The antidiabetic properties of the hot water extract of kola nut (Cola nitida (Vent.) Schott & Endl.) in type 2 diabetic rats

Potential molecular mechanisms underlying the ameliorative effect of Cola nitida (Vent.) Schott & Endl. on insulin resistance in rat skeletal muscles

ETHNOPHARMACOLOGICAL RELEVANCE

Cola nitida (Vent.) Schott & Endl. are among the common medicinal plants employed in traditional medicine for treating diabetes and its complications.

AIM OF THE STUDY

The present study investigated the effect of Cola nitida infusion on the expression of key genes involved in insulin signaling vis-à-vis Insulin receptor substrate 1 (IRS-1), tumor protein P53 gene, glucose transporter type 4 (GLUT4), phosphoinositide 3-kinases (PI3K) and B-cell lymphoma-2 (BCL2) in skeletal muscles of type 2 diabetic (T2D) rats.

METHODS

Type 2 diabetic rats were administered C. nitida infusion at low and high doses (150 and 300 mg/kg bodyweight, respectively), while a high dose of the infusion was also administered to a normal toxicological group. Metformin served as the standard antidiabetic drug. The rats were sacrificed at the end of the experimental period. Their psoas muscles were harvested and assayed for the expressions of IRS1, p53, GLUT4, PI3K and BCL2. The studied genes were further subjected to enrichment analysis using the ShinyGO 0.76 online software.

RESULTS

Induction of T2D upregulated the expressions of IRS-1, p53, PI3K and BCL2 in psoas muscles, while concomitantly downregulating GLUT4 expression. These expressions were significantly reversed in type 2 diabetic rats treated with C. nitida infusion, and the results were statistically significant compared to metformin. Gene enrichment analysis revealed that the genes were linked to intrinsic pathways and biological processes involved in insulin resistance. The infusion further improved muscle glucose uptake, ex vivo. Molecular docking and molecular dynamics stimulation of C. nitida infusion phytoconstituents, caffeine and theobromine with IRS-1, p53, GLUT4, PI3K and BCL2 revealed a strong binding affinity as evident by the RMSD and RMSF values.

CONCLUSION

These results indicate the potentials of C. nitida infusion to improve glucose homeostasis in skeletal muscles of type 2 diabetic rats.

Kolaviron modulates dysregulated metabolism in oxidative pancreatic injury and inhibits intestinal glucose absorption with concomitant stimulation of muscle glucose uptake

This present study investigated the antioxidative and antidiabetic properties of kolaviron by analysing its inhibitory effect on key metabolic activities linked to T2D, in vitro and ex vivo. Kolaviron significantly inhibited α-glucosidase and α-amylase activities, and intestinal glucose absorption dose-dependently, while promoting muscle glucose uptake. Induction of oxidative pancreatic injury significantly depleted glutathione level, superoxide dismutase, catalase, and ATPase activities, while elevating malondialdehyde and nitric oxide levels, acetylcholinesterase and chymotrypsin activities. These levels and activities were significantly reversed in tissues treated with kolaviron. Kolaviron depleted oxidative-induced metabolites, with concomitant restoration of oxidative-depleted metabolites. It also inactivated oxidative-induced ascorbate and aldarate metabolism, pentose and glucuronate interconversions, fructose and mannose metabolism, amino sugar and nucleotide sugar metabolism, and arginine and proline metabolism, while reactivating selenocompound metabolism. These results depict the antidiabetic properties of kolaviron as indicated by its ability to attenuate oxidative-induced enzyme activities and dysregulated metabolisms, and modulated the enzyme activities linked to hyperglycaemia.

Anti-obesity, anti-hyperglycaemic, anti-antipyretic and analgesic activities of Globularia alypum extracts

OBJECTIVES

The aim of this study is to evaluate the anti-obesity, anti-hyperglycaemic, analgesic and antipyretic activities of Globularia alypum (GA).

MATERIALS AND METHODS

GA methanol and water extracts (GAME, GAWE) were administered to high-fat-high-glucose diet (HFFD) rats.

