Release of acetylcholine to raise insulin secretion in Wistar rats by oleanolic acid, one of the active principles contained in Cornus officinalis

A comprehensive review of Cornus officinalis: health benefits, phytochemistry, and pharmacological effects for functional drug and food development

Introduction

Cornus officinalis sieb. et zucc, a deciduous tree or shrub, is renowned for its "Cornus flesh" fruit, which is widely acknowledged for its medicinal value when matured and dried. Leveraging C. officinalis as a foundational ingredient opens avenues for the development of environmentally friendly health foods, ranging from beverages and jams to preserves and canned products. Packed with diverse bioactive compounds, this species manifests a spectrum of pharmacological effects, including anti-inflammatory, antioxidant, antidiabetic, immunomodulatory, neuroprotective, and cardiovascular protective properties.

Methods

This study employs CiteSpace visual analysis software and a bibliometric analysis platform, drawing upon the Web of Science (WOS) database for literature spanning the last decade. Through a comprehensive analysis of available literature from WOS and Google Scholar, we present a thorough summary of the health benefits, phytochemistry, active compounds, and pharmacological effects of C. officinalis. Particular emphasis is placed on its potential in developing functional drugs and foods.

Results and Discussion

While this review enhances our understanding of C. officinalis as a prospective therapeutic agent, its clinical applicability underscores the need for further research and clinical studies to validate findings and establish safe and effective clinical applications.

Morroniside ameliorates glucocorticoid-induced osteoporosis and promotes osteoblastogenesis by interacting with sodium-glucose cotransporter 2

CONTEXT

Morroniside (MOR) possesses antiosteoporosis (OP) effects, but its molecular target and relevant mechanisms remain unknown.

OBJECTIVE

We investigated the effects of MOR on glucocorticoid-induced OP and osteoblastogenesis and its underlying mechanisms.

MATERIALS AND METHODS

The effects of MOR (10-100 μM) on the proliferation and differentiation of MC3T3-E1 cells were studied in vitro. The glucocorticoid-induced zebrafish OP model was treated with 10, 20 and 40 μM MOR for five days to evaluate its effects on vertebral bone density and related osteogenic markers. In addition, molecular targets prediction and molecular docking analysis were carried out to explore the binding interactions of MOR with the target proteins.

RESULTS

In cultured MC3T3-E1 cells, 20 μM MOR significantly increased cell viability (1.64 ± 0.12 vs. 0.95 ± 0.16; p < 0.01) and cell differentiation (1.57 ± 0.01 vs. 1.00 ± 0.04; p < 0.01) compared to the control group. MOR treatment significantly ameliorated vertebral bone loss in the glucocorticoid-induced OP zebrafish model (0.86 ± 0.02 vs. 0.40 ± 0.03; p < 0.01) and restored the expression of osteoblast-specific markers, including ALP, Runx2 and Col-І. Ligand-based target prediction and molecular docking revealed the binding interaction between MOR and the glucose pockets in sodium-glucose cotransporter 2 (SGLT2).

DISCUSSION AND CONCLUSIONS

These findings demonstrated that MOR treatment promoted osteoblastogenesis and ameliorated glucocorticoid-induced OP by targeting SGLT2, which may provide therapeutic potential in managing glucocorticoid-induced OP.

Oleanolic Acid: Extraction, Characterization and Biological Activity

Oleanolic acid, a pentacyclic triterpenoid ubiquitously present in the plant kingdom, is receiving outstanding attention from the scientific community due to its biological activity against multiple diseases. Oleanolic acid is endowed with a wide range of biological activities with therapeutic potential by means of complex and multifactorial mechanisms. There is evidence suggesting that oleanolic acid might be effective against dyslipidemia, diabetes and metabolic syndrome, through enhancing insulin response, preserving the functionality and survival of β-cells and protecting against diabetes complications. In addition, several other functions have been proposed, including antiviral, anti-HIV, antibacterial, antifungal, anticarcinogenic, anti-inflammatory, hepatoprotective, gastroprotective, hypolipidemic and anti-atherosclerotic activities, as well as interfering in several stages of the development of different types of cancer; however, due to its hydrophobic nature, oleanolic acid is almost insoluble in water, which has led to a number of approaches to enhance its biopharmaceutical properties. In this scenario, the present review aimed to summarize the current knowledge and the research progress made in the last years on the extraction and characterization of oleanolic acid and its biological activities and the underlying mechanisms of action.

The Use of Bioactive Compounds in Hyperglycemia- and Amyloid Fibrils-Induced Toxicity in Type 2 Diabetes and Alzheimer’s Disease

It has become increasingly apparent that defective insulin signaling may increase the risk for developing Alzheimer’s disease (AD), influence neurodegeneration through promotion of amyloid formation or by increasing inflammatory responses to intraneuronal β-amyloid. Recent work has demonstrated that hyperglycemia is linked to cognitive decline, with elevated levels of glucose causing oxidative stress in vulnerable tissues such as the brain. The ability of β-amyloid peptide to form β-sheet-rich aggregates and induce apoptosis has made amyloid fibrils a leading target for the development of novel pharmacotherapies used in managing and treatment of neuropathological conditions such as AD-related cognitive decline. Additionally, deposits of β-sheets folded amylin, a glucose homeostasis regulator, are also present in diabetic patients. Thus, therapeutic compounds capable of reducing intracellular protein aggregation in models of neurodegenerative disorders may prove useful in ameliorating type 2 diabetes mellitus symptoms. Furthermore, both diabetes and neurodegenerative conditions, such as AD, are characterized by chronic inflammatory responses accompanied by the presence of dysregulated inflammatory biomarkers. This review presents current evidence describing the role of various small bioactive molecules known to ameliorate amyloidosis and subsequent effects in prevention and development of diabetes and AD. It also highlights the potential efficacy of peptide–drug conjugates capable of targeting intracellular targets.

