Tyramine Derivatives as Potent Therapeutics for Type 2 Diabetes: Synthesis and In Vitro Inhibition of α-Glucosidase Enzyme.

BACKGROUND: Tyramine derivatives 3-16 were prepared and tested first time for their α- glucosidase (Sources: Saccharomyces cerevisiae) inhibitory activity by using an in vitro mechanismbased biochemical assay. All the compounds were found to be new, except compounds 3, 10-12 and 16. OBJECTIVE: In continuation of our research to synthesize and identify potent inhibitors of α-glucosidase enzyme, we intended to synthesize new inhibitors of α-glucosidase enzyme with enhanced efficacy in order to provide the basis for the better treatment of the type-II diabetic. METHODS: Tyramine (1) was allowed to react with a variety of aryl chlorides (2) to yield the corresponding amides. Synthesized compounds were then purified through normal phase column chromatography. Compounds 3-16 were then assessed for their α-glucosidase inhibitory activity in an in vitro biochemical assay. The cytotoxicity of compounds 3-16 was determined by using 3T3 mouse fibroblast cell lines. RESULTS: Compounds 3-5, 8, 13, and 15-16 were found to be more active (IC50 = 103.1±0.46, 37.3±4.51, 56.7±4.2, 23.9±2.31, 43.6±2.88, 55.8±1.73, and 38.2±0.86 µM, respectively) than the acarbose, the standard inhibitor of α-glucosidase enzyme, (IC50= 840.0±1.73 µM). To determine the dissociation constants and mode of inhibition, the kinetic studies were also performed for compounds 4 and 8 (the most potent inhibitors). It was observed that compounds 4 and 8 possess noncompetitive properties as the inhibitors of α-glucosidase. All the compounds were found to be noncytotoxic, except 5 and 12 (IC50= 14.7± 0.24 and 6.6± 0.38 µM, respectively). CONCLUSION: The current study gives the facile synthesis and identification of potent inhibitors of α- glucosidase. The new inhibitors reported here may be investigated further for the designing and development of novel anti-diabetic agents.

2-Mercapto Benzothiazole Derivatives: As Potential Leads for the Diabetic Management.

BACKGROUND: Results of our previous studies on antiglycation activity, and the noncytotoxicity of 2-mercapto benzothiazoles, encouraged us to further widen our investigation towards the identification of leads against diabetes mellitus. METHODS: 33 derivatives of 2-mercapto benzothiazoles 1-33 were evaluated for in vitro α- glucosidase inhibitory activity. Mode of inhibition was deduced by kinetic studies. To predict the interactions of 2-mercapto benzothiazole derivatives 1-33 with the binding pocket of α-glucosidase enzyme, molecular docking studies were performed on the selected inhibitors. RESULTS: Compounds 2-4, 6-7, 9-26, 28 and 30 showed many folds potent α-glucosidase inhibitory activity in the range of IC50 = 31.21-208.63 µM, as compared to the standard drug acarbose (IC50 = 875.75 ± 2.08 µM). It was important to note that except derivative 28, all other derivatives were also found previously to have antiglycating potential in the range of IC50 = 187.12-707.21 µM. CONCLUSION: A number of compounds were identified as dual nature as antiglycating agent and α- glucosidase inhibitors. These compounds may serve as potential lead candidates for the management of diabetes mellitus.

Synthesis, and In Vitro and In Silico α-Glucosidase Inhibitory Studies of 5-Chloro-2-Aryl Benzo[d]thiazoles.

Twenty-five derivatives of 5-chloro-2-aryl benzo[d]thiazole (1-25) were synthesized and evaluated for their α-glucosidase (S. cerevisiae EC 3.2.1.20) inhibitory activity in vitro. Among them eight compounds showed potent activity with IC50 values between 22.1 ±â€¯0.9 and 136.2 ±â€¯5.7 µM, when compared with standard acarbose (IC50 = 840 ±â€¯1.73 µM). The most potent compounds 4, 9, and 10 showed IC50 values in the range of 22.1 ±â€¯0.9 to 25.6 ±â€¯1.5 µM. Compounds 2, 5, 11, and 19 showed IC50 values within the range of 40.2 ±â€¯0.5 to 60.9 ±â€¯2.0 µM. Compounds 1 and 3 were also found to be good inhibitors with IC50 values 136.2 ±â€¯5.7 and 104.8 ±â€¯9.9 µM, respectively. Their activities were compared with α-glucosidase inhibitor drug acarbose (standard) (IC50 = 840 ±â€¯1.73 µM). The remaining compounds were inactive. Structure-activity relationships (SAR) have also been established. Kinetics studies indicated compounds 2, 3, 10, 19, and 25 to be non-competitive, while 1, 5, 9, and 11 as competitive inhibitors of α-glucosidase enzyme. All the active compounds (1-5, 9-11, and 19) were also found to be non-cytotoxic, in comparison to the standard drug i.e., doxorubicin (IC50 = 0.80 ±â€¯0.12 µM) in MTT assay. Furthermore, molecular interactions of active compounds with the enzyme binding sites were predicted through molecular modeling studies.

