Extract of Cassiae semen attenuates diabetic nephropathy via inhibition of advanced glycation end products accumulation in streptozotocin-induced diabetic rats

Cassiae Semen: A comprehensive review of botany, traditional use, phytochemistry, pharmacology, toxicity, and quality control

ETHNOPHARMACOLOGICAL RELEVANCE

Cassiae Semen, belonging to the family Leguminosae, is derived from the dry mature seeds of Cassia obtusifolia L. or Cassia tora L. and has long been used as a laxative, hepatoprotective, improve eyesight, and antidiabetic complications medicine or functional food in Asia.

AIMS OF THE REVIEW

This review summarizes the integrated research progress of botany, traditional uses, phytochemistry, pharmacology, toxicity, and quality control of Cassiae Semen. Additionally, the emerging challenges and possible developing directions are discussed as well.

MATERIALS AND METHODS

The information on Cassiae Semen was collected from published scientific materials, including ancient books of traditional Chinese Medicine; Ph.D. and M. Sc. dissertations; monographs on medicinal plants; pharmacopoeia of various countries and electronic databases, such as PubMed, Web of Science, ACS, Science Direct, J-STAGE, Springer link, Taylor, CNKI and Google Scholar, etc. RESULTS: First, the traditional uses and plant origins of Cassiae Semen are outlined. Secondly, approximately 137 compounds, including anthraquinones, naphthopyranones, naphthalenes, flavones, polysaccharides and other compounds, have been isolated and identified from Cassia obtusifolia L. and Cassia tora L. Third, the pharmacological activities and mechanisms of crude extract of Cassiae Semen and its main bioactive compounds are summarized. Moreover, the processing, toxicity, and quality control are introduced briefly.

CONCLUSIONS

Cassiae Semen is a frequently used Chinese Materia Medica with pharmacological effects that mainly affect the digestive system, cardiovascular systems and nervous system. This review summarized its botany, traditional uses, phytochemistry, and pharmacology, it also exhibited recent scientific research advances and gaps, which provide a deeper insight into the understanding and application of Cassiae Semen. In future research on Cassiae Semen, more attention should be given to the pharmacological activities of naphthopyranones and polysaccharides and the mechanism of action for improving eye diseases. Meanwhile, it is essential to focus on strengthening the study on the pharmacokinetics research and the safety evaluation of related health products research.

Aurantio-obtusin induces hepatotoxicity through activation of NLRP3 inflammasome signaling

Aurantio-obtusin (AO) is a major anthraquinone (AQ) compound derived from Cassiae semen (CS). Although pharmacological studies have shown that the CS extracts can serve as effective agents in preclinical and clinical practice, AQ-induced hepatotoxicity in humans has attracted widespread attention. To explore whether AO induces hepatotoxicity and its underlying mechanisms, we exposed larval zebrafish and mice to AO. We found that AO delayed yolk sac absorption, and increased liver area and inflammation in the larval zebrafish. This inflammation was manifested as an increase in liver neutrophils and the up-regulated mRNA expression of interleukin-6 (Il-6) and tumor necrosis factor-α (Tnf-α) in the larval zebrafish. Furthermore, a pharmacokinetics study showed that AO was quickly absorbed into the blood and rapidly metabolized in the mice. Of note, AO induced hepatotoxicity in a gender-dependent manner, characterized by liver dysfunction, increased hepatocyte necrosis with inflammatory infiltration, and up-regulated mRNAs of Il-6, Tnf-α and monocyte chemotactic protein 1(Mcp1) in the female mice after 28-day oral administration. It also highlighted that AO triggered NOD-like receptor protein (NLRP) signaling in the female mice, as evidenced by the increased NLRP3, Caspase-1, pro-IL-1β, IL-1β and IL-18. Finally, we found that AO led to a significant increase in potassium calcium-activated channel, subfamily N, member 4 (KCNN4) and reactive oxygen species (ROS) levels, along with decreased nuclear factor kappa B p65 (NF-κB p65), in the female mouse livers. In conclusion, AO induced hepatotoxicity by activating NLRP3 inflammasome signaling, at least in part, through increased KCNN4 and ROS production, and NF-κB inhibition.

