Attenuation of diabetic nephropathy by Chaihuang-Yishen granule through anti-inflammatory mechanism in streptozotocin-induced rat model of diabetics

Ethnopharmacological relevance

Traditional Chinese medical herbs have been used in China for a long time to treat different diseases. Based on traditional Chinese medicine (TCM) principle, Chaihuang-Yishen granule (CHYS) was developed and has been employed clinically to treat chronic kidney disease including diabetic nephropathy (DN). The present study was designed to investigate its mechanism of action in treatment of DN.

Materials and methods

Diabetic rats were established by having a right uninephrectomy plus a single intraperitoneal injection of STZ. Rats were divided into four groups of sham, diabetes, diabetes with CHYS and diabetes with fosinopril. CHYS and fosinopril were given to rats by gavage for 20 weeks. Samples from blood, urine and kidney were collected for biochemical, histological, immunohistochemical and molecular analyses.

Results

Rats treated with CHYS showed reduced 24 h urinary protein excretion, decreased serum TC and TG levels, but CHYS treatment did not affect blood glucose level. Glomerular mesangial expansion and tubulointerstitial fibrosis in diabetic rats were significantly alleviated by CHYS treatment. Moreover, CHYS administration markedly reduced mRNA levels of NF-κB p65 and TGF-β1, as well as decreased protein levels of NF-κB p65, MCP-1, TNF-α and TGF-β1 in the kidney of diabetic rats.

Conclusions

CHYS ameliorates renal injury in diabetic rats through reduction of inflammatory cytokines and their intracellular signaling.     

KIOM-79 prevents S100b-induced TGF-β1 and fibronectin expression in mouse mesangial cells

Aim of the study

In this study, we investigated whether KIOM-79 inhibits transforming growth factor-beta 1 (TGF-β1) and fibronectin expression in mouse mesangial cells cultured under S100b, a specific ligand of the receptor for advanced glycation end products (RAGE).

Materials and methods

Cell counting kit (CCK-8) assay was employed to evaluate the viability of KIOM-79-treated mesangial cells. The effect of KIOM-79 on S100b-induced TGF-β1 and fibronectin expression was investigated using RT-PCR, ELISA, and Western blot on mesangial cells.

Results

KIOM-79 (up to 50 μg/ml) appeared to have no effect on cell viability. S100b induced an increase in the expression TGF-β1 and fibronectin. Expression of TGF-β1 and fibronectin was inhibited significantly by KIOM-79 treatment in mesangial cells. KIOM-79 also inhibited the expression of NF-kB and inactivated p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) 1/2 in mesangial cells. KIOM-79 pretreatment inhibited increased malondialdehyde (a product of lipid peroxidation and a marker for oxidative stress) levels in S100b-induced mesangial cells.

Conclusions

These data demonstrate that KIOM-79 inhibits expression of TGF-β1 and fibronectin through inactivation of MAPK/ERK1/2 signaling, reduction in malondiadehyde levels, and inhibition of NF-kB in mesangial cells cultured under diabetic conditions. KIOM-79 could be beneficial for preventing of the development of diabetic complications such as nephropathy.     

Low-dose of multi-glycoside of Tripterygium wilfordii Hook. f., a natural regulator of TGF-β1/Smad signaling activity improves adriamycin-induced glomerulosclerosis in vivo

Ethnopharmacological relevance

Transforming growth factor (TGF)-β1/Smad signaling pathway plays a critical role in the prolonged glomerulosclerosis (GS), which is an important determinant during the progression in chronic kidney disease (CKD). For recent 30 years, multi-glycoside of Tripterygium wilfordii Hook. f. (GTW), an extract from Chinese herbal medicine has been proved clinically effective in improving GS in CKD in China. However, therapeutic mechanisms involved in vivo are still unclear. In this study, we aimed to explain the dose-effects and molecular mechanisms of GTW on GS by regulating TGF-β1/Smad signaling activity in adriamycin (ADR)-induced nephropathy (ADRN).

