Catalpol suppresses advanced glycation end-products-induced inflammatory responses through inhibition of reactive oxygen species in human monocytic THP-1 cells

Heyingwuzi formulation alleviates diabetic retinopathy by promoting mitophagy via the HIF-1α/BNIP3/NIX axis

BACKGROUND

Diabetic retinopathy (DR) is the primary cause of visual problems in patients with diabetes. The Heyingwuzi formulation (HYWZF) is effective against DR.

AIM

To determine the HYWZF prevention mechanisms, especially those underlying mitophagy.

METHODS

Human retinal capillary endothelial cells (HRCECs) were treated with high glucose (hg), HYWZF serum, PX-478, or Mdivi-1 in vitro. Then, cell counting kit-8, transwell, and tube formation assays were used to evaluate HRCEC proliferation, invasion, and tube formation, respectively. Transmission electron microscopy was used to assess mitochondrial morphology, and Western blotting was used to determine the protein levels. Flow cytometry was used to assess cell apoptosis, reactive oxygen species (ROS) production, and mitochondrial membrane potential. Moreover, C57BL/6 mice were established in vivo using streptozotocin and treated with HYWZF for four weeks. Blood glucose levels and body weight were monitored continuously. Changes in retinal characteristics were evaluated using hematoxylin and eosin, tar violet, and periodic acid-Schiff staining. Protein levels in retinal tissues were determined via Western blotting, immunohistochemistry, and immunostaining.

RESULTS

HYWZF inhibited excessive ROS production, apoptosis, tube formation, and invasion in hg-induced HRCECs via mitochondrial autophagy in vitro. It increased the mRNA expression levels of BCL2-interacting protein 3 (BNIP3), FUN14 domain-containing 1, BNIP3-like (BNIP3L, also known as NIX), PARKIN, PTEN-induced kinase 1, and hypoxia-inducible factor (HIF)-1α. Moreover, it downregulated the protein levels of vascular endothelial cell growth factor and increased the light chain 3-II/I ratio. However, PX-478 and Mdivi-1 reversed these effects. Additionally, PX-478 and Mdivi-1 rescued the effects of HYWZF by decreasing oxidative stress and apoptosis and increasing mitophagy. HYWZF intervention improved the symptoms of diabetes, tissue damage, number of acellular capillaries, and oxidative stress in vivo. Furthermore, in vivo experiments confirmed the results of in vitro experiments.

CONCLUSION

HYWZF alleviated DR and associated damage by promoting mitophagy via the HIF-1α/BNIP3/NIX axis.

Anti-inflammatory effect and mechanism of catalpol in various inflammatory diseases

Catalpol is a kind of iridoid glucoside, widely found in a variety of plants, mostly extracted from the rhizome of the traditional medicinal herb rehmanniae. It has various biological activities such as anti-inflammatory, antioxidant, and antitumor. The anti-inflammatory effects of catalpol have been demonstrated in a variety of diseases, such as neurological diseases, atherosclerosis, renal diseases, respiratory diseases, digestive diseases, bone and joint diseases, eye diseases, and periodontitis. The purpose of this review is to summarize the existing literature on the anti-inflammatory effects of catalpol in a variety of inflammatory diseases over the last decade and to focus on the anti-inflammatory mechanisms of catalpol.

Protective effects of catalpol on cardio-cerebrovascular diseases: A comprehensive review

Catalpol, an iridoid glucoside isolated from Rehmannia glutinosa, has gained attention due to its potential use in treating cardio-cerebrovascular diseases (CVDs). This extensive review delves into recent studies on catalpol's protective properties in relation to various CVDs, such as atherosclerosis, myocardial ischemia, infarction, cardiac hypertrophy, and heart failure. The review also explores the compound's anti-oxidant, anti-inflammatory, and anti-apoptotic characteristics, emphasizing the role of vital signaling pathways, including PGC-1α/TERT, PI3K/Akt, AMPK, Nrf2/HO-1, estrogen receptor (ER), Nox4/NF-κB, and GRP78/PERK. The article discusses emerging findings on catalpol's ability to alleviate diabetic cardiovascular complications, thrombosis, and other cardiovascular-related conditions. Although clinical studies specifically addressing catalpol's impact on CVDs are scarce, the compound's established safety and well-tolerated nature suggest that it could be a valuable treatment alternative for CVD patients. Further investigation into catalpol and related iridoid derivatives may unveil new opportunities for devising natural and efficacious CVD therapies.

Role of potential bioactive metabolites from traditional Chinese medicine for type 2 diabetes mellitus: An overview

Type 2 diabetes mellitus (T2DM) is a metabolic disease with persistent hyperglycemia primarily caused by insulin resistance (IR). The number of diabetic patients globally has been rising over the past decades. Although significant progress has been made in treating diabetes mellitus (DM), existing clinical drugs for diabetes can no longer fully meet patients when they face complex and huge clinical treatment needs. As a traditional and effective medical system, traditional Chinese medicine (TCM) has a unique understanding of diabetes treatment and has developed many classic and practical prescriptions targeting DM. With modern medicine and pharmacy advancements, researchers have discovered that various bioactive metabolites isolated from TCM show therapeutic on DM. Compared with existing clinical drugs, these bioactive metabolites demonstrate promising prospects for treating DM due to their excellent biocompatibility and fewer adverse reactions. Accordingly, these valuable metabolites have attracted the interest of researchers worldwide. Despite the abundance of research works and specialized-topic reviews published over the past years, there is a lack of updated and systematic reviews concerning this fast-growing field. Therefore, in this review, we summarized the bioactive metabolites derived from TCM with the potential treatment of T2DM by searching several authoritative databases such as PubMed, Web of Science, Wiley Online Library, and Springer Link. For the convenience of readers, the content is divided into four parts according to the structural characteristics of these valuable compounds (flavonoids, terpenoids, alkaloids, and others). Meanwhile, the detailed mechanism and future directions of these promising compounds curing DM are also summarized in the related sections. We hope this review inspires increasingly valuable and significant research focusing on potential bioactive metabolites from TCM to treat DM in the future.

Catalpol attenuates polycystic ovarian syndrome by regulating sirtuin 1 mediated NF-κB signaling pathway

Oxidative stress plays a central role in polycystic ovary syndrome (PCOS). Catalpol (CAT) is the active ingredient of Rehmannia glutinosa Libosch which has therapeutic effect on PCOS. However, little is known about the mechanism of CAT in PCOS. PCOS rats were induced by subcutaneous injection of dehydroepiandrosteronec for four weeks and then were treated with CAT (50 mg/kg) or carboxyl methyl cellulose (the solvent of CAT) or normal saline for another 4 weeks. Histopathological observation of ovarian tissues, the levels of testosterone, estradiol and progesterone in rat plasma samples, the oxidative stress related-indexes and the expressions of NF-κB pathway-related proteins were determined. KGN cell (human ovarian granulosa cell line) was used as PCOS cell model and was transfected with siSIRT1 in the presence of CAT. The viability, proliferation and apoptosis of cells and the levels of SIRT1 and NF-κB pathway-related proteins were measured. CAT lessened the anthropometric indices and improved ovarian damage in PCOS model rats, and reduced the levels of testosterone, estradiol, progesterone and MDA, increased GSH content, and elevated the activities of catalase, GSH-Px and SOD in ovarian tissues of PCOS model rats. CAT up-regulated SIRT1 level and inhibited the activation of NF-κB signaling pathway in PCOS rat model and KGN cells. Silencing SIRT1 increased the viability and proliferation, whilst decreased the apoptosis of CAT-treated KGN cells. Silencing SIRT1 counteracted the effect of CAT on the level of oxidative stress-related factors and NF-κB signaling pathway in KGN cells. CAT attenuated PCOS by regulating SIRT1 mediated NF-κB signaling pathway.

