Human Pancreatic Α-amylase Research Articles

Anti-diabetic potential, crystal structure, molecular docking, DFT, and optical-electrochemical studies of new dimethyl and diethyl carbamoyl-N, N′-disubstituted based thioureas

Four new thiourea derivatives containing dimethyl and diethyl carbamoyl scaffolds have been synthesized by multicomponent methodology. Docking analysis of α-amylase with thioureas showed that the 3-(3-(dimethyl carbamoyl) thioureido) benzoic acid can effectively bind to the hydrophobic cavity and form hydrogen bonding effectively with the HIS A:103, ASP A:326, ARG A:407, ARG A:411 of human pancreatic α-amylase. The anti-diabetic studies revealed that compound DM3A (IC50 = 19.26 ± 0.23) followed by 3-(3-(diethyl carbamoyl) thioureido) benzoic acid (IC50 = 21.89 ± 0.06) were more potent against α-amylase and α-glucosidase, comparable to that of standard drug acarbose. DM3A displayed best antioxidant potential (DPPH IC50 = 7.97 ± 0.23 µg/ml, TAC IC50 = 8.19 ± 0.64 µg/ml, Total reducig power IC50 = 8.19 ± 0.23 µg/ml) but insignificant hemolytic activity. Further, DFT, molecular electrostatic potential and optical-electrochemical studies were also performed to support the in-silico and in-vitro biological screening results. Finally, the pharmacological profile revealed that DM3A might be possible lead compound. Further, in-vivo research is recommended to fully determine the biological spectrum of these newly synthesized thiourea derivatives.

Identification of novel potential anti-diabetic candidates targeting human pancreatic α-amylase and human α-glycosidase: an exhaustive structure-based screening

Diabetes is a major health issue that has reached alarming levels, affecting nearly half a billion people worldwide. It is a serious and long-term medical condition that has a major impact on the lives and well-being of individuals, families, and societies. Diabetes is among the top 10 diseases responsible for death among adults, with an expected increase to 10.2% (578 million) by 2030 and 10.9% (700 million) by 2045. Carbohydrates are absorbed into the body upon hydrolysis by human pancreatic α-amylase and other intestinal enzymes, such as human α-glucosidase. α-Amylase and α-glucosidase are well-validated therapeutic targets in the treatment of type II diabetes mellitus (T2DM) and play a vital role in modulating blood glucose levels after a meal. Herein, we report novel and diverse molecules identified as potential candidates that are predicted to have affinities for α-amylase and α-glucosidase. These molecules were identified via hierarchical multistep docking of small-molecule databases with estimated binding free energies. A Glide XP score cutoff of –8.0 kcal/mol was implemented to filter out non-potential molecules from the database. Four molecules, amb22034702, amb18105639, amb17153304, and amb9760832, were identified after an exhaustive computational study involving the evaluation of binding interactions and assessment of the pharmacokinetics and toxicity profiles. In-depth analysis of protein–ligand interactions was performed using a 100 ns molecular dynamics (MD) simulation to establish dynamic stability. Furthermore, MM-GBSA based binding free energies were computed for 1000 trajectory snapshots to ascertain the strong binding affinities of these molecules for α-amylase and α-glucosidase. The identified molecules can be considered as promising candidates for further drug development through necessary experimental assessments.

Design and synthesis of epigallocatechin (EGC) analogs selective to inhibit α-amylase over α-glucosidases via the incorporation of caffeine acid and its derivatives

