Hybrid bisindole-thiosemicarbazides analogs (1-18) were synthesized and screened for β-glucuronidase activity. All compounds showed varied degree of β-glucuronidase inhibitory potential when compared with standard d-saccharic acid 1,4-lactone (IC50=48.4±1.25μM). Compounds 4, 7, 9, 6, 5, 12, 17 and 18 showed exceptional β-glucuronidase inhibition with IC50 values ranging from 0.1 to 5.7μM. Compounds 1, 3, 8, 16, 13, 2 and 14 also showed better activities than standard with IC50 values ranging from 7.12 to 15.0μM. The remaining compounds 10, 11, and 15 showed good inhibitory potential with IC50 values 33.2±0.75, 21.4±0.30 and 28.12±0.25μM respectively. Molecular docking studies were carried out to confirm the binding interaction of the compounds.
Despite of many diverse biological activities exhibited by benzimidazole scaffold, it is rarely explored for the α-amylase inhibitory activity. For that purpose, 2-aryl benzimidazole derivatives 1-45 were synthesized and screened for in vitro α-amylase inhibitory activity. Structures of all synthetic compounds were deduced by various spectroscopic techniques. All compounds revealed inhibition potential with IC50 values of 1.48 ± 0.38-2.99 ± 0.14 μM, when compared to the standard acarbose (IC50 = 1.46 ± 0.26 μM). Limited SAR suggested that the variation in the inhibitory activities of the compounds are the result of different substitutions on aryl ring. In order to rationalize the binding interactions of most active compounds with the active site of α-amylase enzyme, in silico study was conducted.
We have synthesized oxadiazole derivatives (1-16), characterized by 1H NMR, 13C NMR and HREI-MS and screened for thymidine phosphorylase inhibitory potential. All derivatives display varied degree of thymidine phosphorylase inhibition in the range of 1.10 ± 0.05 to 49.60 ± 1.30 μM when compared with the standard inhibitor 7-Deazaxanthine having an IC50 value 38.68 ± 1.12 μM. Structure activity relationships (SAR) has been established for all compounds to explore the role of substitution and nature of functional group attached to the phenyl ring which applies imperious effect on thymidine phosphorylase activity. Molecular docking study was performed to understand the binding interaction of the most active derivatives with enzyme active site.
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.
Aim: To synthesize pyrrolopyridine-based thiazolotriazoles as a novel class of α-amylase and α-glucosidase inhibitors and to determine their enzymatic kinetics. Methodology: Pyrrolopyridine-based thiazolotriazole analogs (1-24) were synthesized and characterized through proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance and high-resolution electron ionization mass spectrometry. Results: All synthesized analogs displayed good inhibitory potential of α-amylase and α-glucosidase ranging 17.65-70.7 μM and 18.15-71.97 μM, respectively, compared with the reference drug, acarbose (11.98 μM and 12.79 μM). Analog 3 was the most potent among the synthesized analogs, having α-amylase and α-glucosidase inhibitory activity at 17.65 and 18.15 μM, respectively. The structure-activity relationship and binding modes of interactions between selected analogs were confirmed via docking and enzymatic kinetics studies. The compounds (1-24) were tested for cytotoxicity against the 3T3 mouse fibroblast cell line and were observed to be nontoxic.
Schiff bases of 3,4-dimethoxybenzenamine 1-25 were synthesized and evaluated for their antioxidant activity. All the synthesized compounds were characterized by various spectroscopic techniques. In addition, the characterizations of compounds 13, 15 and 16 were supported by crystal X-ray determinations and their geometrical parameters were compared with theoretical DFT calculations at the B3LYP level of theory. Furthermore, the X-ray crystal data of two non-crystalline compounds 8 and 18 were theoretically calculated and compared with the practical values of compounds 13, 15, 16 and found a good agreement. The compounds showed good DPPH scavenging activity ranging from 10.12 to 84.34 μM where compounds 1-4 and 6 showed stronger activity than the standard n-propyl gallate. For the superoxide anion radical assay, compounds 1-3 showed better activity than the standard.