Catalpol modulating the crosstalking between mesenchymal stromal cells and macrophages via paracrine to enhance angiogenesis and osteogenesis

Due to the inflammatory responses associated with defect occurrence and materials implantation, immunoregulation has emerged as a promising strategy to enhance bone regeneration. It has been widely reported that a material could facilitate osteogenesis if it can guide macrophages to anti-inflammatory M2 phenotype, vice versa, a substrate will influence macrophage phenotype if it is osteoinductive. However, few studies have looked into the intercellular crosstalking directly. Herein, the compound catalpol was selected for its multiple functions to study the interactions between bone marrow mesenchymal stromal cells (BMSCs) and macrophages. This iridoid glucoside exhibits excellent anti-inflammatory and osteoinductive activities. The effects of catalpol on mediating M1/M2 polarization of macrophages, inhibiting osteoclast differentiation, promoting osteogenesis and angiogenesis were systematically investigated to correlate the biological responses of BMSCs and macrophages. To extend its in vivo application, the catalpol was then loaded onto an electrospun polylactide/gelatin composite fibrous mesh and subcutaneously implanted to evaluate the local inflammation and ectopic osteogenesis. The results revealed that the functions of catalpol displayed in modulating cellular behaviors are via cell paracrine to strengthen intercellular crosstalking, hence demonstrating that catalpol itself could serve as a promising bioactive stimulator for bone tissue engineering.

Antidiabetic Effect of Rehmanniae Radix Based on Regulation of TRPV1 and SCD1

Purpose: This study aimed to disclose the antidiabetic mechanisms of Rehmanniae Radix (RR). Methods: The antidiabetic effect of RR was studied in Streptozocin (STZ)-induced diabetes mellitus (DM) rats and HepG2 cells with insulin resistance (IR). Antidiabetic targets and signaling pathways of RR were confirmed by the network pharmacology and transcriptome analysis as well as HK2 cells induced by high glucose (HG). Results: After the DM rats were administrated RR extract (RRE) for 4 weeks, their body weight was 10.70 ± 2.00% higher than those in the model group, and the fasting blood glucose (FBG), AUC of the oral glucose tolerance test, and insulin sensitivity test values were 73.23 ± 3.33%, 12.31 ± 2.29%, and 13.61 ± 5.60% lower in the RRE group, respectively. When compared with the model group, an increase of 45.76 ± 3.03% in the glucose uptake of HepG2 cells with IR was seen in the RRE group. The drug (RR)-components-disease (DM)-targets network with 18 components and 58 targets was established. 331 differentially expressed genes (DEGs) were identified. TRPV1 and SCD1 were important DEGs by the intersectional analysis of network pharmacology and renal transcriptome. The TRPV1 overexpression significantly inhibited apoptosis and oxidative stress of the HK2 cells induced by HG, while SCD1 overexpression induced apoptosis and oxidative stress of the HK2 cells induced by low and high glucose. When compared to the HG group, the mRNA and protein expressions of TRPV1 in the presence of RRE (100 μg/ml) increased by 3.94 ± 0.08 and 2.83 ± 0.40 folds, respectively. Conclusion: In summary, RR displayed an inspiring antidiabetic effect by reducing FBG and IR, upregulating the mRNA and protein expressions of TRPV1, and downregulating mRNA expression of SCD1. Induction of TRPV1 and inhibition of SCD1 by RR was possibly one of its antidiabetic mechanisms.

Catalpol counteracts the pathology in a mouse model of Duchenne muscular dystrophy by inhibiting the TGF-β1/TAK1 signaling pathway

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease caused by a mutation in the gene encoding the dystrophin protein. Catalpol is an iridoid glycoside found in Chinese herbs with anti-inflammatory, anti-oxidant, anti-apoptotic, and hypoglycemic activities that can protect against muscle wasting. In the present study we investigated the effects of catalpol on DMD. Aged Dystrophin-deficient (mdx) mice (12 months old) were treated with catalpol (100, 200 mg·kg-1·d-1, ig) for 6 weeks. At the end of the experiment, the mice were sacrificed, and gastrocnemius (GAS), tibialis anterior (TA), extensor digitorum longus (EDL), soleus (SOL) muscles were collected. We found that catalpol administration dose-dependently increased stride length and decreased stride width in Gait test. Wire grip test showed that the time of wire grip and grip strength were increased. We found that catalpol administration dose-dependently alleviated skeletal muscle damage, evidenced by reduced plasma CK and LDH activity as well as increased the weight of skeletal muscles. Catalpol administration had no effect on dystrophin expression, but exerted anti-inflammatory effects. Furthermore, catalpol administration dose-dependently decreased tibialis anterior (TA) muscle fibrosis, and inhibited the expression of TGF-β1, TAK1 and α-SMA. In primary myoblasts from mdx mice, knockdown of TAK1 abolished the inhibitory effects of catalpol on the expression levels of TGF-β1 and α-SMA. In conclusion, catalpol can restore skeletal muscle strength and alleviate skeletal muscle damage in aged mdx mice, thus may provide a novel therapy for DMD. Catalpol attenuates muscle fibrosis by inhibiting the TGF-β1/TAK1 signaling pathway.

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.

Catalpol protects rat ovarian granulosa cells against oxidative stress and apoptosis through modulating the PI3K/Akt/mTOR signaling pathway

Disrupted follicular development may result in increased follicular atresia, which is a crucial mechanism of various ovarian pathologies. It has been demonstrated that oxidative stress is associated with disrupted follicular development. Catalpol is a natural compound that has been found to possess antioxidative stress. However, the effects of catalpol on oxidative stress-induced disrupted follicular development remain unclear. In the present study, we evaluated the protective effect of catalpol on hydrogen peroxide (H₂O₂)-induced oxidative damage in granulosa cells (GCs), which play crucial roles in the follicular development. Our results showed that catalpol significantly improved cell viability, reduced reactive oxygen species (ROS) and malondialdehyde (MDA) production, and elevated superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in H₂O₂-induced GCs. Catalpol treatment caused significant increase in bcl-2 expression, and decreases in bax and caspase-9 expressions. Compared with the H₂O₂-induced GCs, caspase-3 activity in catalpol-treated cells was markedly decreased. Furthermore, catalpol caused significant activation of PI3K/Akt/mTOR pathway in GCs in response to H₂O₂ stimulation. Additionally, inhibition of this pathway reversed the inhibitory effects of catalpol on H₂O₂-induced oxidative injury and apoptosis in GCs. In conclusion, these findings suggested that catalpol protected GCs from H₂O₂-induced oxidative injury and apoptosis via activating PI3K/Akt/mTOR signaling pathway. Thus, catalpol might serve as a therapeutic approach for regulating disrupted follicular development.

Molecular and Biochemical Pathways of Catalpol in Alleviating Diabetes Mellitus and Its Complications

Catalpol isolated from Rehmannia glutinosa is a potent antioxidant and investigated against many disorders. This review appraises the key molecular pathways of catalpol against diabetes mellitus and its complications. Multiple search engines including Google Scholar, PubMed, and Science Direct were used to retrieve publications containing the keywords “Catalpol”, “Type 1 diabetes mellitus”, “Type 2 diabetes mellitus”, and “diabetic complications”. Catalpol promotes IRS-1/PI3K/AKT/GLUT2 activity and suppresses Phosphoenolpyruvate carboxykinase (PEPCK) and Glucose 6-phosphatase (G6Pase) expression in the liver. Catalpol induces myogenesis by increasing MyoD/MyoG/MHC expression and improves mitochondria function through the AMPK/PGC-1α/PPAR-γ and TFAM signaling in skeletal muscles. Catalpol downregulates the pro-inflammatory markers and upregulates the anti-inflammatory markers in adipose tissues. Catalpol exerts antioxidant properties through increasing superoxide dismutase (sod), catalase (cat), and glutathione peroxidase (gsh-px) activity in the pancreas and liver. Catalpol has been shown to have anti-oxidative, anti-inflammatory, anti-apoptosis, and anti-fibrosis properties that in turn bring beneficial effects in diabetic complications. Its nephroprotective effect is related to the modulation of the AGE/RAGE/NF-κB and TGF-β/smad2/3 pathways. Catalpol produces a neuroprotective effect by increasing the expression of protein Kinase-C (PKC) and Cav-1. Furthermore, catalpol exhibits a cardioprotective effect through the apelin/APJ and ROS/NF-κB/Neat1 pathway. Catalpol stimulates proliferation and differentiation of osteoblast cells in high glucose condition. Lastly, catalpol shows its potential in preventing neurodegeneration in the retina with NF-κB downregulation. Overall, catalpol exhibits numerous beneficial effects on diabetes mellitus and diabetic complications.

