Enhydrin Regulates Postprandial Hyperglycemia in Diabetic Rats by Inhibition of α-Glucosidase Activity

Effects of Smallanthus sonchifolius Flour on Metabolic Parameters: A Systematic Review

Smallanthus sonchifolius, popularly known as yacon, is a member of the Asteraceae family. Due to its medicinal and edible value, yacon is consumed by different populations. Yacon is unique due to its high fructo-oligosaccharide and inulin content, as well as flavonoids, sesquiterpene lactones, and phenolic acids. Roots can be used to produce flour, which is less perishable and can be applied in various industrial products. This systematic review focuses on the effects of yacon flour on metabolic parameters. PubMed, Cochrane, Embase, Science Direct, Scopus, Web of Science, and Google Scholar databases were consulted, and PRISMA guidelines were followed in the selection of the studies. In total, 526 articles were found in the databases, and of these, only 28 full texts were eligible for inclusion. After applying the inclusion and exclusion criteria, seven studies were finally included. The results showed that the use of yacon flour can reduce glycemia, HbA1c, advanced glycation ends, plasma lipids, body fat mass, body weight, and waist circumference and improve intestinal microbiota and the antioxidant status. Further exploration of the effects of yacon flour is warranted, and additional clinical trials are necessary to determine the optimal daily consumption levels required to assist in improving metabolic parameters.

An insight on medicinal attributes of 1,2,3- and 1,2,4-triazole derivatives as alpha-amylase and alpha-glucosidase inhibitors

Diabetes Mellitus (DM) is the globe's common leading disease which is caused by high consumption of glucose. DM compiles groups of metabolic disorders which are characterized by inadequate secretion of insulin from pancreas, resulting in hyperglycemia condition. Many enzymes play a vital role in the metabolism of carbohydrate known as α-amylase and α-glucosidase which is calcium metalloenzyme that leads to breakdown of complex polysaccharides into glucose. To tackle this problem, search for newer antidiabetic drugs is the utmost need for the treatment and/or management of increasing diabetic burden. The inhibition of α-amylase and α-glucosidase is one of the effective therapeutic approaches for the development of antidiabetic therapeutics. The exhaustive literature survey has shown the importance of medicinally privileged triazole specifically 1,2,3-triazol and 1,2,4-triazoles scaffold tethered, fused and/or clubbed with other heterocyclic rings structures as promising agents for designing and development of novel antidiabetic therapeutics. Molecular hybrids namely pyridazine-triazole, pyrazoline-triazole, benzothiazole-triazole, benzimidazole-triazole, curcumin-triazole, (bis)coumarin-triazole, acridine-9-carboxamide linked triazole, quinazolinone-triazole, xanthone-triazole, thiazolo-triazole, thiosemicarbazide-triazole, and indole clubbed-triazole are few examples which have shown promising antidiabetic activity by inhibiting α-amylase and/or α-glucosidase. The present review summarizes the structure-activity relationship (SAR), enzyme inhibitory activity including IC50 values, percentage inhibition, kinetic studies, molecular docking studies, and patents filed of the both scaffolds as alpha-amylase and alpha-glucosidase inhibitors, which may be used for further development of potent inhibitors against both enzymes.

Anti-α-Glucosidase, SAR Analysis, and Mechanism Investigation of Indolo[1,2-b]isoquinoline Derivatives

To find potential α-glucosidase inhibitors, indolo[1,2-b]isoquinoline derivatives (1-20) were screened for their α-glucosidase inhibitory effects. All derivatives presented potential α-glucosidase inhibitory effects with IC₅₀ values of 3.44 ± 0.36~41.24 ± 0.26 μM compared to the positive control acarbose (IC₅₀ value: 640.57 ± 5.13 μM). In particular, compound 11 displayed the strongest anti-α-glucosidase activity, being ~186 times stronger than acarbose. Kinetic studies found that compounds 9, 11, 13, 18, and 19 were all reversible mix-type inhibitors. The 3D fluorescence spectra and CD spectra results revealed that the interaction between compounds 9, 11, 13, 18, and 19 and α-glucosidase changed the conformational changes of α-glucosidase. Molecular docking and molecular dynamics simulation results indicated the interaction between compounds and α-glucosidase. In addition, cell cytotoxicity and drug-like properties of compound 11 were also investigated.

