Therapeutic potential of α-glucosidase inhibitors in type 2 diabetes mellitus: an evidence-based review

Relationships among Postprandial Plasma Active GLP-1 and GIP Excursions, Skeletal Muscle Mass, and Body Fat Mass in Patients with Type 2 Diabetes Treated with Either Miglitol, Sitagliptin, or Their Combination: A Secondary Analysis of the MASTER Study

BACKGROUND

We previously conducted a pilot randomized controlled trial "the MASTER study" and demonstrated that alpha-glucosidase inhibitor miglitol and a dipeptidyl peptidase-4 inhibitor sitagliptin modified postprandial plasma excursions of active glucagon-like peptide-1 (aGLP-1) and active gastric inhibitory polypeptide (aGIP), and miglitol treatment decreased body fat mass in patients with type 2 diabetes (T2D). However, the details regarding the relationships among postprandial plasma aGLP-1 and aGIP excursions, skeletal muscle mass, and body fat mass are unclear.

METHODS

We conducted a secondary analysis of the relationships among skeletal muscle mass index (SMI), total body fat mass index (TBFMI), and the incremental area under the curves (iAUC) of plasma aGLP-1 and aGIP excursions following mixed meal ingestion at baseline and after 24-week add-on treatment with either miglitol alone, sitagliptin alone, or their combination in T2D patients.

RESULTS

SMI was not changed after the 24-week treatment with miglitol and/or sitagliptin. TBFMI was reduced and the rates of aGIP-iAUC change were lowered in the two groups treated with miglitol, although their correlations did not reach statistical significance. We observed a positive correlation between the rates of aGIP-iAUC and TBFMI changes and a negative correlation between the rates of TBFMI and SMI changes in T2D patients treated with sitagliptin alone whose rates of aGIP-iAUC change were elevated.

CONCLUSIONS

Collectively, although T2D patients treated with miglitol and/or sitagliptin did not show altered SMI after 24-week treatment, the current study suggests that there are possible interrelationships among postprandial plasma aGIP excursion modified by sitagliptin, skeletal muscle mass, and body fat mass.

Synthesis and structure-activity relationship studies of benzimidazole-thioquinoline derivatives as α-glucosidase inhibitors

In this article, different s-substituted benzimidazole-thioquinoline derivatives were designed, synthesized, and evaluated for their possible α-glucosidase inhibitory activities. The most active compound in this series, 6j (X = 4-bromobenzyl) exhibited significant potency with an IC₅₀ value of 28.0 ± 0.6 µM compared to acarbose as the positive control with an IC₅₀ value of 750.0 µM. The kinetic study showed a competitive inhibition pattern against α-glucosidase for the 6j derivative. Also, the molecular dynamic simulations were performed to determine key interactions between compounds and the targeted enzyme. The in silico pharmacodynamics and ADMET properties were executed to illustrate the druggability of the novel derivatives. In general, it can be concluded that these derivatives can serve as promising leads to the design of potential α-glucosidase inhibitors.

Survey of Edible Amanita in Northern Thailand and Their Nutritional Value, Total Phenolic Content, Antioxidant and α-Glucosidase Inhibitory Activities

Edible wild mushrooms are extremely popular among consumers and are highly valued for their potential economic benefits in northern Thailand. In this present study, a total of 19 specimens of edible Amanita were collected during investigations of wild edible mushrooms in northern Thailand during the period from 2019 to 2022. Their morphological characteristics and the phylogenetic analyses of the internal transcribed spacer (ITS) and partial large subunit (nrLSU) of ribosomal RNA, RNA polymerase II second-largest subunit (rpb2) and partial translation elongation factor 1-alpha (tef-1) indicated that the collected specimens belonged to A. hemibapha, A. pseudoprinceps, A. rubromarginata, A. subhemibapha, and Amanita section Caesareae. This is the first report of A. pseudoprinceps and A. subhemibapha from Thailand. Full descriptions, illustrations and a phylogenetic placement of all specimens collected in this study are provided. Subsequently, the nutritional composition and total phenolic content, as well as the antioxidant and α-glucosidase inhibitory activities, of each species were investigated. The results indicate that the protein contents in both A. pseudoprinceps and A. subhemibapha were significantly higher than in A. hemibapha and A. rubromarginata. The highest total phenolic content was found in the extract of A. pseudoprinceps. In terms of antioxidant properties, the extract of A. pseudoprinceps also exhibited significantly high antioxidant activity by 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. However, the extract of A. rubromarginata had the lowest total phenolic content and level of antioxidant activity. Additionally, α-glucosidase inhibitory activity varied for different Amanita species and the highest level of α-glucosidase inhibitory activity was found in the extract of A. pseudoprinceps. This study provides valuable information on the nutrient content, phenolic content and the antioxidant and α-glucosidase inhibitory potential of edible Amanita species found in northern Thailand.

Synthesis and biological evaluation of 2,5-disubstituted furan derivatives containing 1,3-thiazole moiety as potential α-glucosidase inhibitors

α-Glucosidase, which is involved in the hydrolysis of carbohydrates to glucose and directly mediates blood glucose elevation, is a crucial therapeutic target for type 2 diabetes. In this work, 2,5-disubstituted furan derivatives containing 1,3-thiazole-2-amino or 1,3-thiazole-2-thiol moiety (III-01 ∼ III-30) were synthesized and screened for their inhibitory activity against α-glucosidase. α-Glucosidase inhibition assay demonstrated that all compounds had IC₅₀ in the range of 0.645-94.033 μM and more potent than standard inhibitor acarbose (IC₅₀ = 452.243 ± 54.142 µM). The most promising inhibitors of the two series were compound III-10 (IC₅₀ = 4.120 ± 0.764 μM) and III-24 (IC₅₀ = 0.645 ± 0.052 μM), respectively. Kinetic study and molecular docking simulation revealed that compound III-10 (Ki = 2.04 ± 0.72 μM) is a competitive inhibitor and III-24 (Ki = 0.44 ± 0.53 μM) is a noncompetitive inhibitor against α-glucosidase. Significantly, these two compounds showed nontoxicity towards HEK293, RAW264.7 and HepG2 cells, suggesting that compounds may be considered as a class of potential candidates for further developing novel antidiabetic drugs.