Liu Wei Di Huang Wan and the Delay of Insulin Use in Patients with Type 2 Diabetes in Taiwan: A Nationwide Study

Introduction

Patients with type 2 diabetes are widely prescribed metformin for controlling blood glucose levels to avoid related comorbidities. In Taiwan, traditional Chinese medicine (TCM) is also commonly used, especially Liu Wei Di Huang Wan (LWDHW), which has been reported to delay the occurrence of kidney failure. However, the effect of combinational therapy of TCM and oral antidiabetic drugs is still unclear. This study aims to estimate their efficacy in delaying insulin use.

Materials and Methods

This case-control study was conducted using one million randomized samples from the National Health Insurance Research Database in Taiwan. The effects of TCM and LWDHW were estimated using the Cox proportional hazards model.

Results

In this study, 70,036 diabetic patients were enrolled; of them, 17,451 (24.9%) used insulin, while the rest (52,585, 75.1%) did not. TCM users had a lower risk for insulin use (HR: 0.58, 95% CI: 0.56–0.60). LWDHW users had a lower risk compared with patients who used other TCM (HR: 0.86, 95% CI: 0.82–0.90) and presented a dose-dependent effect.

Conclusion

The use of LWDHW and oral antidiabetic drugs is highly associated with the delay in the use of insulin. Clinical practitioners may take them into consideration when treating patients with type 2 diabetes.

Multiomics-based characterization of specialized metabolites biosynthesis in Cornus Officinalis

Cornus officinalis, an important traditional medicinal plant, is used as major constituents of tonics, analgesics, and diuretics. While several studies have focused on its characteristic bioactive compounds, little is known on their biosynthesis. In this study, we performed LC-QTOF-MS-based metabolome and RNA-seq-based transcriptome profiling for seven tissues of C. officinalis. Untargeted metabolome analysis assigned chemical identities to 1,215 metabolites and showed tissue-specific accumulation for specialized metabolites with medicinal properties. De novo transcriptome assembly established for C. officinalis showed 96% of transcriptome completeness. Co-expression analysis identified candidate genes involved in the biosynthesis of iridoids, triterpenoids, and gallotannins, the major group of bioactive metabolites identified in C. officinalis. Integrative omics analysis identified 45 cytochrome P450s genes correlated with iridoids accumulation in C. officinalis. Network-based integration of genes assigned to iridoids biosynthesis pathways with these candidate CYPs further identified seven promising CYPs associated with iridoids’ metabolism. This study provides a valuable resource for further investigation of specialized metabolites’ biosynthesis in C. officinalis.

Active Components and Pharmacological Effects of Cornus officinalis: Literature Review

Cornus officinalis Sieb. et Zucc. (Shanzhuyu), a herb and food plant in east Asia, has the properties of tonifying the liver and kidney, and nourishing the essence according to the theory of traditional Chinese medicine. C. officinalis has been commonly used to treat asthenia diseases, liver, and kidney diseases, and reproductive system diseases since ancient times. The objectives of this article were to review the pharmacological effects and phytochemistry of C. officinalis. We conducted a literature review of the pharmacological effects of C. officinalis by different systems and compared the effects with the traditional usages, discussed the research status and potential blanks to be filled. The experimental studies showed that C. officinalis extract and its active components had various pharmacological effects such as anti-oxidation, anti-apoptosis, anti-inflammation, anti-diabetes, anti-osteoporosis, immunoregulation, neuroprotection, and cardiovascular protection, but clinical studies are still needed to assess whether the reported pharmacological activities have confirmed efficacy.

Anticancer Potential of Betulonic Acid Derivatives

Clinical trials have evidenced that several natural compounds, belonging to the phytochemical classes of alkaloids, terpenes, phenols and flavonoids, are effective for the management of various types of cancer. Latest research has proven that natural products and their semisynthetic variants may serve as a starting point for new drug candidates with a diversity of biological and pharmacological activities, designed to improve bioavailability, overcome cellular resistance, and enhance therapeutic efficacy. This review was designed to bring an update regarding the anticancer potential of betulonic acid and its semisynthetic derivatives. Chemical derivative structures of betulonic acid including amide, thiol, and piperidine groups, exert an amplification of the in vitro anticancer potential of betulonic acid. With the need for more mechanistic and in vivo data, some derivatives of betulonic acids may represent promising anticancer agents.

