The role of triterpenes in the management of diabetes mellitus and its complications

Synergistic improved efficacy of Gymnadenia orchidis root Salep and pumpkin seed on induced diabetic complications

OBJECTIVE

Diabetes mellitus occurs due to either deficiency of insulin or resistance to insulin. Synthetic drugs and insulin therapy against diabetes possess numerous drawbacks. Diabetic people are advised to choose low-glycemic food and herbal products to control diabetes. This study aims to examine the synergistic effects of aqueous root Salep ofGymnadenia orchidis Lindl and pumpkin seed powder on Streptozotocin induced diabetic mice.

METHODS

Out of 6 groups, animals in 2 groups were kept as control and rest 4 groups were made diabetic by Streptozotocin. Animals in one diabetic group were supplemented with effective dose (200 mg/kg of body weight) of root Salep, one with pumpkin seed powder (5%) mixed food, and another with Salep and pumpkin seed food. Changes in various biochemical parameters, DNA damage and liver and kidney structures were noted after 21 days treatment.

RESULTS

Salep with pumpkin seed supplementation significantly normalized the alterations of different biochemical parameters of diabetic mice. The DNA damage in blood cells of diabetic mice was recovered by this supplementation. Terpenoids of root Salep and anti-oxidants of pumpkin seed may play the active role against diabetes.

CONCLUSION

The root Salep and pumpkin seed synergistically prevent diabetic complications and could be better supplementation against type-2 diabetes.

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.

Antidiabetic activity, glucose uptake stimulation and α-glucosidase inhibitory effect of Chrysophyllum cainito L. stem bark extract

Background

Chrysophyllum cainito L., a tropical fruit tree, has been used as an alternative medicine for the treatment of diabetic patients in many countries. However, there is very limited scientific rationale for this medical use. The present study aimed to evaluate the antidiabetic activity of the extract from C. cainito stem bark and the possible mechanisms underlying this activity.

Methods

Phytochemistry and in vitro antioxidant capacity of the extract were studied. Hypoglycemic activity of the extract was examined in normal and alloxan-induced diabetic mice. The effect of C. cainito extract on glucose absorption and glucose uptake were conducted using mouse isolated jejunum and abdominal muscle, respectively. Finally, an in vitro effect of C. cainito extract on α-glucosidase activity was evaluated.

Results

C. cainito extract possessed a strong antioxidant activity comparable to the ascorbic acid and butylated hydroxytoluene. The extract at 500 mg/kg significantly reduced the area under curve of blood glucose level in oral glucose tolerance test in normal mice. In alloxan-induced diabetic model, similar to glibenclamide, a single dose of the extract significantly decreased fasting blood glucose level from 387.17 ± 29.84 mg/dl to 125.67 ± 62.09 mg/dl after 6 h of administration. From the isolated jejunum experiment, the extract at any doses used did not inhibit glucose absorption. However, the extract at 50 μg/ml significantly increased the amount of glucose uptake by abdominal muscles in the presence of insulin (P < 0.05). Lastly, it was found that the extract produced stronger inhibition of α-glucosidase activity (IC₅₀ = 1.20 ± 0.09 μg/ml) than acarbose (IC₅₀ = 198.17 ± 4.74 μg/ml).

Conclusion

Direct evidence of antidiabetic activity of C. cainito stem bark with possible modes of action, glucose uptake stimulation and α-glucosidase inhibitory effect, was reported for the first time herein. These data support the potential use of this plant for the treatment of diabetic patients.

Antidiabetic potential of Musa spp. inflorescence: a systematic review

Objectives

Extracts of parts Musa spp. have been used for the treatment of various diseases in traditional medicine. Studies have shown that these extracts have hypoglycaemic properties. The aim of this work was to gather evidence on the antidiabetic effects of Musa spp. inflorescence.

Methods

A systematic review was conducted with searches in three electronic databases, along with manual searches. Studies evaluating the antidiabetic properties of extracts of flower or bract of the genus Musa (in vitro or in vivo) were included.