Natural products are a promising and underappreciated reservoir for the preferred chemical scaffolds in the search of antidiabetic drugs. In this study twenty-one EGC-based derivatives selective to inhibit human pancreatic α-amylase (HPA), the enzyme at the top of the starch digestion pyramid, have been designed and synthesized in terms of the lead myricetin-caffeic acid conjugate 1 reported ever. We focus on methylation of caffeic acid, length of a liker, a double bond contained in the linker on the inhibition activity and selectivity of EGC-based conjugates. As a result, methylation of caffeic acid and the length of a linker affect significantly the activity and selectivity of EGC-based conjugates, but the effect of a double in caffeic acid is limited. Conjugate 2a-1 having a six-carbon-atom linker fused to EGC and caffeic acid demonstrates the most ponent inhibitory activity to HPA and its selectivity towards HPA over α-glucosidase by far superior to that construct 1. Molecular docking studies reveal that conjugate 2a-1 accommodates well to the active site of HPA with four hydrogen bonds in the form of the preorganization of two moieties EGC and caffeic acid via π-stacking interaction. Collectively, conjugating caffeic acid and EGC with an appropriate linker possibly provides a new strategy for finding the specific HPA inhibitors in the discovery of anti-diabetes mellitus drugs.

Molecular docking of phenolic compounds and screening of antioxidant and antidiabetic potential of Olea europaea L. Ethanolic leaves extract

Oxidative stress has a crucial role in diabetic pathophysiology, therefore consuming naturally derived antioxidants as a remedial target. This study examines the naturally occurring antioxidant and antidiabetic of Olea europaea L. ethanolic leaves extract. Olea europaea L. leaves were macerated (OLE) by using absolute ethanol. Phytochemical and physiochemical analysis of OLE was screened using standard methods. The antioxidant effects were examined by DPPH (1, 1-diphenyl-2-picrylhydrazil) radical scavenging assay. In vitro antidiabetic was assayed by α-amylase enzyme inhibition study. Ethanolic extraction of OLE by maceration technique, 10% yield. Loss on drying, foreign organic matters and total ash value of OLE showed 2%, 0.2% and 16.5%, respectively. Phytochemical test on OLE confirmed saponin, flavonoid, glycoside, tannin, phenol and carbohydrate presences. The total phenolic and flavonoid contents of OLE is 490 mg GAE/g and 855 mg RUE/g of extract, respectively. OLE (IC50 38.37 ± 0.26 µg/ml) showed functional DPPH scavenging assay comparable to ascorbic acid (IC50 30.37 ± 0.17 µg/ml). In the alpha-amylase inhibitory activity, Acarbose showed an IC50 value of 20.06 ± 0.19 µg/ml, while OLE portrayed an IC50 value of 37.99 ± 0.15 µg/ml. The kinetic studies revealed that all samples at high concentrations reacted within a very short time, and a steady state was reached almost immediately. The lowest concentration showed slow kinetic behaviour implied longer periods before the constant state was reached. Molecular docking studies evidenced that most of the phenolic compounds of OLE interact with the active site of Human pancreatic α-amylase through the hydrogen bonding and hydrophobic interaction confirming the alpha-amylase inhibitory effect. The results suggest that Olea europaea L. has been a conceivable natural bioactive source as an antioxidant and an antidiabetic agent.

Exploring biological efficacy of novel benzothiazole linked 2,5-disubstituted-1,3,4-oxadiazole hybrids as efficient α-amylase inhibitors: Synthesis, characterization, inhibition, molecular docking, molecular dynamics and Monte Carlo based QSAR studies

In an effort to explore a class of novel antidiabetic agents, we have made an effort to synergize the α-amylase inhibitory potential of 1,3-benzothiazole and 1,3,4-oxadiazole scaffolds by combining the two into a single structure via an ether linkage. The structure of synthesized benzothiazole clubbed oxadiazole derivatives are established by different spectral techniques. The synthesized hybrids are evaluated for their in vitro inhibitory potential against α-amylase. Compound 8f is found to be the most potent with a significant inhibition (87.5 ± 0.74% at 50 μg/mL, 82.27 ± 1.85% at 25 μg/mL and 79.94 ± 1.88% at 12.5 μg/mL) when compared to positive control acarbose (77.96 ± 2.06%, 71.17 ± 0.60%, 67.24 ± 1.16% at 50 μg/mL, 25 μg/mL and 12.5 μg/mL concentration). Molecular docking of the most potent enzyme inhibitor, 8f, shows promising interaction with the binding site of biological macromolecule Aspergillus oryzae α-amylase (PDB ID: 7TAA) and human pancreatic α-amylase (PDB ID: 3BAJ). To a step further, in-depth QSAR studies show a significant correlation between the experimental and the predicted inhibitory activities with the best Rvalidation2= 0.8701. The developed QSAR model can provide ample information about the structural features responsible for the increase and decrease of inhibitory activity. The mechanistic interpretation of the structure-activity relationship (SAR) is done with the help of combined computational calculations i.e. molecular docking and QSAR. Finally, molecular dynamic simulations are performed to get an insight into the binding mode of the most potent derivative with α-amylase from A. oryzae (PDB ID: 7TAA) and human pancreas (PDB ID: 3BAJ).