RESULTS

This study showed that GAME exhibited the highest antioxidant, anti-α-amylase and anti-lipase activities, with half inhibitory concentration (IC50) values 0.067, 1.05 and 2.97 mg/ml respectively. In HFFD rats, the administration of GAME inhibited lipase activity by 36, 37 and 30% in the intestine, pancreas and serum, respectively, reduced body weight by 17.7% and modulated lipid profile. In addition, administration of GAME to HFFD-rats decreased α-amylase activity, improved glucose level and protected liver function. Furthermore, the administration of GA extracts to rats revealed antipyretic (reduction in writhing by 64%) and analgesic (decrease of temperature by 1.11 °C) activities.

CONCLUSION

This study showed that GA extracts exhibited an anti-obesity, anti-hyperglycaemia, anti-pyretic and analgesic activities.

Pharmacologically Active Phytomolecules Isolated from Traditional Antidiabetic Plants and Their Therapeutic Role for the Management of Diabetes Mellitus

Diabetes mellitus is a chronic complication that affects people of all ages. The increased prevalence of diabetes worldwide has led to the development of several synthetic drugs to tackle this health problem. Such drugs, although effective as antihyperglycemic agents, are accompanied by various side effects, costly, and inaccessible to the majority of people living in underdeveloped countries. Medicinal plants have been used traditionally throughout the ages to treat various ailments due to their availability and safe nature. Medicinal plants are a rich source of phytochemicals that possess several health benefits. As diabetes continues to become prevalent, health care practitioners are considering plant-based medicines as a potential source of antidiabetic drugs due to their high potency and fewer side effects. To better understand the mechanism of action of medicinal plants, their active phytoconstituents are being isolated and investigated thoroughly. In this review article, we have focused on pharmacologically active phytomolecules isolated from medicinal plants presenting antidiabetic activity and the role they play in the treatment and management of diabetes. These natural compounds may represent as good candidates for a novel therapeutic approach and/or effective and alternative therapies for diabetes.

Ethnopharmacological Study of Medicinal Plants Used for the Treatment of Cardiovascular Diseases and Their Associated Risk Factors in sub-Saharan Africa

Cardiovascular diseases (CVDs) are the leading cause of global mortality, including deaths arising from non-communicable diseases in sub-Saharan Africa (SSA). Consequently, this study aimed to provide details of medicinal plants (MPs) employed in SSA for the treatment of CVDs and their related risk factors to open new avenues for the discovery of novel drugs. The extensive ethnopharmacological literature survey of these MPs in 41 SSA countries was based on studies from 1982 to 2021. It revealed 1,085 MPs belonging to 218 botanical families, with Fabaceae (9.61%), Asteraceae (6.77%), Apocynaceae (3.93%), Lamiaceae (3.75%), and Rubiaceae (3.66%) being the most represented. Meanwhile, Allium sativum L., Persea americana Mill., Moringa oleifera Lam., Mangifera indica L., and Allium cepa L. are the five most utilised plant species. The preferred plant parts include the leaves (36%), roots (21%), barks (14%), fruits (7%), and seeds (5%), which are mostly prepared by decoction. Benin, Mauritius, Nigeria, South Africa, and Togo had the highest reported use while most of the investigations were on diabetes and hypertension. Despite the nutraceutical advantages of some of these MPs, their general toxicity potential calls for caution in their human long-term use. Overall, the study established the need for governments of SSA countries to validate the efficacy/safety of these MPs as well as provide affordable, accessible, and improved modern healthcare services.

Bridelia ferruginea Benth. (Euphorbiaceae) mitigates oxidative imbalance and lipotoxicity, with concomitant modulation of insulin signaling pathways via GLUT4 upregulation in hepatic tissues of diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Bridelia ferruginea Benth. (Euphorbiaceae) is among the medicinal plants commonly used for the management of type 2 diabetes (T2D) and its complications.

AIM OF THE STUDY

The hepato-therapeutic effect of the butanol fraction of Bridelia ferruginea leaves was investigated in diabetic rats.