Key findings

Overall, 16 studies were found. The reported assays were of hypoglycaemic effects, oral glucose tolerance, inhibitory activities in carbohydrate metabolism and digestive enzymes, enhanced glucose uptake activity and popular use of the extract in patients with diabetes type 2. In vitro studies showed that use of the extract was associated with antidiabetic effects (e.g. increased glucose uptake and inhibition of carbohydrate digestion enzymes). In induced diabetic models, Musa spp. extracts showed dose-dependent glycaemic level reductions compared with pharmacological drugs (P &lt; 0.05).

Summary

In general, promising results regarding antidiabetic activity were found for inflorescence of Musa spp., suggesting that this plant could represent a natural alternative therapy for treating diabetes mellitus type 2.

Protective Effect of Rosamultin against H2O2-Induced Oxidative Stress and Apoptosis in H9c2 Cardiomyocytes

Rosamultin is one of the main active compounds isolated from Potentilla anserina L., which belongs to a triterpene compound. Few studies have examined the effect of rosamultin on oxidative stress and its molecular mechanism. The aim of this present study was to elucidate the protective effect of rosamultin on H₂O₂-induced oxidative damage and apoptosis in H9c2 cardiomyocytes and its mechanism. The results showed that the pretreatment of rosamultin not only increased cell viability but also reduced the release of LDH and CK. Rosamultin inhibited a H₂O₂-induced decrease in SOD, CAT, and GSH-Px activities and an increase in MDA content. Meanwhile, ROS level, intracellular (Ca²⁺) fluorescence intensity, and apoptosis rate in the rosamultin pretreated group were markedly decreased compared with the model group. Rosamultin pretreatment significantly reversed the morphological changes and attenuated H₂O₂-induced apoptosis. Western blot analysis showed that rosamultin enhanced the expression of Bcl-2 and pCryAB and downregulated the expression of Bax, Cyt-c, Caspase-3, and Caspase-9 expression. Additionally, rosamultin might activate PI3K/Akt signal pathways and CryAB relative factors. Therefore, we suggest that rosamultin could have the potential for treating H₂O₂-induced oxidative stress injury through its antioxidant and antiapoptosis effect.

Vasodilator Activity of Compounds Isolated from Plants Used in Mexican Traditional Medicine

Arterial hypertension is one of the main risk factors in the development of cardiovascular diseases. Therefore, it is important to look for new drugs to treat hypertension. In this study, we carried out the screening of 19 compounds (triterpenes, diterpenes, sesquiterpenes, lignans, and flavonoids) isolated from 10 plants used in Mexican traditional medicine to determine whether they elicited vascular smooth muscle relaxation and, therefore, could represent novel anti-hypertension drug candidates. The vasorelaxant activity of these compounds was evaluated on the isolated rat aorta assay and the results obtained from this evaluation showed that three compounds induced a significant vasodilatory effect: meso-dihydroguaiaretic acid [half maximal effective concentration (EC₅₀), 49.9 ± 11.2 µM; maximum effect (Emax), 99.8 ± 2.7%]; corosolic acid (EC₅₀, 108.9 ± 6.7 µM; Emax, 96.4 ± 4.2%); and 5,8,4′-trihydroxy-3,7-dimethoxyflavone (EC₅₀, 122.3 ± 7.6 µM; Emax, 99.5 ± 5.4%). Subsequently, involvement of the NO/cyclic guanosine monophosphate (cGMP) and H₂S/ATP-sensitive potassium channel (K_ATP) pathways on the vasodilator activity of these compounds was assessed. The results derived from this analysis showed that the activation of both pathways contributes to the vasorelaxant effect of corosolic acid. On the other hand, the vasodilator effect of meso-dihydroguaiaretic acid and 5,8,4′-trihydroxy-3,7-dimethoxyflavone, partly involves stimulation of the NO/cGMP pathway. However, these compounds also showed an important endothelium-independent vasorelaxant effect, whose mechanism of action remains to be clarified. This study indicates that meso-dihydroguaiaretic acid, corosolic acid, and 5,8,4′-trihydroxy-3,7-dimethoxyflavone could be used as lead compounds for the synthesis of new derivatives with a higher potency to be developed as drugs for the prevention and treatment of cardiovascular diseases.