Materials and methods

Rats with ADRN, created by unilateral nephrectomy and twice adriamycin injections (ADR, 4 mg/kg and 2 mg/kg) within 4 weeks, were divided into four groups, the Sham group, the Vehicle group, the low-dose GTW-treated group, and the high-dose GTW-treated group, and that, sacrificed at the end of the 6th week after administration. Proteinuria, blood biochemical parameters, glomerulosclerotic morphological makers, podocyte shape, and nephrin expression were examined, respectively. Protein expressions of key signaling molecules in TGF-β1/Smad pathway, such as TGF-β1, Smad3, phosphorylated-Smad2/3 (p-Smad2/3), and Smad7, were also evaluated individually.

Results

The results indicated that the characterizations of ADRN involved the typical prolonged GS, a small amount of abnormal proteinuria, and the failing renal function; TGF-β1/Smad signaling molecules, especially Smad3, p-Smad2/3, and Smad7 were activated in vivo, accompanied by the exasperation of glomerulosclerotic lesion; GTW at high-dose (100 mg/kg) and low-dose (50 mg/kg) could slightly ameliorate the prolonged GS and nephrin expression, furthermore, the anti-proliferative action of GTW at high-dose was superior to that at low-dose, but caused the significant liver injury; in ADRN model rats, protein expressions of TGF-β1, p-Smad2/3, and Smad7 in the kidneys could be regulated with the treatment of GTW at low-dose.

Conclusion

This study farther demonstrated that the low-dose of GTW, as a natural regulator in vivo, could effectively and safely ameliorate the prolonged GS in FSGS model, via the potential molecular mechanisms involving the reduction of ECM components and the suppression of TGF-β1 over-expression, as well as the bidirectional regulation of TGF-β1/Smad signaling activity.     

Ginsenoside-Rg1 protects podocytes from complement mediated injury

Aim of the study

Podocytes injury mediated by complement complex C5b-9 is the main feature of membranous nephropathy (MN). Little work has been done to prove that ginsenoside-Rg1 could inhibit this process. Our study aims to investigate the efficacy of ginsenoside-Rg1 in protecting the podocyte from complement mediated injury.

Materials and methods

We chose sublethal C5b-9 induced podocyte injury as the model of MN in vitro. Ginsenoside-Rg1 was given as an intervention. Morphological changes were observed by electron microscope and fluorescence microscope. The production of reactive oxygen species (ROS) was detected by flow cytometry. The expression of the mitogen activated protein kinase (MAPK) including JNK, ERK and P38 was detected by western-blot technique.

Results

Ginsenoside-Rg1 could protect foot processes of podocytes, suppress the damage of F-actin, decrease the production of ROS, and inhibit the activation of P38 kinase pathway.

Conclusion

These results suggest that ginsenoside-Rg1 could protect podocyte from sMAC-induced injury partly because of its antioxidant property and inhibit the activation of P38 kinase pathway.     

Huangkui capsule,an extract from Abelmoschus manihot (L.) medic,ameliorates adriamycin-induced renal inflammation and glomerular injury via inhibiting p38MAPK signaling pathway activity in rats

Ethnopharmacological relevance

Abelmoschus manihot (L.) medic (AM) is a natural medicinal plant used for the treatment of inflammatory diseases in China. Huangkui capsule (HKC), an extract from AM, has been proved clinically effective in improving renal inflammation and glomerular injury in chronic kidney disease (CKD). However, the dose-effects and the mechanisms involved in vivo are still unclear.

Aim of the study

This study was performed to examine the dose-effects of HKC on renal inflammation and glomerular lesion in adriamycin-induced nephropathy (ADRN), then to clarify the mechanisms in vivo of HKC by investigating its actions on modulating the activation of p38 mitogen-activated protein kinase (p38MAPK) signaling pathway.

Materials and methods

The rats with chronic ADRN, created by the unilateral nephrectomy and twice adriamycin injections (ADR, 4 mg/kg and 2 mg/kg) within 4 weeks, were divided into four groups, a Sham group, a Vehicle group, a high-dose HKC group, and a low-dose HKC group, and that, sacrificed at the end of the 4th week after the administration. The rat's general status, renal morphological appearance, proteinuria, blood biochemical parameters, glomerular morphological changes, podocyte shape, and macrophage (ED1⁺ and ED3⁺ cells) infiltration in glomeruli were examined, respectively. The protein expressions of inflammatory cytokines including tumor necrosis factor (TNF)-α and interleukin (IL)-2, as well as p38MAPK signaling molecules such as transforming growth factor (TGF)-β1, p38MAPK, and phosphorylated-p38MAPK (p-p38MAPK), were also evaluated individually.

