Efficacy of asiatic acid, a pentacyclic triterpene on attenuating the key enzymes activities of carbohydrate metabolism in streptozotocin-induced diabetic rats

Interventional effects of Pueraria oral liquid on T2DM rats and metabolomics analysis

Pueraria lobata, commonly known as kudzu, is a medicinal and food plant widely used in the food, health food, and pharmaceutical industries. It has clinical pharmacological effects, including hypoglycemic, antiinflammatory, and antioxidant effects. However, its mechanism of hypoglycemic effect on type 2 diabetes mellitus (T2DM) has not yet been elucidated. In this study, we prepared a Pueraria lobata oral liquid (POL) and conducted a comparative study in a T2DM rat model to evaluate the hypoglycemic effect of different doses of Pueraria lobata oral liquid. Our objective was to investigate the hypoglycemic effect of Puerarin on T2DM rats and understand its mechanism from the perspective of metabolomics. In this study, we assessed the hypoglycemic effect of POL through measurements of FBG, fasting glucose tolerance test, plasma lipids, and liver injury levels. Furthermore, we examined the mechanism of action of POL using hepatic metabolomics. The study's findings demonstrated that POL intervention led to improvements in weight loss, blood glucose, insulin, and lipid levels in T2DM rats, while also providing a protective effect on the liver. Finally, POL significantly affected the types and amounts of hepatic metabolites enriched in metabolic pathways, providing an important basis for revealing the molecular mechanism of Pueraria lobata intervention in T2DM rats. These findings indicate that POL may regulate insulin levels, reduce liver damage, and improve metabolic uptake in the liver. This provides direction for new applications and research on Pueraria lobata to prevent or improve T2DM.

Asiatic acid rescues intestinal tissue by suppressing molecular, biochemical, and histopathological changes associated with the development of ulcerative colitis

Asiatic acid (AA) is a polyphenolic compound with potent antioxidative and anti-inflammatory activities that make it a potential choice to attenuate inflammation and oxidative insults associated with ulcerative colitis (UC). Hence, the present study aimed to evaluate if AA can attenuate molecular, biochemical, and histological alterations in the acetic acid-induced UC model in rats. To perform the study, five groups were applied, including the control, acetic acid-induced UC, UC-treated with 40 mg/kg aminosalicylate (5-ASA), UC-treated with 20 mg/kg AA, and UC-treated with 40 mg/kg AA. Levels of different markers of inflammation, oxidative stress, and apoptosis were studied along with histological approaches. The induction of UC increased the levels of lipid peroxidation (LPO) and nitric oxide (NO). Additionally, the nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream antioxidant proteins [catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx), and glutathione reductase (GR)] were down-regulated in the colon tissue. Moreover, the inflammatory mediators [myeloperoxidase (MPO), monocyte chemotactic protein 1 (MCP1), prostaglandin E2 (PGE2), nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β)] were increased in the colon tissue after the induction of UC. Notably, an apoptotic response was developed, as demonstrated by the increased caspase-3 and Bax and decreased Bcl2. Interestingly, AA administration at both doses lessened the molecular, biochemical, and histopathological changes following the induction in the colon tissue of UC. In conclusion, AA could improve the antioxidative status and attenuate the inflammatory and apoptotic challenges associated with UC.

Metabolites of traditional Chinese medicine targeting PI3K/AKT signaling pathway for hypoglycemic effect in type 2 diabetes

Type 2 diabetes mellitus is a chronic metabolic disease characterized by insulin resistance, with high morbidity and mortality worldwide. Due to the tightly intertwined connection between the insulin resistance pathway and the PI3K/AKT signaling pathway, regulating the PI3K/AKT pathway and its associated targets is essential for hypoglycemia and the prevention of type 2 diabetes mellitus. In recent years, metabolites isolated from traditional Chinese medicine has received more attention and acceptance for its superior bioactivity, high safety, and fewer side effects. Meanwhile, numerous in vivo and in vitro studies have revealed that the metabolites present in traditional Chinese medicine possess better bioactivities in regulating the balance of glucose metabolism, ameliorating insulin resistance, and preventing type 2 diabetes mellitus via the PI3K/AKT signaling pathway. In this article, we reviewed the literature related to the metabolites of traditional Chinese medicine improving IR and possessing therapeutic potential for type 2 diabetes mellitus by targeting the PI3K/AKT signaling pathway, focusing on the hypoglycemic mechanism of the metabolites of traditional Chinese medicine in type 2 diabetes mellitus and elaborating on the significant role of the PI3K/AKT signaling pathway in type 2 diabetes mellitus. In order to provide reference for clinical prevention and treatment of type 2 diabetes mellitus.

Centella asiatica mitigates the detrimental effects of Bisphenol-A (BPA) on pancreatic islets

Bisphenol-A (BPA) is widely used in food packaging and household products, leading to daily human exposure and potential health risks including metabolic diseases like type 2 diabetes mellitus (T2DM). Understanding BPA's mechanisms and developing intervention strategies is urgent. Centella asiatica, a traditional herbal medicine containing pentacyclic triterpenoids, shows promise due to its antioxidant and anti-inflammatory properties, utilized for centuries in Ayurvedic therapy. We investigated the effect of Centella asiatica (CA) ethanol extract on BPA-induced pancreatic islet toxicity in male Swiss albino mice. BPA administration (10 and 100 μg/kg body weight, twice daily) for 21 days caused glucose homeostasis disturbances, insulin resistance, and islet dysfunction, which were partially mitigated by CA supplementation (200 and 400 mg/kg body weight). Additionally, heightened oxidative stress, elevated levels of proinflammatory cytokines, loss of mitochondrial membrane potential (MMP), abnormal cell cycle, and increased apoptosis were implicated in the detrimental impact of BPA on the endocrine pancreas which were effectively counteracted by CA supplementation. In summary, CA demonstrated a significant ability to mitigate BPA-induced apoptosis, modulate redox homeostasis, alleviate inflammation, preserve MMP, and regulate the cell cycle. As a result, CA emerged as a potent agent in neutralizing the diabetogenic effects of BPA to a considerable extent.

Nobiletin ameliorates streptozotocin-cadmium-induced diabetic nephropathy via NF-κB signalling pathway in rats

This study sought to examine the anti-diabetic effect of nobiletin on streptozotocin (STZ)/cadmium (Cd)-induced diabetic nephrotoxic (DN) rats. The DN was induced using STZ (40 mg/kg b.w) intraperitoneally and Cd through drinking water for 12 weeks. The DN rats were treated with nobiletin of different concentrations (10, 20, and 40 mg/kg/BW). The STZ/Cd-induced DN leads to a significantly increased of the glucose levels, glycosylated haemoglobin, hepatic and kidney function markers, lipid peroxidation levels, and reduction of insulin levels, total haemoglobin, body weight, and antioxidant status markers. Our finding that nobiletin pathological impairment and diminished infiltration of neutrophil in kidney tubules and all biochemical enzymes were near normal levels in DN. More essentially, nobiletin strongly impedes the protein expression of renal nuclear NF-κB p65. Bax protein expression was significantly downregulated and elevated protein expression Bcl-2 was recorded in DN rats. These results show that nobiletin possesses antioxidant as well as anti-diabetic activities and thereby reduces chronic kidney diseases in rats.