Characterization of Antioxidant and α-Glucosidase Inhibitory Compounds of Cratoxylum formosum ssp. pruniflorum and Optimization of Extraction Condition

Cratoxylum formosum ssp. pruniflorum (Kurz.) Gogel (Guttiferae), called kuding tea, is widely distributed in Southeast Asia. In this study, the constituents and biological activity of C. formosum ssp. pruniflorum were investigated. Extract of its leaves, roots and stems showed antioxidant and α-glucosidase inhibitory activity. Interestingly, comparison of the metabolite profiles of leaves, roots and stems of C. formosum ssp. pruniflorum by LC-MS analysis showed a great difference between the roots and leaves, whereas the roots and stems were quite similar. Purification of the roots and leaves of C. formosum ssp. pruniflorum through various chromatographic techniques resulted in the isolation of 25 compounds. The structures of isolated compounds were elucidated on the basis of spectroscopic analysis as 18 xanthones, 5 flavonoids, a benzophenone and a phenolic compound. Among them, a xanthone (16) and a benzophenone (19) were first reported from nature. Evaluation of biological activity revealed that xanthones had a potent α-glucosidase inhibitory activity, while flavonoids were responsible for the antioxidant activity. To maximize the biological activity, yield and total phenolic content of C. formosum ssp. pruniflorum, extraction conditions such as extraction solvent, time and temperature were optimized using response surface methodology with Box-Behnken Design (BBD). Regression analysis showed a good fit of the experimental data, and the optimal condition was obtained as MeOH concentration in EtOAc, 88.1%; extraction time, 6.02 h; and extraction temperature 60.0 °C. α-Glucosidase inhibitory activity, yield and total phenolic content under the optimal condition were found to be 72.2% inhibition, 10.3% and 163.9 mg GAE/g extract, respectively. These results provide useful information about C. formosum ssp. pruniflorum as functional foods for oxidative stress-related metabolic diseases.

Comparison of the Activity of Fecal Enzymes and Concentration of SCFA in Healthy and Overweight Children

In modern societies obesity has become a serious issue which must be urgently addressed. The health implications of neglected obesity are substantial, as not only does it affect individuals' everyday lives, but it also leads to significantly increased mortality due to the development of several disorders such as type-2 diabetes, cardiovascular diseases, cancers, and depression. The objective of this research was to investigate the alterations in selected health markers caused by overweight and obesity in children. The measured parameters were the activity of the fecal enzymes, the concentration of short-chain fatty acids (SCFAs), and the concentration of branched-chain fatty acids (BCFAs). The activity of the fecal enzymes, specifically α-glucosidase, α-galactosidase, β-glucosidase, β-galactosidase, and β-glucuronidase, was determined using spectrophotometry at a wavelength of 400 nm. Furthermore, concentrations of lactic acid, SCFAs (formic, acetic, propionic, butyric, and valeric acids), and BCFAs (isobutyric and isovaleric acids) were determined using the HPLC method. The obtained results reveal that obese children have different fecal enzyme activity and a different profile of fatty acids from children of normal weight. The group of obese children, when compared to children of normal weight, had increased concentrations of BCFAs (p < 0.05) and higher activity of potentially harmful enzymes such as β-glucosidase and β-glucuronidase (p < 0.05). In comparison, children of normal weight exhibited significantly increased concentrations of lactic acid and SCFAs (especially formic and butyric acids) (p < 0.05). Furthermore, their α-glucosidase and α-galactosidase activity were higher when compared to the group of obese children (p < 0.05). These results suggest that the prevalence of obesity has a significant impact on metabolites produced in the gastrointestinal tract, which might result in a higher chance of developing serious diseases.

New benzimidazole-oxadiazole derivatives: Synthesis, α-glucosidase, α-amylase activity, and molecular modeling studies as potential antidiabetic agents

Benzimidazole-1,3,4-oxadiazole derivatives (5a-z) were synthesized and characterized with different spectroscopic techniques such as ¹ H NMR, ¹³ C NMR, and HRMS. The synthesized analogs were examined against α-glucosidase and α-amylase enzymes to determine their antidiabetic potential. Compounds 5g and 5q showed the most activity with 35.04 ± 1.28 and 47.60 ± 2.16 µg/mL when compared with the reference drug acarbose (IC₅₀  = 54.63 ± 1.95 µg/mL). Compounds 5g, 5o, 5s, and 5x were screened against the α-amylase enzyme and were found to show excellent potential, with IC₅₀ values ranging from 22.39 ± 1.40 to 32.07 ± 1.55 µg/mL, when compared with the standard acarbose (IC₅₀  = 46.21 ± 1.49 µg/mL). The antioxidant activities of the effective compounds (5o, 5g, 5s, 5x, and 5q) were evaluated by TAS methods. A molecular docking research study was conducted to identify the active site and explain the functions of the active chemicals. To investigate the most likely binding mode of the substances 5g, 5o, 5q, 5s, and 5x, a molecular dynamics simulation was also carried out.

Identification of potential drug candidates as TGR5 agonist to combat type II diabetes using in silico docking and molecular dynamics simulation studies

A cell surface bile acid receptor TGR5 being considered as a novel target for Type II diabetes found to be expressed in various tissues. A major role for TGR5 is to maintain blood sugar levels and increase in energy expenditure. These benefits make it a potential candidate for the treatment of type 2 diabetes, obesity and other metabolic disorder. To date, many novel TGR5 agonists have been synthesized and evaluated in the literature, but very few in silico computational studies have been reported. The discovery of a high-resolution crystal structure of TGR5 in 2020 provides an excellent opportunity for computational screening of potential agonists. In this study, we, therefore, aim to search novel, less toxic TGR5 agonists by iteratively analyzing molecular docking against TGR5 (PDB ID: 7CFN) by means of structure-based virtual screening. The docking score of the designed coumarin derivatives that have been docked successfully varies between -9.4 and -9.0 kcal/mol. The molecular docking and ADMET profile examinations of compounds D1, D5 and D15 revealed that these have a strong affinity for the active site residues of TGR5. In addition, molecular dynamics simulation (MDS) studies have shown the stability of compounds that bind to TGR5. It can be summarized that designed coumarin derivatives seem to have promising activity as TGR5 agonists.Communicated by Ramaswamy H. Sarma.

Further undescribed cembranoids from South China Sea soft coral Sarcophyton ehrenbergi: Structural elucidation and biological evaluation

A detailed chemical investigation of the South China Sea soft coral Sarcophyton ehrenbergi has yield seven undescribed cembranoids, namely isoehrenbergol D and sarcoehrenolides F-K embodying a rare α,β-unsaturated-lactone moiety at C-6 to C-19, along with two known related compounds, ehrenbergol D and sarcoehrenolide A. Their structures and absolute configurations were unambiguously established in the light of extensive spectroscopic data analysis, modified Mosher's method, X-ray diffraction analysis, and quantum chemical computation method. In a bioassay for α-glucosidase inhibition, ehrenbergol D was evaluated as α-glucosidase inhibitor with an IC₅₀ value of 13.57 μM.

Synthesis and Biological Evaluation of Substituted Pyrazole-Fused Oleanolic Acid Derivatives as Novel Selective α-Glucosidase Inhibitors

A series of novel substituted pyrazole-fused oleanolic acid derivative were synthesized and evaluated as selective α-glucosidase inhibitors. Among these analogs, compounds 4a-4f exhibited more potent inhibitory activities compared with their methyl ester derivatives, and standard drugs acarbose and miglitol as well. Besides, all these analogs exhibited good selectivity towards α-glucosidase over α-amylase. Analog 4d showed potent inhibitory activity against α-glucosidase (IC₅₀ =2.64±0.13 μM), and greater selectivity towards α-glucosidase than α-amylase by ∼33-fold. Inhibition kinetics showed that compound 4d was a non-competitive α-glucosidase inhibitor, which was consistent with the result of its simulation molecular docking. Moreover, the in vitro cytotoxicity of compounds 4a-4f towards hepatic LO2 and HepG2 cells was tested.