Results

HKC at high dose of 2 g/kg/d not only significantly ameliorated the rat's general status, renal morphological appearance, proteinuria, albumin, and glomerulosclerosis, but also obviously reduced the infiltrated ED1⁺ and ED3⁺ macrophages in glomeruli and TNF-α protein expression in the kidney, in addition to these, evidently down-regulated TGF-β1 and p-p38MAPK protein expressions in ADRN rats, but had no influence on podocyte shape and renal function.

Conclusion

HKC could dose-dependently ameliorate renal inflammation and glomerular injury in ADRN rats, by way of reducing the infiltration and the activation of macrophages in glomeruli, and TNF-α protein expression in the kidney, as well as inhibiting p38MAPK signaling pathway activity via the down-regulation of p-p38MAPK and TGF-β1 protein expressions in vivo.     

Zhen-wu-tang, a blended traditional Chinese herbal medicine, ameliorates proteinuria and renal damage of streptozotocin-induced diabetic nephropathy in rats

Ethnopharmacological relevance

Zhen-wu-tang (ZWT) is a blended traditional Chinese medicine specifically used for various kidney diseases.

Aim of the study

The present study is to evaluate the effects of ZWT on diabetic nephropathy and investigate the potential anti-diabetic mechanisms.

Materials and methods

Streptozotocin (STZ)-induced diabetic rats were orally administrated ZWT (80,320 mg/kg b.w.) once a day, for a period of 12 weeks. Body weight, urinary volume, urine protein and blood biochemical parameters were measured every 3 weeks. At the end of the observation period, kidneys were isolated for histology, angiotensin II content determination, real time PCR and Western blot analyses.

Results

ZWT (320 mg/kg b.w.) prevented body weight loss, reduced polyurea, urinary protein excretion, serum creatinine and blood urea nitrogen, although it did not alter the hyperglycemia. It ameliorated glomerular hypertrophy and expansion of the mesangial area, swell and effacement of foot process. It also suppressed the increased expression of angiotensin II, nephrin and podocin.

Conclusions

Data from this study suggest that ZWT possess a protective effect on renal damage of STZ-induced diabetic nephropathy in rats, by suppressing hyperactivity of renal renin-angiotensin system that turns in to modulate renal nephrin and podocin expressions, thereby protecting podocyte from injury.     

Bioactive compounds from Cornus officinalis fruits and their effects on diabetic nephropathy

Ethnoparmacological relevance

The fruit of Cornus officinalis, called “Shanzhuyu”, a traditional medicine in China, is used for the treatment of kidney diseases, including diabetic nephropathy. The aim of this study is to investigate the anti-diabetic nephropathy activity of Shanzhuyu and the active compounds in the fruit.

Materials and methods

The air dried fruit of Cornus officinalis was extracted in 80% EtOH, the obtained residue was fractioned on D101 resin column eluted with H₂O/EtOH solution to get five crude fractions (fr. A–E). The anti-diabetic nephropathy activity of fractions (fr. A–E) was evaluated in vitro by inhibiting the expression of collagen IV (Col V), fibronectin (FN) and IL-6 in high-glucose-induced mesangial cells. By preliminary bio-assay screenings, repeated column chromatography on fraction B–D led the isolation of 22 compounds, whose structures were determined by extensive spectroscopic analysis, and the anti-diabetic nephropathy activity of the isolated compounds was also evaluated.

Results

Two new iridoid glucosides, logmalicids A and B (1 and 2), together with 20 known compounds (3–22) were isolated from the extract of Shanzhuyu under the bioassay-guided screenings. The anti-diabetic nephropathy activity assay displayed that fractions A, D and E could significantly inhibit the production of Col IV; fractions A and C could significantly inhibit the expression of FN and IL-6 in the high-glucose-stimulated mesangial cells at concentration of 50 μg/mL; and loganin (3) and its derivatives (1 and 2) could significantly inhibit the expression of FN and IL-6 at concentration of 10 μM, respectively.

Conclusions

The results suggested that loganin and its derivatives were the active compounds in Cornus officinalis fruit (Shanzhuyu) on diabetic nephropathy. This study further supported the traditional use of Shanzhuyu to treat diabetic nephropathy and related kidney diseases.     