Identification of Phytochemicals and Assessment of Hypoglycemic and Haematological Potentials of Terminalia catappa Linn leaf Extract in Alloxan-induced Diabetic Wistar Rats

INTRODUCTION

Hypoglycemia and anemia are associated with diabetes mellitus. Medicinal plants and orthodox drugs have been used for the management of this disease. This study aimed to validate the ethnomedical claims of Terminalia catappa Linn. leaf extract in reducing hyperglycemia and hematological potentials in alloxan-induced diabetic rats and to identify likely antidiabetic compounds.

MATERIALS AND METHODS

Ultra-high-performance liquid chromatography was used to identify the various phytochemical constituents. Male Wistar rats were randomly divided into five groups containing 6 rats per group. Group 1 (control) received 0.2 ml/kg of distilled water, group 2 received 130 mg/kg of T. catappa aqueous extract, groups 3-5 were diabetic and received 0.2 ml/g distilled water, 130 mg/kg T. catappa extract and 0.75 IU/kg insulin respectively for 14 days. Hematological parameters were measured and an oral glucose tolerance test was carried out using 2 g/kg body weight glucose. A histological analysis of the pancreas was done.

RESULTS

Twenty-five compounds identified as flavonoids, phenolic acids, tannins, and triterpenoids were detected. The blood glucose levels were significantly (p <0.05) elevated in DM groups but were significantly (p <0.05) reduced following Terminalia catappa leaves extract to DM groups. There was s significant (p <0.05) increase in insulin levels improved hematological parameters (RBC, WBC, and platelets), and increased islet population.

CONCLUSION

These results suggest that T. catappa extract has hypoglycemic, insulinogenic, and hematopoietic potentials in diabetic condition and offer protection to the pancreas which could be attributed to the phytochemical constituents thereby justifying its use in traditional therapy.

Asiatic acid exhibits antimetastatic activity in human prostate cancer cells by modulating the MZF-1/Elk-1/Snail signaling axis

Prostate cancer metastasis is associated with poor prognosis and is difficult to treat clinically. Numerous studies have shown that Asiatic Acid (AA) has antibacterial, anti-inflammatory, and antioxidant effects. However, the effect of AA on prostate cancer metastasis is still unclear. This purpose of this study is to investigate the effect of AA on prostate cancer metastasis and to better understand its molecular mechanisms of action. Our results indicate that AA ≤ 30 μM did not influence cell viability and cell cycle distribution in PC3, 22Rv1 and DU145 cells. AA inhibited the migratory and invasive capabilities of three prostate cancer cells to be due to its effects on Snail, but did not have activity on Slug. We observed that AA inhibited the Myeloid zinc finger 1 (MZF-1) and ETS Like-1 (Elk-1) protein interaction and affected the complex's binding capacity to the Snail promoter region, ultimately blocking Snail transcription activity. Kinase cascade analysis revealed that phosphorylation of MEK3/6 and p38MAPK was inhibited by AA treatment. Moreover, knockdown of p38MAPK enhanced AA-suppressed protein levels of MZF-1, Elk-1, and Snail, suggesting that p38MAPK influences prostate cancer cell metastasis. These results provide promise for AA as a future candidate in the development of drug therapies to prevent or treat prostate cancer metastasis.

Edible pentacyclic triterpenes: A review of their sources, bioactivities, bioavailability, self-assembly behavior, and emerging applications as functional delivery vehicles

Edible pentacyclic triterpenes (PTs) are a group of nutraceutical ingredients commonly distributed in human diets. Existing evidence has proven that they have various biological functions, including anticancer, antioxidant, anti-inflammatory and hypoglycemic activities, making them as "functional factor" for a long time. However, their properties of strong hydrophobicity, poor permeability, poor absorption, and rapid metabolism result in low oral bioavailability, which dramatically hinders their efficacy for use. Recently, free PTs have successively been found to self-assemble or co-assemble into self-contained nanostructures with enhanced water dispersibility and oral bioavailability, which seems to be an efficient processing method for increased oral efficacy. Of particular interest, formulating them into nanostructures can also be introduced as functional delivery carriers for bioactive compounds or drugs with various advantages, such as improved stability, controlled release, enhanced oral bioavailability, synergistic bioactivity, and targeted delivery. This review systematically summarized the chemical structures, plant sources, bioactivities, absorption, metabolism, and oral bioavailability of PTs. Notably, we emphasized their self-assembly properties and emerging role as functional delivery carriers for nutrients, suggesting that PT nanostructures are not only efficient oral forms when introduced into foods but also functional delivery materials for nutrients to expand their commercial food applications.

Annona muricata L. peel extract inhibits carbohydrate metabolizing enzymes and reduces pancreatic β-cells, inflammation, and apoptosis via upregulation of PI3K/AKT genes

BACKGROUND AND OBJECTIVE

Annona muricata L. peel has been recognized for many ethnobotanical uses, including diabetes management. However, limited detailed scientific information about its mechanism of antidiabetic activity exists. The objective of this study was to evaluate the anti-diabetic properties of an aqueous extract of A. muricata peel (AEAMP) and its mechanism of action on alloxan-induced diabetic rats.

METHODS

In vitro antidiabetic assays, such as α-amylase and α-glucosidase were analyzed on AEAMP. Alloxan monohydrate (150 mg/kg b.w) was used to induce diabetes in the rats. 150 mg/kg b.w positive control group doses of 6.67, 13.53, and 27.06 mg/kg were administered to 3 groups for twenty-one days. The positive control group was administered 30 mg/kg of metformin. The negative and normal control groups were administered distilled water. The fasting blood glucose, serum insulin, lipid profile, inflammatory cytokines, antioxidant markers, carbohydrate metabolizing enzymes, and liver glycogen were analyzed as well as PI3K/AKT and apoptotic markers PCNA and Bcl2 by RT-PCR.

RESULTS

AEAMP inhibited α-amylase and α-glucosidase enzymes more effectively than acarbose. AEAMP reduced FBG levels, HOMA-IR, G6P, F-1,6-BP, MDA, TG, TC, AI, CRI, IL-6, TNF-α, and NF-κB in diabetic rats. Furthermore, in diabetic rats, AEAMP improved serum insulin levels, HOMA-β, hexokinase, CAT, GST, and HDL-c. Liver PI3K, liver PCNA and pancreas PCNA were not significantly different in untreated diabetic rats when compared to normal rats suggesting alloxan induction of diabetes did not downregulate the mRNA expression of these genes. AEAMP significantly up-regulated expression of AKT and Bcl2 in the liver and pancreatic tissue. It is interesting that luteolin and resorcinol were among the constituents of AEAMP.

CONCLUSIONS

AEAMP can improve β-cell dysfunction by upregulating liver AKT and pancreatic PI3K and AKT genes, inhibiting carbohydrate metabolizing enzymes and preventing apoptosis by upregulating liver and pancreatic Bcl2. However, the potential limitation of this study is the unavailability of equipment and techniques for collecting more data for the study.