Pentacyclic Triterpenes from Cecropia telenitida Can Function as Inhibitors of 11β-Hydroxysteroid Dehydrogenase Type 1

Plant extracts from the genus Cecropia have been used by Latin-American traditional medicine to treat metabolic disorders and diabetes. Previous results have shown that roots of Cecropia telenitida contain pentacyclic triterpenes and these molecules display a hypoglycemic effect in an insulin-resistant murine model. The pharmacological target of these molecules, however, remains unknown. Several lines of evidence indicate that pentacyclic triterpenes inhibit the 11β-hydroxysteroid dehydrogenase type 1 enzyme, which highlights the potential use of this type of natural product as phytotherapeutic or botanical dietary supplements. The main goal of the study was the evaluation of the inhibitory effect of Cecropia telenitida molecules on 11β-hydroxysteroid dehydrogenase type 1 enzyme activity. A pre-fractionated chemical library was obtained from the roots of Cecropia telenitida using several automated chromatography separation steps and a homogeneous time resolved fluorescence assay was used for the bio-guided isolation of inhibiting molecules. The screening of a chemical library consisting of 125 chemical purified fractions obtained from Cecropia telenitida roots identified one fraction displaying 82% inhibition of the formation of cortisol by the 11β-hydroxysteroid dehydrogenase type 1 enzyme. Furthermore, a molecule displaying IC₅₀ of 0.95 ± 0.09 µM was isolated from this purified fraction and structurally characterized, which confirms that a pentacyclic triterpene scaffold was responsible for the observed inhibition. Our results support the hypothesis that pentacyclic triterpene molecules from Cecropia telenitida can inhibit 11β-hydroxysteroid dehydrogenase type 1 enzyme activity. These findings highlight the potential ethnopharmacological use of plants from the genus Cecropia for the treatment of metabolic disorders and diabetes.

Debittering of bitter gourd juice using β-cyclodextrin: Mechanism and effect on antidiabetic potential

Triterpene glycosides namely momordicoside K and momordicoside L causes bitterness in bitter-gourd thereby reducing its consumer acceptance. Reducing bitterness of the juice by addition of β-cyclodextrin (0.25-2%) was attempted and its effect on sensory quality, total phenolic content, antioxidant activity and antidiabetic potential was evaluated. Juice with 1.5% β-cyclodextrin demonstrated highest score (7.7 ± 0.3) for sensory acceptability compared to the control (3.8 ± 0.7). A significantly (p < 0.05) higher total phenolic content and antioxidant activity was observed. A marginal (10%) but significant (p < 0.05) reduction in α-glucosidase inhibition activity without affecting α-amylase activity was noted. Results from NMR, ROESY and FTIR studies indicated formation of an inclusion complex by interaction of hydrophobic triterpenoidal region of momordicosides with β-cyclodextrin.

A Lanosteryl Triterpene from Protorhus longifolia Improves Glucose Tolerance and Pancreatic Beta Cell Ultrastructure in Type 2 Diabetic Rats

Type 2 diabetes remains one of the leading causes of death worldwide. Persistent hyperglycemia within a diabetic state is implicated in the generation of oxidative stress and aggravated inflammation that is responsible for accelerated modification of pancreatic beta cell structure. Here we investigated whether a lanosteryl triterpene, methyl-3β-hydroxylanosta-9,24-dien-21-oate (RA-3), isolated from Protorhus longifolia can improve glucose tolerance and pancreatic beta cell ultrastructure by reducing oxidative stress and inflammation in high fat diet and streptozotocin-induced type 2 diabetes in rats. In addition to impaired glucose tolerance, the untreated diabetic rats showed increased fasting plasma glucose and C-peptide levels. These untreated diabetic rats further demonstrated raised cholesterol, interleukin-6 (IL-6), and lipid peroxidation levels as well as a destroyed beta cell ultrastructure. Treatment with RA-3 was as effective as metformin in improving glucose tolerance and antioxidant effect in the diabetic rats. Interestingly, RA-3 displayed a slightly more enhanced effect than metformin in reducing elevated IL-6 levels and in improving beta cell ultrastructure. Although the involved molecular mechanisms remain to be established, RA-3 demonstrates a strong potential to improve pancreatic beta cell ultrastructure by attenuating impaired glucose tolerance, reducing oxidative stress and inflammation.