Biological, toxicological and molecular docking evaluations of isoxazoline-thiazolidine-2,4-dione analogues as new class of anti-hyperglycemic agents

In this work, three isoxazoline-thiazolidine-2,4-dione derivatives were synthesized and characterized by FT-IR, ¹H-NMR, ¹³C-NMR and ESI-MS spectrometry. All compounds have been investigated for their α-amylase and α-glucosidase inhibitory activities. In vitro enzymatic evaluation revealed that all compounds were inhibitory potent against α-glucosidase with IC₅₀ values varied from 40.67 ± 1.81 to 92.54 ± 0.43 µM, and α-amylase with IC₅₀ in the range of 07.01 ± 0.02 to 75.10 ± 1.06 µM. One of the tested compounds were found to be more potent inhibitor compared to other compounds and standard drug Acarbose (IC_{50 glucosidase}= 97.12 ± 0.35 µM and IC_{50 amylase}= 2.97 ± 0.01 μM). All compounds were then evaluated for their acute toxicity in vivo and shown their safety at a high dose with LD > 2000mg/kg BW. A cell-based toxicity evaluation was performed to determine the safety of compounds on liver cells, using the MTT assay against HepG2 cells, and the results shown that all compounds have non-toxic impact against cell viability and proliferation compared to reference drug (Pioglitazone). Furthermore, the molecular homology analysis, SAR and the molecular binding properties of compound with the active site of α-amylase and α-glucosidase were confirmed through computational analysis. This study has identified the inhibitory potential of a new class of synthesized isoxazoline-thiazolidine-2,4-dione derivatives in controlling both hyperglycemia and type 2 diabetes mellitus without any hepatic toxicity.Communicated by Ramaswamy H. Sarma.

Callyspongia spp.: Secondary Metabolites, Pharmacological Activities, and Mechanisms

One of the most widespread biotas in the sea is the sponge. Callyspongia is a sponge genus found in the seas, making it easily available. In this review, the pharmacological activity and mechanism of action of the secondary metabolites of Callyspongia spp. are addressed, which may lead to the development of new drugs and targeted therapeutic approaches. Several scientific databases, such as Google Scholar, PubMed, ResearchGate, Science Direct, Springer Link, and Wiley Online Library, were mined to obtain relevant information. In the 41 articles reviewed, Callyspongia spp. was reported to possess pharmacological activities such as cytotoxicity against cancer cell lines (36%), antifungal (10%), anti-inflammatory (10%), immunomodulatory (10%), antidiabetic and antiobesity (6%), antimicrobial (8%), antioxidant (4%), antineurodegenerative (4%), antihypercholesterolemic (2%), antihypertensive (2%), antiparasitic (2%), antiallergic (2%), antiviral (2%), antiosteoporotic (2%), and antituberculosis (2%) activities. Of these, the antioxidant, antituberculosis, and anti-inflammatory activities of Callyspongia extract were weaker compared with that of the control drugs; however, other activities, particularly cytotoxicity, show promise, and the compounds responsible may be developed into new drugs.

New cycloalkyl[b]thiophenylnicotinamide-based α-glucosidase inhibitors as promising anti-diabetic agents: Synthesis, in silico study, in vitro and in vivo evaluations

In the present study, a series of cycloalkyl[b]thiophenylnicotinamide derivatives against α-glucosidase were synthesized, and evaluated for their in vitro and in vivo anti-diabetic potential. Most of the synthetic analogues exhibited superior α-glucosidase inhibitory effects than the standard drug acarbose (IC₅₀ = 258.5 μM), in which compound 11b with cyclohexyl[b]thiophene core demonstrated the highest activity with an IC₅₀ value of 9.9 μM and showed higher selectivity towards α-glucosidase over α-amylase by 7.4-fold. Fluorescence quenching experiment confirmed the direct binding of 11b with α-glucosidase, kinetics study revealed that 11b was a mixed-type inhibitor, and its binding mode was analyzed using molecular docking. Moreover, analogs compounds 6a-9b, 11b, 12b did not show in vitro cytotoxicity against LO2 and HepG2 cells. Finally, compound 11b exhibited in vivo hypoglycemic activity by reducing the blood glucose levels in sucrose-loaded rats.

Pharmaceutical Food Science: Search for Bio-Functional Molecules Obtained from Natural Resources to Prevent and Ameliorate Lifestyle Diseases

In this review, our resent pharmaceutical food science research for bio-functional molecules obtained from natural resources that contribute to i) suppression of postprandial blood glucose elevation and/or improvement of glucose tolerance and ii) reduction of visceral fat accumulation and improvement of lipid metabolism were summarized. Based on studies using MONOTORI science, salacinol (1), neokotalanol (4), and trans-tiliroside (20) have been approved or notified by the Consumer Affairs Agency in Japan as functional substances in food with health claims, Food for Specified Health Use and Food with Functional Claims.

The antioxidant and antidiabetic potentials of polyphenolic-rich extracts of Cyperus rotundus (Linn.)

In this study, the rhizome of Cyperus rotundus L was investigated for its antioxidant and antidiabetic effects using in vitro and in silico experimental models. Its crude extracts (ethyl acetate, ethanol and aqueous) were screened in vitro for their antioxidant activity using ferric-reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH), as well as their inhibitory effect on α-glucosidase enzyme. Subsequently, the extracts were subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis to elucidate their possible bioactive compounds. Furthermore, computational molecular docking of selected phenolic compounds was conducted to determine their mode of α-glucosidase inhibitory activity. The aqueous extract displayed the highest level of total phenolic content and significantly higher scavenging activity in both FRAP and DPPH assays compared to ethyl acetate and ethanol extracts. In FRAP and DPPH assays, IC₅₀ values of aqueous extract were 448.626 µg/mL and 418.74 µg/mL, respectively. Aqueous extract further presented higher α-glucosidase inhibitory activity with an IC₅₀ value of 383.75 µg/mL. GC-MS analysis revealed the presence of the following phenolic compounds: 4-methyl-2-(2,4,4-trimethylpentan-2-yl) phenol, Phenol,2-methyl-4-(1,1,3,3-tetramethylbutyl)- and 1-ethoxy-2-isopropylbenzene. Molecular docking study revealed 1-ethoxy-2-isopropylbenzene formed two hydrogen bonds with the interacting residues in the active site of α-glucosidase enzyme. Furthermore, 4-methyl-2-(2,4,4-trimethylpentan-2-yl) phenol had the lowest binding energy inferring the best affinity for α-glucosidase active site. These results suggest the possible antioxidant and antidiabetic potential of Cyperus rotundus.Communicated by Ramaswamy H. Sarma.

