The effect of Gymnema sylvestre supplementation on glycemic control in type 2 diabetes patients: A systematic review and meta-analysis

Hypoglycemic effects of mountain caviar extract and inhibitory mechanism of saponins, including momordin Ic, on glucose absorption

Mountain caviar is a fruit of Kochia scoparia that contains momordin Ic as a major saponin constituent. Its extract (MCE) has been shown to suppress blood glucose elevations in the human oral glucose tolerance test (OGTT) as well as increases in blood glucose in OGTT, gastric emptying (GE), and glucose incorporation in the small intestine in rats. However, the effects of MCE and momordin Ic on glucose absorption in mice and these action mechanisms have not been examined for more than 2 decades. Therefore, we herein investigated the effects of MCE, its saponin fraction, and momordin Ic on blood glucose elevations in mice. Mouse blood glucose elevation tests were performed on carbohydrate-loaded mice. The mountain caviar saponin fraction significantly delayed blood glucose elevations in glucose-, sucrose-, and soluble starch-loaded mice. In glucose-loaded mice, the saponin fraction, MCE, and momordin Ic significantly suppressed rapid glucose elevations after glucose loading, but not sucrose loading. A mouse GE study was performed by loading with glucose and phenolphthalein solution. Momordin Ic and MCE strongly suppressed mouse GE. Intestinal glucose absorption was evaluated by the incorporation of 2-deoxyglucose (2-DG) into Caco-2 cell layers and mouse duodenum wall vesicles. The results obtained showed that momordin Ic inhibited the incorporation of 2-DG into Caco-2 cells and mouse duodenum vesicles. Collectively, these results suggest that MCE, particularly the principal saponin, momordin Ic, preferably suppressed glucose-induced blood glucose elevations and delayed carbohydrate-induced glucose elevations in mice. The underlying mechanism was found to involve the suppression of GE and intestinal glucose absorption.

Novel gurmarin-like peptides from Gymnema sylvestre and their interactions with the sweet taste receptor T1R2/T1R3

Gymnema sylvestre (GS) is a traditional medicinal plant known for its hypoglycemic and hypolipidemic effects. Gurmarin (hereafter Gur-1) is the only known active peptide in GS. Gur-1 has a suppressive sweet taste effect in rodents but no or only a very weak effect in humans. Here, 8 gurmarin-like peptides (Gur-2 to Gur-9) and their isoforms are reported in the GS transcriptome. The molecular mechanism of sweet taste suppression by Gur-1 is still largely unknown. Therefore, the complete architecture of human and mouse sweet taste receptors T1R2/T1R3 and their interaction with Gur-1 to Gur-9 were predicted by AlphaFold-Multimer (AF-M) and validated. Only Gur-1 and Gur-2 interact with the T1R2/T1R3 receptor. Indeed, Gur-1 and Gur-2 bind to the region of the cysteine-rich domain (CRD) and the transmembrane domain (TMD) of the mouse T1R2 subunit. In contrast, only Gur-2 binds to the TMD of the human T1R2 subunit. This result suggests that Gur-2 may have a suppressive sweet taste effect in humans. Furthermore, AF-M predicted that Gα-gustducin, a protein involved in sweet taste transduction, interacts with the intracellular domain of the T1R2 subunit. These results highlight an unexpected diversity of gurmarin-like peptides in GS and provide the complete predicted architecture of the human and mouse sweet taste receptor with the putative binding sites of Gur-1, Gur-2, and Gα-gustducin. In addition, gurmarin-like peptides may serve as promising drug scaffolds for the development of antidiabetic molecules.

Combined Inositols, α-Lactalbumin, Gymnema Sylvestre and Zinc Improve the Lipid Metabolic Profile of Patients with Type 2 Diabetes Mellitus: A Randomized Clinical Trial

Type 2 diabetes mellitus (T2DM) is characterized by high blood glucose levels and lipid alterations. Besides pharmacological treatment, lifestyle modifications and nutraceuticals can be used to manage glucose and lipid profiles, which is crucial for preventing, or avoiding, serious consequences associated with the condition. This randomized controlled clinical trial on 75 patients with T2DM evaluated the effects of a combination of myo-inositol and d-chiro-inositol (40:1), α-lactalbumin, Gymnema sylvestre, and zinc on glucose and lipid profile. The intention-to-treat analysis displayed no significant differences in glucose parameters between the groups; however, the study group displayed reduced levels of total cholesterol (p = 0.01) and LDL (p = 0.03) after 3 months of supplementation. A subgroup analysis involving patients who did not modify their antidiabetic therapy, after 6 months displayed improved levels of total cholesterol (p = 0.03) and LDL (p = 0.04) in the study group versus placebo, along with a greater body weight reduction (p = 0.03) after 3 months. Furthermore, within the study group, levels of HDL (p = 0.03) and triglycerides (p = 0.04) improved after 3 months. These findings support supplementation with myo-inositol and d-chiro-inositol (40:1), α-lactalbumin, Gymnema sylvestre, and zinc as an adjuvant and safe strategy to manage the lipid profiles of patients with T2DM.