Predicting the potential toxicity of 26 components in Cassiae semen using in silico and in vitro approaches

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A combination of in silico and in vitro methods was applied.

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The potential toxicity of 26 components isolated from Cassiae semen is predicted.

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Six compounds were predicted toxic to liver & ten compounds toxic to kidney.

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Special anthraquinones and anthraquinone-glucosides are potential toxicants.

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Specific group of anthraquinones influences hepatic or renal cytotoxicity.

Cassiae semen are dried and ripe seeds of Cassia obtusifolia L. or Cassia tora L. (Fabaceae) and have been made into roasted tea or used as a traditional medicine in Asian countries. However, it was reported to result in liver and renal toxicity. The components of Cassiae semen that induce hepatotoxicity or nephrotoxicity remain unknown. In the present study, we evaluate the potential toxicity of 26 newly isolated compounds from Cassiae semen using quantitative structure–activity relationship (QSAR) methods and co-culture of hepatic and renal cell approaches, and we aim to illustrate the relationship between the structural characteristics and cytotoxicity by general linear models (GLMs). Both the QSAR models and co-culture of hepatic and renal cell systems predicted that 6 compounds were potentially hepatotoxic, 10 compounds were potentially nephrotoxic, and specific anthraquinones and anthraquinone-glucosides were potential toxicants in Cassiae semen. Specific groups such as –OH and –OCH₃ at the R1, R2, R3, and R7 positions influenced the cytotoxicity.

Glycation and Antioxidants: Hand in the Glove of Antiglycation and Natural Antioxidants

The non-enzymatic interaction of sugar and protein resulting in the formation of advanced glycation end products responsible for cell signaling alterations ultimately leads to the human chronic disorders such as diabetes mellitus, cardiovascular diseases, cancer, etc. Studies suggest that AGEs upon interaction with receptors for advanced glycation end products (RAGE) result in the production of pro-inflammatory molecules and free radicals that exert altered gene expression effect. To date, many studies unveiled the potent role of synthetic and natural agents in inhibiting the glycation reaction at a lesser or greater extent. This review focuses on the hazards of glycation reaction and its inhibition by natural antioxidants, including polyphenols.

The genus Cassia L.: Ethnopharmacological and phytochemical overview

Nature gifts medicinal plants with the untapped and boundless treasure of active chemical constituents with significant therapeutic potential that makes these plants a beneficial source in the development of phytomedicines. Genus Cassia, with approximately 500 species, is a large group of flowering plants in the family Fabaceae. Cassia species are widely distributed throughout different regions mainly tropical Asia, North America, and East Africa. In the folk medicinal history, these plants are used as laxative and purgative agents. In the Ayurveda system of medicine, they are used to cure headache and fever. Cassia plants exhibit pharmacological activities at large scales such as antimicrobial, anticancer, antiinflammatory, antioxidant, hypoglycemic, hyperglycemic, antimutagenic, and antivirals. The phytochemical investigations of genus Cassia demonstrate the presence of more than 200 chemical compounds, including piperidine alkaloids, anthracene derivatives (anthraquinones), flavonoids, pentacyclic triterpenoids, sterols, phenylpropanoids, and γ-naphthopyrones. The literature illustrated anthraquinones and flavonoids as major secondary metabolites from this genus. However, some Cassia plants, with rich contents of anthraquinones, still show toxicology properties. As Cassia plants are used extensively in the herbal system of medicine, but only senna dosage forms have achieved the status of the pharmaceutical market as standard laxative agents. In conclusion, further investigations on isolating newer biologically active constituents, unknown underlying mechanisms, toxicology profiles, and clinical studies of Cassia species are needed to be explored. This review article specifies the systematic breach existing between the current scientific knowledge and the fundamentals for the marketization of genus Cassia products.

Phytochemicals against anti-diabetic complications: targeting the advanced glycation end product signaling pathway

The role of advanced glycation end products (AGEs) is not limited to diabetes and diabetes-related complications. There are multiple modulators, including the receptor for advanced glycation end products, high mobility group box 1, glyoxalase 1, nuclear factor-kappa B, tumor necrosis factor-α, chronic unpredictable stress, reactive oxygen species, and inflammatory cytokines, which interact with AGE signaling and control diabetes, modulating these interacting modulators. The progression of diabetes, as well as related complications, can be controlled and treated. Natural products rich in bioactive constituents can interact with AGEs and their related mediators through various signaling cascades, thereby controlling and preventing the progression of diabetes. This review provides a deeper assessment of the signaling pathway, interactions between phytochemicals and AGEs, and its mediators, to develop a multifold therapeutic approach to prevent and treat diabetes and its related complications.