Quantification of Enhydrin and Uvedalin in the Ethanolic Extract of Smallanthus sonchifolius Leaves Validated by the HPLC Method

Yacon leaf (Smallanthus sonchifolius, Asteraceae) ethanolic extracts are widely used in herbal medicine preparation for diabetes. They contain two sesquiterpene lactones (enhydrin (1) and uvedalin (2)) as major bioactive compounds. To provide a suitable method of analysis for the extract's quality control, we developed and validated a simultaneous HPLC-UV method using the compounds as markers. Compounds 1 and 2 were isolated using a freeze crystallization technique followed by a preparative HPLC. Spectrometry data for 1 and 2 were determined and compared to the literature. Chromatographic separation was carried out for 30 min with a mobile phase that used 60% water and 40% acetonitrile and a C18 column (250 × 4.6 mm, 5 µm) as the stationary phase. The flow was set to 1 mL min^-1 and detection was conducted at 210 nm. The validation method was conducted according to the ICH guidelines, which included linearity, precision, accuracy, LOD, and LOQ. The calibration curve of both compounds was linear (R ² > 0.9999), with the limit of detection and quantification as follows, respectively, 0.52 and 1.57 µg/mL for 1, and 0.144 and 0.436 µg/mL for 2. The percentages of recovery and repeatability (%RSD) were, 101.46 and 0.30% for 1, and 97.68 and 0.08% for 2, respectively. The 1 and 2 were 1.67 and 0.88% in the Ykal extract, and 1.26 and 0.56% in the Ycin extract, respectively. The method was found to be linear, precise, accurate, and suitable to be applied for control quality analyses of yacon leaf extract.

New Wild-Type Lacticaseibacillus rhamnosus Strains as Candidates to Manage Type 1 Diabetes

The incidence of type 1 diabetes (T1D) has been dramatically increased in developed countries, and beyond the genetic impact, environmental factors, including diet, seem to play an important role in the onset and development of the disease. In this vein, five Lacticaseibacillus rhamnosus, isolated from traditional fermented Greek products, were screened for potential probiotic properties, aiming at maintaining gut homeostasis and antidiabetic capability to alleviate T1D symptoms. L. rhamnosus cell-free supernatants induced strong growth inhibitory activity against common food spoilage and foodborne pathogenic microorganisms, associated with several diseases, including T1D, and were also able to inhibit α-glucosidase activity (up to 44.87%), a promising property for alternatives to the antidiabetic drugs. In addition, survival rates up to 36.76% were recorded during the application of the static in vitro digestion model. The strains had no hemolytic activity and were sensitive to common antibiotics suggested by the European Food and Safety Association, apart from chloramphenicol. However, it is highly unlikely that the resistance has been acquired. In conclusion, our results suggest a great health-promoting potential of the newly isolated wild-type L. rhamnosus strains, but further confirmation of their efficiency in experimental animal models is considered an essential next research step.

Investigation of Yacon Leaves (Smallanthus sonchifolius) for α-Glucosidase Inhibitors Using Metabolomics and In Silico Approach

Yacon (Smallanthus sonchifolius (Poepp.) H. Robinson) leaves is traditionally consumed as herbal tea in many countries including Indonesia. This plant's antidiabetic properties have been extensively researched, but studies on the responsible active compound identification are scarce. Information on the active compounds is critical for the consistency of Yacon herbal tea quality. The aim of this study was to identify α-glucosidase inhibitors in Indonesian Yacon leaves grown in two different locations using FTIR- and LC-MS/MS-based metabolomics in combination with in silico technique. Yacon leaves ethanol (50 and 95%) and water extracts were tested for α-glucosidase inhibitory activity, with the 95% ethanol extract being the most active. Geographical origins were found to have no major impact on the activity. In parallel, chemical profile of Yacon leaves extract was determined using FTIR and LC-MS/MS. Orthogonal Projection to Latent Structure (OPLS) was used to analyze both sets of data. OPLS analysis of FTIR data showed that compounds associated to α-glucosidase inhibitor activity included those with functional groups -OH, stretched CH, carbonyl, and alkene. It was consistent with the result of OPLS analysis of LC-MS/MS data, which revealed that based on their VIP and Y-related coefficient value, nystose, 1-kestose, luteolin-3'-7-di-O-glucoside, and 1,3-O-dicaffeoilquinic acid isomers, strongly linked to Yacon's α-glucosidase inhibitor activity. In silico study supported these findings, revealing that the four compounds were potent α-glucosidase inhibitors with docking score in the range of - 100.216 to - 115.657 kcal/mol, which are similar to acarbose (- 115.774 kcal/mol) as a reference drug.

Thermal treatment enhances the α-glucosidase inhibitory activity of bitter melon (Momordica charantia) by increasing the free form of phenolic compounds and the contents of Maillard reaction products

Inhibition of α-glucosidase can slow carbohydrate metabolism, which is known as an effective strategy for diabetes treatment. The aim of this study is to evaluate the effect of thermal treatment (50, 60, and 70℃) for 15 days on the α-glucosidase inhibitory activity of bitter melon. The results show that the bitter melon heated at 70℃ for 12 days had the best α-glucosidase inhibitory effect. However, the amount of free polyphenols, 5-hydroxymethyl-2-furfural (5-HMF), and the browning degree of bitter melon generally increased with the time (15 days) and temperature of the thermal treatment, which is positively related to their antioxidant and α-glucosidase inhibitory activities. In conclusion, aged bitter melon shows great α-glucosidase inhibitory activity, which may be related to the increased free form of the involved phenolic compounds and Maillard reaction products. This suggests that thermal processing may be a good way to enhance the application of bitter melon for diabetes treatment. PRACTICAL APPLICATION: The thermal processing of bitter melon provides an application for diabetes treatment. This study demonstrated that heat-treated bitter melon can lower the blood glucose level; therefore, it can be used as a potential anti-hyperglycemic and functional food.