New carbazole linked 1,2,3-triazoles as highly potent non-sugar α-glucosidase inhibitors.

In the present study, a series of new carbazole linked 1H-1,2,3-triazoles (2-27) were synthesized via click reaction of N-propargyl-9H-carbazole (1) and azides of appropriate acetophenones and heterocycles. Synthesized carbazole triazoles including 7, 9, 10, 19, 20, and 23-26 (IC50=0.8±0.01-100.8±3.6µM), exhibited several folds more potent α-glucosidase inhibitory in vitro activity as compared to standard drug, acarbose. Compounds 2-5, 7-13, and 17-27 did not show any cytotoxicity against 3T3 cell lines, except triazoles 6, and 14-16. Among the series, carbazole triazoles 23 (IC50=1.0±0.057µM) and 25 (IC50=0.8±0.01µM) were found to be most active, and could serve as an attractive building block in the search of new non-sugar derivatives as anti-diabetic agents.

In vitro α-Glucosidase Inhibition by Non-sugar based Triazoles of Dibenzoazepine, their Structure-Activity Relationship, and Molecular Docking.

BACKGROUND: α-Glucosidase inhibitors (AGIs) have been reported for their clinical potential against postprandial hyperglycemia, which is responsible for the risks associated with diabetes mellitus 2 and cardiovascular diseases (CVDs). Besides, a number of compounds have been reported as potent AGIs, several side effects are associated with them. METHODS: The aim of present work is to explore new and potent molecules as AGIs. Therefore, a library of dibenzoazepine linked triazoles (1-15) was studied for their in vitro α-glucosidase inhibitory activity. The binding modes of potent compounds in the active site of α-glucosidase enzyme were also explored through molecular docking studies. RESULTS AND CONCLUSION: Among the reported triazoles, compounds 3-9, 11, and 13 (IC50 = 6.0 ± 0.03 to 19.8 ± 0.28 µM) were found to be several fold more active than the standard drug acarbose (IC50 = 840 ± 1.73 µM). Compound 5 (IC50 = 6.0 ± 0.03 µM) was the most potent AGIs in the series, about 77- fold more active than acarbose. Therefore, dibenzoazepine linked-triazoles described here can serve as leads for further studies as new non-sugar AGIs.

A concise synthesis and evaluation of new malonamide derivatives as potential α-glucosidase inhibitors.

A series of new malonamide derivatives were synthesized by Michael addition reaction of N(1),N(3)-di(pyridin-2-yl)malonamide into α,ß-unsaturated ketones mediated by DBU in DCM at ambient temperature. The inhibitory potential of these compounds in vitro, against α-glucosidase enzyme was evaluated. Result showed that most of malonamide derivatives were identified as a potent inhibitors of α-glucosidase enzyme. Among all the compounds, 4K (IC50=11.7 ± 0.5 µM) was found out as the most active one compared to standard drug acarbose (IC50=840 ± 1.73 µM). Further cytotoxicity of 4a-4m were also evaluated against a number of cancer and normal cell lines and interesting results were obtained.

Ultrasonic synthesis of tyramine derivatives as novel inhibitors of α-glucosidase in vitro.