Asiatic acid alleviates metabolism disorders in ob/ob mice: mechanistic insights

Glucolipid metabolism disorders pose a serious and global health problem, and more effective prevention and treatment methods are urgently needed. In this study, ob/ob mice were used to explore the potential mechanism explaining how asiatic acid (AA) regulates glucolipid metabolism disorders. Five-week AA treatment (30 mg kg^-1) significantly improved a host of metabolic factors in ob/ob mice, including hyperglycemia, hyperlipidemia, insulin resistance, and liver histopathology. Combined analysis of untargeted liver metabolomics, liver transcriptomics, and the gut microbiome was conducted, and the results showed that AA alleviates metabolic disorders in ob/ob mice through regulating pyrimidine metabolism, activating PPAR-γ, and modulating gut microbiota. AA treatment remarkedly increased the levels of cytosine and cytidine, two crucial endogenous metabolites related to pyrimidine metabolism, which were significantly decreased in ob/ob mice. AA treatment also affected the levels of 13-S-hydroxyoctadecadienoic acid, an endogenous PPAR-γ agonist. The abundances of Lachnospiraceae_NK4A136_group and norank_f__norank_o__Clostridia_UCG-014 were increased after AA treatment. Meanwhile, correlation analysis showed that endogenous metabolites and gut microbiota were strongly correlated. These findings indicated that AA supplements might be beneficial for the prevention of metabolic disorders.

In Vivo and Ex Vivo Evaluation of 1,3-Thiazolidine-2,4-Dione Derivatives as Euglycemic Agents

Thiazolidinediones (TZDs), used to treat type 2 diabetes mellitus, act as full agonists of the peroxisome proliferator-activated receptor gamma. Unfortunately, they produce adverse effects, including weight gain, hepatic toxicity, and heart failure. Our group previously reported the design, synthesis, in silico evaluation, and acute oral toxicity test of two TZD derivatives, compounds 40 (C40) and 81 (C81), characterized as category 5 and 4, respectively, under the Globally Harmonized System. The aim of this study was to determine whether C40, C81, and a new compound, C4, act as euglycemic and antioxidant agents in male Wistar rats with streptozotocin-induced diabetes. The animals were randomly divided into six groups (n = 7): the control, those with diabetes and untreated, and those with diabetes and treated with pioglitazone, C40, C81, or C4 (daily for 21 days). At the end of the experiment, tissue samples were collected to quantify the level of glucose, insulin, triglycerides, total cholesterol, and liver enzymes, as well as enzymatic and nonenzymatic antioxidant activity. C4, without a hypoglycemic effect, displayed the best antioxidant activity. Whereas C81 could only attenuate the elevated level of blood glucose, C40 generated euglycemia by the end of the treatment. All compounds produced a significant decrease in triglycerides.

Anti-Diabetic Potential of Plant-Based Pentacyclic Triterpene Derivatives: Progress Made to Improve Efficacy and Bioavailability

Diabetes mellitus (DM) results from the inability of the pancreas to produce sufficient insulin or weakened cellular response to the insulin produced, which leads to hyperglycemia. Current treatments of DM focus on the use of oral hypoglycemic drugs such as acarbose, alpha-glucose inhibitors, sulphonylureas, thiazolidinediones, and biguanides to control blood glucose levels. However, these medications are known to have various side effects in addition to their bioavailability, efficacy, and safety concerns. These drawbacks have increased interest in the anti-diabetic potential of plant-derived bioactive compounds such as oleanolic and maslinic acids. Although their efficacy in ameliorating blood glucose levels has been reported in several studies, their bioavailability and efficacy remain of concern. The current review examines the anti-diabetic effects of oleanolic, maslinic, asiatic, ursolic, and corosolic acids and their derivatives, as well as the progress made thus far to enhance their bioavailability and efficacy. The literature for the current review was gathered from leading academic databases-including Google Scholar and PubMed-the key words listed below were used. The literature was searched as widely and comprehensively as possible without a defined range of dates.

Novel Triterpenoids from Cassia fistula Stem Bark Depreciates STZ-Induced Detrimental Changes in IRS-1/Akt-Mediated Insulin Signaling Mechanisms in Type-1 Diabetic Rats

Here, we identified the mechanisms of action of antidiabetic activity of novel compounds isolated from Cassia fistula stem bark in STZ-diabetic animals. Novel triterpenoid compounds (C1, C2 and C3) were treated to STZ-administered diabetic animals at a concentration of 20mg/kg body weight orally for 60 days to assess their effects on plasma glucose, plasma insulin/C-peptide, serum lipid markers and the enzymes of carbohydrate metabolism, glucose oxidation and insulin signaling molecules. Oral administration of novel triterpenoid compounds to STZ-diabetic animals significantly decreased (p < 0.05) the plasma glucose concentration on the 7th, 15th, 30th, 45th and 60th daysin a duration-dependent manner (p < 0.05). Plasma insulin (p < 0.0001)/C-peptide (p < 0.0006), tissue glycogen (p < 0.0034), glycogen phosphorylase (p < 0.005), glucose 6-phosphatase (p < 0.0001) and lipid markers were significantly increased (p < 0.0001) in diabetic rats, whereas glucokinase (p < 0.0047), glycogen synthase (p < 0.003), glucose oxidation (p < 0.001), GLUT4 mRNA (p < 0.0463), GLUT4 protein (p < 0.0475) and the insulin-signaling molecules IR mRNA (p < 0.0195), IR protein (p < 0.0001), IRS-1 mRNA (p < 0.0478), p-IRS-1Tyr612 (p < 0.0185), Akt mRNA (p < 0.0394), p-AktSer473 (p < 0.0162), GLUT4 mRNA (p < 0.0463) and GLUT4 (p < 0.0475) were decreased in the gastrocnemius muscle. In silico analysis of C1-C3 with IRK and PPAR-γ protein coincided with in vivo findings. C1-C3 possessed promising antidiabetic activity by regulating insulin signaling mechanisms and carbohydrate metabolic enzymes.

A comparison between the effect of trans-anethole and metformin on biochemical parameters of polycystic ovary syndrome in rats

Objective:

The effect of trans-anethole and metformin on biochemical and hormonal changes of testosterone-induced Polycystic ovary syndrome (PCOS) in rats was investigated.

Materials and Methods:

Female Wister rats (n=48) were randomly divided into six groups: control; PCOS; PCOS+metformin (300 mg/kg); and PCOS+trans-anethole (20, 40, and 80 mg/kg). PCOS was induced by intraperitoneal injection of testosterone (1 mg/kg/day) for 35 days. After induction of PCOS, trans-anethole and metformin were given orally for 30 days. Finally, blood sugar, insulin, lipid profile, and testosterone and dehydroepiandrosterone (DHEAS) as well as animals’ weight, and water and food intake were determined.

Results:

In all treated and untreated PCOS groups, serum testosterone levels were significantly increased compared to the control group (p<0.001 for all groups). Treatment of rats with trans-anethole or metformin significantly reduced serum levels of cholesterol, insulin, triglycerides, testosterone and DHEAS (only in PCOS+trans-anethole groups) compared to the PCOS group (p<0.01-p<0.001). Weight gain in the PCOS animals increased significantly compared to the control group (p<0.001), while in the metformin- and trans-anethole (40 and 80)-treated animals it decreased significantly compared to the PCOS group (p<0.01-p<0.001).