The potential role of sesquiterpene lactones isolated from medicinal plants in the treatment of the metabolic syndrome - A review

Metabolic syndrome comprises a cluster of metabolic disorders related to the development of cardiovascular disease and type 2 diabetes mellitus. In latter years, plant secondary metabolites have become of special interest because of their potential role in preventing and managing metabolic syndrome. Sesquiterpene lactones constitute a large and diverse group of biologically active compounds widely distributed in several medicinal plants used for the treatment of metabolic disorders. The structural diversity and the broad spectrum of biological activities of these compounds drew significant interests in the pharmacological applications. This review describes selected sesquiterpene lactones that have been experimentally validated for their biological activities related to risk factors of metabolic syndrome, together with their mechanisms of action. The potential beneficial effects of sesquiterpene lactones discussed in this review demonstrate that these substances represent remarkable compounds with a diversity of molecular structure and high biological activity, providing new insights into the possible role in metabolic syndrome management.

Purification, Preliminary Structural Characterization, and In Vitro Inhibitory Effect on Digestive Enzymes by β-Glucan from Qingke (Tibetan Hulless Barley)

Background and Objective. Qingke (Tibetan hulless barley, Hordeum vulgare L.) contains a high content of β-glucan among all the cereal varieties. Although β-glucan has multiple physiological functions, the physiological function of qingke β-glucan was few studied. In this study, the β-glucan was isolated, purified, determined the structural characterization, and measured the inhibitory activity to enzymes correlating blood sugar and lipid. Methods. β-Glucan was isolated from enzymatic aqueous extract of qingke by using deproteinization, decolorization, DEAE-52 column chromatography, and sepharose CL-4B agarose gel column chromatography. The structure of the β-glucan was determined using FT-IR and 13C-NMR spectra analysis, and molecular mass by use of HPSEC-dRI-LS. The kinematic viscosity was measured. The inhibitory effects of this β-glucan on four enzymes were investigated. Results. This β-glucan had a uniform molecular weight of 201,000 Da with β-(1⟶4) as the main chain and β-(1⟶3) as a side chain. The β-glucan presented a relatively strong inhibitory activity on α-glucosidase, moderate inhibition on invertase, and a weak inhibition on α-amylase, whereas it did not inhibit lipase. Conclusion. The study indicates that the enzymatic β-glucan from qingke has the potential as natural auxiliary hypoglycemic additives in functional medicine or foods.

Docking and QSAR analysis of tetracyclic oxindole derivatives as α-glucosidase inhibitors

The α-glucosidase inhibitors are considered as important agents in drug discovery against diabetes mellitus. Molecular docking and quantitative structure-activity relationship (QSAR) were performed based on a series of tetracyclic oxindole derivatives to elucidate key structural properties affecting inhibitory activity and support the design of new α-glucosidase inhibitors. The molecular docking results demonstrate that at least two hydrogen bonds between Thr681 and Arg676 residues and the oxygen atoms in amid groups have an important role in the optimum binding of inhibitors. In addition, the sum of polar contacts of Arg699, Arg670, Glu792 and Glu301 residues with the α-glucosidase inhibitors have more than one third of total binding free energy. The docked conformations of the inhibitors with the best binding free energy were used to construct QSAR models. As a primary survey and a graphical comparing tool, the partial least squares-discriminant analysis (PLS-DA) technique was successfully employed to classify active and inactive inhibitors. The validated QSAR analysis were performed through genetic algorithm-partial least squares (GA-PLS) and support vector machine (SVM) techniques. The QSAR model reveals that important features of J3D, Mor26 u and HOMA have a high predictive capability (R²_p = 0.837, Q²_LOO = 0.871, R²_LSO = 0.790 and r²_m  = 0.758) using GA-PLS/SVM strategy. Generally, the suggested QSAR analysis based on classification, docking and GA-PLS/SVM strategy may help suggest chemical scaffold to design novel oxindole derivatives as α-glucosidase inhibitors.

Evaluation of probiotic potential and anti-hyperglycemic properties of a novel Lactobacillus strain isolated from water kefir grains

A total of eight strains of lactic acid bacteria were isolated from water kefir grains and assessed for their in vitro α-glucosidase inhibitory activity. Lactobacillus mali K8 demonstrated significantly higher inhibition as compared to the other strains, thus was selected for in vitro probiotic potential characterization, antibiotic resistance, hemolytic activity and adaptation to pumpkin fruit puree. L. mali K8 demonstrated tolerance to pH 2.5 and resisted the damaging effects of bile salts, pepsin and pancreatin, comparable to that of Lactobacillus rhamnosus GG ATCC 53103 (reference strain). Lack of hemolytic activity and susceptibility to the five standard antibiotics indicated the safety of the K8 strain. This strain showed singular properties to be used as starters in the pumpkin fruit puree fermentation. These preliminary in vitro tests indicated the safety and functionality of the K8 strain and its potential as a probiotic candidate.