Bioactivity Guided Study for the Isolation and Identification of Antidiabetic Compounds from Edible Seaweed-Ulva reticulata

Managing diabetes is challenging due to the complex physiology of the disease and the numerous complications associated with it. As part of the ongoing search for antidiabetic chemicals, marine algae have been demonstrated to be an excellent source due to their medicinal properties. In this study, Ulva reticulata extracts were investigated for their anti-diabetic effect by examining its inhibitory effects on α-amylase, α-glucosidase, and DPP-IV and antioxidant (DPPH) potential in vitro and its purified fraction using animal models. Among the various solvents used, the Methanolic extract of Ulva reticulata (MEUR) displayed the highest antidiabetic activity in both in vitro and in vivo; it showed no cytotoxicity and hence was subjected to bioassay-guided chromatographic separation. Among the seven isolated fractions (F1 to F7), the F4 (chloroform) fraction exhibited substantial total phenolic content (65.19 μg mL^-1) and total flavonoid content (20.33 μg mL^-1), which showed the promising inhibition against α-amylase (71.67%) and α-glucosidase (38.01%). Active fraction (F4) was further purified using column chromatography, subjected to thin-layer chromatography (TLC), and characterized by spectroscopy techniques. Upon structural elucidation, five distinct compounds, namely, Nonane, Hexadecanoic acid, 1-dodecanol, Cyclodecane methyl, and phenol, phenol, 3,5-bis(1,1-dimethylethyl) were identified. The antidiabetic mechanism of active fraction (F4) was further investigated using various in vitro and in vivo models. The results displayed that in in vitro both 1 and 24 h in vitro cultures, the active fraction (F4) at a concentration of 100 μg mL^-1 demonstrated maximum glucose-induced insulin secretion at 4 mM (0.357 and 0.582 μg mL^-1) and 20 mM (0.848 and 1.032 μg mL^-1). The active fraction (F4) reduces blood glucose levels in normoglycaemic animals and produces effects similar to that of standard acarbose. Active fraction (F4) also demonstrated outstanding hypoglycaemic activity in hyperglycemic animals at a dose of 10 mg/kg B.wt. In the STZ-induced diabetic rat model, the active fraction (F4) showed a (61%) reduction in blood glucose level when compared to the standard drug glibenclamide (68%). The results indicate that the marine algae Ulva reticulata is a promising candidate for managing diabetes by inhibiting carbohydrate metabolizing enzymes and promoting insulin secretion.

Glycemic indices and effect of bitter leaf (Vernonia amygdalina) flavored non-alcoholic wheat beer (NAWB) on key carbohydrate metabolizing enzymes in high fat diet fed (HFD)/STZ-induced diabetic Wistar rats

In a bid to make the use of functional food easier in the management and prevention of diseases, product development and fortification from/with functional foods have become the recent focus of research. This study, therefore, sought to exploit the recent trend in the brewing industry on the production of non-alcoholic beers by investigating the possibility of having a non-alcoholic beer flavored with bitter leaf, a known plant widely reported to have a strong hypoglycemic effect, as against the traditional use of hops, and the effect of the produced beer on the glycemic indices and various diabetic biochemical parameters that serve as biomarkers for type-2 diabetes (T2D). The glycemic indices, as well as the inhibitory potentials of bitter leaf-flavored Non-alcoholic wheat beer (NAWB) in ratios of 100%HP, 100%BL, 75:25BL, 50:50BL, and 25:75BL, on enzymes linked to a high-fat diet/streptozocin (HFD/STZ)-induced T2D albino Wistar rats were investigated. There were no significant difference (p > .05) between the starch (1.72-1.77 mg/100 mL), amylose (0.22-0.24 mg/100 mL), and amylopectin (1.49-1.53 mg/100 mL) contents of the various samples. The Glycemic Index (GI) of the samples ranged from 36 to 73 with 75:25Bl and 50:50BL have the lowest (36) values. The samples reduced blood glucose levels and inhibited pancreatic α-amylase, lipase, and intestinal α-glucosidase activity. The inhibitory potentials of these beer samples on α-amylase and α-glucosidase as well as their ability to reduce blood glucose levels in diabetic rats thus making the bitter leaf flavored NAWB a suitable healthy beverage for better glycemic control in diabetics. PRACTICAL APPLICATIONS: This study revealed the potential of producing non-alcoholic wheat beer flavored with bitter leaves as a possible substitute for hops. The potential inherent in bitter leaf in the management of type 2 diabetes can thus be made available through a far-reaching beverage medium such as non-alcoholic beer to help in the treatment/management of T2D. The results of this research could be an eye-opener to the possible utilization of bitter leaf and by extension other plants that have been reported in the management of T2D. The use of the bitter leaf as a substitute for hops in the production of non-alcoholic beer in the brewing industry could help in a health-oriented campaign for safe drinks that could be helpful in the control of blood glucose levels of diabetic patients.

Pharmacotherapy of type 2 diabetes: An update and future directions

Type 2 diabetes (T2D) is a widely prevalent disease with substantial economic and social impact for which multiple conventional and novel pharmacotherapies are currently available; however, the landscape of T2D treatment is constantly changing as new therapies emerge and the understanding of currently available agents deepens. This review aims to provide an updated summary of the pharmacotherapeutic approach to T2D. Each class of agents is presented by mechanism of action, details of administration, side effect profile, cost, and use in certain populations including heart failure, non-alcoholic fatty liver disease, obesity, chronic kidney disease, and older individuals. We also review targets of novel therapeutic T2D agent development. Finally, we outline an up-to-date treatment approach that starts with identification of an individualized goal for glycemic control then selection, initiation, and further intensification of a personalized therapeutic plan for T2D.

Synthesis of Novel 2,3-Dihydro-1,5-Benzothiazepines as α-Glucosidase Inhibitors: In Vitro, In Vivo, Kinetic, SAR, Molecular Docking, and QSAR Studies

In the present study, a series of 2,3-dihydro-1,5-benzothiazepine derivatives 1B-14B has been synthesized sand characterized by various spectroscopic techniques. The enzyme inhibitory activities of the target analogues were assessed using in vitro and in vivo mechanism-based assays. The tested compounds 1B-14B exhibited in vitro inhibitory potential against α-glucosidase with IC50 = 2.62 ± 0.16 to 10.11 ± 0.32 μM as compared to the standard drug acarbose (IC50 = 37.38 ± 1.37 μM). Kinetic studies of the most active derivatives 2B and 3B illustrated competitive inhibitions. Based on the α-glucosidase inhibitory effect, the compounds 2B, 3B, 6B, 7B, 12B, 13B, and 14B were chosen in vivo for further evaluation of antidiabetic activity in streptozotocin-induced diabetic Wistar rats. All these evaluated compounds demonstrated significant antidiabetic activity and were found to be nontoxic in nature. Moreover, the molecular docking study was performed to elucidate the binding interactions of most active analogues with the various sites of the α-glucosidase enzyme (PDB ID 3AJ7). Additionally, quantitative structure-activity relationship (QSAR) studies were performed based on the α-glucosidase inhibitory assay. The value of correlation coefficient (r) 0.9553 shows that there was a good correlation between the 1B-14B structures and selected properties. There is a correlation between the experimental and theoretical results. Thus, these novel compounds could serve as potential candidates to become leads for the development of new drugs provoking an anti-hyperglycemic effect.