Diet Plus Inositols, α-Lactalbumin and Gymnema sylvestre: The Successful Combo to Restore Body Weight and Metabolic Profile in Obese and Dysmetabolic Patients

The primary control of dysmetabolic patients is extremely challenging worldwide, with inadequate dietary habits and sporadic physical activity among the key risk factors for metabolic syndrome onset. Nowadays, there is no exclusive treatment for this condition, and considering that preventive measures usually fail, new therapeutic approaches need to be proposed and investigated. This present pilot study compared the effects of diet alone and in association with a combination of myo-inositol and d-chiro-inositol in their 40:1 ratio, α-lactalbumin, and Gymnema sylvestre on different metabolic parameters in obese dysmetabolic patients. To this purpose, 37 patients with BMI between 30 and 40 and fasting blood glucose between 100 and 125 mg/dL were divided into two groups: (i) the control group followed a hypocaloric Mediterranean diet, (ii) while the study group was also supplemented with a daily dosage of two sachets, each one containing 1950 mg myo-inositol, 50 mg d-chiro-inositol, 50 mg α-lactalbumin, and 250 mg Gymnema Sylvestre. After a 6-month treatment, all parameters improved in both groups. Nevertheless, the treated group experienced a greater improvement, especially concerning the variation from the baseline of HOMA index, triglycerides, BMI, body weight, and waist circumference. These findings support the supplementation with myo-inositol and d-chiro-inositol in the 40:1 ratio, α-lactalbumin, and Gymnema sylvestre as a therapeutical strategy to potentiate the beneficial effects induced via dietary programs in dysmetabolic patients.

Biotechnological approaches for the production of gymnemic acid from Gymnema sylvestre R. Br

Diabetes is a chronic disease that affects several organs and can be treated using phytochemicals found in medicinal plants. Gymnema sylvestre (Asclepiadaceae) is one such medicinal plant rich in anti-diabetic properties. The plant is commonly known as madhunashini in Sanskrit because of its ability to cure diabetes (sugar). Gymnemic acid (GA) is a phytochemical (a triterpenoid saponin) responsible for the herb's main pharmacological activity. This secondary metabolite has a lot of potential as a phytochemical with pharmacological properties including nephroprotection, hypoglycemia, antioxidant, antimicrobial, and anti-inflammatory. Gymnema has acquired a lot of popularity in recent years due to its low side effects and high efficacy in healing diabetes, which has led to overexploitation by pharmaceutical enterprises for its biomass in the wild for the purification of gymnemic acid. Modern biotechnological techniques involving the establishment of cell and organ cultures from G. sylvestre will assist us in fulfilling the need for gymnemic acid production. The present review provides insights on the establishment of cell and organ cultures for the production of a potent antidiabetic molecule gymnemic acid. Further, the review also delves into the intricacies of the different strategies for improved production of gymnemic acid using various elicitors. There is huge potential for sustainable production of gymnemic acid which could be met by establishment of bioreactor scale production. Understanding and engineering the biosynthetic pathway could also lead to improved GA production. KEY POINTS: • Gymnemic acid is one of the potential anti-diabetic molecules from madhunashini • Cell and organ culture offers potential approach for gymnemic acid production • Elicitation strategies have improved the gymnemic acid production.

The effects of Gymnema Sylvestre supplementation on lipid profile, glycemic control, blood pressure, and anthropometric indices in adults: A systematic review and meta-analysis

There is a growing interest in the considerable health benefits of Gymnema Sylvestre (GS) supplementation, as some studies have reported that it may improve cardiometabolic risk factors. However, the widespread impact of GS supplementation on the parameters mentioned above is not fully resolved. Consequently, this study aimed to examine the effects of GS supplementation on lipid profile, glycemic control, blood pressure, and anthropometric indices in adults. Eligible randomized controlled trials (RCT), published up to November 2021, were identified through PubMed, Scopus, and ISI Web of Science databases. Six studies were included and analyzed using a random-effects model to calculate weighted mean differences (WMDs) with 95% confidence intervals (CI). All studies were conducted in adults that used a GC supplement (>1 week) and assessed our selected cardiovascular risk factors. Outcomes revealed that GS supplementation significantly decreased triglyceride (p < .001), total cholesterol (p < .001), low-density lipoprotein (p < .001), fasting blood sugar (p < .001), and diastolic blood pressure (p = .003). Some limitations, including notable heterogeneity, low quality of studies, and lack of diversity among research participants, should be considered when interpreting our results. Our outcomes suggest that GS supplementation may improve cardiovascular risk factors. Future large-high-quality RCTs with longer duration and various populations are needed to firmly establish the clinical efficacy of the plant.

The effects of dietary supplements and natural products targeting glucose levels: an overview

Identifying effective dietary supplements and medicinal herbs has attracted the attention of clinicians and researchers to complement the standard treatment in controlling diabetes mellitus. In the present overview, we aimed to collect studies with the highest level of evidence to shed light on detecting the most effective dietary supplements and medicinal herbs for controlling glycemic status. For the current overview, four electronic databases, including PubMed, Scopus, Web of Science, and Cochrane Library, were systematically searched from inception to 31 December 2020 and then updated until 1 October 2021 to obtain eligible meta-analyses on either dietary supplements or medicinal herbs and their effects on glycemic status. Fasting blood sugar (FBS) and Hemoglobin A1C (HbA1C) were considered as primary outcomes. Finally, ninety-one meta-analyses on dietary supplements (n = 55) and herbs (n = 36) were included. Evidence showed positive effects of chromium, zinc, propolis, aloe vera, milk thistle, fenugreek, cinnamon, ginger, and nettle on FBS and/or HbA1C. However, mostly the heterogeneity (I2) was high. Other supplements and herbs also showed no reduction in glucose levels or their effects were small. Although some dietary supplements and medicinal herbs showed a significant reduction in FBS and/or HbA1C, mostly their effects from the clinical point of view were not remarkable. In addition, due to high heterogeneity, publication bias, and a limited number of included studies in most cases further clinical trials are needed for making decision on anti-diabetic supplement efficacy.