METHODS

The butanol fraction of B. ferruginea was given to type 2 diabetic rats at both low and high doses (150 and 300 mg/kg bodyweight, respectively), while metformin and glibenclamide served as the standard anti-diabetic drugs. A normal toxicological group was administered a high dose of the fraction. At the end of the experimental period, the rats were sacrificed, and their livers and psoas muscle collected. The liver was assayed for oxidative stress markers, liver glycogen content, lipid metabolite profile (using GC-MS) and their metabolic pathways were analyzed using the MetaboAnalyst 5.0 online server. The expression of GLUT4 was also assayed in the liver and muscle as well as the identification of signaling pathways associated with GLUT4 expression using the Enrichr online server. In silico molecular docking was used to investigate the molecular interactions of some postulated compound found in B. ferruginea with GLUT4. The ability of the fraction to stimulate muscle glucose uptake was determined in isolated rat psoas muscle ex vivo.

RESULTS

Treatment with the high dose of fraction caused an inhibition of lipid peroxidation as well as the elevation of catalase, SOD, glutathione reductase and glutathione peroxidase activities in the rat liver. There was an increased expression of GLUT4 in livers and muscles of diabetic rats following treatment with B. ferruginea. Treatment with the fraction also caused inactivation of diabetes-activated pathways and changes in the distribution of the hepatic lipid metabolites. Molecular docking analysis revealed strong molecular interactions of pyrogallol and sitosterol with GLUT4.

CONCLUSIONS

These data illustrate the hepato-protective effect of B. ferruginea in diabetic rats which compare favorably with the tested anti-diabetic drugs (metformin and glibenclamide).

Approaches to Decrease Hyperglycemia by Targeting Impaired Hepatic Glucose Homeostasis Using Medicinal Plants

Liver plays a pivotal role in maintaining blood glucose levels through complex processes which involve the disposal, storage, and endogenous production of this carbohydrate. Insulin is the hormone responsible for regulating hepatic glucose production and glucose storage as glycogen, thus abnormalities in its function lead to hyperglycemia in obese or diabetic patients because of higher production rates and lower capacity to store glucose. In this context, two different but complementary therapeutic approaches can be highlighted to avoid the hyperglycemia generated by the hepatic insulin resistance: 1) enhancing insulin function by inhibiting the protein tyrosine phosphatase 1B, one of the main enzymes that disrupt the insulin signal, and 2) direct regulation of key enzymes involved in hepatic glucose production and glycogen synthesis/breakdown. It is recognized that medicinal plants are a valuable source of molecules with special properties and a wide range of scaffolds that can improve hepatic glucose metabolism. Some molecules, especially phenolic compounds and terpenoids, exhibit a powerful inhibitory capacity on protein tyrosine phosphatase 1B and decrease the expression or activity of the key enzymes involved in the gluconeogenic pathway, such as phosphoenolpyruvate carboxykinase or glucose 6-phosphatase. This review shed light on the progress made in the past 7 years in medicinal plants capable of improving hepatic glucose homeostasis through the two proposed approaches. We suggest that Coreopsis tinctoria, Lithocarpus polystachyus, and Panax ginseng can be good candidates for developing herbal medicines or phytomedicines that target inhibition of hepatic glucose output as they can modulate the activity of PTP-1B, the expression of gluconeogenic enzymes, and the glycogen content.

Antidiabetic Medicinal Plants Used in Democratic Republic of Congo: A Critical Review of Ethnopharmacology and Bioactivity Data