TGR5 Activation Promotes Stimulus-Secretion Coupling of Pancreatic β-Cells via a PKA-Dependent Pathway

The Takeda-G-protein-receptor-5 (TGR5) mediates physiological actions of bile acids. Since it was shown that TGR5 is expressed in pancreatic tissue, a direct TGR5 activation in β-cells is currently postulated and discussed. The current study reveals that oleanolic acid (OLA) affects murine β-cell function by TGR5 activation. Both a G_αs inhibitor and an inhibitor of adenylyl cyclase (AC) prevented stimulating effects of OLA. Accordingly, OLA augmented the intracellular cAMP concentration. OLA and two well-established TGR5 agonists, RG239 and tauroursodeoxycholic acid (TUDCA), acutely promoted stimulus-secretion coupling (SSC). OLA reduced K_ATP current and elevated current through Ca²⁺ channels. Accordingly, in mouse and human β-cells, TGR5 ligands increased the cytosolic Ca²⁺ concentration by stimulating Ca²⁺ influx. Higher OLA concentrations evoked a dual reaction, probably due to activation of a counterregulating pathway. Protein kinase A (PKA) was identified as a downstream target of TGR5 activation. In contrast, inhibition of phospholipase C and phosphoinositide 3-kinase did not prevent stimulating effects of OLA. Involvement of exchange protein directly activated by cAMP 2 (Epac2) or farnesoid X receptor (FXR2) was ruled out by experiments with knockout mice. The proposed pathway was not influenced by local glucagon-like peptide 1 (GLP-1) secretion from α-cells, shown by experiments with MIN6 cells, and a GLP-1 receptor antagonist. In summary, these data clearly demonstrate that activation of TGR5 in β-cells stimulates insulin secretion via an AC/cAMP/PKA-dependent pathway, which is supposed to interfere with SSC by affecting K_ATP and Ca²⁺ currents and thus membrane potential.

Antioxidant Effects of Bioactive Compounds Isolated from Pressurized Steam-Treated Corni Fructus and Their Protective Effects Against UVB-Irradiated HS68 Cells

This study evaluated the antioxidant and protective effects of bioactive compounds isolated from pressurized steam-treated Corni Fructus (PSC). We had previously tested the protective effects of the furan fraction containing 5-hydroxymethylfurfural (5-HMF), polyphenol fraction containing gallic acid, and iridoid glycoside fraction containing morroniside and loganin. We measured the potency of antioxidant activities of the bioactive compounds isolated from PSC via oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. One fraction in particular (named F-2) not only contained high amounts of phenolics but also had potent antioxidant activities. The protective effects of F-2 were evaluated by measuring the levels of the collagen-degrading enzyme, matrix metalloproteinase-1 (MMP-1), and the marker of collagen biosynthesis, procollagen type I C-peptide (PIP), in UVB-treated HS68 fibroblasts. MMP-1 levels decreased in an F-2 concentration-dependent manner, and PIP secretion from the cultured HS68 cells was significantly higher than that from the UVB-irradiated cultures alone. Further, F-2 attenuated UVB-induced MMP-1 and ameliorated UVB-downregulated collagen type I alpha 1 mRNA expression in HS68 cells. Therefore, F-2 isolated from PSC is a good candidate for the prevention of skin damage from free radicals in various skin conditions.

Corni Fructus: a review of chemical constituents and pharmacological activities

Cornus officinalis Sieb. et Zucc. is part of the genus Cornus of the family Cornaceae. Ripening and dry fruits (Corni Fructus) are recognized as an essential herb medicine in the traditional Chinese medicine (TCM) and have been widely used for over 2000 years. This review provides a comprehensive summary of Corni Fructus (CF), including the botany, phytochemistry, traditional use, and current pharmacological activities. According to the basic theory of TCM, CF usually participates in various Chinese medicinal formulae to exert the essential roles in replenishing liver and kidney, arresting seminal emission and sweat. Based on modern pharmacological studies, about 90 compounds have been isolated and identified from CF. In vivo and in vitro experimental studies indicate that CF exhibits extensive pharmacological activities including hypoglycemic, antioxidant, anti-inflammatory, anticancer, neuroprotective, hepatoprotective, and nephroprotective activities. However, only about 18% of chemical constituents in CF were tested. It means the potential pharmacological activities and clinical values of CF need to be further investigated.

Ethnopharmacology, phytochemistry, and pharmacology of Cornus officinalis Sieb. et Zucc

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis (Cornaceae), known in Chinese as "Shanzhuyu," is a frequently used traditional Chinese medicine. It tastes sour and is astringent and slightly warm in nature. Its fruits have long been used to treat kidney deficiency, high blood pressure, waist and knee pain, dizziness, tinnitus, impotence, spermatorrhea, menorrhagia, and other diseases in China. The main distribution areas are Shanxi and Gansu.

AIM OF THE STUDY

This review focused on the ethnopharmacological uses of the herb. We also focus on the phytochemical, pharmacological, and toxicological studies on C. officinalis. The recent analytical methods developed for the quality control of the herb's constituents are also reviewed. Additionally, future trends and prospects in the study of this herb are proposed.

MATERIALS AND METHODS

Information on C. officinalis was gathered by searching the internet (PubMed, ScienceDirect, Wiley, ACS, CNKI, Scifinder, Web of Science, Google Scholar, and Baidu Scholar) and libraries.