Catalpol Protects Against Spinal Cord Injury in Mice Through Regulating MicroRNA-142-Mediated HMGB1/TLR4/NF-κB Signaling Pathway

Background: Spinal cord injury (SCI) is a devastating condition that leads to paralysis, disability and even death in severe cases. Inflammation, apoptosis and oxidative stress in neurons are key pathogenic processes in SCI. Catalpol (CTP), an iridoid glycoside extracted from Rehmannia glutinosa, has many pharmacological activities, such as anti-inflammatory, anti-oxidative and anti-apoptotic properties.

Purpose: Here, we investigated whether CTP could exert neuroprotective effects against SCI, and explored the underlying mechanism involved.

Methods: SCI was induced by a weight-drop device and treated with CTP (10 mg and 60 mg/kg). Then the locomotor function of SCI mice was evaluated by the BBB scores, spinal cord edema was measured by the wet/dry weight method, oxidative stress markers and inflammatory factors were detected by commercial kits and neuronal death was measured by TUNEL staining. Moreover, the microRNA expression profile in spinal cords from mice following SCI was analyzed using miRNA microarray. In addition, reactive oxygen species (ROS) generation, inflammatory response and cell apoptosis were detected in murine microglia BV2 cells under oxygen-glucose deprivation (OGD) and CTPtreatment.

Results: Our data showed that CTP treatment could improve the functional recovery, as well as suppress the apoptosis, alleviate inflammatory and oxidative response in SCI mice. In addition, CTP was found to be up-regulated miR-142 and the protective effects of CTP on apoptosis, inflammatory and oxidative response may relate to its regulation of HMGB1/TLR4/NF-κB pathway through miR-142.

Conclusion: Our findings suggest that CTP may protect the spinal cord from SCI by suppression of apoptosis, oxidative stress and inflammatory response via miR-142/HMGB1/TLR4/NF-κB pathway.

Design, microwave synthesis, and molecular docking studies of catalpol crotonates as potential neuroprotective agent of diabetic encephalopathy

Catalpol has gained increasing attention for its potential contributions in controlling glycolipid metabolism and diabetic complications, which makes used as a very promising scaffold for seeking new anti-diabetic drug candidates. Acylation derivatives of catalpol crotonate (CCs) were designed as drug ligands of glutathione peroxidase (GSH-Px) based on molecular docking (MD) using Surfex-Docking method. Catalpol hexacrotonate (CC-6) was synthesized using microwave assisted method and characterized by FT-IR, NMR, HPLC and HRMS. The MD results indicate that with the increasing of esterification degree of hydroxyl, the C log P of CCs increased significantly, and the calculated total scores (Total_score) of CCs are all higher than that of catalpol. It shows that CCs maybe served as potential lead compounds for neuroprotective agents. It was found that the maximum Total_score of isomers in one group CCs is often not that the molecule with minimum energy. MD calculations show that there are five hydrogen bonds formed between CC-6 and the surrounding amino acid residues. Molecular dynamics simulation results show that the binding of CC-6 with GSH-Px is stable. CC-6 was screened for SH-SY5Y cells viability by MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay, the result indicates CC-6 can effectively reverse SZT induced cells apoptosis with dose-dependent manner, which can indirectly show that CC-6 is a potential neuroprotective agent.

Network Pharmacology-Based Identification of the Mechanisms of Shen-Qi Compound Formula in Treating Diabetes Mellitus

Aim

The purpose of this research is to identify the mechanisms of Shen-Qi compound formula (SQC), a traditional Chinese medicine (TCM), for treating diabetes mellitus (DM) using system pharmacology.

Methods

The active components and therapeutic targets were identified, and these targets were analyzed using gene ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and protein-protein interaction (PPI) analysis. Finally, an integrated pathway was constructed to show the mechanisms of SQC.

Results

A total of 282 active components and 195 targets were identified through a database search. The component-target network was constructed, and the key components were screened out according to their degree. Through the GO, PPI, and KEGG analyses, the mechanism network of SQC treating DM was constructed.

Conclusions

This study shows that the mechanisms of SQC treating DM are related to various pathways and targets. This study provides a good foundation and basis for further in-depth verification and clinical application.

Loganin and catalpol exert cooperative ameliorating effects on podocyte apoptosis upon diabetic nephropathy by targeting AGEs-RAGE signaling

BACKGROUND/AIMS

Rehmanniae Radix (RR) and Cornus officinalis (CO) are a typical herbal pair used to treat diabetic nephropathy (DN) in clinical practice. DN can be effectively treated by catalpol (Cat) and loganin (Log), the main active components of RR and CO respectively, through combating apoptosis, oxidative stress and inflammation. Herein, a spontaneous DN and podocyte injury model induced by advanced glycation end products (AGEs), i.e. KK-Ay mice, was used to explore the cooperative effects of Log and Cat on DN and the mechanism targeting the AGEs-RAGE (receptor for AGE) pathway.

METHODS AND KEY FINDINGS

Log and Cat alone or in combination mitigated diabetic symptoms, decreased the level of fasting blood glucose, and increased that of serum insulin. The two drugs alone or in combination protected renal function from damage, prevented extracellular matrix hyperplasia and glycogen deposition, as well as alleviated the loss of podocytes detected by histological assay and immunohistochemistry. Flow cytometry revealed that Log and Cat alone or in combination relieved the apoptosis of AGEs-induced podocytes in vitro. Silencing RAGE by RNA interference played a protective role in podocyte apoptosis, whereas overexpression of it worked oppositely. Western blot exhibited that Log and Cat alone or in combination inhibited the activation of RAGE/p38 MAPK/p65 NF-κB and RAGE/Nox4/p65 NF-κB pathways in podocytes. The inhibitory effects of drug combination were more evident than those of individual treatments.

SIGNIFICANCE

Log and Cat cooperatively resisted the apoptosis of podocytes upon DN by targeting AGEs-RAGE and its downstream pathways p38 MAPK and Nox4.

Antidiabetic and protective effects of Scrophularia striata ethanolic extract on diabetic nephropathy via suppression of RAGE and S100A8 expression in kidney tissues of streptozotocin-induced diabetic rats

Background The present study was conducted to examine the antidiabetic effects of Scrophularia striata ethanolic extract and to evaluate its effects on oxidative stress markers and RAGE and S100A8 gene expressions in the kidney of type 1 diabetic rats. Methods A total of 36 rats (weight 200-250 g) were randomly assigned into six groups as follows: Cnt, Cnt + S. striata 100, and Cnt + S. striata 200 that received normal saline, 100 mg/kg bw, and 200 mg/kg bw of ethanol extract of S. striata, respectively; and group Dibt, Dibt + S. striata 100, and Dibt + S. striata 200 that received normal saline, 100 mg/kg bw, and 200 mg/kg bw of ethanol extract of S. striata, respectively. Type 1 diabetes was induced in rats by a single injection of streptozotocin (55 mg/kg bw). After 60 days of treatment, biochemical factors and oxidative stress markers (superoxide dismutase [SOD] and malondialdehyde [MDA]) were measured using spectrophotometric methods. RAGE and S100A8 gene expressions were analyzed using real-time polymerase chain reaction. Results Diabetes significantly impairs serum and urine fasting blood glucose (FBG), lipid profile, creatinine, urea, and albumin parameters. After the treatment with S. striata extract, these parameters are close to the normal range. It was shown that the S. striata extract significantly decreased the kidney expression levels of RAGE and S100A8 genes and improved oxidative stress markers (SOD and MDA) in the kidney tissues when compared with the diabetic control group. It was also found that the beneficial effects of the S. striata were dose dependent. Conclusions The ethanolic extract of S. striata has beneficial antidiabetic effects. Moreover, by reducing RAGE and S100A8 gene expressions and by improving oxidative stress, S. striata might be used as adjuvant treatment for diabetic complications.