Conclusion:

These results showed that trans-anethole significantly decreased serum levels of insulin, DHEAS and blood lipids. It can be concluded that trans-anethole ameliorates PCOS biochemical and hormonal change in PCOS rats; therefore, it might be suggested as a beneficial remedy for further clinical evaluations in PCOS patients.

Antidiabetic effect of konjac glucomannan via insulin signaling pathway regulation in high-fat diet and streptozotocin-induced diabetic rats

Type 2 diabetes mellitus is a chronic metabolic disorder that tends to disarray various metabolic pathways. Dietary-mediated T2DM prevention garners much attention in recent decades. Hence, this study was intended to elucidate the antidiabetic properties of Konjac glucomannan (KGM) in diabetic rats. Our experimental design includes five groups, with six rats in each group. Group 1 feeding standard diet pallet alone served as control rats; group 2 was KGM control rats administered intragastrically with KGM (120 mg/kg b.w.). Group 3 was developed as diabetic rats with a high-fat diet and an intraperitoneal injection of Streptozotocin-40 mg/kg b.w. Group 4 were diabetic rats treated with KGM (80 mg/kg b.w.), and group 5 were diabetic rats received rosiglitazone treatment (4 mg/kg b.w.). The results showed that STZ-induced diabetic rats significantly elevate liver marker enzymes and gluconeogenesis enzymes. Diminished glycolytic enzymes, liver glycogen, insulin signaling genes, and proteins were also seen in diabetic rats. Treatment with KGM augmented glycolytic enzymes and liver glycogen. On the other hand, KGM diminished gluconeogenesis, liver marker enzymes, upregulated gene, and protein expression of the insulin pathway. The current results suggest dietary KGM can offer a better health benefit in the treatment of T2DM.

Corosolic acid and its structural analogs: A systematic review of their biological activities and underlying mechanism of action

BACKGROUND

The corosolic acid (CA), also known as plant insulin, is a pentacyclic triterpenoid extracted from plants such as Lagerstroemia speciosa. It has been shown to have anti-diabetic, anti-inflammatory and anti-tumor effects. Its structural analogs ursolic acid (UA), oleanolic acid (OA), maslinic acid (MA), asiatic acid (AA) and betulinic acid (BA) display similar individual pharmacological activities to those of CA. However, there is no systematic review documenting pharmacological activities of CA and its structural analogues. This study aims to fill this gap in literature.

PURPOSE

This systematic review aims to summarize the medical applications of CA and its analogues.

METHODS

A systematic review summarizes and compares the extraction techniques, pharmacokinetic parameters, and pharmacological effects of CA and its structural analogs. Hypoglycemic effect is one of the key inclusion criteria for searching Web of Science, PubMed, Embase and Cochrane databases up to October 2020 without language restrictions. 'corosolic acid', 'ursolic acid', 'oleanolic acid', 'maslinic acid', 'asiatic acid', 'betulinic acid', 'extraction', 'pharmacokinetic', 'pharmacological' were used to extract relevant literature. The PRISMA guidelines were followed.

RESULTS

At the end of the searching process, 140 articles were selected for the systematic review. Information of CA and five of its structural analogs including UA, OA, MA, AA and BA were included in this review. CA and its structural analogs are pentacyclic triterpenes extracted from plants and they have low solubilities in water due to their rigid scaffold and hydrophobic properties. The introduction of water-soluble groups such as sugar or amino groups could increase the solubility of CA and its structural analogs. Their biological activities and underlying mechanism of action are reviewed and compared.

CONCLUSION

CA and its structural analogs UA, OA, MA, AA and BA are demonstrated to show activities in lowering blood sugar, anti-inflammation and anti-tumor. Their oral absorption and bioavailability can be improved through structural modification and formulation design. CA and its structural analogs are promising natural product-based lead compounds for further development and mechanistic studies.

Actions and Therapeutic Potential of Madecassoside and Other Major Constituents of Centella asiatica: A Review

Centella asiatica is a popular herb well-known for its wide range of therapeutic effects and its use as a folk medicine for many years. Its therapeutic properties have been well correlated with the presence of asiaticoside, madecassoside, asiatic and madecassic acids, the pentacyclic triterpenes. The herb has been extensively known to treat skin conditions; nevertheless, several pre-clinical and clinical studies have scientifically demonstrated its effectiveness in other disorders. Among the active constituents that have been identified in Centella asiatica, madecassoside has been the subject of only a relatively small number of scientific reports. Therefore, this review, while including other major constituents of this plant, focuses on the therapeutic potential, pharmacokinetics and toxicity of madecassoside.

Ursolic Acid and Related Analogues: Triterpenoids with Broad Health Benefits

Ursolic acid (UA) is a well-studied natural pentacyclic triterpenoid found in herbs, fruit and a number of traditional Chinese medicinal plants. UA has a broad range of biological activities and numerous potential health benefits. In this review, we summarize the current data on the bioavailability and pharmacokinetics of UA and review the literature on the biological activities of UA and its closest analogues in the context of inflammation, metabolic diseases, including liver and kidney diseases, obesity and diabetes, cardiovascular diseases, cancer, and neurological disorders. We end with a brief overview of UA’s main analogues with a special focus on a newly discovered naturally occurring analogue with intriguing biological properties and potential health benefits, 23-hydroxy ursolic acid.

Ethnopharmacological perspectives of glucokinase activators in the treatment of diabetes mellitus

Traditional medicinal plants have wide-reaching utilisation in the treatment of diabetes especially in developing countries where medical resources are meagre. Traditionally used anti-diabetic plants act by numerous mechanisms, however, only a few of them act through activation of the glucokinase enzyme. Glucokinase is a key regulatory enzyme in glucose metabolism thereby controls glucose homeostasis and insulin secretion. The present review significantly analyses the knowledge about various plant-based glucokinase activators including numerous phytochemicals which modulate the activity and gene expression of glucokinase and would provide data support and perspective regarding future research in the discovery and development of different plant-derived glucokinase activators.

Pharmacological reflection of plants traditionally used to manage diabetes mellitus in Tanzania

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing national prevalence of diabetes mellitus (DM) and its complications have overstretched the health care system in Tanzania and influenced patients to use herbal medicines as alternative therapeutic strategies. Therefore, an urgent need exists to validate the safety and efficacy of plants used locally.

AIM OF THE STUDY

To identify plants used for the management of DM in Tanzania and analyses their pharmacological, phytochemistry, and safety evidence with a special focus on the mechanism of action.

METHODS

Researchers searched Medline, web of science, and Scopus for published articles. Also, specialized herbarium documents of Muhimbili Institute of traditional medicine were reviewed. Articles were assessed for relevance, quality, and taxonomical accuracy before being critically reviewed.