RESULTS

This review compiled the ethnopharmacological uses, including the classic prescriptions and historical applications. Approximately 300 chemical compounds have been isolated and identified from C. officinalis. The major active components of the plant are organic acids and iridoids, among which morroniside and loganin have been extensively investigated. The fruit of the plant has been used in treating many diseases in traditional medicine. Scientific studies indicated the herb's wide range of pharmacological activities, such as hepatic and renal protection, antidiabetes activity, cardioprotection, antioxidation, neuroprotection, antitumor activity, anti-inflammation, analgesic effects, antiaging activity, antiamnesia, antiosteoporosis, and immunoregulation. The analytical methods developed for the quantitative and qualitative determination of various compounds in the herb were further reviewed.

CONCLUSIONS

In this paper, we reviewed various studies conducted on C. officinalis, especially in areas of its ethnopharmacological use, as well as on its phytochemistry, pharmacology, and modern analytical methods used. Some of the herb's ethnomedical indications have been confirmed by the herb's pharmacological effects, such as its hepatic and renal protection and the antidiabetic effects. In particular, the crude extract and its chemical composition have exerted good therapeutic effect in diabetic treatment. C. officinalis entails additional attention on its pharmacological effects and drug development to expand its effective use clinically. Many advanced technologies are used for quality testing, but the detection component is exceedingly scarce for synthetically evaluating the quality of C. officinalis herbs. Thus, further research is necessary to investigate the quality control and toxicology of the plant, to further elucidate its clinical use, and to control herbal quality.

Inhibition of key enzymes linked to type 2 diabetes by compounds isolated from Aframomum melegueta fruit

CONTEXT

The use of Aframomum melegueta K. Schum. (Zingiberaceae) fruit for treatment of diabetes has recently been established in Nigeria. However, compounds responsible for the antidiabetic action have not been identified.

OBJECTIVE

The present study carried out the bioassay-guided isolation of possible bioactive compounds responsible for the antidiabetic action of A. melegueta fruit.

MATERIALS AND METHODS

The A. melegueta fruit was sequentially extracted using ethyl acetate (EtOAc), ethanol and water, and the most active extract (EtOAc) was subjected to column chromatography on a silica gel column using solvent gradient systems of hexane (HEX):EtOAc and EtOAc:MeOH and the isolation of compounds was guided by α-glycosidase and α-amylase inhibitory activities at various concentrations (30-240 μg/mL).

RESULTS

According to the results, 3 arylalkanes, 6-paradol (1), 6-shogaol (2) and 6-gingerol (3) and a pentacyclic triterpene, oleanolic acid (4) were isolated from A. melegueta fruit. All the compounds exhibited inhibitory effects against α-amylase and α-glucosidase. 6-Gingerol (3) and oleanolic acid (4) showed higher inhibitory activity against α-amylase (IC50: 6-gingerol: 81.78 ± 7.79 μM; oleanolic acid: 91.72 ± 1.63 μM) and α-glucosidase (IC50: 6-gingerol: 21.55 ± 0.45 μM; oleanolic acid: 17.35 ± 0.88 μM) compared to the standard drug, acarbose and other isolated compounds. The kinetics of the enzyme action of the compounds showed a noncompetitive mode of inhibition.

CONCLUSION

The data of this study suggest that the 6-gingerol (3) and oleanolic acid (4) showed higher α-amylase and α-glucosidase inhibitory action and therefore could be responsible for the antidiabetic activity of A. melegueta fruit.

Natural Triterpenoids for the Treatment of Diabetes Mellitus: A Review

Triterpenoids, an important group of secondary metabolites, are widely distributed in nature. Many triterpenoids have been found with potential therapeutic effect against diabetes mellitus. However, the use of triterpenoids for the treatment of diabetes has not been systematically discussed previously. This review summarized the anti-diabetic activity of natural triterpenoids reported since the late 1980s with the emphasis on the molecular mechanisms.

Extracted Triterpenes from Antrodia cinnamomea Reduce the Inflammation to Promote the Wound Healing via the STZ Inducing Hyperglycemia-Diabetes Mice Model

This research evaluated the effects of triterpenes on the regulation of STZ-induced hyperglycaemic diabetes through an anti-inflammatory response. Diabetic mice were orally administered various concentrations of triterpenes on a daily basis. Weight gain, volume of drinking water, and liver and spleen weight were recorded and evaluated. These evaluations presented a positive regulation to the abnormal metabolism appearance compared to the diabetic mice. In the diabetic mice, the detection of adiponectin production or elevated levels of inflammatory factors such as CCL1 and TPO expression were found to reduce hyperglycaemia and thereby induce an inflammatory response. Moreover, to the best of our knowledge, hyperglycaemia impairs the tissue healing associated with an increased and prolonged inflammatory response. An investigation of the anti-inflammatory response in wound healing as affected by the triterpenes verified the promotion of wound recovery.

Anti-hyperglycemic and anti-hyperlipidemic effects of Vaccinium myrtillus fruit in experimentally induced diabetes (antidiabetic effect of Vaccinium myrtillus fruit)

BACKGROUND

Diabetes mellitus (DM) is a metabolic disorder that is associated with an increased risk of cardiovascular disease. Vaccinium myrtillus (bilberry) is a useful plant with antidiabetic properties in traditional medicine. The aim of this study was to investigate the effects of bilberry against DM. Diabetes was induced using intraperitoneal injection of alloxan (120 mg kg(-1) body weight (BW)). Bilberry powder (2 g d(-1)) and glibenclamide (positive control; 0.6 mg kg(-1) BW) were administered for 4 weeks following alloxan injection. Serum glucose, insulin, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), very-low-density lipoprotein cholesterol (VLDL-C), triglycerides (TG) and C-reactive protein (CRP) were determined at baseline and at 2nd and 4th week of the study.