Antidiabetic bioactive compounds from Tetrastigma angustifolia (Roxb.) Deb and Oxalis debilis Kunth.: Validation of ethnomedicinal claim by in vitro and in silico studies

Tetrastigma angustifolia (Roxb.) Deb is an evergreen shrub belonging to the family Vitaceae. This plant species has been used for thousand years in Ayurvedic medicine. Ethnomedicinal study also documents the use of T. angustifolia leaves in the management of diabetes. On the other hand, Oxalis debilis Kunth. is a tristylous plant commonly known as pink woodsorrel belong to the family Oxalidaceae. This plant has been used traditionally for the treatment of dysentery and diarrhea. Ethnobotanical study also reports the use of leaf decoction of O. debilis in the treatment of diabetes. In our earlier work, the antidiabetic activity of hydro-alcoholic leaf extracts of T. angustifolia and O. debilis have been reported. In spite of ethnomedicinal implications and several scientific studies in the recent past, phytochemical investigations in support of the antidiabetic potential of these plant species are yet to be explored. Therefore, the present study was aimed at the isolation of bioactive phytoconstituents as antidiabetic principle(s) from T. angustifolia and O. debilis leaves. In this paper, two bioactive compounds, namely apigenin derivative (AGD) and stigmasterol (STM) were isolated from the methanolic leaf extracts of T. angustifolia and O. debilis, respectively by column chromatographic technique. The structures of the isolated compounds were established by spectroscopic/ spectrometric techniques including FT-IR, 1H NMR and 13C NMR and Mass. The isolated flavonoids were identified as 8-hydroxyapigenin 7-O-β-D-glucopyranoside, a derivative of apigenin (AGD) and stigmasta-5,22-dien-3β-ol i.e., stigmasterol (STM). The antidiabetic potential of AGD and STM was evaluated by in vitro α-glucosidase and α-amylase inhibitory assays. To validate the antidiabetic efficacy, molecular docking and dynamics studies were performed using AutoDock Vina and GROMACS software. In vitro assays revealed the antidiabetic potential of AGD and STM with α-glucosidase and α-amylase inhibitory activities. From docking and MD simulation studies, promising binding affinity of AGD and STM for human lysosomal α-glucosidase (5NN8) and human pancreatic α-amylase enzymes (1B2Y) with favorable binding modes, stable protein-ligand complexes and well defined protein-ligand interactions were observed. Based on in vitro and in silico studies, our study reports the antidiabetic potential of the isolated apigenin derivative, AGD (a new flavonoid molecule) and stigmasterol, STM (an existing plant sterol) with α-glucosidase and α-amylase inhibitory activities. However, the flavonoid molecule, AGD possesses better antidiabetic profile than the steroid molecule, STM particularly against human α-amylase enzyme. Our present investigation successfully validates the traditional as well as ethnomedicinal claims of T. angustifolia and O. debilis as antidiabetic medicines.