Clinical trials of traditional Chinese medicine in the treatment of diabetic nephropathy—A systematic review based on a subgroup analysis

Ethnopharmacological relevance

The purpose of this study is to systematically evaluate the efficacy of traditional Chinese medicine (TCM) decoctions with different ingredients in the treatment of diabetic nephropathy (DN).

Materials and methods

Papers obtained after the retrieval of randomized controlled clinical trials (RCTs) of TCM treatments of diabetic nephropathy through online database (e.g. Medline, CBM, CNKI, VIP, the online database of Chinese medicine, CDFD, CMFD, and CENTRAL FROM Cochrane Library, etc.) as well as research data in our library. They were published between January 2001 and December 2012. According to the categories of the main TCM ingredients, all the cases in the literature were divided into a liver–kidney YIN deficiency group, a QI-BLOOD YIN-and-YANG deficiency group, and a spleen–kidney YANG deficiency group. Stata 11.0 was applied for subgroup analysis.

Results

A total of 21 Chinese RCTs were included in this review. The Q values of the three groups were 13.18, 0.25 and 3.27, respectively, P>0.05, and thus, there was no clinical heterogeneity. The combined relative risk (RR) value and its 95% confidence interval were 1.48 (1.37, 1.60), 1.19 (1.06, 1.34), and 1.33 (1.19, 1.50), respectively, P<0.05.

Conclusions

Compared with the qi-blood yin-and-yang deficiency group and the spleen–kidney yang deficiency group, the liver–kidney yin deficiency group has better prospects in clinical application to ensure renal function during the treatment of DN, and this possibility is worthy of further study.     

Korean red ginseng (Panax ginseng) ameliorates type 1 diabetes and restores immune cell compartments

Ethnopharmacological relevance

Historical records reveal that in traditional medicine, a disease similar to diabetes was treated with ginseng. Korean red ginseng has been considered beneficial as a dietary supplement for its anti-diabetic potential.

Aim

This study was designed to investigate the prophylactic potential of Korean red ginseng (KRG) extract (Panax ginseng C.A. Meyer Radix Rubra) in a well-established mouse model of Type 1 diabetes (T1D).

Materials and methods

The prophylactic effect of KRG extract was evaluated in mice fed with KRG extract for two weeks prior to induction of diabetes by streptozotocin (STZ) administration. Glucose levels and glucose challenge test results of KRG-treated diabetic mice were compared to those of untreated diabetic mice and healthy control mice. Examination of the immune compartments in lymphoid organs and immunohistochemical staining of pancreas for islet cell morphology and insulin producing beta cells were performed.

Results

KRG extract significantly lowered blood glucose levels to an average of 250 mg/dl from 350 mg/dl and improved glucose challenge testing when applied as prophylaxis. Histological findings indicated that KRG extract protected against STZ-induced destruction of pancreatic tissue and restored insulin secretion. Strikingly, this effect was accompanied by restoration of lymphocytes in secondary lymphoid organs, suggesting that KRG extract facilitated immune homeostasis.

Conclusion

This is the first report to demonstrate the prophylactic function of KRG extract in ameliorating the hyperglycemia of T1D. Immune compartments of diabetic mice were found to be preserved in KRG-treated mice suggesting that Korean red ginseng may benefit T1D patients, not only for its hypoglycemic but also for its immunomodulatory effects.     

KIOM-79 prevents apoptotic cell death and AGEs accumulation in retinas of diabetic db/db mice

Aim of the study

KIOM-79 retards the development of diabetic nephropathy in animal models of type 1 and type 2 diabetes. In this study, we evaluated whether KIOM-79 could prevent apoptotic cell death and advanced glycation end products (AGEs) accumulation in the retinas of diabetic db/db mice.

Material and methods

Mice were treated orally with KIOM-79 (150 mg/kg body weight) once daily for 12 weeks. Levels of retinal ganglion cell death were measured by terminal dUTP nick-end labeling (TUNEL) assay. In the retina, the activity of caspase-3 (a marker of apoptosis) and the formation of AGEs were measured by immunohistochemical staining.

Results

KIOM-79 reduced the number of TUNEL-immunoreactive retinal cells. KIOM-79 attenuated caspase-3 expression and AGEs accumulation in the retina.

Conclusions

These data show that KIOM-79 can prevent apoptosis in neuronal cells, AGEs accumulation in the retina, and retard the development of diabetic retinopathy.     