The current study involves the synthesis of Schiff bases based on 1,2,4-triazoles skeleton and assessing their α-amylase and α-glucosidase profile. Furthermore, the precise structures of the synthesized derivatives were elucidated using various spectroscopic methods such as 1H-NMR, 13C-NMR and HREI-MS. Using glimepiride as the reference standard, the in vitro α-glucosidase and α-amylase inhibitory activities of the synthesized compounds were evaluated in order to determine their potential anti-diabetic properties. All analogues showed varied range of inhibitory activity having IC50 values ranging from 17.09 ± 0.72 to 45.34 ± 0.03 μM (α-amylase) and 16.35 ± 0.42 to 42.31 ± 0.09 μM (α-glucosidase), respectively. Specifically, the compounds 1, 7 and 8 were found to be significantly active with IC50 values of 17.09 ± 0.72, 19.73 ± 0.42, and 23.01 ± 0.04 μM (against α-amylase) and 16.35 ± 0.42, 18.55 ± 0.26, and 20.07 ± 0.02 μM (against α-glucosidase) respectively. The obtained results were compared with the Glimepiride reference drug having IC50 values of 13.02 ± 0.11 μM (for α-glucosidase) and 15.04 ± 0.02 μM (for α-amylase), respectively. The structure-activity relationship (SAR) studies were conducted based on differences in substituent patterns at varying position of aryl rings A and B may cause to alter the inhibitory activities of both α-amylase and α-glucosidase enzymes. Additionally, the molecular docking study was carried out to explore the binding interactions possessed by most active analogues with the active sites of targeted α-amylase and α-glucosidase enzymes.
A new series of triazinoindole analogs 1-11 were synthesized, characterized by EI-MS and (1)H NMR, evaluated for α-glucosidase inhibitory potential. All eleven (11) analogs showed different range of α-glucosidase inhibitory potential with IC50 value ranging between 2.46±0.008 and 312.79±0.06 μM when compared with the standard acarbose (IC50, 38.25±0.12 μM). Among the series, compounds 1, 3, 4, 5, 7, 8, and 11 showed excellent inhibitory potential with IC50 values 2.46±0.008, 37.78±0.05, 28.91±0.0, 38.12±0.04, 37.43±0.03, 36.89±0.06 and 37.11±0.05 μM respectively. All other compounds also showed good enzyme inhibition. The binding modes of these analogs were confirmed through molecular docking.
4-Methylbenzimidazole 1-28 novel derivatives were synthesized and evaluated for their antiglycation and antioxidant activities. Compounds 1-7 and 11 showed excellent activities ranged 140-280 μM, better than standard drug rutin (294.46 ± 1.50 μM). Compound 1-28 were also evaluated for DPPH activities. Compounds 1-8 showed excellent activities, ranging 12-29 μM, better than standard drug n-propylgallate (IC50 = 30.30 ± 0.40 μM). For superoxide anion scavenging activity, compounds 1-7 showed better activity than standard n-propylgallate (IC50 = 106.34 ± 1.6 μM), ranged 82-104 μM. These compounds were found to be nontoxic to THP-1 cells.
In our effort directed toward the discovery of new anti-diabetic agent for the treatment of diabetes, a library of biscoumarin derivative 1-18 was synthesized and evaluated for α-glucosidase inhibitory potential. All eighteen (18) compounds displayed assorted α-glucosidase activity with IC50 values 16.5-385.9 μM, if compared with the standard acarbose (IC50 = 906 ± 6.387 μM). In addition, molecular docking studies were carried out to explore the binding interactions of biscoumarin derivatives with the enzyme. This study has identified a new class of potent α-glucosidase inhibitors.
Phenolic Schiff bases are known for their diverse biological activities and ability to scavenge free radicals. To elucidate (1) the structure-antioxidant activity relationship of a series of thirty synthetic derivatives of 2-methoxybezohydrazide phenolic Schiff bases and (2) to determine the major mechanism involved in free radical scavenging, we used density functional theory calculations (B3P86/6-31+(d,p)) within polarizable continuum model. The results showed the importance of the bond dissociation enthalpies (BDEs) related to the first and second (BDEd) hydrogen atom transfer (intrinsic parameters) for rationalizing the antioxidant activity. In addition to the number of OH groups, the presence of a bromine substituent plays an interesting role in modulating the antioxidant activity. Theoretical thermodynamic and kinetic studies demonstrated that the free radical scavenging by these Schiff bases mainly proceeds through proton-coupled electron transfer rather than sequential proton loss electron transfer, the latter mechanism being only feasible at relatively high pH.