A facile approach synthesis of benzoylaryl benzimidazole as potential α-amylase and α-glucosidase inhibitor with antioxidant activity

Synthetic routes to a series of benzoylarylbenzimidazol 3a-h have been derived from 3,4-diaminobenzophenone and an appropriate arylaldehyde in the presence of ammonium chloride or a mixture of ammonium chloride and sodium metabisulfite as catalyst. The antioxidant activity of targeted compounds 3a-h has been measured by four different methods and the overall antioxidant evaluation of the compounds indicated the significant MCA, FRAP, and (DPPH-SA) of the compounds except for the compound 3h. In vitro antidiabetic assay of α-amylase and α-glucosidase suggest a good to excellent activity for most tested compounds. The target benzimidazole 3f containing hydroxyl motif at para-position of phenyl revealed an important activity inhibitor against α- amylase (IC50 = 12.09 ± 0.38 µM) and α-glucosidase (IC50 = 11.02 ± 0.04 µM) comparable to the reference drug acarbose. The results of the anti hyperglycemic activity were supported by means of in silico molecular docking calculations showing strong binding affinity of compounds 3a-h with human pancreatic α-amylase (HPA) and human lysosomal acid-α-glucosidase (HLAG) active sites that confirm a good to excellent activity for most of tested compounds.

Bioactive Antidiabetic Flavonoids from the Stem Bark of Cordia dichotoma Forst.: Identification, Docking and ADMET Studies

Cordia dichotoma Forst. (F. Boraginaceae) has been traditionally used for the management of a variety of human ailments. In our earlier work, the antidiabetic activity of methanolic bark extract of C. dichotoma (MECD) has been reported. In this paper, two flavonoid molecules were isolated (by column chromatography) and identified (by IR, NMR and mass spectroscopy/spectrometry) from the MECD with an aim to investigate their antidiabetic effectiveness. Molecular docking and ADMET studies were carried out using AutoDock Vina software and Swiss ADME online tool, respectively. The isolated flavonoids were identified as 3,5,7,3′,4′-tetrahydroxy-4-methoxyflavone-3-O-l-rhamnopyranoside and 5,7,3′-trihydroxy-4-methoxyflavone-7-O-l-rhamnopyranoside (quercitrin). Docking and ADMET studies revealed the promising binding affinity of flavonoid molecules for human lysosomal α-glucosidase and human pancreatic α-amylase with acceptable ADMET properties. Based on computational studies, our study reports the antidiabetic potential of the isolated flavonoids with predictive pharmacokinetics profile.

Synthesis, characterization, in vitro and in silico studies of bis-hydrazone complexes derived from terephthalic dihydrazide

Bis-hydrazone of terephthalic dihydrazide was designed and synthesized using terephthalic dihydrazide and picolinaldehyde. Various bioactive benzoic acids such as benzoic acid, aspirin and salicylic acid were selected as a counter ion moiety for preparing bis-hydrazone complexes (BHCs). The prepared BHCs were well characterized using spectroscopic techniques like 1H NMR, 13C NMR and FT-IR. The BHCs showed very good in vitro antidiabetic activity in the α-amylase enzyme inhibitory method and moderate activity in the α-glucosidase inhibitory method. The molecular docking interactions of BHCs were performed against the human pancreatic α-amylase enzyme (1HNY.pdb) and homology model of α-glucosidase (3A4A.pdb) to prove the enzyme inhibitory activity. The BHCs showed very good binding energy, the complex BHB showed 5 numbers of hydrogen bonding interactions with amino acid residues of 1HNY.pdb and BHS showed 5 numbers of hydrogen bonding interactions with 3A4A.pdb. Further, the molecular orbital studies were performed using density functional theory calculations in order to support the docking study.

Synthesis, α-glucosidase and α-amylase inhibitory activities, acute toxicity and molecular docking studies of thiazolidine-2,4-diones derivatives