Synthesis of N-Substituted Iminosugar C-Glycosides and Evaluation as Promising α-Glucosidase Inhibitors

A series of N-substituted iminosugar C-glycosides were synthesized and tested for α-glucosidase inhibition. The results suggested that 6e is a promising and potent α-glucosidase inhibitor. Enzymatic kinetic assays indicated that compound 6e may be classified as an uncompetitive inhibitor. The study of structure-activity relationships of those iminosugars provided a starting point for the discovery of new α-glucosidase inhibitors.

Phenoxy pendant isatins as potent α-glucosidase inhibitors: reciprocal carbonyl⋯carbonyl interactions, antiparallel π⋯π stacking driven solid state self-assembly and biological evaluation

Carbonyl-carbonyl (CO⋯CO) interactions are recently explored noncovalent interactions of significant interest owing to their role in the stability of biomacromolecules. Currently, substantial efforts are being made to understand the nature of these interactions. In this study, twelve phenoxy pendant isatins 1-12 have been evaluated for their α-glucosidase inhibitory potential in addition to the analysis of X-ray single crystals of 4 and 9. Both compounds 4 and 9 showed intriguing and unique self-assembled structures. The CO⋯CO and antiparallel displaced π⋯π stacking interactions are mainly involved in the formation of 1D-stair like supramolecular chains of 4 whereas antiparallel π⋯π stacking interactions drive the formation of 1D-columnar stacks of 9. These compounds not only highlight the potential of the isatin moiety in forming strong CO⋯CO and antiparallel π⋯π stacking interactions but also are interesting models to provide considerable insight into the nature of these interactions. The in vitro biological studies revealed that all twelve phenoxy pendant isatins 1-12 are highly potent inhibitors of α-glucosidase enzyme with IC50 values ranging from 5.32 ± 0.17 to 150.13 ± 0.62 μM, showing many fold more potent activity than the standard drug, acarbose (IC50 = 873.34 ± 1.67). Easy access and high α-glucosidase inhibition potential of these phenoxy pendant isatins 1-12 provide an attractive platform for finding more effective medication for controlling postprandial hyperglycemia.

PLG-007 and Its Active Component Galactomannan-α Competitively Inhibit Enzymes That Hydrolyze Glucose Polymers

PLG-007 is a developmental therapeutic compound that has been clinically shown to reduce the magnitude of postprandial glucose excursions and has the potential to be an adjunct treatment for diabetes and inflammatory-related diseases. The present investigation is aimed at understanding the molecular mechanism of action of PLG-007 and its galactomannan (GM) components GMα and GMβ (in a 1:4 mass ratio, respectively) on enzyme (i.e., α-amylase, maltase, and lactase) hydrolysis of glucose polymers using colorimetric assays and 13C HSQC NMR spectroscopy. The starch–iodine colorimetric assay indicated that GMα strongly inhibits α-amylase activity (~16-fold more potent than GMβ) and thus is the primary active component in PLG-007. 13C HSQC experiments, used to follow the α-amylase-mediated hydrolysis of starch and amylopectin, further demonstrate the α-amylase inhibitory effect of GMα via α-amylase-mediated hydrolysis of starch and amylopectin. Maltohexaose (MT6) was used to circumvent the relative kinetic complexity of starch/amylopectin degradation in Michaelis–Menten analyses. The Vmax, KM, and Ki parameters were determined using peak volume integrals from 13C HSQC NMR spectra. In the presence of PLG-007 with α-amylase and MT6, the increase in KM from 7.5 ± 0.6 × 10−3 M (control) to 21 ± 1.4 × 10−3 M, with no significant change in Vmax, indicates that PLG-007 is a competitive inhibitor of α-amylase. Using KM values, Ki was estimated to be 2.1 ± 0.9 × 10−6 M; however, the microscopic Ki value of GMα is expected to be larger as the binding stoichiometry is likely to be greater than 1:1. Colorimetric assays also demonstrated that GMα is a competitive inhibitor of the enzymes maltase and lactase. Overall, this study provides insight as to how PLG-007 (GMα) is likely to function in vivo.

Novel Hydroxychalcone-Based Dual Inhibitors of Aldose Reductase and α-Glucosidase as Potential Therapeutic Agents against Diabetes Mellitus and Its Complications

We designed a novel series of bifunctional inhibitors of α-glucosidase and aldose reductase (ALR2) based on the structure of hydroxychalcone. The two enzymes relate to blood glucose level and anomalously elevated polyol pathway of glucose metabolism under hyperglycemia, respectively. Most compounds in the series exhibited a potent inhibitory activity for both enzymes, and a significant antioxidant property was shown. Further in vivo studies of 11j and 14d using streptozotocin (STZ)-induced diabetic rats as a model found that 11j achieved not only good antihyperglycemic and glucose tolerance effect in a dose-dependent manner (p < 0.01) but also showed effective inhibition of polyol pathway. 14d significantly suppressed the maltose-induced postprandial glucose elevation. Additionally, they effectively improved lipid metabolisms and restored an antioxidant ability. Therefore, the two compounds may be promising agents for the prevention and treatment of diabetic complications.

Different Interactive Effects of Metformin and Acarbose With Dietary Macronutrient Intakes on Patients With Type 2 Diabetes Mellitus: Novel Findings From the MARCH Randomized Trial in China