Catalpol ameliorates Sjögren's Syndrome by modulating interplay of T and B cells

Catalpol is an active ingredient of Rehmanniae Radix, a medical herb used frequently in treating primary Sjogren's Syndrome (pSS). However, no study has assessed the therapeutic effects of catalpol in treating Sjogren's Syndrome. This study aimed to investigate the therapeutic effects of catalpol for pSS by evaluating the water consumption, stimulated salivary flow rates, sialadenitis, T cell subsets and related cytokine levels. Catalpol treated mice had improved stimulated salivary flow rates and water consumption compared to mice from the control group. Catalpol also reduced the lymphocytic infiltration and prevented the formation of ectopic germinal centers. These effects, especially in the catalpol high dose group, were associated with elevated CD4⁺ CXC-R5⁺ PD-1⁺ Foxp3⁺ T follicular regulatory (Tfr) cells (1.572 % vs 1.118 %, P = 0.0005) and a higher ratio of Tfr cells to T follicular helper (Tfh) cells (2.137 vs 1.541, P = 0.0007). Downregulated levels of IFN-γ and BAFF in serum and submandibular glands were also noted in catalpol treated groups. Our work indicated that catalpol might be a potential drug for treating pSS by regulating the interplay between T and B cells.

Radix Rehmanniae and Corni Fructus against Diabetic Nephropathy via AGE-RAGE Signaling Pathway

BACKGROUND AND AIMS

Radix Rehmanniae and Corni Fructus (RC) have been widely applied to treat diabetic nephropathy (DN) for centuries. But the mechanism of how RC plays the therapeutic role against DN is unclear as yet.

METHODS

The information about RC was obtained from a public database. The active compounds of RC were screened by oral bioavailability (OB) and drug-likeness (DL). Gene ontology (GO) analysis was performed to realize the key targets of RC, and an active compound-potential target network was created. The therapeutic effects of RC active compounds and their key signal pathways were preliminarily probed via network pharmacology analysis and animal experiments.

RESULTS

In this study, 29 active compounds from RC and 64 key targets related to DN were collected using the network pharmacology method. The pathway enrichment analysis showed that RC regulated advanced glycosylation end product (AGE-) RAGE and IL-17 signaling pathways to treat DN. The animal experiments revealed that RC significantly improved metabolic parameters, inflammation renal structure, and function to protect the kidney against DN.

CONCLUSIONS

The results revealed the relationship between multicomponents and multitargets of RC. The administratiom of RC might remit the DM-induced renal damage through the AGE-RAGE signaling pathway to improve metabolic parameters and protect renal structure and function.

Inhibition of lncRNA Neat1 by catalpol via suppressing transcriptional activity of NF-κB attenuates cardiomyocyte apoptosis

Oxidative stress is considered as a major pathogenesis in myocardial damage; however, effective therapies are limited so far. The present study aimed to investigate the in vitro antioxidative mechanism of Catalpol in cardiomyocytes. The results indicated that Catalpol attenuated high glucose (HG)-induced apoptosis in mouse cardiomyocytes via significantly downregulating long noncoding RNA (lncRNA) nuclear paraspeckle assembly transcript 1 (Neat1) expression. Furthermore, Catalpol downregulated Neat1 expression and attenuated apoptosis by inhibiting production of intracellular reactive oxygen species (ROS) in HG-treated cardiomyocytes. Moreover, Catalpol also suppressed HG-induced degradation of IκBα and the nuclear localization of nulear factor-κB (NF-κB) by decreasing the intracellular ROS levels. Additionally, chromatin immunoprecipitation (ChIP) and dual-luciferase activity assays validated that NF-κB bound to Neat1 promoter to activate Neat1 expression. In summary, these results implied that Catalpol protected mouse cardiomyocytes against oxidative injury at least partly through ROS-NF-κB-Neat1 axis.

Anil Kumar N, Sharopov F, Ramírez-Alarcón K, Ruiz-Ortega A, Abdulmajid Ayatollahi S, Valere Tsouh Fokou P, Kobarfard F, Amiruddin Zakaria Z, Iriti M, Taheri Y, Martorell M, Sureda A, N. Setzer W, Durazzo A, Lucarini M, Santini A, Capasso R, Adrian Ostrander E, -ur-Rahman A, Iqbal Choudhary M, C. Cho W, Sharifi-Rad J. Antidiabetic Potential of Medicinal Plants and Their Active Components

Diabetes mellitus is one of the major health problems in the world, the incidence and associated mortality are increasing. Inadequate regulation of the blood sugar imposes serious consequences for health. Conventional antidiabetic drugs are effective, however, also with unavoidable side effects. On the other hand, medicinal plants may act as an alternative source of antidiabetic agents. Examples of medicinal plants with antidiabetic potential are described, with focuses on preclinical and clinical studies. The beneficial potential of each plant matrix is given by the combined and concerted action of their profile of biologically active compounds.

Catalpol in Diabetes and its Complications: A Review of Pharmacology, Pharmacokinetics, and Safety

This review aimed to provide a general view of catalpol in protection against diabetes and diabetic complications, as well as its pharmacokinetics and safety concerns. The following databases were consulted with the retrieval of more than 100 publications through June 2019: PubMed, Chinese National Knowledge Infrastructure, WanFang Data, and web of science. Catalpol exerts an anti-diabetic effect in different animal models with an oral dosage ranging from 2.5 to 200 mg/kg in rats and 10 to 200 mg/kg in mice. Besides, catalpol may prevent the development of diabetic complications in kidney, heart, central nervous system, and bone. The underlying mechanism may be associated with an inhibition of inflammation, oxidative stress, and apoptosis through modulation of various cellular signaling, such as AMPK/PI3K/Akt, PPAR/ACC, JNK/NF-κB, and AGE/RAGE/NOX4 signaling pathways, as well as PKCγ and Cav-1 expression. The pharmacokinetic profile reveals that catalpol could pass the blood-brain barrier and has a potential to be orally administrated. Taken together, catalpol is a well-tolerated natural compound with promising pharmacological actions in protection against diabetes and diabetic complications via multi-targets, offering a novel scaffold for the development of anti-diabetic drug candidate. Further prospective and well-designed clinical trials will shed light on the potential of clinical usage of catalpol.

The protective effect and mechanism of catalpol on high glucose-induced podocyte injury

BACKGROUND

Catalpol, a natural iridoid glycoside in Rehmannia glutinosa, can alleviate proteinuria associated with diabetic nephropathy (DN), however, whether catalpol has a protective effect against podocyte injury in DN remains unclear.

