A Synergistic Formulation of Plant Extracts Decreases Postprandial Glucose and Insulin Peaks: Results from Two Randomized, Controlled, Cross-Over Studies Using Real-World Meals

A comprehensive in-vitro/in-vivo screening toolbox for the elucidation of glucose homeostasis modulating properties of plant extracts (from roots) and its bioactives

Plant extracts are increasingly recognized for their potential in modulating (postprandial) blood glucose levels. In this context, root extracts are of particular interest due to their high concentrations and often unique spectrum of plant bioactives. To identify new plant species with potential glucose-lowering activity, simple and robust methodologies are often required. For this narrative review, literature was sourced from scientific databases (primarily PubMed) in the period from June 2022 to January 2024. The regulatory targets of glucose homeostasis that could be modulated by bioactive plant compounds were used as search terms, either alone or in combination with the keyword "root extract". As a result, we present a comprehensive methodological toolbox for studying the glucose homeostasis modulating properties of plant extracts and its constituents. The described assays encompass in-vitro investigations involving enzyme inhibition (α-amylase, α-glucosidase, dipeptidyl peptidase 4), assessment of sodium-dependent glucose transporter 1 activity, and evaluation of glucose transporter 4 translocation. Furthermore, we describe a patch-clamp technique to assess the impact of extracts on KATP channels. While validating in-vitro findings in living organisms is imperative, we introduce two screenable in-vivo models (the hen's egg test and Drosophila melanogaster). Given that evaluation of the bioactivity of plant extracts in rodents and humans represents the current gold standard, we include approaches addressing this aspect. In summary, this review offers a systematic guide for screening plant extracts regarding their influence on key regulatory elements of glucose homeostasis, culminating in the assessment of their potential efficacy in-vivo. Moreover, application of the presented toolbox might contribute to further close the knowledge gap on the precise mechanisms of action of plant-derived compounds.

Could Natural Products Help in the Control of Obesity? Current Insights and Future Perspectives

Obesity is a global issue faced by many individuals worldwide. However, no drug has a pronounced effect with few side effects. Green tea, a well-known natural product, shows preventive effects against obesity by decreasing lipogenesis and increasing fat oxidation and antioxidant capacity. In contrast, other natural products are known to contribute to obesity. Relevant articles published on the therapeutic effect of natural products on obesity were retrieved from PubMed, Web of Science, and Scopus. The search was conducted by entering keywords such as "obesity", "natural product", and "clinical trial". The natural products were classified as single compounds, foods, teas, fruits, herbal medicines-single extract, herbal medicines-decoction, and herbal medicines-external preparation. Then, the mechanisms of these medicines were organized into lipid metabolism, anti-inflammation, antioxidation, appetite loss, and thermogenesis. This review aimed to assess the efficacy and mechanisms of effective natural products in managing obesity. Several clinical studies reported that natural products showed antiobesity effects, including Coffea arabica (coffee), Camellia sinensis (green tea), Caulerpa racemosa (green algae), Allium sativum (garlic), combined Ephedra intermedia Schrenk, Thea sinensis L., and Atractylodes lancea DC extract (known as Gambisan), Ephedra sinica Stapf, Angelica Gigantis Radix, Atractylodis Rhizoma Alba, Coicis semen, Cinnamomi cortex, Paeoniae radix alba, and Glycyrrhiza uralensis (known as Euiiyin-tang formula). Further studies are expected to refine the pharmacological effects of natural products for clinical use.

Inhibitory Potential of α-Amylase, α-Glucosidase, and Pancreatic Lipase by a Formulation of Five Plant Extracts: TOTUM-63

