes and modulation of the pathway up regulates antioxidants. NFB controls the expression of genes involved in the inflammatory response. Natural substances have antioxidant and anti-inflammatory activities and have an impact on NFB and KEAP1/Nrf2/ARE pathways. The preclinical studies explored the effectiveness of whole herbs, plants or seeds and their active ingredients in established diabetic nephropathy. They ameliorate oxidative stress induced kidney damage, enhance antioxidant system, and decrease inflammatory process and fibrosis; most likely by activating KEAP1/Nrf2/ARE pathway and by deactivating NFB pathway. Whole natural products contain balanced antioxidants that might work synergistically to induce beneficial therapeutic outcome. In this context, more clinical studies involving whole plants or herbal products or mixtures of different herbs and plants and their active ingredients might change our strategies for the management of diabetic nephropathy. The natural products might be useful as preventive interventions and studies are required in this field.

Inhibitory effect of curcumin on angiogenesis in a streptozotocin-induced diabetic rat model: An aortic ring assay

BACKGROUND

Curcumin (diferuloylmethane) has been associated with the inhibition of angiogenesis, as well as the prevention of cancers and inflammatory processes. The aim of this study was to assess the efficacy of curcumin in suppressing angiogenesis in the cultured endothelial cells of rat aortic rings.

METHODS

Eight-week-old male Wistar rats were randomized into five groups each with a different treatment and cell culturing paradigm: controls cultured in the absence of VEGF (vascular endothelial growth factor) (C), controls cultured in the presence of VEGF (C-V), controls treated with curcumin and then cultured in media lacking VEGF (C-TC), diabetics cultured in media supplemented with VEGF (D-V) and diabetics treated with curcumin and then cultured in media supplemented with VEGF (D-V-TC). Each group consisted of 8 animals. Diabetes was induced in by streptozotocin (STZ; 60 mg/kg body weight, IV). After 8 weeks, animals were sacrificed and their aortas were excised. Ring-shaped explants were embedded in a 96-well culture plate. Angiogenesis response was measured by counting the number of primary microtubules in each well.

RESULTS

Optic microscopy revealed that the D-V group had the highest number of microvessels, while angiogenesis was not observed in the C or C-TC groups. The number of primary microtubules was significantly lower in the D-V-TC group compared to the D-V group (P < 0.05). The D-V-TC group had a significantly higher number of microvessels compared to the C-TC group (P < 0.05).

CONCLUSION

Curcumin attenuates angiogenesis response in stertozotocin-induced diabetic rats.

Review of Herbal Traditional Chinese Medicine for the Treatment of Diabetic Nephropathy

Diabetic nephropathy (DN) is the most serious chronic complications of diabetes; 20-40% of diabetic patients develop into end stage renal disease (ESRD). However, exact pathogenesis of DN is not fully clear and we have great difficulties in curing DN; poor treatment of DN led to high chances of mortality worldwide. A lot of western medicines such as ACEI and ARB have been demonstrated to protect renal function of DN but are not enough to delay or retard the progression of DN; therefore, exploring exact and feasible drug is current research hotspot in medicine. Traditional Chinese medicine (TCM) has been widely used to treat and control diabetes and its complications such as DN in a lot of scientific researches, which will give insights into the mechanism of DN, but they are not enough to reveal all the details. In this paper, we summarize the applications of herbal TCM preparations, single herbal TCM, and/or monomers from herbal TCM in the treatment of DN in the recent 10 years, depicting the renal protective effects and the corresponding mechanism, through which we shed light on the renal protective roles of TCM in DN with a particular focus on the molecular basis of the effect and provide a beneficial supplement to the drug therapy for DN.

The Effect of Curcumin on an Animal Intestinal Ischemia/Reperfusion Model for Bacterial Translocation and Inflammatory Response

Ischemia/reperfusion (IR) injury of the intestine is a major problem in abdominal pathological condition and is associated with a high morbidity and mortality. The purpose of the study is to investigate the effects of curcumin on the bacterial translocation incidence and inflammatory response in rats submitted to bowel ischemia reperfusion injury. Thirty-two Wistar albino rats with a weight of 200 to 250 g were used in the study. They were randomly divided into 3 groups (n = 10 for each group): sham only operated group(group I); IR group (group II); and IR + curcumin treatment group (group III). Curcumin (curcumin from Curcuma longa) 20 mg/kg/day was given orally to the curcumin group. All animals were given 109 E. Coli by orogastric intubation 12 hours before sampling. Seventy-two hours after the first operation, mesenteric lymph node and blood samples were obtained and cultured. Blood samples of 2 mL were obtained for a polymerase chain reaction study. A piece of terminal ileum was also sampled for histopathologic examination. Mesenteric lymph node and blood cultures of all control animals were positive for microbiological growth, and polymerase chain reaction results were positive in seven of the eight rats. Histopathologically, edema, vasodilatation and inflammatory cell infiltration were found to be less in the other groups in comparison to the control group. Curcumin reduced bacterial translocation in blood, hepatocellular damage, and plasma cytokine levels. Curcumin reduced the incidence of bacterial translocation in intestinal I/R. rats. These results suggest that Curcumin would be clinically useful in the treatment of intestinal I/R injury.

Protective effects of curcumin on acute gentamicin-induced nephrotoxicity in rats

Background: Gentamicin-induced nephrotoxicity is one of the most common causes of acute kidney injury (AKI). The phenotypic alterations that contribute to acute kidney injury include inflammatory response and oxidative stress. Curcumin has a wide range biological functions, especially as an antioxidant. This study was designed to evaluate the renoprotective effects of curcumin treatment in gentamicin-induced AKI. Methods: Gentamicin-induced AKI was established in female Sprague–Dawley rats. Rats were treated with curcumin (100 mg/kg body mass) by intragastric administration, once daily, followed with an intraperitoneal injection of gentamicin sulfate solution at a dose of 80 mg/kg body mass for 8 consecutive days. At days 3 and 8, the rats were sacrificed, and the kidneys and blood samples were collected for further analysis. Results: The animals treated with gentamicin showed marked deterioration of renal function, together with higher levels of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) in the plasma as compared with the controls. Animals that underwent intermittent treatment with curcumin exhibited significant improvements in renal functional parameters. We also observed that treatment with curcumin significantly attenuated renal tubular damage, apoptosis, and oxidative stress. Curcumin treatment exerted anti-apoptosis and anti-oxidative effects by up-regulating Nrf2/HO-1 and Sirt1 expression. Conclusions: Our data clearly demonstrate that curcumin protects kidney from gentamicin-induced AKI via the amelioration of oxidative stress and apoptosis of renal tubular cells, thus providing hope for the amelioration of gentamicin-induced nephrotoxicity.