Antidiabetic potential of some less commonly used plants in traditional medicinal systems of India and Nigeria

In Vitro and Molecular Docking Evaluation of the Anticholinesterase and Antidiabetic Effects of Compounds from Terminalia macroptera Guill. & Perr. (Combretaceae)

Alzheimer's disease (AD) and diabetes are non-communicable diseases with global impacts. Inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are suitable therapies for AD, while α-amylase and α-glucosidase inhibitors are employed as antidiabetic agents. Compounds were isolated from the medicinal plant Terminalia macroptera and evaluated for their AChE, BChE, α-amylase, and α-glucosidase inhibitions. From 1H and 13C NMR data, the compounds were identified as 3,3'-di-O-methyl ellagic acid (1), 3,3',4'-tri-O-methyl ellagic acid-4-O-β-D-xylopyranoside (2), 3,3',4'-tri-O-methyl ellagic acid-4-O-β-D-glucopyranoside (3), 3,3'-di-O-methyl ellagic acid-4-O-β-D-glucopyranoside (4), myricetin-3-O-rhamnoside (5), shikimic acid (6), arjungenin (7), terminolic acid (8), 24-deoxysericoside (9), arjunglucoside I (10), and chebuloside II (11). The derivatives of ellagic acid (1-4) showed moderate to good inhibition of cholinesterases, with the most potent being 3,3'-di-O-methyl ellagic acid, with IC50 values of 46.77 ± 0.90 µg/mL and 50.48 ± 1.10 µg/mL against AChE and BChE, respectively. The compounds exhibited potential inhibition of α-amylase and α-glucosidase, especially the phenolic compounds (1-5). Myricetin-3-O-rhamnoside had the highest α-amylase inhibition with an IC50 value of 65.17 ± 0.43 µg/mL compared to acarbose with an IC50 value of 32.25 ± 0.36 µg/mL. Two compounds, 3,3'-di-O-methyl ellagic acid (IC50 = 74.18 ± 0.29 µg/mL) and myricetin-3-O-rhamnoside (IC50 = 69.02 ± 0.65 µg/mL), were more active than the standard acarbose (IC50 = 87.70 ± 0.68 µg/mL) in the α-glucosidase assay. For α-glucosidase and α-amylase, the molecular docking results for 1-11 reveal that these compounds may fit well into the binding sites of the target enzymes, establishing stable complexes with negative binding energies in the range of -4.03 to -10.20 kcalmol-1. Though not all the compounds showed binding affinities with cholinesterases, some had negative binding energies, indicating that the inhibition was thermodynamically favorable.

Therapeutic Benefit of Vernonia amygdalina in the Treatment of Diabetes and Its Associated Complications in Preclinical Studies

Diabetes mellitus (DM), a complex heterogeneous metabolic disorder characterized by a defect in the function of insulin, is on the rapid rise globally. Sustained hyperglycemia which is a major sign of DM is linked to the generation of reactive oxygen species which promotes adverse complications of the disorder. Traditional herbal treatment of DM is a common practice in Africa and other tropical parts of the world. Vernonia amygdalina (VA), one of the highly researched species in the Asteraceae family, has proven to possess potent antidiabetic properties. Several phytochemicals identified in multiple extracts from VA are purported to be responsible for the antidiabetic potential of the plant. In this review, we discuss the therapeutic potential of VA in diabetes and its associated complications. We appraise the current evidence and further suggest potential areas that could be effectively exploited in future VA research on diabetes.

The use of South African botanical species for the control of blood sugar

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus (DM) is one of the most prevalent diseases globally and is of considerable concern to global health. Approximately 425 million people are estimated to have DM globally and this is predicted to increase to >642 million by 2040. Whilst the prevalence of DM in South Africa is slightly lower than the global average, it is expected to rise rapidly in future years as more South Africans adopt a high calorie "westernised" diet. Traditional medicines offer an alternative for the development of new medicines to treat DM and the usage of South African plants is relatively well documented.

AIM OF THE STUDY

To critically review the literature on the anti-diabetic properties of South African plants and to document plant species used for the treatment of DM. Thereafter, a thorough examination of the related research will highlight where research is lacking in the field.