Antidiabetic oral agents and nutrition management are frequently used together as first-line therapies for type 2 diabetes mellitus (T2DM). However, less is known about their interaction. The interactive effect of two classic antidiabetic medications, namely, acarbose and metformin, with dietary intakes of macronutrients on glycemic control and cardiometabolic risk factors was investigated in the metformin and acarbose in Chinese as the initial hypoglycemic treatment (MARCH) randomized clinical trial. The patients with newly diagnosed T2DM from China were included in the trial. Participants were randomized to receive either metformin or acarbose monotherapy as the initial treatment, followed by a 24-week treatment phase, during which add-on therapy was used if necessary. Dietary intakes of carbohydrate, protein, fat, and total energy were calculated by a 24-h food diary recall method. Linear mixed-effect models combined with a subgroup analysis were used to investigate independent and interactive effects of drugs and diet on clinical outcomes. A data analysis was performed on 551 of the 788 patients randomly assigned to treatment groups. Metformin therapy was independently associated with higher triglycerides (TGs, β = 0.471, P = 0.003), 2 h postprandial plasma glucose (2hPPG, β = 0.381, P = 0.046) but lower low-density lipoprotein cholesterol (LDL-C, β = −0.149, P = 0.013) compared with acarbose therapy. Higher carbohydrates and lower fat intakes were independently associated with poorer glycemic control, less weight loss, and greater insulin secretion. Higher total energy intake was also independently associated with higher fasting (β = 0.0002, P = 0.001) and postprandial blood glucose (β = 0.0004, P = 0.001). Interaction and subgroup analyses demonstrated that glucagon-like peptide-1 (GLP-1) was positively related to total energy (β = 0.268, P = 0.033), carbohydrates intake, and insulin secretion (β = 2,045.2, P = 0.003) only in the acarbose group, while systolic blood pressure (SBP) was negatively related to protein intake in the metformin group (β = 23.21, P = 0.014). The results of this study showed that metformin and acarbose mainly exerted different interactive effects with dietary energy, carbohydrate, and protein intakes on GLP-1 secretion, insulin release, and SBP. The interaction between drug therapy and nutrition intervention in glycemia highlights the complexity of combination therapy.

Blood pressure and blood sugar-lowering effects of purified gambir on diabetic hypertensive Wistar Kyoto rats

OBJECTIVES

Antioxidants protect people from diabetes and its cardiovascular complication. Purified gambir (Uncaria gambir Roxb.) is a potential medicinal plant for treating this condition based on the antioxidant activity of its catechin compound. This study tries to reveal the potential activity of purified gambir as a blood pressure-lowering drug while lowering blood glucose in diabetic hypertensive rats induced by oral NaCl-Prednisone and Alloxan.

METHODS

Rats were induced by oral NaCl 0.8% and Prednisone 5 mg/kg BW for 14 days to obtain hypertensive condition. Alloxan 125 mg/kg BW was given intra peritoneal injection on the 8th day to obtain diabetic hypertensive condition. The animal was divided into five groups, normal control group treated with vehicle, treatment groups were treated with purified gambir at dose of 2.5; 5 and 10 mg/kg BW respectively, while the positive control group were treated with a combination of captopril-glibenclamide at dose of 2.25 and 0.45 mg/kg BW. All animals were treated orally for 14 days. Fasting blood glucose and cardiovascular parameters (SBP, DBP, MAP, HR, BF and BV) were measured on days 1, 3, 7, and 14. NO level were measured on day 0 and day 14. Data were analyzed using two-way ANOVA followed by Duncan Multiple Range Test.

RESULTS

The purified gambir has blood pressure and blood sugar-lowering activity (p<0.05). The NO levels of the treatment group also increased significantly (p<0.05).

CONCLUSIONS

This study indicated that purified gambir could be an alternative medicine to manage blood glucose and blood pressure in the diabetic hypertensive model.

Links between Insulin Resistance and Periodontal Bacteria: Insights on Molecular Players and Therapeutic Potential of Polyphenols

Type 2 diabetes is a metabolic disease mainly associated with insulin resistance during obesity and constitutes a major public health problem worldwide. A strong link has been established between type 2 diabetes and periodontitis, an infectious dental disease characterized by chronic inflammation and destruction of the tooth-supporting tissue or periodontium. However, the molecular mechanisms linking periodontal bacteria and insulin resistance remain poorly elucidated. This study aims to summarize the mechanisms possibly involved based on in vivo and in vitro studies and targets them for innovative therapies. Indeed, during periodontitis, inflammatory lesions of the periodontal tissue may allow periodontal bacteria to disseminate into the bloodstream and reach tissues, including adipose tissue and skeletal muscles that store glucose in response to insulin. Locally, periodontal bacteria and their components, such as lipopolysaccharides and gingipains, may deregulate inflammatory pathways, altering the production of pro-inflammatory cytokines/chemokines. Moreover, periodontal bacteria may promote ROS overproduction via downregulation of the enzymatic antioxidant defense system, leading to oxidative stress. Crosstalk between players of inflammation and oxidative stress contributes to disruption of the insulin signaling pathway and promotes insulin resistance. In parallel, periodontal bacteria alter glucose and lipid metabolism in the liver and deregulate insulin production by pancreatic β-cells, contributing to hyperglycemia. Interestingly, therapeutic management of periodontitis reduces systemic inflammation markers and ameliorates insulin sensitivity in type 2 diabetic patients. Of note, plant polyphenols exert anti-inflammatory and antioxidant activities as well as insulin-sensitizing and anti-bacterial actions. Thus, polyphenol-based therapies are of high interest for helping to counteract the deleterious effects of periodontal bacteria and improve insulin resistance.

Inhibition on α-Glucosidase Activity and Non-Enzymatic Glycation by an Anti-Oxidative Proteoglycan from Ganoderma lucidum

The prevention of postprandial hyperglycemia and diabetic complications is crucial for diabetes management. Inhibition of α-glucosidase to slow carbohydrate metabolism is a strategy to alleviate postprandial hyperglycemia. In addition, suppression of non-enzymatic glycation can diminish the advanced glycation end products and reduce the oxidative stress and inflammation, thereby preventing the diabetic complications. In this study, an anti-oxidative proteoglycan (named FYGL) extracted from Ganoderma lucidum was investigated in vitro for its inhibitory effect on α-glucosidase and non-enzymatic glycation using molecular kinetics, intrinsic fluorescence assay, and bovine serum albumin glycation models. The molecular kinetics and fluorescence assay revealed that FYGL decreases α-glucosidase activity by forming a FYGL-α-glucosidase complex. To evaluate the anti-glycation effect, fructose-glycated and methylglyoxal-glycated BSA models were analyzed by spectroscopic and SDS-PAGE methods. Results showed that FYGL inhibited the glycation at every stage and suppressed glycoxidation, possibly due to its anti-oxidative capacity and FYGL-BSA complex formation. Furthermore, we demonstrated in vivo that FYGL could alleviate postprandial hyperglycemia in db/db mice as well as AGE accumulation and vascular injury in diabetic rats. Overall, FYGL possesses anti-postprandial hyperglycemia and anti-glycation functions and would be potentially used in clinic for diabetes and related complication management.

Anti-α-glucosidase and anti-oxidative isoflavonoids from the immature fruits of Maclura tricuspidata

The composition of a plant, together with its efficacy, vary depending on its maturity and plant parts. In this study, the chemical constituents of immature fruits of Maclura tricuspidata (Moraceae) were investigated together with their anti-diabetic and antioxidant effects. A total of 34 compounds were isolated from the immature fruits of M. tricuspidata using various chromatographic methods. Structure elucidation using extensive spectroscopic analysis led to the characterization of isolated compounds as isoflavonoids with prenyl substituents. Among them, macluraisoflavones A-O were first isolated from nature. The anti-diabetic and antioxidant activity of the isolated compounds were also suggested by α-glucosidase inhibitory activity and DPPH radical scavenging activity, respectively. In particular, macluraisoflavone I, an isoflavonoid with 2,2-dimethylpyran and 2-hydroperoxy-3-methylbut-3-enyl moieties, showed potent α-glucosidase inhibitory activity and DPPH radical scavenging activity. Further molecular docking analysis suggested hydrogen bond and alkyl interactions between α-glucosidase and macluraisoflavone I. Therefore, the immature fruits of M. tricuspidata can be used as an important natural product with antioxidant and anti-diabetic properties.