Development of a conventional immunochemical detection system for determination of Nδ-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine in methylglyoxal-modified proteins

Methylglyoxal (MGO) produced during glycolysis is known to react with arginine residues on proteins to generate advanced glycation end products, such as N^δ-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine (MG-H1). Since the production of MGO is increased during hyperglycemia or metabolic disorders in vivo, it is considered that the measurement of MG-H1 is useful for evaluating abnormalities in carbohydrate metabolism. Thus, we prepared a monoclonal antibody against MG-H1 to develop a conventional measurement system for MG-H1. Reactivity and specificity of the antibody to MGO-modified protein were confirmed by enzyme-linked immunosorbent assay and western blotting, respectively. The measurement of MG-H1 content by the antibody was positively correlated with that by electrospray ionization-liquid chromatography-tandem mass spectrometry and the ratio of modified arginine residues by amino acid analysis. Our results demonstrated that immunochemical methods could be useful for the estimation of MG-H1 content in modified proteins.

Hepatoprotective effects of Cassia semen ethanol extract on non-alcoholic fatty liver disease in experimental rat

CONTEXT

Cassia semen (Cs), a seed of Cassia obtusifolia L. (Leguminosae), is a popular functional beverage. Previous studies reported that Cs displayed antioxidant, antifungal and strong liver protective effects.

OBJECTIVE

This study evaluates the hepatoprotective effects of Cs on non-alcoholic fatty liver disease (NAFLD).

MATERIALS AND METHODS

Seventy-two male Wistar rats raised with high-fat diet (HFD) were randomly allotted into model, metformin (0.2 g/kg) and Cs (0.5, 1, and 2 g/kg)-treated groups. Another 12 rats were raised with normal feed as control group; all the rats were orally administrated with drugs and vehicle for 6 weeks. Alanine transferase (ALT), aspartate transaminase (AST), triglycerides (TG), total cholesterol (TC), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-8 and low density lipoprotein receptor (LDL-R) mRNA levels were measured at the end of the experiment.

RESULTS

Twelve weeks of HFD administration significantly increased the levels of AST, ALT, TG, TC, TNF-α, IL-6, IL-8 and MDA, decreased SOD (199.42 vs. 137.70 U/mg protein) and GSH (9.76 vs. 4.55 mg/g protein) contents, compared to control group. Cs administration group significantly decreased the elevated biomarkers with the ED₅₀ = 1.2 g/kg for NAFLD rats. Cs treatment also prevents the decreased expression of LDL-R mRNA, and improved the histopathological changes compared to model group.

CONCLUSIONS

The hepatoprotective effect of Cs on NAFLD may possibly be due to its antioxidant effect. Cs may become a potent hepatoprotective agent in clinical therapy in the future.

Anthraquinones in the aqueous extract of Cassiae semen cause liver injury in rats through lipid metabolism disorder

BACKGROUND

Cassiae semen has been used as the tea or medicine component to treat hyperlipidemia or for hepatoprotection. However, Cassiae semen was reported to be a potentially hepatotoxic herb, and the underlying hepatotoxicity mechanisms or specific hepatotoxic components of Cassiae semen are unknown.

PURPOSE

In this study, we aimed to explore the potential hepatotoxicity mechanisms and the hepatotoxic components of Cassiae semen.

METHODS

Both young adult male and female SD rats were orally administrated with the aqueous extract of the seeds of Senna obtusifolia (L.) H.S.Irwin & Barneby at doses of 4.73, 15.75, 47.30 g/kg for 28 days, and the body weight, liver coefficient, bile acids, histopathology, serum levels of TC, TG, LDL, HDL, ALP, ALT, AST, and LDH were examined. Lipidomic analysis of rat serum was performed by LC-MS to investigate the specifically changed lipids caused by the aqueous extract treatment. The components absorbed in plasma were detected by UHPLC-Q-Exactive-MS. MTT assay was used to evaluate the cytotoxicity of these components absorbed in plasma.