In the present study, a series of thiazolidine-2,4-diones derivatives (3a–3e) and (4a–4e) were synthesized and characterized by 1H NMR, 13C NMR and ESI-MS spectrometry. All compounds were screened for their α-glucosidase and α-amylase inhibitory activities. In vitro biological investigations revealed that most of compounds were active against α-glucosidase with IC50 values in the range of 43.85 ± 1.06 to 380.10 ± 1.02 µM, and α-amylase with IC50 in the range of 18.19 ± 0.11 to 208.10 ± 1.80 µM. Some of the tested compounds were found to be more potent inhibitors than the clinical drug Acarbose (IC50glucosidase = 97.12 ± 0.35 µM and IC50amylase = 2.97 ± 0.004 μM). The lead compounds were evaluated for their acute toxicity on Swiss mice and found to be completely non-toxic with LD > 2000 mg/kg BW. Furthermore, the Structure–activity relationship (SAR) and the binding interactions of all compounds with the active site of α-glucosidase and α-amylase were confirmed through molecular docking and stabilizing energy calculations. This study has identified the inhibitory potential a new class of synthesized thiazolidine-2,4-diones in controlling both hyperglycemia and type 2 diabetes mellitus. Furthermore, the theoretical binding mode of the target molecules was evaluated by molecular docking studies against the 3D Crystal Structure of human pancreatic α-amylase (PDB ID: 1B2Y) and α-glucosidase (PDB ID: 3W37) Communicated by Ramaswamy H. Sarma

Improvement in serum amylase and glucose levels in diabetic rats on oral administration of bisdemethoxycurcumin from Curcuma longa and limonoids from Azadirachta indica.

Curcuma longa and Azadirachta indica are traditionally used in Indian cuisine and Ayurvedic medicine as nutraceuticals against diabetes. The crude C.longa isopropanol extract, bisdemethoxycurcumin (BDMC), the purified bioactive component from C.longa, and limonoids azadiradione, gedunin from A.indica, are able to inhibit in vitro the antidiabetic target human pancreatic α-amylase independently. However, no reports on their in vivo efficacy in animal models exist. Thus, the antidiabetic effect of these orally administered human pancreatic α-amylase inhibitors was performed on streptozotocin-induced Sprague-Dawley rats. Initially, the normal rats were treated with test compounds (10-100mg/kg of body weight) in corn oil (5ml/kg), and as no lethality was observed in these doses, further studies were carried out with lowest concentration of 10mg/kg of body weight. A reduction in area under curve (AUC) suggested glucose-lowering effect of these compounds in starch fed diabetic rats. The efficacy study showed a significant improvement in body weight, blood glucose levels, serum amylase, and fructosamine levels as well in other serum parameters associated with diabetes with respect to liver and renal functions. Hence, under in vivo conditions, inhibition of α-amylase activity by BDMC and limonoids affirms it as one of the mechanisms of action resulting in reduction of blood glucose levels. PRACTICAL APPLICATIONS: Bisdemethoxycurcumin from C.longa and limonoids, namely, azadiradione and gedunin, from A.indica are potent inhibitors of the antidiabetic target human pancreatic α-amylase. Oral Starch Tolerance Test (OSTT) and 28-day efficacy study to check the effect of these orally administered inhibitors in diabetic rat models showed significant improvements in serum blood glucose and amylase levels as well as in other diabetes related serum parameters, namely, bilirubin, lipids, lactate dehydrogenase, alkaline phosphatase, and urea. The study contributes to understanding the action and efficacy of these pancreatic α-amylase inhibitors and suggests a potential role for them as nutraceuticals/therapeutics in management of post-prandial hyperglycemia.

Molecular docking and molecular dynamics studies of bioactive compounds contained in noni fruit (Morinda citrifolia L.) against human pancreatic α-amylase

Human pancreatic α-amylase inhibition is currently a promising therapeutic target against type 2 diabetes (DMT2) because it can reduce aggressive digestion of carbohydrates into absorbable monosaccharides. In Indonesia, medicinal plants, e.g. Morinda citrifolia fruit, have been empirically utilized as a blood-sugar reducer, however, the inhibitory activity of compounds in this plant against human pancreatic α-amylase is still limited or none. Therefore, this study aimed to test the interaction of 7 compounds (americanin, asperulosidic acid, damnacanthal, quercetin, rutin, scopoletin, and ursolic acid) contained in noni fruit against human pancreatic α-amylase by molecular docking and molecular dynamics and compared their binding modes with that of acarbose. Results of the molecular docking simulation indicated that the ursolic acid compound possesses the best binding energy (-8.58 kcal/mol) and comparable to that of acarbose (-8.59 kcal/mol). The molecular dynamics study at 100 ns simulation, the values of RMSD, RMSF, the radius of gyration (Rg), the solvent-accessible surface area (SASA), principal component analysis (PCA), and MM-PBSA binding free energy were stable and identical to those of acarbose. It could be concluded that ursolic acid might be potential in inhibiting human pancreatic α-amylase, thus, potential to be developed as an anti-DMT2 drug candidate. Communicated by Ramaswamy H. Sarma

Insights into the Inhibition Mechanism of Human Pancreatic α-Amylase, a Type 2 Diabetes Target, by Dehydrodieugenol B Isolated from Ocimum tenuiflorum.