RESULTS

We identified 62 plant species used locally for DM management. Moringa oleifera Lam. and Cymbopogon citratus (D.C) stapf were the most mentioned. Fifty-four phytochemicals from 13 species had DM activities. These were mainly; polyphenolics, phytosterols, and triterpenoids. Extracts, fractions, and pure compounds from 18 species had in vitro antidiabetic activities of which 14 had α-glucosidase and α-amylase inhibition effects. The most studied -Momordica charantia L. increased; glucose uptake and adiponectin release in 3T3-L1 adipocytes, insulin secretion, insulin receptor substrate-1 (IRS-1), GLUT-4 translocation, and GLP-1 secretion; and inhibited protein tyrosine phosphatase 1 B (PTP1B). Preclinical studies reported 30 species that lower plasma glucose with molecular targets in the liver, skeletal muscles, adipose tissues, pancreases, and stomach. While three species; Aspilia mossambiscensis (Oliv.) Willd, Caesalpinia bonduc (L.) Roxb, and Phyllanthus amarus Schumach. & Thonn. had mild toxicity in animals, 33 had no report of their efficacy in DM management or toxicity.

CONCLUSION

Local communities in Tanzania use herbal medicine for the management of DM. However, only a fraction of such species has scientific evidence. A. mossambiscensis, C. bonduc., and P. amarus had mild toxicity in animals. Together, our findings call for future researches to focus on in vitro, in vivo, and phytochemical investigation of plant species for which their use in DM among the local communities in Tanzania have not been validated.

Ethnobotany, Phytochemistry and Pharmacological Features of Centella asiatica: A Comprehensive Review

Centella asiatica (CA) or Gotu cola is an herbal plant from the Apiaceae family with a long history of usage in different traditional medicines. It has long been used for the treatment of various ailments such as central nervous system (CNS), skin and gastrointestinal disorders especially in the Southeast Asia. This chapter focused on the phytochemical constituent and pharmacological activities of CA based on preclinical and clinical studies. Additionally, botanical description and distribution, traditional uses, interactions, and safety issues are reviewed. Electronic databases of Google Scholar, Scopus, PubMed, and Web of Science were searched to obtain relevant studies on the pharmacological activities of CA. Approximately, 124 chemical compounds including triterpenoids, polyphenolic compounds, and essential oils have been isolated and identified from CA. Ethnomedicinal applications of CA mostly include treatment of gastrointestinal diseases, wounds, nervous system disorders, circulatory diseases, skin problems, respiratory ailments, diabetes and sleep disorders in various ethnobotanical practices. Pharmacological studies revealed a wide range of beneficial effects of CA on CNS, cardiovascular, lung, liver, kidney, gastrointestinal, skin, and endocrine system. Among them, neuroprotective activity, wound healing and treatment of venous insufficiency, as well as antidiabetic activity seem to be more frequently reported. At the moment, considering various health benefits of CA, it is marketed as an oral supplement as well as a topical ingredient in some cosmetic products. Additional preclinical studies and particularly randomized controlled trials are needed to clarify the therapeutic roles of CA.

Mitigating Perspectives of Asiatic Acid in the Renal Derangements of Streptozotocin-Nicotinamide Induced Diabetic Rats

BACKGROUND

The present study was conducted to evaluate the mitigating effects of Asiatic Acid (AA), on the changes in carbohydrate metabolism, insulin signaling molecules and renal function markers in Streptozotocin (STZ)-Nicotinamide (NAD) induced diabetic rats.

METHODS

AA (20 mg/kg BW) was supplemented orally to the diabetic rats for 42 days. The levels of plasma glucose, Hemoglobin (Hb), glycosylated hemoglobin (HbA1c) insulin and renal function markers, carbohydrate metabolic enzymes in the kidney and insulin signaling molecules in skeletal muscle were measured.

RESULTS

The administration of AA elicited a significant decrease in the levels of plasma glucose, insulin resistance, HbA1c, urea, uric acid, creatinine, glycogen, glycogen synthase, glucose-6- phosphatase, and fructose-1,6-bisphosphatase and a significant increase of body weight development, insulin, Hb, hexokinase, and glycogen phosphorylase and mRNA expressions of insulin signaling molecule like insulin receptor 1, insulin receptor 2 and glucose transporter-4 in the STZ-NAD induced diabetic rats. Further, the protective effect of AA was evidenced by its histological annotation of the kidney tissues.

CONCLUSION

Hence, this study concluded that AA can protect against renal dysfunction by attenuating carbohydrate metabolic disorder and subsequently enhances glucose utilization and renal function in STZ-NAD-induced diabetic rats.

Serjanic Acid Improves Immunometabolic Markers in a Diet-Induced Obesity Mouse Model

Plant extracts from Cecropia genus have been used by Latin-American traditional medicine to treat metabolic disorders and diabetes. Previous reports have shown that roots of Cecropia telenitida that contains serjanic acid as one of the most prominent and representative pentacyclic triterpenes. The study aimed to isolate serjanic acid and evaluate its effect in a prediabetic murine model by oral administration. A semi-pilot scale extraction was established and serjanic acid purification was followed using direct MALDI-TOF analysis. A diet induced obesity mouse model was used to determine the impact of serjanic acid over selected immunometabolic markers. Mice treated with serjanic acid showed decreased levels of cholesterol and triacylglycerols, increased blood insulin levels, decreased fasting blood glucose and improved glucose tolerance, and insulin sensitivity. At transcriptional level, the reduction of inflammation markers related to adipocyte differentiation is reported.

Evaluation of oxidative stress biomarkers of rabbits' liver exposed to thermooxidized virgin olive oil obtained from blanquette olive cultivars

Objective: This work aimed to study the effect of temperature in variation of fatty acid profiles of virgin olive oil (VOO) and to evaluate the impact of the consumption of this thermo oxidized VOO on metabolic oxidative stress. Materials and methods: Effect of consumption of fresh or thermo-oxidized VOO on rabbits was studied. The animals were distributed in groups of six rabbits each and were fed for four weeks with the incorporation of 15% VOO either fresh or heated during one, two, three or four hours. The liver was examined for the level of reduced glutathione (GSH), glutathione S-transferase (GST), catalase (CAT) and activity malondialdehyde (MDA). Results: The diet of VOO heated for three and four hours resulted in a significant increase (p < 0.01) in liver of MDA and GST compared to the control group. The results also showed a significant decrease in GSH levels and CAT activity induced in rabbits of the group treated with VOO heated for three and four hours. Conclusions: The consumption of thermo-oxidized VOO is more dangerous to health than the consumption of fresh olive oil or low oxidation value VOO.

Protective effect of triterpenes against diabetes-induced β-cell damage: An overview of in vitro and in vivo studies

Accumulative evidence shows that chronic hyperglycaemia is a major factor implicated in the development of pancreatic β-cell dysfunction in diabetic patients. Furthermore, most of these patients display impaired insulin signalling that is responsible for accelerated pancreatic β-cell damage. Indeed, prominent pathways involved in glucose metabolism such as phosphatidylinositol 3-kinase/ protein kinase B (PI3-K/AKT) and 5' AMP-activated protein kinase (AMPK) are impaired in an insulin resistant state. The impairment of this pathway is associated with over production of reactive oxygen species and pro-inflammatory factors that supersede pancreatic β-cell damage. Although several antidiabetic drugs can improve β-cell function by modulating key regulators such as PI3-K/AKT and AMPK, evidence of their β-cell regenerative and protective effect is scanty. As a result, there has been continued exploration of novel antidiabetic therapeutics with abundant antioxidant and antiinflammatory properties that are essential in protecting against β-cell damage. Such therapies include triterpenes, which have displayed robust effects to improve glycaemic tolerance, insulin secretion, and pancreatic β-cell function. This review summarises most relevant effects of various triterpenes on improving pancreatic β-cell function in both in vitro and in vivo experimental models. A special focus falls on studies reporting on the ameliorative properties of these compounds against insulin resistance, oxidative stress and inflammation, the well-known factors involved in hyperglycaemia associated tissue damage.