RESULTS

The serum levels of ALP, AST, ALT, LDH were increased on day 7 with some of which gradually dropped to normal level on day 28. In high dose of the aqueous extract treated group, the histopathological changes were observed based on the cytoplasmic vacuolation in the liver and the increase of bile acids, indicating the hepatotoxicity of the aqueous extract. The changes of TC, TG, LDL, HDL indicated the disorder of lipid metabolism. By comparing the difference in lipids between high dose group and control group, the results showed that the alterations were primarily focused on glycerophospholipid metabolism in both male and female rats. In addition, the glycerolipid metabolism in female rats also changed. Further analyses found that PC (18:2/20:4) and LysoPC 18:0 were significantly increased. Among these phytochemicals detected in plasma, nine components in the aqueous extract were considered to have the highest concentrations, particularly some types of anthraquinones (AQs) existing in Cassiae semen (AQs-in-CS), such as obtusifolin, aurantio-obtusin, and obtusin. The MTT assay showed that emodin, obtusifolin, rhein, aurantio-obtusin, and obtusin inhibited cell viability. Considering plasma concentrations and cytotoxicity of these components, our study indicates that the AQs-in-CS (obtusifolin, aurantio-obtusin and obtusin), emodin and rhein are the potential hepatotoxic phytochemicals in the aqueous extract.

Anti-diabetic and renoprotective effects of Cassiae Semen extract in the streptozotocin-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cassiae Semen, the dried seed of Cassia obtusifolia L. (Leguminosae), is a traditional Chinese medicine. It has long been used as the treatment of diabetic hyperlipidemia and diabetic constipation in Traditional Chinese Medicine formulae.

AIM OF THE STUDY

The present study was designed to investigate the anti-diabetic and renoprotective effects of Cassiae Semen extract (CSE) in streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

Quality control of CSE was performed using HPLC. CSE were orally administered at 27, 54 and 81 mg/kg dose to high-sucrose-high-fat (HSHF) diet and STZ-induced diabetic rats for 60 days. Body weight, glucose metabolism and lipid metabolism profiles were measured to assess the anti-diabetic effect of CSE. Oxidative stress markers and inflammatory factors were determined using commercial kits. Renal function related parameters were also measured. Histopathological examination of kidney was conducted for the validation of pathological changes in the diabetic rats. Immunohistochemical examination of kidney was measured to investigate the expression of RAGE in renal tissues.

RESULTS

Five compounds, including two anthraquinones and three naphtopyrones were simultaneously determined in CSE. Compared with diabetic control, groups treated with CSE exhibited an anti-diabetic effect, including a significant amelioration in body weight, glycemic control, oral glucose tolerance and lipid metabolism (P < 0.01). Moreover, oxidative stress and inflammatory responses decreased after oral administration of CSE (P < 0.01). CSE also showed protective effects on renal functions, decreasing the ratio of kidney/body weight, 24 h urine volume, 24 h urine protein, serum creatinine (Scr) and blood urea nitrogen (BUN) (P < 0.01). Additionally, renal protective effect was also observed in histopathological examination. Immunohistochemical analysis showed that CSE downregulated the expression of RAGE.

CONCLUSIONS

It turned out that CSE had both anti-diabetic and renoprotective effects in diabetic rats. CSE can be a potential agent in the treatment of type 2 diabetes mellitus (T2DM) and its complications.