Controlling post-prandial hyperglycemia and hyperlipidemia, particularly by regulating the activity of digestive enzymes, allows managing type 2 diabetes and obesity. The aim of this study was to assess the effects of TOTUM-63, a formulation of five plant extracts (Olea europaea L., Cynara scolymus L., Chrysanthellum indicum subsp. afroamericanum B.L.Turner, Vaccinium myrtillus L., and Piper nigrum L.), on enzymes involved in carbohydrate and lipid absorption. First, in vitro inhibition assays were performed by targeting three enzymes: α-glucosidase, α-amylase, and lipase. Then, kinetic studies and binding affinity determinations by fluorescence spectrum changes and microscale thermophoresis were performed. The in vitro assays showed that TOTUM-63 inhibited all three digestive enzymes, particularly α-glucosidase (IC50 of 13.1 µg/mL). Mechanistic studies on α-glucosidase inhibition by TOTUM-63 and molecular interaction experiments indicated a mixed (full) inhibition mechanism, and higher affinity for α-glucosidase than acarbose, the reference α-glucosidase inhibitor. Lastly, in vivo data using leptin receptor-deficient (db/db) mice, a model of obesity and type 2 diabetes, indicated that TOTUM-63 might prevent the increase in fasting glycemia and glycated hemoglobin (HbA1c) levels over time, compared with the untreated group. These results show that TOTUM-63 is a promising new approach for type 2 diabetes management via α-glucosidase inhibition.

Comparison of Glycemic Response to Carbohydrate Meals without or with a Plant-Based Formula of Kidney Bean Extract, White Mulberry Leaf Extract, and Green Coffee Extract in Individuals with Abdominal Obesity

Due to the rising prevalence of obesity and type 2 diabetes, a strategy that can positively influence diet quality in a simple way is being explored, since a low glycemic index (GI) diet is advised in the dietoprophylaxis and diet therapy of diabetes. Methods: Twenty-three women with abdominal obesity participated in the study. The postprandial glycemic response and glycemic index were determined after three carbohydrate meals (noodle soup, white rice, strawberry sorbet) without or with the addition of a plant-base supplement (extracts of kidney bean, white mulberry leaf, and green coffee) with a potentially hypoglycemic effect. For two products (instant noodle soup and white rice), the addition of the plant supplement resulted in a reduction in glicemic iAUC values (respectively, by: 17.1%, p = 0.005 and 5.3%; p = 0.03; 40.6%, p = 0.004 and 5.3%, p = 0.019). However, this effect was not observed for strawberry sorbet. The blood glucose concentrations 30 min after the consumption of instant noodle soup and white rice with the plant-based formula addition significantly affected the GI value of tested meals (p = 0.0086, r = 0.53; p = 0.0096, r = 0.53), which may indicate the effect of this plant supplement on enterohormone and/or insulin secretion. Conclusion: A formula containing kidney bean, white mulberry leaves, and green coffee extracts may therefore be a notable factor in lowering postprandial glycemia and the GI of carbohydrate foods. However, further research is needed to determine for which food groups and meals its use may be most effective.

Breakfast Skipping among a Multi-Ethnic Population of Young Men and Relationship with Sociodemographic Determinants and Weight Status

Breakfast skipping is linked with obesity incidence. This study was conducted to assess the prevalence of breakfast skipping among a multi-ethnic population of young men residing in Saudi Arabia and its relationship with sociodemographic determinants and weight status. A total of 3600 young men aged 20 to 35 years and living in Riyadh, Saudi Arabia, were involved in this cross-sectional study. Sociodemographic determinants and breakfast-consumption frequency were collected from subjects by personal interviews. This study defines breakfast skipping as skipping breakfast at least one day per week. Weight and height were measured following standardized methods. The prevalence of breakfast skipping was observed among 52.8% of the study subjects. Nationality was a predictor of breakfast skipping, with the lowest and highest rates of breakfast skipping reported among young men from Bangladesh (14.0%) and Saudi Arabia (86.5%), respectively. Weight status was another predictor of breakfast skipping, as the mean body mass index for breakfast skippers (25.4 kg/m2) was significantly (p-value < 0.001) higher than that for breakfast consumers (24.8 kg/m2). Overweight/obese subjects have a significantly higher rate of breakfast skipping (56.9%) than underweight/normal weight subjects (48.9%). In conclusion, breakfast skipping prevalence is relatively high among young men residing in Saudi Arabia. The findings confirm a relationship between breakfast skipping and sociodemographic determinants and weight status.

Breakfast Skipping in a Multi-Ethnic Population of Middle-Aged Men and Relationship With Sociodemographic Variables and Weight Status

Background

Breakfast eating is regarded to be necessary for maintaining a healthy body weight. On the other hand, breakfast skipping has been linked with obesity incidence. This study was carried out to determine the prevalence of breakfast skipping among a multi-ethnic group of middle-aged men living in Saudi Arabia and the association between breakfast skipping and sociodemographic variables and weight status.