RESULTS

Bilberry supplementation resulted in a significant reduction of glucose compared with the diabetic control as well as glibenclamide treatment. Bilberry elevated insulin, reduced TC, LDL-C, VLDL-C and TG levels, and prevented HDL-C decline. Serum insulin, TC and LDL-C levels were not affected by glibenclamide, and CRP did not significantly change with either bilberry or glibenclamide. Histological examinations revealed a significant elevation of islet size in the bilberry and glibenclamide-treated groups.

CONCLUSION

Dietary supplementation with bilberry fruits may protect against impaired glucose and lipid metabolism in DM.

Evaluation of the Effects of Cornus mas L. Fruit Extract on Glycemic Control and Insulin Level in Type 2 Diabetic Adult Patients: A Randomized Double-Blind Placebo-Controlled Clinical Trial

Background. The plant Cornus mas L. (cornelian cherry) is traditionally used as an antidiabetic supplement; however, there is no related clinical trial. In this study, we evaluated the effects of the fruit extract of this plant on biomarkers of glycemic control in adult patients with type 2 diabetes. Methods. Sixty patients with type 2 diabetes were randomly assigned to two groups to receive either the extract or placebo capsules (2 capsules twice daily) for 6 weeks. Each drug capsule contained 150 mg of anthocyanins. Fasting plasma levels of glucose, insulin, HgbA1C, and triglyceride as well as 2-hour postprandial glucose level (2Hpp) were measured before and after the intervention and finally the mean values were compared between groups. Results. After 6 weeks of intervention, significant increase in insulin level (1.13 ± 1.90 versus -0.643 ± 1.82, P < 0.05) as well as decrease in HgbA1C (-0.24 ± 0.429 versus 0.023 ± 0.225, P < 0.05) and TG (-23.66 ± 55.40 versus 2.83 ± 15.71, P < 0.05) levels was observed in drug group compared to placebo. Conclusion. Daily consumption of the fruit extract of Cornus mas L. improves glycemic control by increasing insulin level and reduces TG serum level in type 2 diabetic adult patients.

Early use of oleanolic acid provides protection against 6-hydroxydopamine induced dopamine neurodegeneration

Oleanolic acid is a triterpenoid that has been shown to possess antioxidant properties. In this study we investigated the effects of oleanolic acid in a parkinsonian rat model. Unilateral 6-hydroxydopamine (6-OHDA) lesions were carried out on postnatal day (PND) 60 in 4 groups viz. (1) Rats that started oleanolic acid treatment 7 days prior to lesion. (2) Rats not treated with oleanolic acid. (3) Rats that started oleanolic acid treatment 1 day post-lesion. (4) Rats treated with oleanolic acid 7 days post-lesion. The degree of forelimb impairment was assessed using limb use asymmetry and forelimb akinesia tests. Neurochemical changes were assessed using a Dopamine ELISA kit and mitochondrial apoptosis was measured using a mitochondrial apoptosis detection kit. In this study, animals injected with 6-OHDA displayed forelimb use asymmetry that was ameliorated by treatment with oleanolic acid 7 days pre- and 1 day post-lesion. In the cylinder test, rats injected with 6-OHDA favored using the forelimb ipsilateral (unimpaired) to the lesioned hemisphere while rats treated with oleanolic acid used the forelimb contralateral (impaired) to the lesioned hemisphere significantly more. Rats treated with oleanolic acid 7 days pre- and 1 day post-lesion had more dopamine in the striatum than the non-treated or the 7 days after lesion rats. Similarly, 6-OHDA-induced membrane depolarization was decreased in rats that received oleanolic acid treatment pre- or immediately post-lesion. This suggests that early treatment with oleanolic acid protects dopamine neurons from the toxic effects of 6-OHDA.

Interactions of the active components of Punica granatum (pomegranate) with the essential renal and hepatic human Solute Carrier transporters

Abstract Context: Solute carrier transporters (SLCs) are membrane proteins responsible for cellular influx of various substances including many pharmaceutical agents; therefore, they largely impact on drug disposition and elimination in body. Punica granatum Linnaeus (Lythraceae), pomegranate, is a fruit with antidiabetic potential. Oleanolic acid (OA), ursolic acid (UA), and gallic acid (GA) are the major bioactive components of pomegranate. Co-administration of these compounds with other drugs could result in altered drug pharmacokinetics, possibly due to competing for transporter proteins.

OBJECTIVE

We investigated the interactions of these three compounds with the essential hepatic and renal SLC transporters.

MATERIALS AND METHODS

Uptake of radiolabeled transporter model substrates was assessed in HEK293 cells over-expressing SLC transporters including the organic anion transporters (OATs), organic anion transporting polypeptides (OATPs) and organic cation transporters (OCTs), in the presence or absence of 10.0 µM UA, OA, or GA. Their IC50 values on specific SLC transporters were also evaluated using varying concentrations of the particular compound (ranging from 0.10 nM to 80.0 µM).