Newboulasides A and B, two new caffeic acid glycosides from Newbouldia laevis with α-amylase inhibitory activity

Chemical investigation of the ethanol extract of the leaves of Newbouldia laevis (P. Beauv) led to the isolation of two new caffeic acid glycosides, Newboulasides A (1) and B (2). The structures of these compounds were determined on the basis of extensive spectroscopic methods, including 1D-, 2D-NMR and MS data. The extracts and fractions and the isolated compounds were evaluated for their inhibition of α-amylase enzyme activity. The extract showed inhibition of α-amylase activity with IC₅₀ value of 102.91 µg/mL, while the isolated compounds (1 and 2) exhibited pronounced inhibition with IC₅₀ values of 4.95 and 4.44 µg/mL respectively, comparable to the standard - Acarbose with IC₅₀ value of 4.05 µg/mL. Our findings demonstrated that the inhibition of α-amylase activity may be part of the mechanisms through which N. leavis exhibits antidiabetic effect.

Safety Assessment of Glucose-Lowering Drugs and Importance of Structured Education during Ramadan: A Systematic Review and Meta-Analysis

BACKGROUND

Ramadan is the sacred month of the Islamic Hijri (lunar) calendar, and during this entire month, healthy adult Muslims abstain from eating and drinking from dawn to sunset. Muslims with Type 2 Diabetes Mellitus (T2DM) who choose to fast during Ramadan encounter major risks such as hypoglycemia, hyperglycemia, diabetic ketoacidosis, dehydration, and thrombosis. Although patients with poor glycemic control and on multiple insulin injections are at high risk and exempt from fasting, many still insist on it. Thus, healthcare professionals play a pivotal role in managing diabetes-related complications in patients who fast during Ramadan. However, there is a lack of standard guidelines to be followed in association with structured education and administration of drugs and dosage. Therefore, we performed a systematic review and meta-analysis of the literature to determine the safety and efficacy of different classes of drugs and the importance of structured education during Ramadan.

METHODS

In this review, an extensive PubMed search was performed to obtain literature on T2DM patients who fast during the month of Ramadan until the year 2020. Preference was given to fully downloadable articles. The articles were extracted based on the eligibility criteria. The extracted data were analyzed using Review Manager software version 5.3.

RESULTS

A total of 32 articles were included for the review and 7 studies for meta-analysis. Majority of the studies demonstrated the importance of structured education either as a group session or as a one-on-one session with the healthcare professionals in preventing diabetes-related risks during Ramadan. As far as glucose-lowering drugs are concerned, DPP-4 inhibitor combined with metformin remains the drug of choice for T2DM patients who fast during Ramadan. The newer class of glucose-lowering agents appear to lower the risk of hypoglycemia in comparison with sulphonylureas, while among sulphonylureas gliclazide is relatively safe. The meta-analysis indicates that DPP-4 inhibitors would significantly reduce the risk of hypoglycemia as compared to sulphonylurea (odds ratio = 0.38, 95% CI: 0.26 to 0.55, p < 0.00001).

CONCLUSION

The results of our systematic review show that structured education and counselling by healthcare professionals can be an effective tool in preventing complications associated with fasting during Ramadan in people with T2DM. Additionally, the safest class of oral glucose-lowering drugs preferred during Ramadan fasting in T2DM patients is DPP-4 inhibitors.

Therapeutic potentials of agonist and antagonist of adenosine receptors in type 2 diabetes

Type 2 diabetes has been a global health challenge over the decades and is among the leading causes of death. Several treatment approaches have been developed, but more effective and new therapies are still needed. The role of adenosine in glucose and lipid homeostasis has offered a different therapeutic approach. Adenosine mediates its physiological role through the activation of adenosine receptors. These adenosine receptors have been implicated in glucose and lipid homeostasis. The ability of agonists and antagonists of adenosine receptors to activate or inhibit the adenosine signalling cascade and thereby affecting the balance of glucose and lipid homeostasis has challenged the studies of agonists and antagonists of adenosine receptors, both preclinical and clinical, as potential anti-diabetic drugs. This review provides a background on different anti-diabetic therapeutic approaches, outlining the role of adenosine receptors in glucose and lipid homeostasis, and mechanisms underlying the action of agonists/antagonists of adenosine receptors as a therapeutic potential towards type 2 diabetes.

Aromatic Constituents from the Leaves of Actinidia arguta with Antioxidant and α-Glucosidase Inhibitory Activity

As the leaf of Actinidia arguta has shown antioxidant activity, a study was conducted to identify the active ingredients. Forty-eight compounds were isolated from the leaves of A. arguta through various chromatographic techniques. Further characterization of the structures on the basis of 1D and 2D NMR and MS data identified several aromatic compounds, including phenylpropanoid derivatives, phenolics, coumarins, flavonoids and lignans. Among them, five compounds were newly reported, naturally occurring, and named argutosides A-D (1-4), which consist of phenylpropanoid glycosides that are conjugated with a phenolic moiety, and argutoside E (5), which is a coumarin glycoside that is conjugated with a phenylpropanoid unit. The isolated compounds showed good antioxidant and α-glucosidase inhibitory activity with differences in activity depending on the structures. Molecular docking analysis demonstrated the interaction between the hydroxyl and carbonyl groups of compounds 1 and 5 with α-glucosidase. Taken together, the leaves of A. arguta are rich in aromatic compounds with diverse structures. Therefore, the leaves of A. arguta and their aromatic components might be beneficial for oxidative stress and glucose-related diseases.

Synthesis of new clioquinol derivatives as potent α-glucosidase inhibitors; molecular docking, kinetic and structure-activity relationship studies

Diabetes mellitus is a chronic metabolic disorder with increasing prevalence and long-term complications. The aim of this study was to identify α-glucosidase inhibitory compounds with potential anti-hyperglycemic activity. For this purpose, a series of new clioquinol derivatives 2a-11a was synthesized, and characterized by various spectroscopic techniques. The enzyme inhibitory activities of the resulting derivatives were assessed using an in-vitro mechanism-based assay. All the tested compounds 2a-11a of the series showed a significant α-glucosidase inhibition with IC₅₀ values 43.86-325.81 µM, as compared to the standard drug acarbose 1C₅₀: 875.75 ± 2.08 µM. Among them, compounds 4a, 5a, 10a, and 11a showed IC₅₀ values of 105.51 ± 2.41, 119.24 ± 2.37, 99.15 ± 2.06, and 43.86 ± 2.71 µM, respectively. Kinetic study of the active analogues showed competitive, non-competitive, and mixed-type inhibitions. Furthermore, the molecular docking study was performed to elucidate the binding interactions of most active analogues with the various sites of α-glucosidase enzyme. The results indicate that these compounds have the potential to be further studied as new anti-diabetic agents.