Use of human pancreatic α-amylase (HPA) inhibitors is one of the effective antidiabetic strategies to lower postprandial hyperglycemia via reduction in the dietary starch hydrolysis rate. Many natural products from plants are being studied for their HPA inhibitory activity. The present study describes isolation of dehydrodieugenol B (DDEB) from Ocimum tenuiflorum leaves using sequential solvent extraction, structure determination by one-dimensional (1D) and two-dimensional (2D) NMR analyses, and characterization as an HPA inhibitor using kinetics, binding thermodynamics, and molecular docking. DDEB uncompetitively inhibited HPA with an IC50 value of 29.6 μM for starch and apparent Ki′ of 2.49 and Ki of 47.6 μM for starch and maltopentaose as substrates, respectively. The circular dichroism (CD) study indicated structural changes in HPA on inhibitor binding. Isothermal titration calorimetry (ITC) revealed thermodynamically favorable binding (ΔG of −7.79 kcal mol–1) with a dissociation constant (Kd) of 1.97 μM and calculated association constant (Ka) of 0.507 μM. Molecular docking showed stable HPA–inhibitor binding involving H-bonds and Pi-alkyl, alkyl–alkyl, and van der Waals (vDW) interactions. The computational docking results support the noncompetitive nature of DDEB binding. The present study could be helpful for exploration of the molecule as a potential antidiabetic drug candidate to control postprandial hyperglycemia.

Grain Dimension, Nutrition and Nutraceutical Properties of Black and Red Varieties of Rice in India

Traditional colored rice varieties in India are the source of carbohydrates, phytochemicals and minerals. They facilitate the growth of probiotics in intestine and protect human from many chronic diseases. The present study investigated the nutritional properties such as total sugars, digestible sugars, resistant sugars, hydrolysis index, glycemic index and total proteins of thirteen colored varieties of rice in India. Nutraceutical properties like anti diabetic and prebiotic activity were investigated by standard methods. Chak hao poreiton and mappillai samba grains were 6.3 mm in length. Lowest length of 5.1 mm was recorded in 60 m Kuruvai. Among the rice varieties, mappillai samba has high concentration of digestible starch of 91% and Chak hao poreiton had low concentration of 62%. Resistant starch was 38% in Chak hao poreiton and 8% in mappillai samba. Lowest glycemic index of 52 and 53 were recorded in karuthakar poha and Chak hao poreiton respectively. Anthocyanin extracted from Chak hao poreiton inhibited 24% of human pancreatic α-amylase activity. It significantly increased the probiotic number from 0.15 CFU/mL to 1.95 CFU/mL. The study revealed that the black rice variety, Chak hao poreiton was rich in resistant starch and exhibited low glycemic index. The anthocyanins from Chak hao poreiton possessed significant antidiabetic and prebiotic activity. Molecular docking studies revealed the interaction of anthocyanin with pancreatic α-amylase, β-glucosidase and GLUT1.