RESULTS

Our results demonstrated UA could significantly inhibit OAT3 and OATP2B1 uptake (IC50: 18.9 ± 8.20 µM and 11.0 ± 5.00 µM, respectively) and GA has a pronounced inhibitory effect on OATP1B3 uptake (IC50: 1.60 ± 0.60 μM).

DISCUSSION AND CONCLUSION

Our study reports the interactions of OA, UA, and GA with the essential SLC transporters. This information may contribute to elucidating the drug-drug/herb interactions involved with these three compounds and form the basis of therapeutic optimization when drugs are co-administered.

Biochemical and histopathological study of the anti-hyperglycemic and anti-hyperlipidemic effects of cornelian cherry (Cornus mas L.) in alloxan-induced diabetic rats

BACKGROUND

Anthocyanins are phytochemicals with a multitude of pharmacological actions including anti-diabetic and anti-hyperlipidemic effects. This study was undertaken to evaluate the anti-hyperglycemic and anti-hyperlipidemic effects of cornelian cherry (Cornus mas L., CM) fruits - that are rich in anthocyanins and known to have medicinal properties- in alloxan-induced diabetic rats.

METHODS

Twenty-eight adult male rats were randomly assigned to four groups of seven animals each: non-diabetic control, diabetic control, glibenclamide-treated (0.6 mg/kg/day; 4 weeks) and CM fruit-treated (2 g/day; 4 weeks) group. Diabetes was induced by a single injection of alloxan (120 mg/kg). Fasting serum levels of glucose, total cholesterol (TC), low- (LDL-C) and high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), aspartate (AST) and alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were measured at the end of study period.

RESULTS

Diabetic rats had significantly elevated levels of serum glucose, LDL-C, TG, AST, ALP and ALT and decreased levels of HDL-C compared to the non-diabetic group (p<0.05). Treatment with either glibenclamide or CM counterbalanced the above-mentioned abnormalities. The effects of CM were comparable to those of glibenclamide at the doses tested in this study. Serum glucose, TG, ALP and HDL concentrations in the normal group were significantly changed compared to the diabetic control group (p<0.05). There were no significant changes in evaluated biochemical parameters between the glibenclamide and CM groups with normal group. Histopathological examinations revealed a less severe hepatic portal inflammation in the CM-treated vs. other study groups.

CONCLUSIONS

Dietary supplementation with CM fruits effectively prevents the development of diabetes mellitus, dyslipidemia and hepatic inflammation in alloxan-induced diabetes.

Biochemical basis of the antidiabetic activity of oleanolic acid and related pentacyclic triterpenes

Oleanolic acid (OA), a natural component of many plant food and medicinal herbs, is endowed with a wide range of pharmacological properties whose therapeutic potential has only partly been exploited until now. Throughout complex and multifactorial mechanisms, OA exerts beneficial effects against diabetes and metabolic syndrome. It improves insulin response, preserves functionality and survival of β-cells, and protects against diabetes complications. OA may directly modulate enzymes connected to insulin biosynthesis, secretion, and signaling. However, its major contributions appear to be derived from the interaction with important transduction pathways, and many of its effects are consistently related to activation of the transcription factor Nrf2. Doing that, OA induces the expression of antioxidant enzymes and phase II response genes, blocks NF-κB, and represses the polyol pathway, AGEs production, and hyperlipidemia. The management of type 2 diabetes requires an integrated approach, which includes the early intervention to prevent or delay the disease progression, and the use of therapies to control glycemia and lipidemia in its late stages. In this sense, the use of functional foods or drugs containing OA is, undoubtedly, an interesting path.

Antiplatelet activity of a novel formula composed of malic acid, succinic acid and citric acid from Cornus officinalis fruit

The present study investigated the antiplatelet activity of a novel formula composed by malic acid, succinic acid and citric acid with a ratio of 3:2:2. The IC50 and inhibition of platelet aggregation induced by various agonists as well as platelet adhesion were evaluated in vitro. Of note, the IC50 for the formula inhibiting adenosine diphosphate (ADP)-induced platelet aggregation was 0.185 mg/mL. Meanwhile, the formula showed more potent inhibitory effect on platelet aggregation induced by ADP and thrombin than the single component at same concentration (0.37 mg/mL). Moreover, the formula could prevent platelet adhesion significantly without influence on platelet viability.

Synergistic antihyperglycemic effects between plant-derived oleanolic acid and insulin in streptozotocin-induced diabetic rats