METHODS

In this study, we used a high glucose (HG)-induced podocyte injury model to evaluate the protective effect and mechanism of catalpol against HG-induced podocyte injury. Cell viability was determined by the 3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The levels of lactate dehydrogenase (LDH), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by commercial assay kits. Cell apoptosis and reactive oxygen species (ROS) were determined by using flow cytometry. Tumour necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) levels were determined by enzyme-linked immunosorbent assay (ELISA). The protein expression levels of B-cell lymphoma-2 (Bcl-2), Bcl2-associated x (Bax), cleaved caspase-3, nicotinamide adenine dinucleotide phosphate oxidase enzyme 4 (NOX4), toll-like receptor 4 (TLR4), myeloid differentiation primary response gene 88 (MyD88), p38 mitogen-activated protein kinase (p38 MAPK), phosphorylated p38 MAPK (p-p38 MAPK), nuclear factor kappa B inhibitor alpha (IκBα) and phosphorylated IκBα (p-IκBα) were measured by western blotting. In addition, Bcl-2, Bax, caspase-3 and nuclear factor kappa B (NF-κB) levels were determined by immunofluorescence staining.

RESULTS

Catalpol significantly increased cell viability and decreased LDH release in HG-induced podocyte injury. Catalpol significantly decreased ROS generation, apoptosis, level of MDA, levels of inflammatory cytokine TNF-α, IL-1β, and IL-6 and increased SOD activity in HG-induced podocyte injury. Moreover, catalpol significantly decreased expression of cleaved caspase-3, Bax, NOX4, TLR4, MyD88, p-p38 MAPK, p-IκBα and NF-κB nuclear translocation, as well as increased Bcl-2 expression in HG-induced podocyte injury.

CONCLUSION

Catalpol can protect against podocyte injury by ameliorating apoptosis and inflammation. These protective effects may be attributed to the inhibition of NOX4, which alleviates ROS generation and suppression of the TLR4/MyD88 and p38 MAPK signaling pathways to prevent NF-κB activation. Therefore, catalpol could be a promising drug for the prevention of DN.

Protective effects of catalpol on diabetes mellitus-induced male reproductive damage via suppression of the AGEs/RAGE/Nox4 signaling pathway

AIMS

Diabetes mellitus (DM)-induced reproductive damage is an important cause of infertility for male DM patients, we herein evaluated the effects of catalpol on diabetic reproductive damage through the suppression of the AGEs/RAGE/Nox4 signaling pathway.

METHODS

KK-Ay diabetic reproductive damage mice were administered with catalpol for 8 weeks, the testis/body weight ratio, testicular histopathology, the levels of endogenous hormone and the activity of testicular marker enzymes were determined. In vitro, the GC-2 cell injury model was induced by advanced glycation end-products (AGEs) and pretreated with catalpol. Cell viability, apoptosis, and oxidative stress markers were detected and the mechanism based on the AGEs/RAGE/Nox4 pathway was explored.

KEY FINDINGS

Catalpol showed remarkable capacity on protecting diabetic reproductive damage by improving the histomorphology of the testes, increasing the testis/body weight ratio and activity of acid phosphatase (ACP), lactate dehydrogenase (LDH), gamma-glutamyl transferase (γ-GT). The reduced testosterone (T), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels in DM mice were also reversed with catalpol intervention. Moreover, catalpol showed markedly effects of anti-oxidative in vivo and in vitro, which significantly down-regulated reactive oxygen species (ROS) levels and restored superoxide dismutase (SOD) activity, meanwhile decreased GC-2 cell apoptosis and Bax/Bcl-2 ratio. Moreover, the over-expression of receptors for AGEs (RAGE), NADPH oxidase type 4 (Nox4) and phosphorylation of nuclear transcription factor-κB p65 (NF-κB p65) were suppressed by catalpol.

SIGNIFICANCE

Catalpol could alleviate DM-induced male reproductive damage by inhibiting oxidative stress-induced apoptosis and inflammation mediated by AGEs/RAGE/Nox4 signaling pathway.

Bioactivities of Natural Catalpol Derivatives

Catalpol, a famous molecule of iridoids, possesses extensive pharmacological activities. Our studies found that compounds with low-polarity substituents at the 6-O position of catalpol exhibited higher NF-κB inhibitory potency than catalpol. However, catalpol derivatives are not much focused. Here this review provides extensive coverage of naturally occurring catalpol derivatives discovered from 1888 until 2018. It covers their distribution, chemotaxonomic significance, chemical structures, and bioactivities from more than 200 peer-reviewed articles, and highlights the structure-activity relationship of catalpol derivatives.

Catalpol ameliorates advanced glycation end product-induced dysfunction of glomerular endothelial cells via regulating nitric oxide synthesis by inducible nitric oxide synthase and endothelial nitric oxide synthase

Catalpol (Cat.) is an iridoid glucoside extracted from the root of Rehmannia glutinosa Libosch. In this study, we investigated whether Cat. could protect the mouse glomerular endothelial cells against the deleterious effect induced by advanced glycation end products (AGEs) and explored potential mechanisms. We found that 10 μM Cat. showed a protective effect on dead cells stimulated by AGEs. Cat. significantly decreased the expression of p-NF-κBp65 and inducible nitric oxide synthase (iNOS) and increased the expression of phosphorylated-endothelial nitric oxide synthase (p-eNOS; Ser1177), PI3K, p-Akt (Thr308), and total-Akt. Moreover, Cat. restored the integrity of glomerular endothelial barrier by increasing endothelial tight gap junction protein and ameliorated the endothelial hyperpermeability induced by AGEs via modulating the nitric oxide (NO) production. Additionally, Cat. attenuated the massive release of NO induced by AGEs, inhibiting the macrophage infiltration by modulating the NO production, accompanied by the decrease in the release of monocyte chemoattractant protein-1 and intercellular cell adhesion molecule-1 in vitro. Therefore, Cat. ameliorated AGEs-induced endothelial dysfunction via inhibiting the NF-κB/iNOS pathway and activating the PI3K/Akt/eNOS pathway. © 2019 IUBMB Life, 71(9):1268-1283, 2019.

Effects of catalpol on bronchial asthma and its relationship with cytokines

An animal (BALB/c mice) model of catalpol associated with bronchial asthma in vivo was established, and the effects of catalpol and its relationship with cytokines were investigated. A total of 30 adult BALB/c mice were randomly divided into a positive control group, a model group, and a catalpol group, with 10 mice in each group. The lung function of mice, the cell count, and the cytokine concentrations in bronchoalveolar lavage fluid (BALF) were detected. The levels of cytokines [interleukin 4 (IL-4), interleukin 5 (IL5), and interferon gamma (IFN-γ)] in BALF were measured with enzyme-linked immunosorbent assay methods. The total number of cells in the BALF of the group treated with catalpol was significantly lower than the model group. After treatment with catalpol, the eosinophils and neutrophils of the mice were remarkably reduced compared with the model group. The malondialdehyde content in the lung tissue homogenate of the mice was also decreased in the catalpol group. The cytokines IL-5 and IL-4 exhibited a similar tendency: the concentrations of IL-4 and IL-5 for the catalpol group were dramatically decreased compared with the model group. However, the IFN-γ concentration for the catalpol group was higher than the model group. The results indicated that IL-5 may involve in the pathologic process of asthma-like IL-4, and an inflammatory reaction may still exist in the airway during the remission stage of asthma. The imbalances of the cytokine network might be an important molecular basis in the asthma pathogenesis. It is suggested that catalpol may be a potential drug for the clinical treatment of asthma.