Neuroprotective Properties of Asiatic Acid against 5-Fluorouracil Chemotherapy in the Hippocampus in an Adult Rat Model

5-fluorouracil or 5-FU (a chemotherapeutic medication) has been revealed to induce memory deficits in many cancer patients. Asiatic acid (AA) is a triterpenoid extract from Centella asiatica. This compound can ameliorate intracellular oxidative stress caused by chemotherapy drugs. Recent studies have shown that AA is capable of inhibiting neuronal generation and memory deficit produced by 5-FU chemotherapy. This study aimed to assess the molecular mechanisms of AA related to hippocampal neurogenesis and memory in rats receiving 5-FU. Male Sprague Dawley rats were given AA (30 mg/kg) orally and given 5-FU (25 mg/kg) by i.v. injection 5 times. Some rats were given AA for 20 days before and during 15-FU treatment (preventive), some received AA for 20 days after 5-FU treatment (recovery), and some underwent treatment with AA throughout the time of the experiment (throughout) for 40 days. Treatment with 5-FU caused significant reductions in Notch1, sex determining region Y-box 2 (SOX2), nestin, doublecortin (DCX), and nuclear factor erythroid 2-related factor 2 (Nrf2) levels within the hippocampus. In addition, 5-FU significantly increased p21 positive cell number in the subgranular zone (SGZ) and malondialdehyde (MDA) levels in the hippocampus. Administration with both AA and 5-FU in prevention and throughout was able to prevent decreases in Notch1 SOX2, nestin, DCX, and Nrf2 caused by 5-FU. Treatment with AA also led to decreases in p21 positive cells and MDA levels in the hippocampus. These findings exhibit that AA has the ability to counteract the down-regulation of neurogenesis within the hippocampus and memory deficits caused by 5-FU via inhibiting oxidative stress and increasing neuroprotective properties.

Asiatic acid prevents the development of interstitial lung disease in a hypochlorous acid-induced mouse model of scleroderma

Interstitial lung disease is the most common complication of systemic sclerosis (SSc) and is associated with a high rate of mortality. Due to the complex pathogenesis of SSc, the therapies currently available remain limited. In the present study, the effect of asiatic acid (AA) on SSc-associated pulmonary fibrosis (PF) and its association with the transforming growth factor-β1 (TGF-β1)/Smad2/3 signaling pathway were evaluated. A hypochlorous acid (HOCl)-induced model of SSc was used to evaluate the therapeutic effect of AA on PF in SSc, where AA was administered to SSc mice by gavage. PF was alleviated in the AA-treated SSc mice groups when examined under light microscopy. In addition, there was a decrease in histopathological progression and collagen in the lungs. AA significantly reduced expression of type I collagen in the lungs of mice with SSc. It also significantly suppressed α-smooth muscle actin expression, which attenuated the conversion of fibroblasts into muscle fibroblasts. These AA-associated antifibrosis and anti-immune effects were mediated through the significant downregulation of advanced oxidation protein product, E-selectin, and anti-DNA topoisomerase-1 autoantibody levels in the serum. Furthermore, the expression levels of TGF-β1 and the phosphorylated-Smad2/3/Smad2/3 ratios in AA-treated SSc mice were similar to the control. The presence of pulmonary inflammation and fibrosis was confirmed in the HOCl-induced SSc mice and the results demonstrated that selective inhibition of reactive oxygen species prevented PF. By focusing on the classical TGF-β1/Smad2/3 signaling pathway, a mechanism of action of AA was identified to be associated with the inhibition of Smad2/3 activation through negative regulation of Smad2/3 phosphorylation.

Effects of Black Pepper (Piper nigrum L.) Chloroform Extract on the Enzymatic Activity and Metabolism of Escherichia coli and Staphylococcus aureus

The chemical composition and antimicrobial mechanism of action of black pepper chloroform extract (BPCE) were investigated, as well as the potential antibacterial activities of BPCE against Escherichia coli and Staphylococcus aureus. The results showed that 1H-Cycloprop[e]azulen-7-ol, decahydro-1,1,7-trimethyl-4-methylene-, [1ar-(1aα,4aα,7β,7a,β,7bα.)]- (8.39%) and 2-methylene-4,8,8-trimethyl-4-vinyl-bicyclo[5.2.0]nonane (6.92%) were identified as the two primary components of BPCE. The release of intracellular transaminases from bacteria after being incubated with BPCE revealed that the bacterial cell walls and membranes were degraded and that protein synthesis was inhibited to some extent. The inhibition of bacterial Na+/K+-ATPase activity upon the addition of BPCE also indicated an enhanced permeability of bacterial cell membranes. Moreover, an analysis of hexokinase and pyruvate kinase activities showed that BPCE affected the metabolic rate of glycolysis and disrupted the normal metabolism of bacteria. This phenomenon was supported by an observed accumulation of lactic acid (LA) in the treated bacterial cells. Overall, our results indicated that BPCE damaged bacterial cell walls and membranes, which was followed by a disruption of bacterial cell respiration.

Geraniol, a natural monoterpene, ameliorates hyperglycemia by attenuating the key enzymes of carbohydrate metabolism in streptozotocin-induced diabetic rats

CONTEXT

Geraniol, an acyclic monoterpene alcohol is found in medicinal plants, is used traditionally for several medical purposes including diabetes.

OBJECTIVES

The present study evaluates the antihyperglycemic potential of geraniol on key enzymes of carbohydrate metabolism in streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

Diabetes was induced in experimental rats, by a single intraperitoneal (i.p) injection of STZ [40 mg/kg body weight (b.w.)]. Different doses of geraniol (100, 200 and 400 mg/kg b.w.) and glyclazide (5 mg/kg b.w.) were administrated orally to diabetic rats for 45 days. Body weight, food intake, plasma glucose, insulin, blood haemoglobin (Hb), glycosylated haemoglobin (HbA_1c), hepatic glucose metabolic enzymes and glycogen were examined.

RESULTS

The LD₅₀ value of geraniol is 3600 mg/kg b.w. at oral administration in rats. Administration of geraniol in a dose-dependent manner (100, 200, 400 mg/kg b.w.) and glyclazide (5 mg/kg b.w.) for 45 days significantly improved the levels of insulin, Hb and decreased plasma glucose, HbA_1C in diabetic-treated rats. Geraniol at its effective dose (200 mg/kg b.w.) ameliorated the altered activities of carbohydrate metabolic enzymes near normal effects compared with two other doses (100 and 400 mg/kg b.w.). Geraniol treatment to diabetic rats improved hepatic glycogen content suggesting its anti-hyperglycemic potential. Geraniol supplement was found to preserve the normal histological appearance of hepatic cells and pancreatic β-cells in diabetic rats.