Lupeol and Its Role in Chronic Diseases

Lupeol belongs to pentacyclic lupane-type triterpenes and exhibits in edible vegetables, fruits and many plants. Many researches indicated that lupeol possesses many beneficial pharmacological activities including antioxidant, anti-inflammatory, anti-hyperglycemic, anti-dyslipidemic and anti-mutagenic effects. From various disease-targeted animal models, these reports indicated that lupeol has anti-diabetic, anti-asthma, anti-arthritic, cardioprotective, hepatoprotective, nephroprotective, neuroprotective and anticancer efficiency under various routes of administration such as topical, oral, subcutaneous, intraperitoneal and intravenous. It is worth mentioning that clinical trials of lupeol were performed to treat canine oral malignant melanoma and human moderate skin acne in Japan and Korea. The detailed mechanism of anti-inflammatory, anti-diabetic, hepatoprotective and anticancer activities was further reviewed from published papers. These evidence indicate that lupeol is a multi-target agent to exert diverse pharmacological potency with many potential targeting proteins such as α-glucosidase, α-amylase, protein tyrosine phosphatase 1B (PTP 1B) and TCA cycle enzymes and targeting pathway such as IL-1 receptor-associated kinase-mediated toll-like receptor 4 (IRAK-TLR4), Bcl-2 family, nuclear factor kappa B (NF-kB), phosphatidylinositol-3-kinase (PI3-K)/Akt and Wnt/β-catenin signaling pathways. This review also provides suggestion that lupeol might be a valuable and potential lead compound to develop as anti-inflammatory, anti-diabetic, hepatoprotective and anticancer drugs.

Potential of Lichen Compounds as Antidiabetic Agents with Antioxidative Properties: A Review

The advancement in the knowledge of potent antioxidants has uncovered the way for greater insight in the treatment of diabetic complications. Lichens are a rich resource of novel bioactive compounds and their antioxidant potential is well documented. Herein we review the antidiabetic potential of lichens which have received considerable attention, in the recent past. We have correlated the antidiabetic and the antioxidant potential of lichen compounds. The study shows a good accordance between antioxidant and antidiabetic activity of lichens and points out the need to look into gathering the scarce and scattered data on biological activities for effective utilization. The review establishes that the lichen extracts, especially of Parmotrema sp. and Ramalina sp. have shown promising potential in both antidiabetic and antioxidant assays. Ubiquitous compounds, namely, zeorin, methylorsellinate, methyl-β-orcinol carboxylate, methyl haematommate, lecanoric acid, salazinic acid, sekikaic acid, usnic acid, gyrophoric acid, and lobaric acid have shown promising potential in both antidiabetic as well as antioxidant assays highlighting their potential for effective treatment of diabetic mellitus and its associated complications. The available compilation of this data provides the future perspectives and highlight the need for further studies of this potent herbal source to harvest more beneficial therapeutic antidiabetic drugs.

Clinical application prospect of umbilical cord-derived mesenchymal stem cells on clearance of advanced glycation end products through autophagy on diabetic wound

Nowadays, wound healing delay due to diabetes is considered to be closely related to the accumulation of advanced glycation end products (AGEs). Although mesenchymal stem cells (MSCs) exhibit positive effects on diabetic wound healing, related mechanisms are still not fully elucidated. It has been reported that MSCs can improve the activity of autophagy in injured tissues, thereby playing an important role in wound healing. The autophagy induced by MSCs may be beneficial to diabetic wound healing via removing AGEs, which provide new ideas for clinical treatment of diabetic wounds with the potential of broad application prospects. In this study, the current research situation and application prospect of umbilical cord-derived MSCs on the clearance of AGEs in diabetic wound were reviewed.