RhoA/ROCK-2 Pathway Inhibition and Tight Junction Protein Upregulation by Catalpol Suppresses Lipopolysaccaride-Induced Disruption of Blood-Brain Barrier Permeability

Lipopolysaccaride (LPS) directly or indirectly injures brain microvascular endothelial cells (BMECs) and damages the intercellular tight junction that gives rise to altered blood-brain barrier (BBB) permeability. Catalpol plays a protective role in LPS-induced injury, but whether catalpol protects against LPS-caused damage of BBB permeability and the underlying mechanism remain to be delineated. Prophylactic protection with catalpol (5 mg/kg, i.v.) consecutively for three days reversed the LPS-induced damage of BBB by decreased Evans Blue (EB) leakage and restored tight junctions in C57 mice. Besides, catalpol co-administrated with LPS increased BMECs survival, decreased their endothelin-1, TNF-Α and IL-6 secretion, improved transmembrane electrical resistance in a time-dependent manner, and in addition increased the fluorescein sodium permeability coefficient of BMECs. Also, transmission electron microscopy showed catalpol protective effects on tight junctions. Fluorescence staining displayed that catalpol reversed the rearrangement of the cytoskeleton protein F-actin and upregulated the tight junction protein of claudin-5 and ZO-1, which have been further demonstrated by the mRNA and protein expression levels of ZO-1, ZO-2, ZO-3, claudin-5, and occludin. Moreover, catalpol concurrently downregulated the mRNA and protein levels of RhoA, and ROCK2, the critical proteins in the RhoA/ROCK2 signaling pathway. This study thus indicated that catalpol, via inhibition of the RhoA/ROCK2 signaling pathway, reverses the disaggregation of cytoskeleton actin in BMECs and prevents down-regulation of junctional proteins, such as claudin-5, occludin, and ZO-1, and decreases endothelin-1 and inflammatory cytokine secretion, eventually alleviating the increase in LPS-induced BBB permeability.

Medicinal Plants with Multiple Effects on Diabetes Mellitus and Its Complications: a Systematic Review

PURPOSE OF REVIEW

This systematic review describes evidence concerning medicinal plants that, in addition to exerting hypoglycemic effects, decrease accompanying complications such as nephropathy, neuropathy, retinopathy, hypertension, and/or hyperlipidemia among individuals with diabetes mellitus (DM).

RECENT FINDINGS

Studies on the antidiabetic mechanisms of medicinal plants have shown that most of them produce hypoglycemic activity by stimulating insulin secretion, augmenting peroxisome proliferator-activated receptors (PPARs), inhibiting α-amylase or α-glucosidase, glucagon-like peptide-1 (GLP-1) secretion, advanced glycation end product (AGE) formation, free radical scavenging plus antioxidant activity (against reactive oxygen or nitrogen species (ROS/RNS)), up-regulating or elevating translocation of glucose transporter type 4 (GLUT-4), and preventing development of insulin resistance. Not only are medicinal plants effective in DM, but many of them also possess a variety of effects on other disease states, including the complications of DM. Such plants may be appropriate alternatives or adjuncts to available antidiabetic medications.

Phytotherapy in the Management of Diabetes: A Review

Phytotherapy has long been a source of medicinal products and over the years there have been many attempts to use herbal medicines for the treatment of diabetes. Several medicinal plants and their preparations have been demonstrated to act at key points of glucidic metabolism. The most common mechanisms of action found include the inhibition of α-glucosidase and of AGE formation, the increase of GLUT-4 and PPARs expression and antioxidant activity. Despite the large amount of literature available, the actual clinical effectiveness of medicinal plants in controlling diabetes-related symptoms remains controversial and there is a crucial need for stronger evidence-based data. In this review, an overview of the medicinal plants, which use in the management of diabetes is supported by authoritative monographs, is provided. References to some species which are currently under increasing clinical investigation are also reported.

Antiangiogenic effects of catalpol on rat corneal neovascularization

To investigate the effects of catalpol on corneal neovascularization (CNV) and associated inflammation, eye drops (5 mM catalpol or PBS) were administered four times daily to alkali-burn rat models of CNV and inflammation. Clinical evaluations of CNV and the degree of inflammation were performed on days 0, 4, 7, 10 and 14 under slit lamp microscopy. Eyes were collected on day 14 and prepared for hematoxylin and eosin, and immunofluorescence staining; corneal cell apoptosis was investigated via terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) staining. Protein expression levels of angiogenic and proinflammatory factors, including vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), tumor necrosis factor-α (TNF-α) and necrosis factor-κB (NF-κB) were determined by western blotting. The effects of catalpol on cell proliferation were investigated in vitro using human umbilical vein endothelial cells (HUVECs) and a Cell Counting kit-8 (CCK-8); alterations in migration and tube formation were investigated via HUVEC wound closure and tube formation assays. HUVEC viability and proliferative ability were inhibited in a dose-dependent manner; catalpol also decreased HUVEC cell migration and tube forming ability. Within alkali-burn rat models, decreased inflammation and CNV was associated with catalpol administration; as demonstrated with TUNEL, corneal cell apoptosis was decreased in response to catalpol. Western blot analysis revealed reduced protein expression levels of VEGF and TNF-α; however, PEDF and phosphorylated-NF-κB p65 were increased due to catalpol administration. The present study demonstrated the inhibitory effects exerted by catalpol on CNV and inflammation within alkali-burned rat models. Topical application of catalpol in vivo was associated with reduced CNV and inflammation; therefore, catalpol may be considered an anti-inflammatory agent for the clinical treatment of CNV.

Detection of RAGE expression and its application to diabetic wound age estimation

With the prevalence of diabetes, it is becoming important to analyze the diabetic wound age in forensic practice. The present study investigated the time-dependent expression of receptor for advanced glycation end products (RAGE) during diabetic wound healing in mice and its applicability to wound age determination by immunohistochemistry, double immunofluorescence, and Western blotting. After an incision was created in genetically diabetic db/db mice and control mice, mice were killed at posttraumatic intervals ranging from 6 h to 14 days, followed by the sampling of wound margin. Compared with control mice, diabetic mice showed the delayed wound healing. In control and diabetic wound specimens, RAGE immunoreactivity was observed in a small number of polymorphonuclear cells (PMNs), a number of macrophages, and fibroblasts. Morphometrically, the positive ratios of RAGE in macrophages or fibroblasts considerably increased in diabetic wounds during late repair, which exceeded 60% at 7 and 10 days post-injury. There were no control wound specimens to show a ratio of >60% in macrophages or fibroblasts. By Western blotting analysis, the ratios of RAGE to GAPDH were >1.4 in all diabetic wound samples from 7 to 10 days post-injury, which were >1.8 at 10 days after injury. By comparison, no control wound specimens indicated a ratio of >1.4. In conclusion, the expression of RAGE is upregulated and temporally distributed in macrophages and fibroblasts during diabetic wound healing, which might be closely involved in prolonged inflammation and deficient healing. Moreover, RAGE is promising as a useful marker for diabetic wound age determination.

Activation of α7nAChR Promotes Diabetic Wound Healing by Suppressing AGE-Induced TNF-α Production

Diabetes frequently presents accumulation of advanced glycation end products (AGEs), which might induce excessive TNF-α production from macrophages to cause impaired wound healing. Recent studies have shown that activation of α7 nicotinic acetylcholine receptor (α7nAChR) on macrophages efficiently suppressed TNF-α synthesis. The aim of this study was to investigate the accumulation of AGEs in the wounds and determine whether PNU282987, an α7nAChR agonist, can improve wound repair by inhibiting AGE-mediated TNF-α production in a streptozotocin (STZ)-induced diabetic mouse model. Animals were assigned into four groups: wounded control group, wounded diabetic group, wounded diabetic group treated intraperitoneally with PNU282987, or wounded diabetic group treated intraperitoneally with vehicle. Compared with the non-diabetic control mice, the diabetic mice exhibited delayed wound healing that was characterized by elevated accumulation of AGEs, increased TNF-α level and macrophage infiltration, and decreased fibroblast number and collagen deposition at the late stage of repair. Besides, macrophages of diabetic wounds showed expression of α7nAChR. During late repair, PNU282987 treatment of diabetic mice significantly reduced the level of TNF-α, accelerated wound healing, and elevated fibroblast number and collagen deposition. To investigate the cellular mechanism of these observations, RAW 264.7 cells, a macrophage cell line, were incubated with AGEs in the presence or absence of PNU282987. TNF-α production from AGE-stimulated macrophages was significantly decreased by PNU282987 in a dose-dependent manner. Furthermore, PNU282987 significantly inhibited AGE-induced nuclear factor-κB (NF-κB) activation and receptor for AGE (RAGE) expression. These results strongly suggest that activating α7nAChR can promote diabetic wound healing by suppressing AGE-induced TNF-α production, which may be closely associated with the blockage of NF-κB activation in macrophages.