Studies from our laboratories indicate that Syzygium cordatum leaf extract contains triterpene mixtures [oleanolic acid (OA) and ursolic acid (UA)] with hypoglycemic properties. The aims of this study were to investigate the hypoglycemic effects of Syzygium aromaticum-derived OA and whether OA influenced the blood glucose lowering effects of insulin in streptozotocin (STZ)-induced diabetic rats. We envisaged that OA may provide a strategy with different mechanism of action for effective diabetic therapy because no single-marketed antidiabetic drug is capable of achieving long-lasting blood glucose control. The effects of various doses of OA and/or standard antidiabetic drugs on blood glucose were monitored in nondiabetic and STZ-induced diabetic rats given a glucose load after an 18-h fast. Rats treated with deionized water and standard antidiabetic drugs acted as untreated and treated positive controls, respectively. Blood glucose concentrations were measured at 15-min intervals for the first hour and hourly thereafter for 3 h. Blood glucose concentrations were also monitored in animals treated with OA and/or standard antidiabetic drugs for 5 weeks. OA like insulin decreased blood glucose concentrations in nondiabetic and STZ-induced diabetic rats. Combined OA and insulin treatment had even greater antihyperglycemic response, suggestive of a synergistic effect of the two. After 5 weeks, STZ-induced diabetic rats exhibited hyperglycemia and depleted hepatic and muscle glycogen concentrations. OA treatment lowered the blood glucose with concomitant restoration of glycogen concentrations to near normalcy. Our results suggest that OA may have a role in improving insulin sensitivity. These findings merit further research in this field.

A novel screening model for the molecular drug for diabetes and obesity based on tyrosine phosphatase Shp2

Tyrosine phosphatase Src-homology phosphotyrosyl phosphatase 2 (Shp2) was identified as a potential molecular target for therapeutic treatment of diabetes and obesity. However, there is still no systematic research on the enhancers for the Shp2 enzyme. The present study established a novel powerful model for the high-throughput screening of Shp2 enhancers and successfully identified a new specific Shp2 enhancer, oleanolic acid, from Chinese herbs.

Antioxidant activities of oleanolic acid in vitro: possible role of Nrf2 and MAP kinases

Oleanolic acid (OA) is a natural triterpenoid, which has been used in Chinese medicine for the treatment of liver disorders for many years. Its pharmacological activities have been the focus of intense research in recent years. However, there is little research on the antioxidant activities of OA. In the present study, we aim to investigate whether OA produces its protective effects mainly through antioxidant mechanisms and whether OA plays as an antioxidant through quenching reactive oxygen species (ROS), inhibiting lipid peroxidation or stimulating cellular antioxidant defenses. In the in vitro antioxidant activity-assessing models, OA acted as not only a free radical-scavenger through direct chemical reactions but also a biological molecule, which may enhance the antioxidant defenses. tert-Butyl hydroperoxide (tBHP) induced ROS generation, damaged plasma membrane and decreased cell viability and the expression of key antioxidant enzymes and MAP kinases in QZG cells. OA ameliorated the oxidative injury induced by tBHP through increasing the generation of antioxidant (glutathione) and the expression of key antioxidant enzymes mediated by nuclear factorerythroid 2 p45-related factor 2 (Nrf2), in which process, activation of JNK and ERK, but not p38, was involved. The present study, for the first time, investigated the antioxidant activities of OA systematically. OA probably functions mainly through indirect biological effect and protects QZG cells against cytotoxicity induced by tBHP through increasing the generation of antioxidant and the expression of oxidative stress sensitive transcription factor-Nrf2, and MAP kinases, mainly JNK and ERK. These findings may significantly better the understanding of OA and advance therapeutic approaches to the diseases which are associated with oxidative stress.

Anti-inflammatory and analgesic effects of the aqueous extract of corni fructus in murine RAW 264.7 macrophage cells

Corni fructus is the fruit of Cornus officinalis Sieb. et Zucc, which is classified into the dogwood family of Cornaceae. Corni fructus has antineoplastic, antioxidative, and antidiabetic effects, but its anti-inflammatory and analgesic effects are unknown. Here, we investigated the anti-inflammatory and analgesic effects of an aqueous extract of corni fructus using murine RAW 264.7 macrophage cells. For this study, we used the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, western blot analysis, prostaglandin (PG) E(2) immunoassay, and nitric oxide (NO) detection. In addition, the analgesic effect of corni fructus was assessed by the acetic acid-induced writhing response in mice. The aqueous extract of corni fructus suppressed PGE(2) synthesis and NO production by inhibiting the lipopolysaccharide-induced expression of cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) in murine RAW 264.7 macrophage cells. The extract also suppressed increases in nuclear factor-kappaB (NF-kappaB) levels in the nucleus. In vivo study showed that the extract suppressed the acetic acid-induced writhing response in mice. The aqueous extract of corni fructus exerts anti-inflammatory and analgesic effects by suppressing COX-2 and iNOS expression through the down-regulation of NF-kappaB binding activity.

Oleanolic Acid, a plant triterpenoid, significantly improves survival and function of islet allograft