Methods

This cross-sectional study included 1,800 middle-aged men aged 36–59 years. Participants' sociodemographic information and frequency of breakfast eating were obtained through personal interviews. The body mass index was determined after measuring body weight and height using standardized methods.

Results

The prevalence of breakfast skipping was 42.1% of the study participants. Nationality was a predictor of breakfast skipping. Bangladeshi participants (N = 100) have the lowest rate of breakfast skipping (9.0%), whilst Saudi participants (N = 161) have the highest rate (73.3%). Weight status was another predictor of breakfast skipping as breakfast skippers had a significantly higher average body mass index (27.1 ± 3.8) than breakfast consumers (26.2 ± 3.5). Overweight/obese participants have a significantly higher breakfast skipping rate (44.9%) than participants with underweight/normal weight (36.6%).

Conclusion

The rate of breakfast skipping is relatively high among middle-aged men living in Saudi Arabia. The data support a link between breakfast skipping and sociodemographic variables and weight status.

Green coffee: economic relevance and a systematic review of the effects on human health

Coffee is probably the most popular beverage after water and is an important component in diet and health since its consumption is high worldwide. Globally, it is the most relevant food commodity being just behind crude oil. Besides its pleasant flavor, it is an antioxidant source due to polyphenols, which are protective compounds against several diseases. This study aimed to evaluate the economic relevance and perform a systematic review of green coffee's effects on human health. Databases such as MEDLINE-PubMed, EMBASE, COCHRANE, and GOOGLE SCHOLAR were searched, and PRISMA guidelines were followed. Green coffee is considered a novel food product because consumers usually consume only roasted coffee. It can be marketed as such or as an extract. Due to the content of bioactive compounds, which are partially lost during the roasting process, the extracts are usually marketed concerning the potential regarding health effects. Green coffee can be used as dietary supplements, cosmetics, and pharmaceuticals, as a source of antioxidants. It can benefit human health, such as improvement in blood pressure, plasma lipids, and body weight (thus contributing to the improvement of risk components of Metabolic Syndrome). Moreover, benefits for cognitive functions may also be included.

Skipping breakfast is associated with overweight and obesity: A systematic review and meta-analysis

OBJECTIVE

In recent years, many original studies have shown that skipping breakfast has been associated with overweight and obesity; however, the results of different studies are inconsistent. Therefore, we conducted a systematic review and meta-analysis of observational studies to synthesize the associations between skipping breakfast and the risk of overweight/ obesity.

METHODS

We did a systematic search using Pubmed, and Ovid searched up to August 2019. Observational studies (cohort studies and cross-sectional studies) reporting adjusted Odds Ratio or Risk Ratio estimates for the association between breakfast skipping and overweight/obesity (including abdominal obesity). Summary odds ratio (or Risk Ratio) and 95% confidence intervals calculated with a random-effects model.

RESULTS

45 observational studies (36 cross-sectional studies and 9 cohort studies) were included in this meta-analysis. In cross-sectional studies, The ORs of low frequency breakfast intake per week versus high frequency were 1.48 (95% CI 1.40-1.57; I²=54.0%; P=0.002) for overweight/obesity, 1.31 (95% CI 1.17-1.47; I²=43.0%; P=0.15) for abdominal obesity. In cohort studies, The RR of low-frequency breakfast intake per week versus high frequency was 1.44 (95% CI 1.25-1.66; I²=61%; P=0.009) for overweight/obesity.

CONCLUSIONS

This meta-analysis confirmed that skipping breakfast is associated with overweight/obesity, and skipping breakfast increases the risk of overweight/obesity. The results of cohort studies and cross-sectional studies are consistent. There is no significant difference in these results among different ages, gender, regions, and economic conditions.