The Bioactivity of Thiazolidin-4-Ones: A Short Review of the Most Recent Studies

Thiazolidin-4-ones is an important heterocyclic ring system of a pharmacophore and a privileged scaffold in medicinal chemistry. This review is focused on the latest scientific reports regarding biological activities of thiazolidin-4-ones published in 2020 and 2021. The review covers recent information about antioxidant, anticancer, anti-inflammatory, analgesic, anticonvulsant, antidiabetic, antiparasitic, antimicrobial, antitubercular and antiviral properties of thiazolidin-4-ones. Additionally, the influence of different substituents in molecules on their biological activity was discussed in this paper. Thus, this study may help to optimize the structure of thiazolidin-4-one derivatives as more efficient drug agents. Presented information may be used as a practical hint for rational design of new small molecules with biological activity, especially among thiazolidin-4-ones.

Isatin-hydrazide conjugates as potent α-amylase and α-glucosidase inhibitors: Synthesis, structure and invitro evaluations

Managing diabetes that is a global life-threatening problem, remains a challenge for the scientific community. The inhibition of α-amylase and α-glucosidase enzymes which are responsible for the digestion of dietary carbohydrates is an effective strategy to control postprandial hyperglycemia. Herein, we report the novel and highly potent inhibitors of α-amylase and α-glucosidase, namely isatin-hydrazide conjugates 1a - 1j that are easily accessed in two steps from simple and inexpensive commercially available isatin. The in vitro bio-evaluations of these compounds revealed that conjugates 1a, 1h and 1f are highly potent inhibitors of α-amylase with IC₅₀ values of 19.6, 12.1 and 18.3 µg/ml, respectively as compared to the standard, acarbose (IC₅₀ = 36.2 µg/ml). Similarly, the conjugates 1a, 1b, 1d, 1f and 1i showed significant activity against α-glucosidase with IC₅₀ values of 14.8, 25.6, 13.2, 14.5 and 16.5 µg/ml, respectively as compared to the acarbose (IC₅₀ = 34.5 µg/ml). Notably, the compounds 1a and 1f were found to be highly potent against both α-amylase and α-glucosidase enzymes, demonstrating about two-fold better inhibitory activity than the reference inhibitor. Molecular docking studies were performed to recognize the possible binding modes of the compounds with the active pocket of the enzymes. The results of this study divulge the potential of these compounds as powerful and inexpensive lead molecules for future investigations.

Effectiveness of Magnolol, a Lignan from Magnolia Bark, in Diabetes, Its Complications and Comorbidities-A Review

Diabetes mellitus is a chronic metabolic disease characterized by disturbances in carbohydrate, protein, and lipid metabolism, often accompanied by oxidative stress. Diabetes treatment is a complicated process in which, in addition to the standard pharmacological action, it is necessary to append a comprehensive approach. Introducing the aspect of non-pharmacological treatment of diabetes allows one to alleviate its many adverse complications. Therefore, it seems important to look for substances that, when included in the daily diet, can improve diabetic parameters. Magnolol, a polyphenolic compound found in magnolia bark, is known for its health-promoting activities and multidirectional beneficial effects on the body. Accordingly, the goal of this review is to systematize the available scientific literature on its beneficial effects on type 2 diabetes and its complications. Taking the above into consideration, the article collects data on the favorable effects of magnolol on parameters related to glycemia, lipid metabolism, or oxidative stress in the course of diabetes. After careful analysis of many scientific articles, it can be concluded that this lignan is a promising agent supporting the conventional therapies with antidiabetic drugs in order to manage diabetes and diabetes-related diseases.

Synthesis, α-amylase and α-glucosidase inhibition and molecular docking studies of indazole derivatives

Herein, we report the synthesis and inhibitory potential of indazole (Methyl 1H-indazole-4-carboxylate) derivatives (1-13) against α-amylase and α-glucosidase enzymes. The described derivatives demonstrated good inhibitory potential with IC50 values, ranging between 15.04 ± 0.05 to 76.70 ± 0.06 µM ± SEM for α-amylase and 16.99 ± 0.19 to 77.97 ± 0.19 µM ± SEM for α-glucosidase, respectively. In particular, compounds (8-10 and 12) displayed significant inhibitory activities against both the screened enzymes, with their inhibitory potential comparable to the standard acarbose (12.98 ± 0.03 and 12.79 ± 0.17 µM ± SEM, respectively). Additionally, the influence of different substituents on enzyme inhibition activities was assessed to study the structure activity relationships. Molecular docking simulations were performed to rationalize the binding of derivatives/compounds with enzymes. All the synthesized derivatives (1-13) were characterized with the aid of spectroscopic instruments such as 1H-NMR, 13C-NMR, HR-MS, elemental analysis and FTIR.Communicated by Ramaswamy H. Sarma.

Novel tetrahydrobenzo[b]thiophen-2-yl)urea derivatives as novel α-glucosidase inhibitors: Synthesis, kinetics study, molecular docking, and in vivo anti-hyperglycemic evaluation

α-Glucosidase inhibitors, which can inhibit the digestion of carbohydrates into glucose, are one of important groups of anti-type 2 diabetic drugs. In the present study, we report our effort on the discovery and optimization of α-glucosidase inhibitors with tetrahydrobenzo[b]thiophen-2-yl)urea core. Screening of an in-house library revealed a moderated α-glucosidase inhibitors, 5a, and then the following structural optimization was performed to obtain more efficient derivatives. Most of these derivatives showed increased inhibitory activity against α-glucosidase than the parental compound 5a (IC₅₀ of 26.71 ± 1.80 μM) and the positive control acarbose (IC₅₀ of 258.53 ± 1.27 μM). Among them, compounds 8r (IC₅₀ = 0.59 ± 0.02 μM) and 8s (IC₅₀ = 0.65 ± 0.03 μM) were the most potent inhibitors, and showed selectivity over α-amylase. The direct binding of both compounds with α-glucosidase was confirmed by fluorescence quenching experiments. Kinetics study revealed that these compounds were non-competitive inhibitors, which was consistent with the molecular docking results that compounds 8r and 8s showed high preference to bind to the allosteric site instead of the active site of α-glucosidase. In addition, compounds 8r and 8s were not toxic (IC₅₀ > 100 μM) towards LO2 and HepG2 cells. Finally, the in vivo anti-hyperglycaemic activity assay results indicated that compounds 8r could significantly decrease the level of plasma glucose and improve glucose tolerance in SD rats treated with sucrose. The present study provided the tetrahydrobenzo[b]thiophen-2-yl)urea chemotype for developing novel α-glucosidase inhibitors against type 2 diabetes.