From the Cover: Identification of Natural Products as Inhibitors of Human Organic Anion Transporters (OAT1 and OAT3) and Their Protective Effect on Mercury-Induced Toxicity

Mercury accumulates in kidneys and produces acute kidney injury. Semen cassiae (SC), a widely consumed tea and herbal medicine in Eastern Asia, has been reported to have protective effects on kidneys. In this study, SC extract was shown to almost abolish the histological alterations induced by mercuric chloride in rat kidneys. A total of 22 compounds were isolated from SC, and 1,7,8-methoxyl-2-hydroxyl-3-methyl-anthraquinone was detected in SC for the first time. Among the eight compounds identified in the blood of rats after SC treatment, six were strong inhibitors of human organic anion transporter 1 and 3 (OAT1 and OAT3). Inhibitory studies revealed that OAT1 and OAT3 were inhibited by SC constituents, in both a competitive and noncompetitive manner. Both OAT1- and OAT3-overexpressing cells were susceptible to the cytotoxicity of the cysteine-mercury conjugate, but only OAT1-overexpressing cells could be protected by 200 μM probenecid or 10 μM of the eight inhibitors in SC, suggesting that OAT1 is the major determinant in the cellular uptake of mercury. To facilitate the identification of inhibitors of OAT1 and OAT3, models of OAT1 and OAT3 were constructed using recently determined protein templates. By combining in silico and in vitro methods, inhibitors of OAT1 and OAT3 were predicted and validated from SC constituents. Collectively, the present study suggests that additional inhibitors of OAT1 and OAT3 can be predicted and validated from natural products by combining docking and in vitro screening, and could be a source of pharmaceutical compounds for developing treatments for mercury-induced kidney injury.

Semen cassiae Extract Inhibits Contraction of Airway Smooth Muscle

β₂-adrenoceptor agonists are commonly used as bronchodilators to treat obstructive lung diseases such as asthma and chronic obstructive pulmonary disease (COPD), however, they induce severe side effects. Therefore, developing new bronchodilators is essential. Herbal plants were extracted and the extracts’ effect on airway smooth muscle (ASM) precontraction was assessed. The ethyl alcohol extract of semen cassiae (EESC) was extracted from Semen cassia. The effects of EESC on the ACh- and 80 mM K⁺-induced sustained precontraction in mouse and human ASM were evaluated. Ca²⁺ permeant ion channel currents and intracellular Ca²⁺ concentration were measured. HPLC analysis was employed to determine which compound was responsible for the EESC-induced relaxation. The EESC reversibly inhibited the ACh- and 80 mM K⁺-induced precontraction. The sustained precontraction depends on Ca²⁺ influx, and it was mediated by voltage-dependent L-type Ca²⁺ channels (LVDCCs), store-operated channels (SOCs), TRPC3/STIM/Orai channels. These channels were inhibited by aurantio-obtusin, one component of EESC. When aurantio-obtusin removed, EESC’s action disappeared. In addition, aurantio-obtusin inhibited the precontraction of mouse and human ASM and intracellular Ca²⁺ increases. These results indicate that Semen cassia-contained aurantio-obtusin inhibits sustained precontraction of ASM via inhibiting Ca²⁺-permeant ion channels, thereby, which could be used to develop new bronchodilators.

Semen Cassiae Extract Improves Glucose Metabolism by Promoting GlUT4 Translocation in the Skeletal Muscle of Diabetic Rats

Diabetes mellitus is a clinical syndrome characterised by hyperglycaemia; its complications lead to disability and even death. Semen Cassiae is a traditional Chinese medicine, which has anti-hypertensive, anti-hyperlipidaemia, anti-oxidation, and anti-ageing properties. Our study was designed to evaluate the action of total anthraquinones of Semen Cassiae extract (SCE) on the improvement of glucose metabolism in diabetic rats and to elucidate the underlying mechanism. First, we evaluated the effect of SCE on normal rats. Next, we observed the effect of SCE using a rat model of diabetes, which was established by feeding rats with high-energy diet for 4 weeks and a single intraperitoneal injection of streptozotocin (STZ; 30 mg/kg) 3 weeks after starting the high-energy diet. Rats in different SCE groups (administered 54, 108, and 324 mg/kg/day of SCE) and metformin group (162 mg/kg/day, positive control drug) were treated with the corresponding drugs 1 week before starting high-energy diet and treatment continued for 5 weeks; meanwhile, rats in the control group were administered the same volume of sodium carboxymethyl cellulose solution (vehicle solution). One week after STZ injection, fasting blood glucose (FBG), oral glucose tolerance (OGT), fasting serum insulin (FSI) and serum lipids were quantified. Finally, the expression of proteins in the phosphatidylinositol-3-kinase (PI3K)–Akt–AS160–glucose transporter isoform 4 (GLUT4) signalling pathway was detected by western blotting. The data indicated that the levels of FBG and serum lipids were significantly lowered, and OGT and FSI were markedly increased in diabetic rats treated with SCE (108 mg/kg/day); however, SCE did not cause hypoglycaemia in normal rats. The molecular mechanisms were explored in the skeletal muscle. SCE markedly restored the decreased translocation of GLUT4 in diabetic rats. Moreover, the protein expressions of phosphorylated-AS160 (Thr642), phosphorylated-Akt (Ser473) and PI3K were significantly increased after SCE treatment in the skeletal muscle. These results indicate that SCE exerts an anti-hyperglycaemic effect by promoting GLUT4 translocation through the activation of the PI3K–Akt–AS160 signalling pathway. Our findings suggest that treatment with SCE, containing anthraquinones, could be an effective approach to enhance diabetes therapy.