Guava (Psidium guajava) Fruit Extract Prepared by Supercritical CO2 Extraction Inhibits Intestinal Glucose Resorption in a Double-Blind, Randomized Clinical Study

Inhibition of intestinal glucose resorption can serve as an effective strategy for the prevention of an increase in blood glucose levels. We have recently shown that various extracts prepared from guava (Psidium guajava) inhibit sodium-dependent glucose cotransporter 1 (SGLT1)- and glucose transporter 2 (GLUT2)-mediated glucose transport in vitro (Caco-2 cells) and in vivo (C57BL/6N mice). However, the efficacy in humans remains to be confirmed. For this purpose, we conducted a parallelized, randomized clinical study with young healthy adults. Thirty-one volunteers performed an oral glucose tolerance test (OGTT) in which the control group received a glucose solution and the intervention group received a glucose solution containing a guava fruit extract prepared by supercritical CO₂ extraction. The exact same extract was used for our previous in vitro and in vivo experiments. Blood samples were collected prior to and up to two hours after glucose consumption to quantitate blood glucose and insulin levels. Our results show that, in comparison to the control group, consumption of guava fruit extract resulted in a significantly reduced increase in postprandial glucose response over the basal fasting plasma glucose levels after 30 min (Δ control 2.60 ± 1.09 mmol/L versus Δ intervention 1.96 ± 0.96 mmol/L; p = 0.039) and 90 min (Δ control 0.44 ± 0.74 mmol/L versus Δ intervention -0.18 ± 0.88 mmol/L; p = 0.023). In addition, we observed a slightly reduced, but non-significant insulin secretion (Δ control 353.82 ± 183.31 pmol/L versus Δ intervention 288.43 ± 126.19 pmol/L, p = 0.302). Interestingly, storage time and repeated freeze-thawing operations appeared to negatively influence the efficacy of the applied extract. Several analytical methods (HPLC-MS, GC-MS, and NMR) were applied to identify putative bioactive compounds in the CO₂ extract used. We could assign several substances at relevant concentrations including kojic acid (0.33 mg/mL) and 5-hydroxymethylfurfural (2.76 mg/mL). Taken together, this clinical trial and previous in vitro and in vivo experiments confirm the efficacy of our guava fruit extract in inhibiting intestinal glucose resorption, possibly in combination with reduced insulin secretion. Based on these findings, the development of food supplements or functional foods containing this extract appears promising for patients with diabetes and for the prevention of insulin resistance. Trial registration: 415-E/2319/15-2018 (Ethics Commissions of Salzburg).

Antioxidant activity, α-glucosidase inhibition and phytochemical profiling of Hyophorbe lagenicaulis leaf extracts

Background

Diabetes mellitus type II (DMT-2) is a widely spread metabolic disorder both in developed and developing countries. The role of oxidative stress is well established in DMT-2 pathogenesis. The synthetic drugs for DMT-2 are associated with serious side complications. Antioxidant and α-glucosidase inhibitory actions of phytochemicals from various plant species are considered as an alternative to synthetic drugs for DMT-2 management. The present study aimed to evaluate the antioxidant activity, α-glucosidase inhibitory potential and phytochemical profiling of Hyophorbe lagenicaulis.

Methods

The total phenolic and flavonoid contents, in vitro antioxidant activity (α, α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging and phosphomolybdenum method) and α-glucosidase inhibition of ultrasonicated hydroethanolic H. lagenicaulis leaf extracts were determined spectrophotometrically. The results of DPPH assay and α-glucosidase inhibition were reported in terms of IC₅₀ value. The phytochemical profiling was accomplished by UHPLC-Q-TOF/MS/MS technique.

Results and Discussion

Findings leaped 60% ethanolic extract as rich fraction regarding total phenolic and flavonoid contents. The 60% ethanolic fraction was a promising source of natural antioxidants and α-glucosidase inhibitory agents as indicated by anti-radical and enzyme inibitory activities. Kaempferol, rutin, hesperetin 5-O-glucoside, kaempferol-coumaroyl-glucoside, luteolin 3-glucoside, Isorhamnetin-3-O-rutinoside, trimethoxyflavone derivatives and citric acid were identified by UHPLC-Q-TOF-MS/MS. These compounds were believed to be responsible for the strong antioxidant and enzyme inhibitory activity of plant extracts. The extensive metabolite profiling of H. lagenicaulis was carried out the first time as never reported previously. The H. lagenicaulis might be an appropriate choice to manage diabetes mellitus in an alternate way. The findings may be further exploited extensively for toxicity evaluation to proceed with functional food development having antidiabetic attributes.