Marsectohexol and other pregnane phytochemicals derived from Gongronema latifolium as α-amylase and α-glucosidase inhibitors: in vitro and molecular docking studies

This study employed in vitro and in silico techniques to screen isolated pregnane phytochemicals (P1–P4), as well as their source pregnane-rich chromatographic fractions, which were derived from Gongronema latifolium Benth (GLB), for their inhibitory potentials against α-amylase, α-glucosidase, and sucrase enzyme activities. The results show that, most pregnane-rich chromatographic fractions and isolated compounds exhibited good inhibitory activities against α-amylase, and α-glucosidase enzymes. Among the isolated compounds, marsectohexol (P2) is the most favourable structure that showed inhibition against α-amylase (IC50 = 3.712 µg/mL) when compared with the reference inhibitor, acarbose ((IC50 = 15.418 µg/mL). Based on negative and low value of ∆G (Gibb’s free energy), docking scores revealed that, marsectohexol has the highest binding affinity (− 8.8 kcal/mol) to human pancreatic α-amylase (HPA) as compared to the standard acarbose (− 8.1 kcal/mol). Marsectohexol and the other phytocompounds were also found to dock into the active site of HPA; interacting with key catalytic amino acid residues (ASP197, GLU233 and ASP300), which are known to involve in the nucleophilic, and the acid/base catalysis of the enzyme. Although, the pregnane phytocompounds have considerable high affinity binding to the human lysosomal α-glucosidase, they interacted with pockets other than the active site. In conclusion, at least, marsectohexol and three other constituent pregnane phytochemicals of GLB are potential inhibitors of the carbohydrate-hydrolyzing enzymes. These compounds may account for the anti-hyperglyceamic and antidiabetic potentials of this food herb.

Investigation of molecular docking, biological and DFT studies of Schiff base transition metal complexes

The Schiff base ligand obtained from the reaction of 2-amino-3-hydroxypyridine, 2,4,6-trihydroxy benzaldehyde is described. Cu(II), Ni(II), Co(II), and Zn(II)complexes have been analyzed by various spectroscopic techniques like FT-IR, UV-visible, mass spectrometry and NMR. Based on spectral data octahedral geometry has been assigned to the complexes. In the present study the prepared Schiff base ligand and all the metal complexes have been synthesized and studied for their in vitro anti diabetic, antioxidant and antibacterial activities. Geometry optimization and the chemical stability and reactivity of complexes clearly understood with help of frontier molecular orbital’s (HOMO-LUMO) using B3LYP/LACVP++ basis sets based on density functional theory. Furthermore, Molecular docking study of the Schiff base ligand and their metal (II) complexes showed good binding score with human pancreatic α-amylase (PDB: 1HNY).

Therapeutic potential of Chromolaena odorata phyto-constituents against human pancreatic α-amylase

Type II Diabetes Mellitus (DM) is caused by insulin resistance in peripheral tissue and impaired insulin secretion through a dysfunction of the pancreatic β-cell. Acarbose is an anti-DM drug, it is effective but its continuous use may lead to undesirable side effects. Hence, the development of novel drugs from natural source that have both anti-diabetic and anti-oxidant activities, with little or no side effect during long-term use is of great importance. To investigate the anti-DM and anti-oxidant phyto-constituents of Chromoleana odorata, e-pharmacophore model was generated using human pancreatic α–amylase (HPA) standard inhibitor, Acarbose to map important pharmacophoric features of HPA, and used to screen several phyto-constituents of C. odorata to match at least 4 sites of the generated hypothesis. Glide and Induced Fit Docking followed by Prime MM-GBSA calculation, drug-likeness and ADME studies were employed for high fitness (>1.0) compounds retrieved from e-pharmacophore screening process. The drug-likeness properties of the lead compounds, Quercetin and Ombuin were analyzed taking into account the Lipinski’s and Veber’s rules. Further, machine-learning approach was used to generate QSAR model. The computed model, kpls_desc_19 was used to predict the bioactivity (pIC50) of Quercetin and Ombuin. Phyto-constituents of C. odorata; Quercetin and Ombuin have shown better and promising results when compared to that of the standard, acarbose. Based on the present study, orally delivered Quercetin and Ombuin from C. odorata are relatively better inhibitor of HPA, thus they can be a useful therapeutic candidate in the management/treatment of DM when compared to acarbose. Communicated by Ramaswamy H. Sarma

Novel enantiopure isoxazolidine and C-alkyl imine oxide derivatives as potential hypoglycemic agents: Design, synthesis, dual inhibitors of α-amylase and α-glucosidase, ADMET and molecular docking study