Eucommia ulmoides Ameliorates Glucotoxicity by Suppressing Advanced Glycation End-Products in Diabetic Mice Kidney

Eucommia ulmoides Oliv. (EU), also known as Du-Zhong, is a medicinal herb commonly used in Asia to treat hypertension and diabetes. Despite evidence of the protective effects of EU against diabetes, its precise effects and mechanisms of action against advanced glycation end-products (AGEs) are unclear. In this study, we evaluated the effects of EU on AGEs-induced renal disease and explored the possible underlying mechanisms using streptozotocin (STZ)-induced diabetic mice. STZ-induced diabetic mice received EU extract (200 mg/kg) orally for 6 weeks. EU treatment did not change blood glucose and glycated hemoglobin (HbA1c) levels in diabetic mice. However, the EU-treated group showed a significant increase in the protein expression and activity of glyoxalase 1 (Glo1), which detoxifies the AGE precursor, methylglyoxal (MGO). EU significantly upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) expression but downregulated that of receptor for AGE (RAGE). Furthermore, histological and immunohistochemical analyses of kidney tissue showed that EU reduced periodic acid-Schiff (PAS)-positive staining, AGEs, and MGO accumulation in diabetic mice. Based on these findings, we concluded that EU ameliorated the renal damage in diabetic mice by inhibiting AGEs formation and RAGE expression and reducing oxidative stress, through the Glo1 and Nrf2 pathways.

Enhanced hemodynamic responses to angiotensin II in diabetes are associated with increased expression and activity of AT1 receptors in the afferent arteriole

The prevalence of hypertension is about twofold higher in diabetic than in nondiabetic subjects. Hypertension aggravates the progression of diabetic complications, especially diabetic nephropathy. However, the mechanisms for the development of hypertension in diabetes have not been elucidated. We hypothesized that enhanced constrictive responsiveness of renal afferent arterioles (Af-Art) to angiotensin II (ANG II) mediated by ANG II type 1 (AT1) receptors contributes to the development of hypertension in diabetes. In response to an acute bolus intravenous injection of ANG II, alloxan-induced diabetic mice exhibited a higher mean arterial pressure (MAP) (119.1 ± 3.8 vs. 106.2 ± 3.5 mmHg) and a lower renal blood flow (0.25 ± 0.07 vs. 0.52 ± 0.14 ml/min) compared with nondiabetic mice. In response to chronic ANG II infusion, the MAP measured with telemetry increased by 55.8 ± 6.5 mmHg in diabetic mice, but only by 32.3 ± 3.8 mmHg in nondiabetic mice. The mRNA level of AT1 receptor increased by ~10-fold in isolated Af-Art of diabetic mice compared with nondiabetic mice, whereas ANG II type 2 (AT2) receptor expression did not change. The ANG II dose-response curve of the Af-Art was significantly enhanced in diabetic mice. Moreover, the AT1 receptor antagonist, losartan, blocked the ANG II-induced vasoconstriction in both diabetic mice and nondiabetic mice. In conclusion, we found enhanced expression of the AT1 receptor and exaggerated response to ANG II of the Af-Art in diabetes, which may contribute to the increased prevalence of hypertension in diabetes.