DISCUSSION AND CONCLUSIONS

The present findings suggest that geraniol can potentially ameliorate key enzymes of glucose metabolism in experimental diabetes even though clinical studies used to evaluate this possibility are warranted.

Asiatic acid abridges pre-neoplastic lesions, inflammation, cell proliferation and induces apoptosis in a rat model of colon carcinogenesis

The utmost aim of this present study was to investigate the anti-inflammatory, antiproliferative and proapoptotic potential of Asiatic acid (AA) on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in experimental rats. Rats were divided into six groups and received modified pellet diet for 32 weeks. Group 1 served as control rats. Group 2 received AA (4 mg/kg b.w. p.o.). Group 3-6 rats received 15 DMH (20 mg/kg b.w., s.c.) injections once a week starting from the 4th week. Besides DMH, rats received AA (4 mg/kg b.w. p.o.) in group 4 starting 2 weeks before carcinogen treatment till the end of the last DMH; group 5 starting 2 days after last DMH till the end of the experiment; and group 6 throughout the experiment. Pre-neoplastic lesions, xenobiotic metabolizing enzymes, inflammation, cell proliferation and apoptotic markers were analysed in our study. Our results ascertained AA supplementation to DMH-exposed rats significantly decreased the incidence of aberrant crypt foci (ACF) and phase I xenobiotic enzymes; and increased the phase II xenobiotic enzymes and mucin content as compared to DMH-alone-exposed rats. Moreover the increased expressions of mast cells, argyrophilic nucleolar organizer regions (AgNORs), proliferating cell nuclear antigen (PCNA) and cyclin D1 observed in the DMH-alone-exposed rats were reverted and were comparable with those of the control rats, when treated with AA. Concordantly AA also induced apoptosis by downregulating the expression of Bcl-2 and upregulating Bax, cytochrome c, caspase-3 and -9 in the DMH-alone-exposed rats. Thus AA was able to inhibit DMH-induced colon carcinogenesis by detoxifying the carcinogen, decreasing the preneoplastic lesions by virtue of its anti-inflammatory, antiproliferative and proapoptotic effects. Therefore our findings suggest that AA could be used as an effective chemopreventive agent against DMH induced colon carcinogenesis.

Asiatic acid enhances survival of human AC16 cardiomyocytes under hypoxia by upregulating miR-1290

Asiatic acid (AA) could attenuate ischemia/reperfusion induced myocardial apoptosis through upregulating the Akt/GSK-3β/HIF-1α pathway. HIF-3α is a negative regulator of HIF-1α, whose mRNA is a potential target of miR-1290. AA could upregulate miR-1290 in non-small-cell lung cancer A549 cells. This work aimed to investigate whether AA could inhibit hypoxia induced cardiomyocyte apoptosis through regulating the miR-1290/HIF3A/HIF-1α axis. The AC16 human myocardial cell line cultured under normoxic or hypoxic conditions was treated with various doses of AA for 24 h. Afterwards cell viability, apoptosis and the expression of miR-1290, HIF3A, and HIF1A were evaluated. Cells transfected with miR-1290 mimic or inhibitor were used to determine the role of miR-1290 in the anti-apoptosis effect of AA and the expression of HIF3A and HIF1A. Dual luciferase assay was performed to confirm miR-1290 targeting of HIF3A. HIF3A overexpression was achieved by transfection of HIF3A1 overexpressing lentivirus, and its effect on miR-1290 and AA-regulated survival of cardiomyocytes was evaluated. AA treatment protected cardiomyocytes from hypoxia-induced apoptosis and upregulated miR-1290 and HIF1A, but downregulated HIF3A under hypoxia. The protective effect of AA was abolished by miR-1290 knockdown, whereas enhanced by miR-1290 overexpression. In addition, miR-1290 knockdown increased HIF1A expression, but reduced HIF3A expression in cardiomyocytes. Dual luciferase assay confirmed miR-1290 direct targeting the 3' UTR of HIF3A. HIF3A overexpression counteracted the anti-apoptosis effect of AA or miR-1290. In conclusion, AA can protect cardiomyocytes against hypoxia-induced apoptosis through regulating the miR-1290/HIF3A/HIF-1α axis, and miR-1290 may be a potential target in the prevention of myocardial ischemia-reperfusion injury. © 2017 IUBMB Life, 69(9):660-667, 2017.

Protective effects of asiatic acid in a spontaneous type 2 diabetic mouse model

Asiatic acid (AA) has been demonstrated to exhibit anti-diabetic activity. However, the mechanisms and underlying signaling pathways remain to be elucidated. The present study was performed to confirm the protective effect of AA and demonstrate its ability to regulate the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase-3β (GSK-3β) signaling pathway in db/db mice. Db/db mice fed on a high-fat diet were used to model diabetes mellitus. Modeled mice were divided randomly into the model control, pioglitazone hydrochloride tablet (PH) and AA groups. Age-matched C57 BL/6J mice served as normal controls. Lipid and glucose levels, and glycogen synthesis rates were assessed following treatment. Pathological changes were detected using hematoxylin and eosin staining. Expression of the PI3K/AKT/GSK-3β signaling pathway at the mRNA level was measured using quantitative polymerase chain reaction analysis. The model control group revealed typical characteristics of obesity and diabetes, including high glucose and lipid levels, and decreased glycogen synthesis. Four weeks of treatment with AA or PH ameliorated these abnormalities. AA and PH treatments mitigated the upregulation of PI3K, AKT, insulin receptor, and insulin receptor substrate-1 mRNA expression in modeled mice. Furthermore, AA and PH treatments decreased GSK-3β and glucose-6-phosphatase mRNA expression compared with the normal control group. The results of the present study confirmed that AA possesses anti-diabetic activity in db/db mice. The PI3K/AKT/GSK-3β signaling pathway may mediate this protective effect.

Abelmoschus esculentus fractions potently inhibited the pathogenic targets associated with diabetic renal epithelial to mesenchymal transition

Although Abelmoschus esculentus (AE) is known for anti-hyperglycemia, few reports have addressed its target. Our recent studies have focused on diabetic renal epithelial to mesenchymal transition (EMT), which plays a critical role in fibrosis that accompanies increasing vimentin and suggested signals DPP-4/AT-1/TGF-β1. This study aimed to investigate whether AE is useful for preventing diabetic renal EMT. We used a succession of extractions and obtained the corresponding fractions F1-F5, each with its own individual properties: F1 inhibits high glucose-stimulated vimentin, AT-1, TGF-β1, and DPP-4, and recovers E-cadherin in tubular cells; F2 decreases high glucose-induced vimentin, AT-1 and DPP-4; F3-F5 do not reduce the expression of vimentin. Chemical analysis revealed that F1 is rich of flavonoid glycosides especially quercetin glucosides, and pentacyclic triterpene ester. F2 contains a large amount of carbohydrates and polysaccharides composed of uronic acid, galactose, glucose, myo-inositol etc. In conclusion, AE has the potential to serve as an adjuvant for diabetic nephropathy, with F1 and F2 especially deserving further investigation and development.