MATERIALS AND METHODS

A review of published ethnobotanical books, reviews and primary scientific studies was undertaken to identify plants used to treat DM in traditional South African healing systems and to identify gaps in the published research. The study was non-biased, without taxonomic preference and included both native and introduced species. To be included, species must be recorded in the pharmacopeia of at least one South African ethnic group for the treatment of DM.

RESULTS

One hundred and thirty-seven species are recorded as therapies for DM, with leaves and roots most commonly used. The activity of only 43 of these species have been verified by rigorous testing, and relatively few studies have examined the mechanism of action.

CONCLUSION

Despite relatively extensive ethnobotanical records and a diverse flora, the anti-diabetic properties of South African medicinal plants is relatively poorly explored. The efficacy of most plants used traditionally to treat DM are yet to be verified and few mechanistic studies are available. Further research is required in this field.

Acalypha Wilkesiana 'Java White': Identification of Some Bioactive Compounds by Gc-Ms and Their Effects on Key Enzymes Linked to Type 2 Diabete

In this study, we identified bioactive compounds from the ethanolic extracts of the leaves, stem bark and root bark of Acalypha wilkesiana through GC-MS analysis and investigated the effects of these extracts on some of the enzymes linked to type 2 diabetes. Plant parts were extracted sequentially with ethyl acetate, ethanol and water. GC-MS analysis revealed the presence of long-chain alkyl acids, esters, ketones and alcohols including phytol and phytol acetate along with some secondary metabolites such as xanthone, vitamin E and various types of sterols including stigmasterol, campesterol and sitosterol. Ethanolic extracts of all the parts showed a dose- -dependent inhibition of α-glucosidase and α-amylase activity. The extracts also demonstrated anti-lipase activity. The ethanolic extract of root bark showed the highest inhibition of enzymes compared to other extracts. The EC50 values (concentrations for 50 % inhibition) of α-glucosidase, α-amylase and lipase inhibition were 35.75 ± 1.95, 6.25 ± 1.05 and 101.33 ± 5.21 μg mL-1, resp. The study suggests that A. wilkesiana ethanolic extracts have the ability to inhibit the activity of enzymes linked to type 2 diabetes. Further studies are needed to confirm the responsible bioactive compounds in this regard.

An overview of anti-diabetic plants used in Gabon: Pharmacology and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed.

MATERIALS AND METHODS

Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including 'Diabetes', 'Gabon', 'Toxicity', 'Constituents', 'hyperglycaemia' were used.

RESULTS

A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver.

CONCLUSION

An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.

Ethnopharmacological values of cassava and its potential for diabetes and dyslipidemia management: Knowledge survey and critical review of report

Background:

Beyond nutritional values are the pharmacological potentials of cassava comparative with other staple carbohydrate plant-based foods such as wheat. The knowledge of applicability to diabetes and its cardiovascular complications management seems not just limited but unacknowledged. As a preliminary study, a community’s knowledge of pharmacological value of cassava is investigated.

Methods:

Descriptive observational study using questionnaire-based “cross-sectional” survey was conducted. 136 Participants completed the survey and 101 respondents were selected for evaluation. Open-ended questions were used qualitatively to generate experience and view cassava values for diabetes and dyslipidemia. While categorical (yes or no) questions were used quantitatively to generate numerical results for diabetes, critical reanalysis of a report data was performed, especially comparing carbohydrate/fiber and fat/fiber ratios of cassava with wheat in view of dyslipidemia.

Result:

On the positive side, 42% of the participants believe that cassava has medicinal values. This includes 6% (among the 42) who believes that the plant is useful in treating diabetes and 24% who do not know it may be useful in diabetes management. Critical review showed that cassava may contribute up to sixteen times more fiber and four times less digestible sugar, as well as carbohydrate/fiber and fat/fiber ratios being 14 and 55 times less than wheat.

Conclusion:

There is evidence that relative to wheat flour meal, for instance, cassava contributes less fat and much more fiber. Since fat is pro-obesity, which in turn is pro-diabetic/metabolic syndrome; and fiber is anti-dyslipidemic; cassava has pharmacological values to be appreciated over some carbohydrate plant-based foods.