Catalpol alleviates ovalbumin-induced asthma in mice: Reduced eosinophil infiltration in the lung

BACKGROUND

Radix Rehmanniae Preparata is a traditional Chinese herbal medicine used to treat asthma, and catalpol is one of the main active ingredients in this herb. In the present study, the effects of catalpol on asthma and the underlying mechanism were explored.

METHODS

Mice with ovalbumin (OVA)-induced asthma were given 5 or 10mg/kg catalpol from Day 15 to Day 28 (intraperitoneal injection). Histopathologic changes were detected by Hematoxylin and Eosin staining and Periodic Acid Schiff staining. The levels of IgE, interleukin (IL)-4, IL-5 and eotaxin were measured by ELISA. The numbers of lymphocytes, monocytes, basophils and eosinophils in the bronchoalveolar lavage fluid were determined by Wright-Giemsa staining. The expression and distribution of eotaxin and C-C chemokine receptor 3 (CCR3) were detected by immunohistochemistry and immunofluorescence. The expression of interleukin-5 receptor α (IL-5Rα) was detected by Western blot assay.

RESULTS

Catalpol inhibited OVA-induced inflammation and IgE secretion in the lung. OVA-induced type 2 inflammation was suppressed by catalpol as evidenced by decreased levels of IL-4 and IL-5. Moreover, catalpol inhibited the aberrant eosinophil infiltration in the lungs, and also suppressed OVA-induced elevation of eosinophil chemokine eotaxin and its receptor CCR3. In addition, IL-5Rα expression in the bone marrow cells derived from catalpol-treated asthmatic mice was lower than that from the untreated asthmatic mice.

CONCLUSION

Our study demonstrated that catalpol attenuated OVA-induced asthma and inhibit the infiltration of inflammatory cells, especially eosinophils, into the lung. This study suggests that catalpol may become a promising drug for the treatment of asthma.

Effects of rumenic acid rich conjugated linoleic acid supplementation on cognitive function and handgrip performance in older men and women

The purpose of this study was to investigate the effects of 8weeks at 6g per day of RAR CLA versus placebo on cognitive function and handgrip performance in older men and women. Sixty-five (43 women, 22 men) participants (mean±SD; age=72.4±5.9yrs; BMI=26.6±4.2kg·m^-2) were randomly assigned to a RAR CLA (n=30: 10 men, 20 women) or placebo (PLA; high oleic sunflower oil; n=35: 12 men, 23 women) group in double-blind fashion and consumed 6g·d^-1 of their allocated supplement for 8weeks. Before (Visit 1) and after supplementation (Visit 2), subjects completed the Serial Sevens Subtraction Test (S₇), Trail Making Test Part A (TM_A) and Part B (TM_B), and Rey's Auditory Verbal Learning Test (RAVLT) to measure cognitive function. The RAVLT included 5, 15-item auditory word recalls (R_1-5), an interference word recall (R_B), a 6th word recall (R₆), and a 15-item visual word recognition trial (R_R). For handgrip performance, subjects completed maximal voluntary isometric handgrip strength (MVIC) testing before (MVIC_PRE) and after (MVIC_POST) a handgrip fatigue test at 50% MVIC_PRE. Hand joint discomfort was measured during MVIC_PRE, MVIC_POST, and the handgrip fatigue test. There were no treatment differences (p>0.05) for handgrip strength, handgrip fatigue, or cognitive function as measured by the Trail Making Test and Serial Seven's Subtraction Test in men or women. However, RAR CLA supplementation improved cognitive function as indicated by the RAVLT R₅ in men. A qualitative examination of the mean change scores suggested that, compared to PLA, RAR CLA supplementation was associated with a small improvement in joint discomfort in both men and women. Longer-term studies are needed to more fully understand the potential impact of RAR CLA on cognitive function and hand joint discomfort in older adults, particularly in those with lower cognitive function.

Antidiabetic and antioxidant effects of catalpol extracted from Rehmannia glutinosa (Di Huang) on rat diabetes induced by streptozotocin and high-fat, high-sugar feed

Background

Diabetes, associated with hyperlipidemia and oxidative stress, would lead to an increased production of reactive oxygen species. Rehmannia glutinosa (Di Huang) is widely used to nourish yin, invigorate the kidney (shen), and treat xiao ke (a diabetes-like syndrome in Chinese medicine). This study aims to investigate the antidiabetic and antioxidant effects of catalpol from R. glutinosa on rat diabetes induced by streptozotocin (STZ) and high-fat, high-sugar feed.

Methods

Rats (eight rats in each group at least) were induced diabetes by an initial high-fat high-sugar feed for 3 weeks, followed by an intraperitoneal injection of STZ (30 mg/kg) for 3 days, and rats were fasted overnight before treatments. Catalpol at a dose of 0, 5, 10, 20 or 50 mg/kg was administrated through bolus intravenous injection to the experimental rats to find the most effective anti-hyperglycemic dose of catalpol to further study body weight loss, water intake, and food intake. The most effective catalpol dose was given to the diabetic model rats with hyperlipidemia, and the levels of blood sugar, plasma total cholesterol (TC), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) were measured after catalpol administration once a day for 2 weeks. An oral glucose challenge test (OGCT) was performed after above experiments in which the most effective dose of catalpol has been determined. Levels of glutathione peroxidase (GSH-PX), catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA) were measured by corresponding reagent kits and morphological changes of the pancreas were observed with histopathological examination using H&E stain.

Results

Catalpol at a dose of 50 mg/kg ameliorated body weight loss and increased water and food intake. Catalpol also attenuated the increase of plasma TC (P = 0.0067) and TG (P = 0.0084) and increased HDL-C (P = 0.0336). The OGCT revealed that catalpol reduced the increase of plasma glucose. The activities of antioxidative enzymes (SOD, P = 0.0037; GSH-PX, P = 0.0066; CAT, P = 0.005) were enhanced and MDA was reduced (P = 0.003). Furthermore, catalpol reduced the morphological impairment of the pancreas.

Conclusion

Catalpol protected against STZ-induced diabetes with high-fat and high-sugar feed with ameliorated structural impairment of the pancreas and restored balance between oxidative enzymes and antioxidative enzymes.

Anti-Inflammatory Activity Comparison among Scropoliosides-Catalpol Derivatives with 6-O-Substituted Cinnamyl Moieties

We have previously shown that scropolioside B has higher anti-inflammatory activity than catalpol does after the inhibition of nuclear factor (NF)-κB activity and IL-1β expression, maturation, and secretion. Various scropoliosides were extracted, isolated, and purified from Scrophularia dentata Royle ex Benth. We then compared their anti-inflammatory activities against LPS-induced NF-κB activity, cytokines mRNA expression, IL-1β secretion, and cyclooxygenase-2 activity. The inhibitory effects of the scropoliosides varied depending on whether the 6-O-substituted cinnamyl moiety was linked to C′′ 2-OH, C′′3-OH, or C′′4-OH, and on the number of moieties linked, which is closely related to the enhancement of antiinflammatory activity. Among these compounds, scropolioside B had the strongest antiinflammatory effects.