Cassiae semen: A review of its phytochemistry and pharmacology (Review)

Cassiae semen (Leguminosae), a well-known traditional Chinese medicine, has been used for a number of centuries in areas of Southeast Asia, including Korea, Japan and China. The present review aims to provide updated and comprehensive information, on the botany, phytochemistry and pharmacology of Cassiae semen. The available information on Cassiae semen was collected using several different resources, including classic books on Chinese herbal medicine and a number of scientific databases, including the China Academic Journals full-text database, PubMed, SciFinder, the Web of Science and Science Direct. To date >70 chemical compounds have been isolated from Cassiae semen, and the major components have been determined to be anthraquinones, naphthopyrones and volatile oil. The crude extracts and pure compounds of Cassiae semen have been used as effective agents in preclinical and clinical practice due to their beneficial activities, including antihyperlipidemic, antidiabetic, neuroprotective, hepatoprotective, antibacterial, antioxidant and hypotensive activities. With the body of reported data, it has been suggested that Cassiae semen has convincing medicinal potential. However, the pharmacological mechanisms of the main bioactive compounds and the association between structure and activity require further investigation.

Osteomeles schwerinae extracts inhibits the binding to receptors of advanced glycation end products and TGF-β1 expression in mesangial cells under diabetic conditions

BACKGROUND

Osteomeles schwerinae C. K. Schneid. (Rosaceae, OSSC) is a medicinal plant traditionally used to treat various diseases in Asia. The chemical constituents of OSSC have an inhibitory effect on aldose reductase activity, which has been implicated in the pathogenesis of diabetic complications. However, the protective effects of the pharmacological activity and potential mechanisms in diabetic nephropathy are still not known.

OBJECTIVE

In the present study, OSSC extracts and major compounds were examined for their effects on binding to the receptors of advanced glycation end products (RAGE) and on transforming growth factor-beta1 (TGF-β1) expression-related signal mechanisms in mouse glomerular mesangial cells (GMCs).

MATERIALS AND METHODS

A simple, rapid and efficient method was developed for the simultaneous determination of the marker compounds in the ethanol extract of the leaves and twigs of OSSC using HPLC-diode array detector (DAD). In this study, we determined the effects of OSSC extract and hyperoside on AGE and RAGE binding, and studied the mechanism of OSSC extract effects on AGE-bovine serum albumin (BSA)-treated GMCs. GMCs overexpressing human RAGE were cultured in AGE-BSA labeled with Alexa 488, and OSSC extract. AGE/RAGE binding were measured using fluorescence (excitation 485 nm/emission 528 nm). TGF-β1 protein expression levels were determined by western blot analyses.

RESULTS

OSSC extracts of leaves and twigs inhibited on AGE/RAGE binding and TGF-β1 protein expression in a dose-dependent manner in GMCs. Furthermore, OSSC extracts reduced the effects on AGE-BSA-induced reactive oxidative species (ROS) formation and nuclear translocalization of transcription factor NF-κB. OSSC extracts inhibited phosphorylation of extracellular signal-regulated protein kinases1/2 (ERK1/2), p38 mitogen-activated protein kinases (p38MAPK), and IκB. Hyperoside also inhibited AGE/RAGE binding and ROS formation, and reduced TGF-β1 expression and IkB phosphorylation.

CONCLUSIONS

OSSC extracts and hyperoside may attenuate AGE/RAGE binding and expression of TGF-β1 by downregulating of pERK1/2, p38MAPK and IκB phosphorylations in GMCs under diabetic condition and retard the development of diabetic complications such as diabetic nephropathy.

Extraction and characterization of polysaccharides from Semen Cassiae by microwave-assisted aqueous two-phase extraction coupled with spectroscopy and HPLC