In an effort to explore a new class of antidiabetic inhibitors, a new series of isoxazolidine and C-alkyl imine oxide derivatives scaffolds were designed, synthesized and fully characterized. The newly synthesized analogues were evaluated for their human pancreatic α-amylase (HPA) and human lysosomal acid-α-glucosidase (HLAG) inhibitory activities and have shown a higher potency than acarbose. The compounds 7b (23.1 ± 1.1 μM) and 7a (36.3 ± 1.6 μM) were identified as the potent HPA and HLAG inhibitors with inhibitory effect up to 9 and 21-fold higher than acarbose, respectively. Antihyperglycemic activity results were supported by molecular docking approach of the most potent compounds 7b and 7a showing stronger interactions with the active site of HPA and HLAG as well as by in silico absorption, distribution, metabolism, excretion and toxicity (ADMET) profile suggesting their satisfactory oral druglikeness without toxic effect. Therefore, it can be concluded that both 7b and 7a can be used as effective lead molecules for the development of HPA and HLAG inhibitors for the management of T2DM.

X-ray crystallographic structural studies of α-amylase I from Eisenia fetida.

The earthworm Eisenia fetida possesses several cold-active enzymes, including α-amylase, β-glucanase and β-mannanase. E. fetida possesses two isoforms of α-amylase (Ef-Amy I and II) to digest raw starch. Ef-Amy I retains its catalytic activity at temperatures below 10°C. To identify the molecular properties of Ef-Amy I, X-ray crystal structures were determined of the wild type and of the inactive E249Q mutant. Ef-Amy I has structural similarities to mammalian α-amylases, including the porcine pancreatic and human pancreatic α-amylases. Structural comparisons of the overall structures as well as of the Ca2+-binding sites of Ef-Amy I and the mammalian α-amylases indicate that Ef-Amy I has increased structural flexibility and more solvent-exposed acidic residues. These structural features of Ef-Amy I may contribute to its observed catalytic activity at low temperatures, as many cold-adapted enzymes have similar structural properties. The structure of the substrate complex of the inactive mutant of Ef-Amy I shows that a maltohexaose molecule is bound in the active site and a maltotetraose molecule is bound in the cleft between the N- and C-terminal domains. The recognition of substrate molecules by Ef-Amy I exhibits some differences from that observed in structures of human pancreatic α-amylase. This result provides insights into the structural modulation of the recognition of substrates and inhibitors.

Screening chemical inhibitors for alpha-amylase from leaves extracts of Murraya koenigii (Linn.) and Aegle marmelos L.

Aqueous leaves extracts of Murraya koenigii (M. koenigii) and Aegle marmelos (A. marmelos) were prepared and effect of the extracts on inhibiting alpha-amylase playing essential roles on converting starch into glucose have been examined using in vitro assays. Alpha amylase inhibitory assay was used to asses the in vitro antidiabetic activity of the extracts. Gas chromatography-mass spectrometry (GC-MS) analysis was performed to identify the volatile molecules of the extracts. Identified molecule were converted as ligand and docked against human pancreatic α-amylase (0.95Å; PDB ID: 5U3A) using Autodock tool. The data analyzes suggested that the alpha-amylase inhibition potential of the extract obtained from M.koenigii was stronger than that of the A.marmelos at low concentrations (<1mg/mL), whereas both the extracts depicted similar inhibition effects on the enzyme at high concentration (>1mg/mL). The phytochemicals present in both the plant extracts were identified by using their respective GC-MS data and the data analyzes revealed that the extracts of M.koenigii and A.Marmelos seemed to consist of about 20 and 24 diverse chemical molecules, respectively. Through the molecular docking studies, azulene of M.koenigii and hydroxycyclodecadiene of A.marmelos showed higher binding affinity on alpha-amylase. Concentration-dependent alpha-amylase inhibition effects of the extracts were observed and M.koenigii contains more alpha-amylase inhibitory effects due to the presence of azulene. This is primary lead to find out the better anti diabetic natural based drug to the society after clinical trial.