Several studies have been conducted and published on medicinal plants used to manage Diabetes Mellitus worldwide. It is of great interest to review available studies from a country or a region to resort to similarities/discrepancies and data quality. Here, we examined data related to ethnopharmacology and bioactivity of antidiabetic plants used in the Democratic Republic of Congo. Data were extracted from Google Scholar, Medline/PubMed, Scopus, ScienceDirect, the Wiley Online Library, Web of Science, and other documents focusing on ethnopharmacology, pharmacology, and phytochemistry antidiabetic plants used in the Democratic Republic of Congo from 2005 to September 2021. The Kew Botanic Royal Garden and Plants of the World Online web databases were consulted to verify the taxonomic information. CAMARADES checklist was used to assess the quality of animal studies and Jadad scores for clinical trials. In total, 213 plant species belonging to 72 botanical families were reported. Only one plant, Droogmansia munamensis, is typically native to the DRC flora; 117 species are growing in the DRC and neighboring countries; 31 species are either introduced from other regions, and 64 are not specified. Alongside the treatment of Diabetes, about 78.13% of plants have multiple therapeutic uses, depending on the study sites. Experimental studies explored the antidiabetic activity of 133 plants, mainly in mice, rats, guinea pigs, and rabbits. Several chemical classes of antidiabetic compounds isolated from 67 plant species have been documented. Rare phase II clinical trials have been conducted. Critical issues included poor quality methodological protocols, author name incorrectly written (16.16%) or absent (14.25%) or confused with a synonym (4.69%), family name revised (17.26%) or missing (1.10%), voucher number not available 336(92.05%), ecological information not reported (49.59%). Most plant species have been identified and authenticated (89.32%). Hundreds of plants are used to treat Diabetes by traditional healers in DRC. However, most plants are not exclusively native to the local flora and have multiple therapeutic uses. The analysis showed the scarcity or absence of high-quality, in-depth pharmacological studies. There is a need to conduct further studies of locally specific species to fill the gap before their introduction into the national pharmacopeia.

Cola nitida infusion modulates cardiometabolic activities linked to cardiomyopathy in diabetic rats

This study investigated the therapeutic mechanism of Cola nitida seeds on diabetic cardiomyopathy in hearts of diabetic rats. Type 2 diabetic (T2D) rats were treated with C. nitida infusion at 150 or 300 mg/kg body weight (bw). The rats were sacrificed after 6 weeks of treatment, and their hearts harvested. There was an upsurge in oxidative stress on induction of T2D as depicted by the depleted levels of glutathione, superoxide dismutase and catalase activities, and elevated malondialdehyde level. The activities of acetylcholinesterase, and ATPase were significantly elevated, with suppressed ENTPDase and 5'nucleotodase activities in hearts of T2D rats depicting cholinergic and purinergic dysfunctions. Induction of T2D further led to elevated activity of ACE and altered myocardial morphology. Treatment with C. nitida infusion led to reversal of these biomarkers' activities and levels, while maintaining an intact morphology. The infusion caused decreased lipase activity and depletion of diabetes-generated cardiac lipid metabolites, while concomitantly generating saturated and unsaturated fatty acids, fatty esters and alcohols. There was also an inactivation of plasmalogen synthesis and mitochondrial beta-oxidation of long chain saturated fatty acids pathways in T2D rats treated with C. nitida infusion. These results indicate the therapeutic effect of C. nitida infusion against diabetic cardiomyopathy.

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.

Cola Nitida (Kola Nuts) Attenuates Hepatic Injury in Type 2 Diabetes by Improving Antioxidant and Cholinergic Dysfunctions and Dysregulated Lipid Metabolism

BACKGROUND

The therapeutic effect of Cola nitida hot infusion against diabetes hepatic injury was investigated in livers of diabetic rats. Cola nitida was infused in boiling water and concentrated.

METHODS

The concentrated infusion was administered to T2D rats at low and high doses (150 and 300 mg/kg body weight (bw), respectively). The normal group (positive control) and another diabetic group (negative control) were administered distilled water, while metformin served as the standard drug. A toxic group that consists of normal rats administered a high dose of C. nitida. After 6 weeks, the rats were sacrificed, and their livers were collected. They were assayed for oxidative stress markers, myeloperoxidase, acetylcholinesterase and ATPase activities. Hepatic lipid metabolites were profiled with GC-MS and their metabolic pathways were analyzed using the MetaboAnalyst 4.0 online server.

RESULTS

Treatment with C. nitida caused a significant elevation of glutathione level and SOD activity, while concomitantly inhibiting lipid peroxidation, myeloperoxidase, acetylcholinesterase and ATPase activities in hepatic tissues of the rats. Treatment with C. nitida also caused significant depletion of diabetes-generated lipid metabolites, with concomitant generation of fatty esters and steroids as well as inactivation of diabetes-activated pathways.

CONCLUSION

These data demonstrate the therapeutic effect of C. nitida against diabetic hepatotoxicity in diabetic rats.