Columbin, a diterpenoid furanolactone, was isolated purely for the first time from the plant species Tinspora bakis. The anti-inflammatory effects of columbin were studied in vitro, in silico and in vivo. The effect of columbin on nitric oxide was examined on lipopolysaccharide-interferon-gamma (LPS/IFN) induced RAW264.7 macrophages. In vitro and in silico cyclooxygenase-1 and cyclooxygenase-2 inhibitory activities of columbin using biochemical kit and molecular docking, respectively, were investigated. Mechanism of columbin in suppressing NF-kappaB-translocation was tested using Cellomics®NF-κB activation assay and ArrayScan Reader in LPS-stimulated RAW264.7 cells. Moreover, effects of columbin in vivo that were done on carrageenan-induced mice paw-oedema were tested. Lastly, the in vitro and in vivo toxicities of columbin were examined on human liver cells and mice, respectively. Treatment with columbin or N(ω)-nitro-l-arginine methyl ester (l-NAME) inhibited LPS/IFN-γ-induced NO production without affecting the viability of RAW264.7. Pre-treatment of stimulated cells with columbin did not inhibit the translocation of NF-κB to the nucleus in LPS-stimulated cells. COX-1 and COX-2 inhibitory activities of columbin were 63.7±6.4% and 18.8±1.5% inhibition at 100μM, respectively. Molecular docking study further helped in supporting the observed COX-2 selectivity. Whereby, the interaction of columbin with Tyr385 and Arg120 signifies its higher activity in COX-2, as Tyr385 was reported to be involved in the abstraction of hydrogen from C-13 of arachidonate, and Arg120 is critical for high affinity arachidonate binding. Additionally, columbin inhibited oedema formation in mice paw. Lastly, the compound was observed to be safe in vitro and in vivo. This study presents columbin as a potential anti-inflammatory drug.
4-Thiazolidinone analogs 1-20 were synthesized, characterized by (1)H NMR and EI-MS and investigated for urease inhibitory activity. All twenty (20) analogs exhibited varied degree of urease inhibitory potential with IC50 values 1.73-69.65μM, if compared with standard thiourea having IC50 value of 21.25±0.15μM. Among the series, eight derivatives 3, 6, 8, 10, 15, 17, 19, and 20 showed outstanding urease inhibitory potential with IC50 values of 9.34±0.02, 14.62±0.03, 8.43±0.01, 7.3±0.04, 2.31±0.002, 5.75±0.003, 8.81±0.005, and 1.73±0.001μM, respectively, which is better than the standard thiourea. The remaining analogs showed good to excellent urease inhibition. The binding interactions of these compounds were confirmed through molecular docking studies.
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.
A series of thiazole derivatives 1-21 were prepared, characterized by EI-MS and (1)H NMR and evaluated for α-glucosidase inhibitory potential. All twenty one derivatives showed good α-glucosidase inhibitory activity with IC50 value ranging between 18.23±0.03 and 424.41±0.94μM when compared with the standard acarbose (IC50, 38.25±0.12μM). Compound (8) (IC50, 18.23±0.03μM) and compound (7) (IC50=36.75±0.05μM) exhibited outstanding inhibitory potential much better than the standard acarbose (IC50, 38.25±0.12μM). All other analogs also showed good to moderate enzyme inhibition. Molecular docking studies were carried out in order to find the binding affinity of thiazole derivatives with enzyme. Studies showed these thiazole analogs as a new class of α-glucosidase inhibitors.