KIOM-79 prevents xylose-induced lens opacity and inhibits TGF-beta2 in human lens epithelial cells cultured under high glucose

Aim of the study

To investigate the effects of KIOM-79 in preventing the development of diabetic complications, such as cataracts.

Materials and methods

The inhibitory effects of KIOM-79 were assessed in a model of xylose-induced lens opacity and on changes mediated by high levels of glucose in human lens epithelial (HLE-B3) cells.

Results

In lenses treated with KIOM-79, opacity was significantly improved and glutathione (GSH) was increased compared to controls. In HLE-B3 cells treated with KIOM-79, high glucose-mediated increases in TGF-β2, αB-crystallin, and fibronectin were significantly inhibited in a dose-dependent manner. KIOM-79 decreased the phosphorylation of p-Smad2/3, pp38MAPK, pp44/42, and NF-κB signaling in cells grown under high glucose conditions.

Conclusion

KIOM-79 is protective against lens opacity and protects HLE-B3 cells from the toxic effects of high glucose. Therefore, KIOM-79 may provide a potential therapeutic approach for preventing diabetic complications, such as cataracts.     

“Qufeng Tongluo” acupuncture prevents the progression of glomerulonephritis by decreasing renal sympathetic nerve activity

Ethnopharmacological relevance

Although the exact mechanism(s) underlying acupuncture remain unknown, acupuncture and acupuncture-like somatic nerve stimulation have been used to treat different kidney diseases and several complications related to them.The aim of this preliminary study was to assess the effectiveness of acupuncture on glomerulonephritis (GN) according to the theory of “Wind-hided renal collaterals” previously proposed.

Material and methods

We used a New Zealand white rabbit model of cationized bovine serum albumin (cBSA)-induced glomerulonephritis and then administered them metoprolol, irbesartan or acupuncture to evaluate the effectiveness of acupuncture treatment and preliminarily explore its potential mechanism.

Results

After immunization, our results showed that compared to the cBSA+MET and cBSA+IRB medication groups, “Qufeng Tongluo” significantly lowered parameters of renal function and improved podocyte injury in the 3rd, 6th and 8th weeks of treatment. Moreover, acupuncture increased the protein expression of phosphorylated ERK1/2.

Conclusions

Our study suggests that a potential mechanism by which acupuncture has an antihypertensive effect and can significantly halt deteriorating renal function due to cBSA GN might be mediated by inhibiting the Erk1/2 MAPK pathway to reduce renal sympathetic nerve activity (RSNA).     

Analysis of TCM syndrome elements and relevant factors for senile diabetes

Objective

To explore the laws governing the distribution of TCM syndrome elements (SEs) of senile diabetes (SD) and their relationship to relevant factors.

Method

An investigation of patients who met the inclusion criteria was conducted by trained doctors, using case report forms. All related data were collected, including body mass index (BMI =body weight [kg]/height² [m]), glycated hemoglobin, illness course, complications, symptoms, and tongue and pulse manifestation. The SEs of each patient were judged by three qualified associate chief physicians independently.

Result

The main SEs of SD are Yin deficiency, Qi deficiency, blood stasis, and phlegm turbidity. Yin deficiency, Qi deficiency, blood stasis, and phlegm turbidity are most commonly seen among 4-SE combinations. Yang deficiency is typically related to illness course and BMI, phlegm turbidity to hypertension and hyperlipidemia, excessive heat to diabetic microangiopathy, and blood stasis to illness course and diabetic macroangiopathy.

Conclusion

SD pathogenesis has a deficiency in origin and excess in superficiality. Deficiency syndrome mainly manifests as deficiency of both Qi and Yin, and concurrently in Yang deficiency. Excess syndrome is characterized by blood stasis and phlegm turbidity. SE analysis provides a basis for the prevention and treatment of SD with Traditional Chinese Medicine (TCM) and lays the foundation for objectively evaluating multicentric clinical research for SD in TCM.     

Anti-diabetic effects of Centratherum anthelminticum seeds methanolic fraction on pancreatic cells, β-TC6 and its alleviating role in type 2 diabetic rats

Ethnopharmacological relevance

Seeds of Centratherum anthelminticum (Asteraceae) have been popularly used in Ayurvedic medicine to treat diabetes and skin disorders. Folk medicine from Rayalaseema (Andhra Pradesh, India) reported wide spread usage in diabetes.