Tyramine derivatives 3-27 were synthesized by using conventional and environmental friendly ultrasonic techniques. These derivatives were then evaluated for the first time for their α-glucosidase (Sources: Saccharomyces cerevisiae and mammalian rat-intestinal acetone powder) inhibitory activity by using in vitro mechanism-based biochemical assays. Compounds 7, 14, 20, 21 and 26 were found to be more active (IC50 = 49.7 ± 0.4, 318.8 ± 3.7, 23.5 ± 0.9, 302.0 ± 7.3 and 230.7 ± 4.0 µM, respectively) than the standard drug, acarbose (IC50 = 840.0 ± 1.73 µM (observed) and 780 ± 0.028 µM (reported)) against α-glucosidase obtained from Saccharomyces cerevisiae. Kinetic studies were carried out on the most active members of the series in order to determine their mode of inhibition and dissociation constants. Compounds 7, 20 and 26 were found to be the competitive inhibitors of α-glucosidase. These compounds were also screened for their protein antiglycation, and dipeptidyl peptidase-IV (DPP-IV) inhibitory activities. Only compounds 20, 22 and 27 showed weak antiglycation activity with IC50 values 505.27 ± 5.95, 581.87 ± 5.50 and 440.58 ± 2.74 µM, respectively. All the compounds were found to be inactive against DDP-IV enzyme. Inhibition of α-glucosidase, DPP-IV enzymes and glycation of proteins are valid targets for the discovery of antidiabetic drugs. Cytotoxicity of compounds 3-27 was also evaluated by using mouse fibroblast 3T3 cell lines. All the compounds were found to be noncytotoxic. The current study describes the synthesis α-glucosidase inhibitory activity of derivatives, based on a natural product tyramine template. The compounds reported here may serve as the starting point for the design and development of novel α-glucosidase inhibitors as antidiabetic agents.

Dihydropyrano [2,3-c] pyrazole: Novel in vitro inhibitors of yeast α-glucosidase.

Inhibition of α-glucosidase enzyme activity is a reliable approach towards controlling post-prandial hyperglycemia associated risk factors. During the current study, a series of dihydropyrano[2,3-c] pyrazoles (1-35) were synthesized and evaluated for their α-glucosidase inhibitory activity. Compounds 1, 4, 22, 30, and 33 were found to be the potent inhibitors of the yeast α-glucosidase enzyme. Mechanistic studies on most potent compounds reveled that 1, 4, and 30 were non-competitive inhibitors (Ki=9.75±0.07, 46±0.0001, and 69.16±0.01µM, respectively), compound 22 is a competitive inhibitor (Ki=190±0.016µM), while 33 was an uncompetitive inhibitor (Ki=45±0.0014µM) of the enzyme. Finally, the cytotoxicity of potent compounds (i.e. compounds 1, 4, 22, 30, and 33) was also evaluated against mouse fibroblast 3T3 cell line assay, and no toxicity was observed. This study identifies non-cytotoxic novel inhibitors of α-glucosidase enzyme for further investigation as anti-diabetic agents.

New α-glucosidase inhibiting anthracenone from the barks of Harungana madagascariensis Lam.

Two new 10-hydroxy-9(10H)-anthracenone, madagascenone A (1) and B (2), were isolated from the barks of Harungana madagascariensis Lam. The structures of the compounds were determined using 1D- and 2D-NMR and mass spectroscopic techniques. Both of the compounds showed an in vitro α-glucosidase inhibition with IC50 = 69.9 ± 4.21 and 122.3 ± 1.13 µM, respectively, more potent than the standard acarbose (IC50 = 840 ± 1.23 µM).

2-Arylquinazolin-4(3H)-ones: A new class of α-glucosidase inhibitors.

Twenty-five derivatives of 2-arylquinazolin-4(3H)-ones (1-25) were evaluated for their yeast (Saccharomyces cerevisiae) α-glucosidase inhibitory activities. All synthetic compounds, except 1 and 6, were found to be several hundred fold more active (IC50 values in the range of 0.3±0.01-117.9±1.76µM), than the standard drug, acarbose (IC50=840±1.73µM). The enzyme kinetic studies on the most active compounds 12, 4, 19, and 13 were performed for the determination of their modes of inhibition and dissociation constants Ki. Study of the modes of inhibition of compounds 12, and 4 were also performed using molecular modeling techniques. In brief, current study identifies a novel class of α-glucosidase inhibitors which can be further studied for the treatment of hyperglycemia and obesity.

Evaluation of 2-indolcarbohydrazones as potent α-glucosidase inhibitors, in silico studies and DFT based stereochemical predictions.

2-Indolcarbohydrazones 1-28 were synthesized and evaluated for their α-glucosidase inhibitory potential. A varying degree of inhibitory potential with IC50 values in the range of 2.3±0.11-226.4±6.8µM was observed while comparing these outcomes with the standard acarbose (IC50=906.0±6.3µM). The stereochemistry of ten (10) randomly selected compounds (1, 3, 6, 8, 12, 18, 19, 23, 25 and 28) was predicted by Density Functional Theory (DFT). The stability of E isomer was deduced by comparing the calculated and experimental vibration modes of νCO, νNC and νCH (CH in NCH-R). It was observed that except compound 18, all other compounds were deduced to have E configuration while molecular modeling studies revealed the key interactions between enzyme and synthesized compounds.