Catalpol preserves neural function and attenuates the pathology of Alzheimer's disease in mice

Alzheimer's disease (AD) is the most common form of dementia and there currently are no effective treatment strategies available. Catalpol is an iridoid glucoside, and large quantities can be isolated from the genus Rehmannia (Orobanchaceae). The present study assessed whether catalpol had any protective effects against Alzheimer's disease using a murine model. Reactive oxygen species (ROS)-associated enzymes as well as soluble Aβ40 and Aβ42 were detected using kits. Thioflavin‑S staining was performed to detect senile plaques and reverse-transcription quantitative polymerase chain reaction was used to assess iroquois homeobox protein 3 (IRX3) and obesity‑associated genes, while western blot analysis was used for β‑secretase 1 (BACE1), insulin‑degrading enzyme (IDE) and neprilysin (NEP) detection. The Morris water maze was used to detect the learning ability and spatial memory. The results revealed that catalpol was able to reduce the oxidative stress in the cerebral cortex by regulating the activities and concentration of ROS‑associated enzymes superoxide dismutase, glutathione peroxidase and catalase, however not malondialdehyde. Catalpol was also identified to be able to reduce the levels of soluble Aβ40 and Aβ42 in the cerebral cortex and thus inhibit the formation of senile plaques. These effects were observed to be regulated by IDE, however not by BACE1 or NEP. It is suggested that catalpol is not capable of directly regulating the expression of IRX3 and obesity‑associated genes. Subsequent to the treatment with catalpol, impairments in learning and memory were also observed to be relieved using the Morris water maze test. The results of the present study indicate that catalpol may be a potential drug for the treatment of neurodegenerative diseases such as AD.

Advanced Glycation End Products Enhance Macrophages Polarization into M1 Phenotype through Activating RAGE/NF-κB Pathway

Atherosclerotic lesions are accelerated in patients with diabetes. M1 (classically activated in contrast to M2 alternatively activated) macrophages play key roles in the progression of atherosclerosis. Since advanced glycation end products (AGEs) are major pathogenic factors and active inflammation inducers in diabetes mellitus, this study assessed the effects of AGEs on macrophage polarization. The present study showed that AGEs significantly promoted macrophages to express IL-6 and TNF-α. M1 macrophage markers such as iNOS and surface markers including CD11c and CD86 were significantly upregulated while M2 macrophage markers such as Arg1 and CD206 remained unchanged after AGEs stimulation. AGEs significantly increased RAGE expression in macrophages and activated NF-κB pathway, and the aforementioned effects were partly abolished by administration of anti-RAGE antibody or NF-κB inhibitor PDTC. In conclusion, our results suggest that AGEs enhance macrophage differentiation into proinflammatory M1 phenotype at least partly via RAGE/NF-κB pathway activation.

Evaluation of the Effects of Some Brazilian Medicinal Plants on the Production of TNF- α and CCL2 by THP-1 Cells

Several plant species are traditionally used in Brazil to treat various inflammatory diseases. Tumor necrosis factor- (TNF-) α and chemokine (C-C motif) ligand 2 (CCL2) are key inflammatory mediators in diseases like rheumatoid arthritis and atherosclerosis, respectively; nevertheless, only a few extracts have been assayed against these targets. We herein report the effect of 19 plant extracts on TNF-α and CCL2 release by lipopolysaccharide- (LPS-) stimulated THP-1 cells, a human monocytic leukemia cell line, along with their radical scavenging activity on DPPH. The extracts of Caryocar brasiliense, Casearia sylvestris, Coccoloba cereifera, and Terminalia glabrescens inhibited TNF-α production in a concentration-dependent manner. Fractionation of these extracts potentiated the anti-TNF-α effect, which was shown to concentrate in polar fractions, mainly composed by polyphenols. Significant CCL2 inhibition was elicited by Lippia sidoides and Terminalia glabrescens extracts, whose fractionation resulted in highly active low polar fractions. All assayed extracts showed strong radical scavenging activity, but antioxidant activity did not correlate with inhibition of TNF-α or CCL2 production. Our results allowed identifying extracts with selective capacity to block cytokine production; therefore, further purification of these extracts may yield molecules that could be useful in the treatment of chronic inflammatory diseases.

Ancient records and modern research on the mechanisms of chinese herbal medicines in the treatment of diabetes mellitus

Over the past decades, Chinese herbal medicines (CHM) have been extensively and intensively studied through from both clinical and experimental perspectives and CHM have been proved to be effective in the treatment of diabetes mellitus (DM). This study, by searching ancient records and modern research papers, reviewed CHM in terms of their clinical application and principal mechanism in the treatment of DM. We summarized the use of CHM mentioned in 54 famous ancient materia medica monographs and searched papers on the hypoglycemic effect of several representative CHM. Main mechanisms and limitations of CHM and further research direction for DM were discussed. On the basis of the study, we were led to conclude that TCM, as a main form of complementary and alternative medicine (CAM), was well recorded in ancient literatures and has less adverse effects as shown by modern studies. The mechanisms of CHM treatment of DM are complex, multilink, and multitarget, so we should find main hypoglycemic mechanism through doing research on CHM monomer active constituents. Many CHM monomer constituents possess noteworthy hypoglycemic effects. Therefore, developing a novel natural product for DM and its complications is of much significance. It is strongly significant to pay close attention to CHM for treatment of DM and its complications.

Scropolioside B inhibits IL-1β and cytokines expression through NF-κB and inflammasome NLRP3 pathways

Chronic inflammation is associated with various chronic illnesses including immunity disorders, cancer, neurodegeneration, and vascular diseases. Iridoids are compounds with anti-inflammatory properties. However their anti-inflammatory mechanism remains unclear. Here, we report that scropolioside B, isolated from a Tibetan medicine (Scrophularia dentata Royle ex Benth.), blocked expressions of TNF, IL-1, and IL-32 through NF-κB pathway. Scropolioside B inhibited NF-κB activity in a dose-dependent manner with IC50 values of 1.02 μmol/L. However, catalpol, similar to scropolioside B, was not effective in inhibiting NF-κB activity. Interestingly, scropolioside B and catalpol decreased the expression of NLRP3 and cardiolipin synthetase at both the mRNA and protein level. Our results showed that scropolioside B is superior in inhibiting the expression, maturation, and secretion of IL-1β compared to catalpol. These observations provide further understanding of the anti-inflammatory effects of iridoids and highlight scropolioside B as a potential drug for the treatment of rheumatoid arthritis and atherosclerosis.

Catalpol ameliorates sodium taurocholate-induced acute pancreatitis in rats via inhibiting activation of nuclear factor kappa B

Catalpol, an iridoid glucoside extracted from the traditional Chinese herbal medicine, Rehmannia glutinosa, is reported to exert neuroprotective, anti-inflammatory, anti-tumor and anti-apoptotic effects. The main aim of the present study was to investigate whether catalpol ameliorates experimental acute pancreatitis (AP) induced by sodium taurocholate (STC). AP was induced in rats via retrograde injection of 4% STC (0.1 mL/100 g) into the biliopancreatic duct. Rats were pre-treated with saline or catalpol (50 mg/kg) 2 h before STC injection. At 12, 24 and 48 h after injection, the severity of AP was evaluated using biochemical and morphological analyses. Pretreatment with catalpol led to a significant reduction in serum amylase and lipase activities, pancreatic histological damage, myeloperoxidase (MPO) activity, interleukin (IL)-1β, IL-6 and TNF-α levels, and activation of nuclear factor kappa B (NF-κB). Moreover, administration of catalpol increased the viability of pancreatic acinar cells and inhibited NF-κB expression in vitro. Our results collectively support the potential of catalpol as a highly effective therapeutic agent for treatment of AP.

Role of multiligand/RAGE axis in platelet activation

In the context of plaque progression, platelet hyperactivity associated with hyperlipidemia contributes to the development of a pro-thrombotic state. In this context, it has been demonstrated that advanced glycation end products (AGEs) significantly increases platelet activation and receptor for AGEs (RAGE) expression at the platelet surface membrane. In addition to AGEs, other ligands (S100, HMGB1 and amyloid β, among others) of RAGE have raised particular attention in platelet activation. Therefore, in this article we describe platelet hyperactivity by AGEs via RAGE-independent and RAGE-dependent pathways.