Aim of the study

To investigate the hypoglycemic properties and mechanism of the methanolic fraction of C. anthelminticum seeds (CAMFs) on mouse β-TC6 pancreatic cell line and streptozotocin (STZ)-induced diabetic rat models.

Materials and Methods

We investigated the crude methanolic fraction of C. anthelminticum seeds (CAMFs) on β-TC6 cell line and confirmed its effects on type 1 and type 2 diabetic rats to understand its mechanism in managing diabetes mellitus. CAMFs were initially tested on β-TC6 cells for cytotoxicity, 2-NBDG glucose uptake, insulin secretion and glucose transporter (GLUT-1, 2 and 4) protein expression. Furthermore, streptozotocin (STZ)-induced type 1 diabetic and STZ-nicotinamide-induced type 2 diabetic rats were intraperitoneally (i.p) injected or administered orally with CAMFs daily for 28 days. The effect of CAMFs on blood glucose and insulin levels was subsequently evaluated.

Results

In cell line studies, CAMFs showed non-cytotoxic effect on β-TC6 cell proliferation compared to untreated control cells at 50 μg/ml. CAMFs increased glucose uptake and insulin secretion dose-dependently by up-regulating GLUT-2 and GLUT-4 expression in these cells. Further in vivo studies on streptozotocin induced diabetic rat models revealed that CAMFs significantly reduced hyperglycemia by augmenting insulin secretion in type 2 diabetic rats. However, CAMFs displayed less significant effects on type 1 diabetic rats.

Conclusions

CAMFs demonstrated anti-diabetic potential on β-TC6 cells and type 2 diabetic rat model, plausibly through enhancing glucose uptake and insulin secretion.     

The anti-inflammation effect of Moutan Cortex on advanced glycation end products-induced rat mesangial cells dysfunction and High-glucose–fat diet and streptozotocin-induced diabetic nephropathy rats

Ethnopharmacological relevance

Moutan Cortex (MC, family: Paeonia suffruticosa Andr.) is a well-known traditional herbal medicine that has been shown to hold a protective effect on inflammation in several diseases. However, its anti-inflammatory activity on diabetic nephropathy (DN) has been less reported. The present study was conducted to evaluate the potential attenuation activities of MC on inflammation in AGEs-induced rat mesangial cells dysfunction and high-glucose–fat diet and streptozotocin (STZ)-induced DN rats and explore the possible mechanism underlying its DN effect.

Materials and methods

The inflammation in mesangial cells (HBZY-1) was induced by 200 μg/ml advanced glycation end products (AGEs). DN rats model was established by an administration high-glucose–fat diet and an intraperitoneal injection of STZ (30 mg/kg). Interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) level in cell supernatant and rats serum were detected by appropriate kits. A co-culture system of mesangial cells and macrophages was performed to evaluate the migration of macrophages. Immunohistochemical assay was applied to examine transforming growth factor beta1 (TGF-β1), IL-6, MCP-1 and intercellular adhesion molecule-1 (ICAM-1) expression in kidney tissues of rats. Furthermore, western blot analysis was carried out to examine TGF-β1, IL-6, MCP-1, ICAM-1 and RAGE protein expressions in mesangial cells.

Results

Pretreatment with MC could significantly inhibit AGEs-induced migration of macrophages in the co-culture system of mesangial cell and macrophage. MC could decrease IL-6 and MCP-1 levels in serum of DN rats in a dose-dependent manner. Furthermore, MC also improved the blood glucose, serum creatinine and urine protein levels. Both immunocytochemistry analysis and western blot analysis showed that MC decreased significantly the over-expression of IL-6, MCP-1, TGF-β1, ICAM-1 and RAGE in mesangial cells or kidney tissues. Additionally, the protein expression of proinflammatory cytokine could also be down-regulated by the pretreatment of RAGE-Ab (5 μg/ml).

Conclusion

These findings indicated that the extract of MC had an amelioration activity on the inflammation in AGEs-induced mesangial cells dysfunction and high-glucose–fat diet and STZ-induced DN rats. The protective effect might be associated with the intervention of MC via target of RAGE. These findings suggested that MC might be a benefit agent for the prevention and treatment of DN.     