Myrtenal alleviates hyperglycaemia, hyperlipidaemia and improves pancreatic insulin level in STZ-induced diabetic rats

CONTEXT

Myrtenal is monoterpene a constituent of essential oils found mainly in herbs such as mint, pepper, cumin, etc. It exerts admirable pharmacological activities against many diseases including diabetes. Hyperlipidaemia is a secondary complication of diabetes and also a major risk factor for cardiovascular diseases.

OBJECTIVE

The present study investigated the possible antihyperlipidaemic efficacy of myrtenal on plasma glucose, pancreatic insulin, plasma and tissue lipid levels in streptozotocin (STZ) induced diabetic rats.

MATERIALS AND METHODS

Diabetes was induced in male Wistar rats by a single intraperitoneal injection of STZ (40 mg/kg b.w.). Myrtenal (80 mg/kg) was administered orally to diabetic rats for a period of 28 d. Plasma glucose, pancreatic insulin, TC, TGs, FFAs, PLs, LDL-C, HDL-C, VLDL, atherogenic index, (HMG-CoA) reductase, LPL, LCAT and liver histology were analyzed.

RESULTS

Diabetic rats showed significantly (p < 0.05) increased plasma glucose (273.18 mg/dL), total cholesterol (142 mg/dL), triglycerides (126 mg/dL), free fatty acids (118 mg/dL), phospholipids (153 mg/dL), low-density lipoprotein (88.07 mg/dL), very low-density lipoprotein (25.2 mg/dL), atherogenic index, whereas a decrease in the levels of pancreatic insulin (97.48 ng/mg) and high-density lipoprotein (29.12 mg/dL). In addition, the activity of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase (0.94 HMG-CoA ratio/(mevalonate) increased significantly in contrast to the activities of lipoprotein lipase (4.87 μmoles of glycerol liberated/h/L) and lecithin cholesterol acyltransferase (54.61 μmoles of cholesterol esterified/h/L) in diabetic rats. Treatment with myrtenal significantly (p < 0.05) improved the levels of plasma glucose, pancreatic insulin and lipid profiles. Moreover, the histopathological analysis of liver was also in agreement with the biochemical findings.

DISCUSSION AND CONCLUSIONS

The present study indicates that myrtenal possess antihyperglycaemic and antihyperlipidemic properties, and could potentially be a useful phytochemical in treating diabetes.

Asiatic acid influences parasitaemia reduction and ameliorates malaria anaemia in P. berghei infected Sprague-Dawley male rats

BACKGROUND

Current malaria treatment is either "anti-parasitic", "anti-infectivity" or both without addressing the pathophysiological derangement (anti-disease aspect) associated with the disease. Asiatic acid is a natural phytochemical with oxidant, antioxidant and anti-inflammatory properties whose effect on malarial and accompanying pathophysiology are yet to be investigated. Asiatic acid influence in P. berghei-infected Sprague Dawley rats on %parasitaemia and malarial anaemia were investigated.

METHODS

Plasmodium berghei-infected rats (90-120 g) were orally administered with Asiatic acid (5, 10, 20 mg/kg) and 30 mg/kg chloroquine as a positive control. Changes in %parasitaemia and haematological parameters in Asiatic acid administered rats were monitored in a 21 day study and compared to controls.

RESULTS

All animals developed stable parasitaemia (15-20 %) by day 7. Asiatic acid doses suppressed parasitaemia, normalised haematological measurements and influenced biophysical characteristics changes. Most positive changes were associated with intragastric administration of 10 mg/kg Asiatic acid dose. Peak %parasitaemia in Asiatic acid administration occurred at days 12 with a shorter time course compared to day 9 for chloroquine (30 mg/kg) treatment with a longer time course.

CONCLUSIONS

Oral Asiatic acid administration influenced %parasitaemia suppression, ameliorated malarial anaemia and increased biophysical properties on infected animals. Asiatic acid may be a replacement alternative for chloroquine treatment with concomitant amelioration of malaria pathophysiology. Due to different action time courses, Asiatic acid and chloroquine may be possible candidates in combination therapy.

ASIATIC ACID INFLUENCES GLUCOSE HOMEOSTASIS IN P. BERGHEI MURINE MALARIA INFECTED SPRAGUE-DAWLEY RATS

Background:

Glucose homeostasis derangement is a common pathophysiology of malaria whose aetiology is still controversial. The Plasmodium parasite, immunological and inflammatory responses, as well as chemotherapeutics currently used cause hypoglycaemia in malaria. Anti-parasitic and anti-disease drugs are required to combat malaria while ameliorating the pathophysiology of the infection. Asiatic acid has anti-hyperglycaemic, antioxidant, pro-oxidant properties useful in glucose homeostasis but its influence in malaria is yet to be reported. Here we present findings on the influence of asiatic acid on glucose metabolism in vivo using P. berghei-infected Sprague Dawley rats.

Materials and Methods:

Acute as well as sub-chronic studies were carried out in vivo where physicochemical properties and glucose homeostasis were monitored after administration of asiatic acid (10mg/kg) in both non-infected and infected animals. Glucose metabolism associated biochemical changes in malaria were also investigated.

Results:

In acute studies, asiatic acid improved oral glucose response while in the sub-chronic state it maintained food and water intake and suppressed parasitaemia. Normoglycaemic control was maintained in infected animals through insulin suppression and increasing glucagon secretion, in both acute and chronic studies. Asiatic acid administration curtailed lactate concentration towards normal.

Conclusion:

Per oral post-infection asiatic acid administration preserved drinking and eating habits, inhibited sickness behaviour while suppressing parasitaemia. Reciprocal relationship between insulin and glucagon concentrations was maintained influencing glucose homeostasis positively and inhibition of hyperlactaemia in malaria.

Abbreviations: ip -intraperitoneal, po -per oral, ig -intragastric, AA-Asciatic acid, OGTT-oral glucose tolerance test, OS-oxidative stress, ROS-reactive oxygen species, NO-nitric oxide, ONOO^- - peroxynitrite, BRU-Biomedical Research Unit, SD-Sprague Dawley,

Asiatic acid inhibits pulmonary inflammation induced by cigarette smoke

Asiatic acid (AA) is one of the major components of Titrated extract of Centella asiatica (TECA), which has been reported to possess antioxidant and anti-inflammatory activities. The purpose of this study was to investigate the protective effect of AA on pulmonary inflammation induced by cigarette smoke (CS). AA significantly attenuated the infiltration of inflammatory cells in bronchoalveolar lavage fluid (BALF) of CS exposure mice. AA also decreased ROS production and NE activity, and inhibited the release of proinflammatory cytokines in BALF. AA reduced the recruitment of inflammatory cells and MCP-1 expression in lung tissue of CS exposure mice. AA also attenuated mucus overproduction, and decreased the activation of MAPKs and NF-kB in lung tissue. Furthermore, AA increased HO-1 expression and inhibited the reduced expression of SOD3 in lung tissue. These findings indicate that AA effectively inhibits pulmonary inflammatory response, which is an important process in the development of chronic obstructive pulmonary disease (COPD) via suppression of inflammatory mediators and induction of HO-1. Therefore, we suggest that AA has the potential to treat inflammatory disease such as COPD.