Comparison of In-Vitro and Ex-Vivo Wound Healing Assays for the Investigation of Diabetic Wound Healing and Demonstration of a Beneficial Effect of a Triterpene Extract

Diabetes mellitus is a frequent cause for chronic, difficult-to-treat wounds. New therapies for diabetic wounds are urgently needed and in-vitro or ex-vivo test systems are essential for the initial identification of new active molecules. The aim of this study is to compare in-vitro and ex-vivo test systems for their usability for early drug screening and to investigate the efficacy of a birch bark triterpene extract (TE) that has been proven ex-vivo and clinically to accelerate non-diabetic wound healing (WH), in a diabetic context. We investigated in-vitro models for diabetic WH, i.e. scratch assays with human keratinocytes from diabetic donors or cultured under hyperglycaemic conditions and a newly developed porcine ex-vivo hyperglycaemic WH model for their potential to mimic delayed diabetic WH and for the influence of TE in these test systems. We show that keratinocytes from diabetic donors often fail to exhibit significantly delayed WH. For cells under hyperglycaemic conditions significant decrease is observed but is influenced by choice of medium and presence of supplements. Also, donor age plays a role. Interestingly, hyperglycaemic effects are mainly hyperosmolaric effects in scratch assays. Ex-vivo models under hyperglycaemic conditions show a clear and substantial decrease of WH, and here both glucose and hyperosmolarity effects are involved. Finally, we provide evidence that TE is also beneficial for ex-vivo hyperglycaemic WH, resulting in significantly increased length of regenerated epidermis to 188±16% and 183±11% (SEM; p<0.05) compared to controls when using two different TE formulations. In conclusion, our results suggest that microenvironmental influences are important in WH test systems and that therefore the more complex hyperglycaemic ex-vivo model is more suitable for early drug screening. Limitations of the in-vitro and ex-vivo models are discussed. Furthermore our data recommend TE as a promising candidate for in-vivo testings in diabetic wounds.

Lupane-type triterpenes and their anti-cancer activities against most common malignant tumors: A review

In recent times, a great deal of interest has been motivated on plant derived compounds known as nutraceuticals. These compounds exert important beneficial activities that improve people's health status when are consumed regularly, and now they appear as a viable option to explore their possible therapeutic effects against diseases like cancer. Particularly, lupane-type triterpenes have shown great ability to modulate multiple cancer-related signaling pathways and processes, including NF-κB, Wnt/β-catenin, PI3K/Akt, apoptosis, and many other routes related to proliferation or cell death, which are uncontrolled in malignant tumors. These investigations have promoted in vitro and in vivo studies, searching their mechanisms of action; although more research is still needed to prove its potential in human clinical trials. This review focuses on the ability of betulin, betulinic acid and lupeol to show benefits against the most common types of malignant tumors, which are considered a major global threat for public health.

New potential phytotherapeutics obtained from white mulberry (Morus alba L.) leaves

The present work demonstrates the profound and unique phyto-pharmacological and nutritional profile of white mulberry (Morus alba L.) leaves which containing considerable amounts of easy digestive proteins, carbohydrates, micro- and macronutrients, polyphenols, free amino acids, organic acids. The wide range of significant biopharmaceutical activities of the aqueous and polar organic solvents extracts from mulberry leaves - including antidiabetic, antibacterial, anticancer, cardiovascular, hypolipidemic, antioxidant, antiatherogenic, and anti-inflammatory - have been critically discussed. The main objective was to demonstrate the results of recently published study on the components of white mulberry leaves exhibiting their biological activity in the various pathological and health human ailments. In addition, we intend to drawn the attention of researchers and public health workers for the extended exploration of this deciduous plant leaves as the source of potential indigenous nutraceuticals and functional food products to enable development of alternative prevention and treatment protocols offered in therapy of the common non-communicable diseases and malignances.