Ameliorative effects of Hydrolea zeylanica in streptozotocin-induced oxidative stress and metabolic changes in diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Hydrolea zeylanica L. Vahl. (Hydroleaceae) is an aquatic medicinal plant used as leafy vegetable in some parts of India. In south Odisha and Hazaribag district of Jharkhand, India, decoction of leaves is used as household remedy for diabetes. To our knowledge, no prior studies have examined the antidiabetic activity of H. zeylanica to validate its ethnomedicinal claim.

PURPOSE

With this aim in mind, we examined the bioactivity of hydroalcohol fraction of leaves of H. zeylanica (HAHZ) in streptozotocin-induced oxidative stress in diabetic rats.

MATERIALS AND METHODS

In vitro antidiabetic and free radical scavenging activities of different fractions of H. zeylanica were performed. The most effective bioactive fraction e.g. HAHZ was considered for kinetic studies to understand the mode of inhibition of α-glucosidase and α-amylase. To understand the chemical composition, GC-MS/MS and LC-MS/MS analysis of HAHZ were performed. To find out the molecular mechanism of action of HAHZ, streptozotocin-induced oxidative stress and metabolic changes in diabetic rats were studied.

RESULTS

HAHZ demonstrated significantly higher radical scavenging and antidiabetic activities. Kinetic analysis revealed that HAHZ inhibited α-glucosidase competitively, and α-amylase mixed competitively. To understand the chemical composition, GC-MS/MS and LC-MS/MS analysis of HAHZ identified 32 compounds and among which R-limonene (0.52%), perillartine (0.41%), N-formyl-L-lysine (1.49%), limonen-6-ol, pivalate (1.43%), lidocaine (1.70%) and gamolenic acid (2.80%) were reported to have antioxidant and antidiabetic activities. HAHZ-400 mg/kg showed significant (p < 0.001) improvement in serum markers (SGOT, SGPT, ALP, total bilirubin, total protein, triglycerides, total cholesterol, HDL-C, LDL-C) and oxidative markers (MDA, SOD, CAT, GSH) in serum, liver and pancreas at effective dose dependent manner. In histopathological observation, HAHZ-400 mg/kg showed marked improvement in restoring cellular architecture of liver and pancreas.

CONCLUSION

In diabetic rats, the improvement in glycemic control mechanism was achieved upon stimulating insulin secretion by R-limonene, perillartine, N-formyl-L-lysine, limonen-6-ol, pivalate, lidocaine and gamolenic acid of HAHZ.

Comparative Antidiabetic Activity of Aqueous, Ethanol, and Methanol Leaf Extracts of Persea americana and Their Effectiveness in Type 2 Diabetic Rats

Native to Mexico, Persea americana Mill. (avocado) is a fruit tree whose different parts (leaf, bark, roots, and stone) are used in traditional medicine especially against diabetes mellitus. The aim of this study was to investigate the beneficial effects of 28-day treatment with aqueous, ethanolic, and methanolic leaf extracts on glucose homeostasis in type 2 diabetic mellitus using Wistar rats. Type 2 diabetes was induced with nicotinamide (120 mg/kg, i.p.) and streptozotocin (65 mg/kg, i.p.). After 28 days of treatment, histopathological examination of the pancreas, kidneys, liver, and muscle (tibialis anterior) were realized. Biochemical markers were determined and an intestinal absorption test of D-glucose was performed. All extracts (100 mg/kg/day, p.o.) significantly (p < 0.001) reduced blood glucose level at the 28^th day of treatment with a more pronounced effect for methanolic extract. The treatments were well tolerated and induced a restoration of T-CHOL and HDL-C levels compared to the control group. Methanolic extract reduced the AIP (atherogenic index of plasma) by 45%. Histopathological analyzes of the pancreas showed regeneration of islets of Langerhans. Methanolic extract was the most effective in preventing intestinal glucose uptake up to 60.90% in relation to metformin. These results justify the use of this plant in traditional medicine against type 2 diabetes. However, other complementary studies should be done to identify the molecules responsible for this activity and their signaling voice.