A hospital-based case-control study of viral encephalitis was carried out at Port Dickson Hospital, in the state of Negeri Sembilan, Malaysia. Between March and May 1999, 69 clinically diagnosed viral encephalitis cases and 31 controls were interviewed. Job histories on pig farming activities were assessed by a group of epidemiologists and veterinary surgeons. Results show that among clinical cases of viral encephalitis, 52 (75.4%) cases were diagnosed to have Nipah virus infection based on positive serology for antibodies to the cross-reacting Hendra virus antigen. The Nipah virus encephalitis was significantly associated with a history of working in pig farms (p < 0.001, OR = 196.0, 95% CI = 20.4-4741.6), history of contact with animals (p < 0.001, OR = 38.3, 95% CI = 8.2-209.0) and with history of direct contact with pigs (p = 0.002, OR = 34.4, 95% CI = 2.6-1,024.4). The Nipah virus infection was also significantly associated with history of feeding/cleaning pigs (p < 0.001, OR = 102, 95% CI = 11.9-2,271.5). These results provide evidence that involvement in pig farming activities is significantly associated with the risk of getting Nipah virus infection. They are potential risk factors for Nipah virus transmission in the major pig-producing area of Bukit Pelandok, Port Dickson Negeri Sembilan.
Despite of many diverse biological activities exhibited by benzimidazole scaffold, it is rarely explored for the urease inhibitory potential. For that purpose, benzimidazole analogues 1-19 were synthesized and screened for in vitro urease inhibitory potential. Structures of all synthetic analogues were deduced by different spectroscopic techniques. All analogues revealed inhibition potential with IC50 values of 0.90 ± 0.01 to 35.20 ± 1.10 μM, when compared with the standard thiourea (IC50 = 21.40 ± 0.21 μM). Limited SAR suggested that the variations in the inhibitory potentials of the analogues are the result of different substitutions on phenyl ring. In order to rationalize the binding interactions of most active compounds with the active site of urease enzyme, molecular docking study was conducted.
New triazinoindole bearing thiazole/oxazole analogues (1-21) were synthesized and characterized through spectroscopic techniques such as HREI-MS, 1H and 13C NMR. The configuration of compound 2i and 2k was confirmed through NOESY. All analogues were evaluated against α-amylase inhibitory potential. Among the synthesized analogues, compound 1h, 1i, 1j, 2a and 2f having IC50 values 1.80 ± 0.20, 1.90 ± 0.30, 1.2 ± 0.30, 1.2 ± 0.01 and 1.30 ± 0.20 μM respectively, showed excellent α-amylase inhibitory potential when compared with acarbose as standard (IC50 = 0.91 ± 0.20 µM). All other analogues showed good to moderate inhibitory potential. Structural activity relationship (SAR) has been established and binding interactions were confirmed through docking studies.
Leishmaniasis has affected a wider part of population around the globe. Most often, the existing regiments to battle against leishmaniasis are inadequate and limited. In our ongoing efforts to develop new leishmanicidal agents, we have synthesized a series of novel and symmetrical bis-Schiff base-disulfide hybrids 1-27. Intermediate disulfide was synthesized from corresponding 2-aminothiol followed by reacting the coupled adduct with various aromatic aldehydes. All these compounds showed outstanding inhibition when compared with standard (Table 1). Out of twenty seven analogues, twenty two analogues i.e. 1-5, 7-13, 17-21, 23-27 analogues showed excellent inhibitory potential with EC50 values ranging from 0.010 ± 0.00 to 0.096 ± 0.01 μM while five compounds i.e. 6, 14-16, and 22 showed good inhibitory potential with EC50 values ranging from 0.10 ± 0.00 to 0.137 ± 0.01 μM when compared with the standard Amphotericin B. Structure-activity relationship has been established while molecular docking studies were performed to pin the binding interaction of active molecules. This study will help to develop new antileishmanial lead compounds.
Chromen-4-one substituted oxadiazole analogs 1-19 have been synthesized, characterized and evaluated for β-glucuronidase inhibition. All analogs exhibited a variable degree of β-glucuronidase inhibitory activity with IC50 values ranging in between 0.8 ± 0.1-42.3 ± 0.8 μM when compared with the standard d-saccharic acid 1,4 lactone (IC50 = 48.1 ± 1.2 μM). Structure activity relationship has been established for all compounds. Molecular docking studies were performed to predict the binding interaction of the compounds with the active site of enzyme.