Protection of glycyrrhizic acid against AGEs-induced endothelial dysfunction through inhibiting RAGE/NF-κB pathway activation in human umbilical vein endothelial cells

Ethnopharmacological relevance

Licorice (Glycyrrhiza uralensis roots) is used as a traditional medicine for the treatment of diabetes mellitus and its vascular complications. Glycyrrhizic acid (GA, also known as Glycyrrhizin), a triterpenoid saponin glycoside, is considered to be a bioactive component in Licorice and is beneficial to diabetic vascular complications.

Aim of study

The present study was conducted to evaluate the potential protective activities on AGEs-induced endothelial dysfunction, including anti-apoptosis, antioxidant stress and anti-proinflammatory responses, and explore the underlying mechanism.

Materials and methods

Human umbilical vein endothelial cells (HUVECs) were incubated and pre-treated with GA (10⁻⁹–10⁻⁶ M) or RAGE-Ab (5 μg/ml) in the presence or absence of 200 μg/ml AGEs. AO/EB fluorescence staining assay was performed to evaluate anti-apoptosis activity. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) level in cell supernatant were detected by kits while the intracellular reactive oxygen species (ROS) generation was determined by 2,7-dichlorodihydrofluorescin diacetate (DCFH-DA) kit. Immunocytochemistry analysis was designed to determine transforming growth factor beta1(TGF-β1) protein expression while immunofluorescence analysis for RAGE and NF-kB. The protein expressions of TGF-β1, RAGE and NF-kB were analyzed by Western blot analysis.

Results

Pretreatment with GA at a concentration of 10⁻⁸–10⁻⁶ M significantly reduced the AGEs-induced apoptosis in HUVECs. GA significantly increased antioxidant enzyme SOD activity and decreased peroxide degradation product MDA level in a dose-dependent manner. Furthermore, GA also remarkably inhibited the overgeneration of AGEs-induced ROS. Both immunocytochemistry analysis and western blot analysis showed that GA significantly decreased the protein expression of poinflammatory cytokine TGF-β1 in a similar manner which RAGE-Ab did. Additionally, AGEs-induced RAGE and NF-kB protein expressions were down-regulated significantly by the pretreatment with GA or RAGE-Ab.

Conclusion

These findings provide evidences that GA possesses protective activity on AGEs-induced endothelial dysfunction, including anti-apoptosis, anti-inflammation and antioxidant stress, via inhibiting RAGE/NF-kB pathway. GA might be an alternative for the prevention and treatment of diabetic vascular complications in an appropriate dosage.     

Management of diabetic complications: A chemical constituents based approach

Ethnopharmacological relevance

Long term hyperglycemia leads to development of complications associated with diabetes. Diabetic complications are now a global health problem without effective therapeutic approach. Hyperglycemia and oxidative stress are important components for the development of diabetic complications. Over the past few decades, herbal medicines have attracted much attention as potential therapeutic agents in the prevention and treatment of diabetic complications due to their multiple targets and less toxic side effects. This review aims to assess the current available knowledge of medicinal herbs for attenuation and management of diabetic complications and their underlying mechanisms.

Material and methods

Bibliographic investigation was carried out by scrutinizing classical text books and peer reviewed papers, consulting worldwide accepted scientific databases (SCOPUS, PUBMED, SCIELO, NISCAIR, Google Scholar) to retrieve available published literature. The inclusion criteria for the selection of plants were based upon all medicinal herbs and their active compounds with attributed potentials in relieving diabetic complications. Moreover, plants which have potential effect in ameliorating oxidative stress in diabetic animals have been included.

Results

Overall, 238 articles were reviewed for plant literature and out of the reviewed literature, 127 articles were selected for the study. Various medicinal plants/plant extracts containing flavonoids, alkaloids, phenolic compounds, terpenoids, saponins and phytosterol type chemical constituents were found to be effective in the management of diabetic complications. This effect might be attributed to amelioration of persistent hyperglycemia, oxidative stress and modulation of various metabolic pathways involved in the pathogenesis of diabetic complications.

Conclusion

Screening chemical candidate from herbal medicine might be a promising approach for new drug discovery to treat the diabetic complications. There is still a dire need to explore the mechanism of action of various plant extracts and their toxicity profile and to determine their role in therapy of diabetic complications. Moreover, a perfect rodent model which completely mimics human diabetic complications should be developed.