BACKGROUND.: Oleanolic acid (OA) is a ubiquitous triterpenoid, with potent antioxidant and anti-inflammatory properties. Here, we tested whether these combined properties of OA can prevent nonimmunologic primary nonfunctioning and immunologic phenomena ascribed to graft rejection hence prolong islet allograft survival. METHODS.: Islet transplants were performed under kidney capsule of streptozotocin-induced diabetic C57BL/6 mice with BALB/c islets. Recipients were treated with 0.5 mg/day of OA intraperitoneally, and serum samples were collected once in 2 days and used for luminex, ELISA, and donor-specific antibody screening. Transplanted mice were killed at different time intervals to obtain splenocytes and kidney samples for ELISPOT, mixed leukocyte reaction, and immunohistochemical studies. RESULTS.: After transplantation, the decrement of blood glucose was significantly faster in mice receiving OA less than 2+/-1 days compared with untreated (4+/-2 days). OA prolonged survival of transplanted islets up to 23+/-3 days and reversed diabetes even with 250 islets. Treatment group showed increased serum interleukin (IL)-10 (twofold) and decreased inducible protein-10 and IL-4 (threefold) in luminex. Significantly reduced frequency of interferon-gamma (4.5-fold), IL-4 (3.5-fold), IL-2 (2.3-fold), and IL-17 (fourfold) producing T-cell populations were found in ELISPOT. OA-treated grafts had significant reduced and delayed infiltration of CD4+ and CD8+ T cells. OA also delayed donor-specific antibody generation up to 19 days after transplantation. Combined treatment with cyclosporine A, OA further prolonged the islet allograft survival to 34+/-3 days. CONCLUSIONS.: In conclusion, OA is an attractive, dietary nontoxic plant triterpenoid, which suppresses the production of proinflammatory cytokines and delays graft-specific immune responses to prolong islet allograft survival.

Effect of butanol fraction from Cassia tora L. seeds on glycemic control and insulin secretion in diabetic rats

Cassia tora L. seeds have previously been reported to reduce blood glucose level in human and animals with diabetes. In the present study, the effects of Cassia tora L. seed butanol fraction (CATO) were studied on postprandial glucose control and insulin secretion from the pancreas of the normal and diabetic rats. Diabetes was induced by an i.p. injection of Streptozotocin (55 mg/kg BW) into the male Sprague-Dawley rats. The postprandial glucose control was monitored during a 240 min-period using a maltose loading test. In normal rats, rats fed CATO (20 mg/100 g BW/d) showed lower postprandial glucose levels in all the levels from 30 min up to 180 min than those in the control rats without CATO (p<0.05). In diabetic rats, those levels in the CATO group seemed to be lower during the 30~180 min, but only glucose level at 30 min showed significant difference compared to that in the control group. Moreover, CATO delayed the peak time of the glucose rise in both normal and diabetic rats in the glucose curves. On the other hand, when CATO was administered orally to the diabetic rats for 5 days, 12 hr fasting serum glucose level was decreased in the diabetic rats (p<0.05). Degree of a decrease in 12 hr fasting serum insulin levels was significantly less in the diabetic CATO rats as compared to diabetic control rats. On the last day of feeding, beta cells of the pancreas were stimulated by 200 mg/dL glucose through a 40 min-pancreas perfusion. Amounts of the insulin secreted from the pancreas during the first phase (11~20 min) and the second phase (21~40 min) in the CATO fed diabetic rats were significantly greater than those in the diabetic control group (p<0.05). These findings indicated that constituents of Cassia tora L. seeds have beneficial effect on postprandial blood glucose control which may be partially mediated by stimulated insulin secretion from the pancreas of the diabetic rats.

Traditional chinese medicine in treatment of metabolic syndrome

In management of metabolic syndrome, the traditional Chinese medicine (TCM) is an excellent representative in alternative and complementary medicines with a complete theory system and substantial herb remedies. In this article, basic principle of TCM is introduced and 25 traditional Chinese herbs are reviewed for their potential activities in the treatment of metabolic syndrome. Three herbs, ginseng, rhizoma coptidis (berberine, the major active compound) and bitter melon, were discussed in detail on their therapeutic potentials. Ginseng extracts made from root, rootlet, berry and leaf of Panax quinquefolium (American ginseng) and Panax ginseng (Asian ginseng), are proved for anti-hyperglycemia, insulin sensitization, islet protection, anti-obesity and anti-oxidation in many model systems. Energy expenditure is enhanced by ginseng through thermogenesis. Ginseng-specific saponins (ginsenosides) are considered as the major bioactive compounds for the metabolic activities of ginseng. Berberine from rhizoma coptidis is an oral hypoglycemic agent. It also has anti-obesity and anti-dyslipidemia activities. The action mechanism is related to inhibition of mitochondrial function, stimulation of glycolysis, activation of AMPK pathway, suppression of adipogenesis and induction of low-density lipoprotein (LDL) receptor expression. Bitter melon or bitter gourd (Momordica charantia) is able to reduce blood glucose and lipids in both normal and diabetic animals. It may also protect beta cells, enhance insulin sensitivity and reduce oxidative stress. Although evidence from animals and humans supports the therapeutic activities of ginseng, berberine and bitter melon, multi-center large-scale clinical trials have not been conducted to evaluate the efficacy and safety of these herbal medicines.

Oleanolic acid enhances insulin secretion in pancreatic beta-cells

We investigated the effect of oleanolic acid, a plant-derived triterpenoid, on insulin secretion and content in pancreatic beta-cells and rat islets. Oleanolic acid significantly enhanced insulin secretion at basal and stimulatory glucose concentrations in INS-1 832/13 cells and enhanced acute glucose-stimulated insulin secretion in isolated rat islets. In the cell line the effects of oleanolic acid on insulin secretion were comparable to that of the sulfonylurea tolbutamide at basal glucose levels and with the incretin mimetic Exendin-4 under glucose-stimulated conditions, yet neither Ca(2+) nor cAMP rose in response to oleanolic acid. Chronic treatment with oleanolic acid increased total cellular insulin protein and mRNA levels. These effects may contribute to the anti-diabetic properties of this natural product.