A novel and rapid method for simultaneous extraction and separation of the different polysaccharides from Semen Cassiae (SC) was developed by microwave-assisted aqueous two-phase extraction (MAATPE) in a one-step procedure. Using ethanol/ammonium sulfate system as a multiphase solvent, the effects of MAATPE on the extraction of polysaccharides from SC such as the composition of the ATPS, extraction time, temperature and solvent-to-material ratio were investigated by UV-vis analysis. Under the optimum conditions, the yields of polysaccharides were 4.49% for the top phase, 8.80% for the bottom phase and 13.29% for total polysaccharides, respectively. Compared with heating solvent extraction and ultrasonic assisted extraction, MAATPE exhibited the higher extraction yields in shorter time. Fourier-transform infrared spectra showed that two polysaccharides extracted from SC to the top and bottom phases by MAATPE were different from each other in their chemical structures. Through acid hydrolysis and PMP derivatization prior to HPLC, analytical results by indicated that a polysaccharide of the top phases was a relatively homogeneous homepolysaccharide composed of dominant gucose glucose while that of the bottom phase was a water-soluble heteropolysaccharide with multiple components of glucose, xylose, arabinose, galactose, mannose and glucuronic acid. Molar ratios of monosaccharides were 95.13:4.27:0.60 of glucose: arabinose: galactose for the polysaccharide from the top phase and 62.96:14.07:6.67: 6.67:5.19:4.44 of glucose: xylose: arabinose: galactose: mannose: glucuronic acid for that from the bottom phase, respectively. The mechanism for MAATPE process was also discussed in detail. MAATPE with the aid of microwave and the selectivity of the ATPS not only improved yields of the extraction, but also obtained a variety of polysaccharides. Hence, it was proved as a green, efficient and promising alternative to simultaneous extraction of polysaccharides from SC.

FK506 reduces albuminuria through improving podocyte nephrin and podocin expression in diabetic rats

Objective and design

Several works in the setting of early experimental diabetic nephropathy using anti-inflammatory drugs, such as the calcineurin inhibitor FK506, have shown prevention of the development or amelioration of renal injury including proteinuria. The exact mechanisms by which anti-inflammatory drugs lower the albuminuria have not been still clarified well.

Materials

The diabetic rats were induced by using streptozotocin.

Treatment

The diabetic rats were subjected to oral FK506 treatment at a dose of 0.5 or 1.0 mg/kg daily for 4 weeks.

Methods

Renal histology for the ultrastructural evaluation was determined by electron microscope, followed by analyses of renal nephrin and podocin and detection of renal iNOS⁺ macrophages and NF-κB-p-p65⁺.

Results

Elevated 24-h urinary albumin excretion rate was markedly attenuated by FK506 treatment. In diabetic model rats, FK506 treatment at a dose of 0.5 or 1.0 mg/kg significantly increased the expression of nephrin and podocin when compared to control. As expected, rats in control diabetic group had an increase in GBM thickening and foot process effacement when compared to normal rats; increased GBM thickening and foot process effacement were ameliorated by FK506 treatment with 0.5 and 1.0 mg/kg. Histologically, there was marked accumulation of ED-1⁺cells (macrophages) in diabetic kidneys, and FK506 treatment failed to inhibit it. In contrast, FK506 treatment at 0.5 and 1.0 mg/kg doses significantly inhibited the elevated ED-1⁺/iNOS⁺ cells in the kidneys of diabetic rats. ED-1⁺/NF-κB-p-p65⁺ cells were significantly increased in positive diabetic kidneys compared to those of normal rats. FK506 treatment at 0.5 and 1.0 mg/kg significantly attenuated the elevated ED-1⁺/NF-κB-p-p65⁺ cells in diabetic kidneys. Additionally, a positive correlation was observed between ED-1⁺/iNOS⁺ cells and albuminuria (r = 0.87, p < 0.05). Likewise, ED-1⁺/iNOS⁺ cells were correlated negatively with both nephrin and podocin protein (r = −0.70, p < 0.05; r = −0.68, p < 0.05, respectively).

Conclusion

Our results show that FK506 not only upregulates expression of nephrin and podocin but also inhibits macrophage activation to protect against podocyte injury.

Prevention of protein glycation by natural compounds

Non-enzymatic protein glycosylation (glycation) contributes to many diseases and aging of organisms. It can be expected that inhibition of glycation may prolong the lifespan. The search for inhibitors of glycation, mainly using in vitro models, has identified natural compounds able to prevent glycation, especially polyphenols and other natural antioxidants. Extrapolation of results of in vitro studies on the in vivo situation is not straightforward due to differences in the conditions and mechanism of glycation, and bioavailability problems. Nevertheless, available data allow to postulate that enrichment of diet in natural anti-glycating agents may attenuate glycation and, in consequence, ageing.