In this study, a stepwise reaction afforded thiazolidinone-based benzothiazole derivatives 1–15, and the synthesized derivatives were then screened for biological significance and found to be the leading candidates against α-amylase and α-glucosidase enzymes. Almost all derivatives showed excellent to good activity ranging against α-amylase, IC50 = 2.10 ± 0.70 to 37.50 ± 0.70 μM, and α-glucosidase, IC50 = 3.20 ± 0.05 to 39.40 ± 0.80 μM. Some analogues such as 4 (2.40 ± 0.70 and 3.50 ± 0.70 μM), 5 (2.30 ± 0.05 and 4.80 ± 0.10 μM), and 6 (2.10 ± 0.70 and 3.20 ± 0.70 μM) were found with folds better activity than that of the standard drug acarbose (9.10 ± 0.10 and 10.70 ± 0.10 μM), respectively. Moreover, the structure–activity relationship (SAR) has been established for all compounds. A molecular docking study has been carried out to explore the binding interactions against α-amylase and α-glucosidase enzymes.
Alzheimer’s disease (AD) is a progressive neurological illness that is distinguished clinically by cognitive and memory decline and adversely affects the people of old age. The treatments for this disease gained much attention and have prompted increased interest among researchers in this field. As a springboard to explore new anti-Alzheimer’s chemical prototypes, the present study was carried out for the synthesis of benzoxazole-oxadiazole analogues as effective Alzheimer’s inhibitors. In this research work, we have focused our efforts to synthesize a series of benzoxazole-oxadiazole (1–19) and evaluating their anti-Alzheimer properties. In addition, the precise structures of synthesized derivatives were confirmed with the help of various spectroscopic techniques including 1H-NMR, 13C-NMR and HREI-MS. To find the anti-Alzheimer potentials of the synthesized compounds (1–19), in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), inhibitory activities were performed using Donepezil as the reference standard. From structure-activity (SAR) analysis, it was confirmed that any variation found in inhibitory activities of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes were due to different substitution patterns of substituent(s) at the variable position of both acetophenone aryl and oxadiazole aryl rings. The results of the anti-Alzheimer assay were very encouraging and showed moderate to good inhibitory potentials with IC50 values ranging from 5.80 ± 2.18 to 40.80 ± 5.90 µM (against AChE) and 7.20 ± 2.30 to 42.60 ± 6.10 µM (against BuChE) as compared to standard Donepezil drug (IC50 = 33.65 ± 3.50 µM (for AChE) and 35.80 ± 4.60 µM (for BuChE), respectively. Specifically, analogues 2, 15 and 16 were identified to be significantly active, even found to be more potent than standard inhibitors with IC50 values of 6.40 ± 1.10, 5.80 ± 2.18 and 6.90 ± 1.20 (against AChE) and 7.50 ± 1.20, 7.20 ± 2.30 and 7.60 ± 2.10 (against BuChE). The results obtained were compared to standard drugs. These findings reveal that benzoxazole-oxadiazole analogues act as AChE and BuChE inhibitors to develop novel therapeutics for treating Alzheimer’s disease and can act as lead molecules in drug discovery as potential anti-Alzheimer agents.
Twenty-one analogs were synthesized based on benzimidazole, incorporating a substituted benzaldehyde moiety (1–21). These were then screened for their acetylcholinesterase and butyrylcholinesterase inhibition profiles. All the derivatives except 13, 14, and 20 showed various inhibitory potentials, ranging from IC50 values of 0.050 ± 0.001 µM to 25.30 ± 0.40 µM against acetylcholinesterase, and 0.080 ± 0.001 µM to 25.80 ± 0.40 µM against butyrylcholinesterase, when compared with the standard drug donepezil (0.016 ± 0.12 µM and 0.30 ± 0.010 µM, against acetylcholinesterase and butyrylcholinesterase, respectively). Compound 3 in both cases was found to be the most potent compound due to the presence of chloro groups at the 3 and 4 positions of the phenyl ring. A structure-activity relationship study was performed for all the analogs except 13, 14, and 20, further, molecular dynamics simulations were performed for the top two compounds as well as the reference compound in a complex with acetylcholinesterase and butyrylcholinesterase. The molecular dynamics simulation analysis revealed that compound 3 formed the most stable complex with both acetylcholinesterase and butyrylcholinesterase, followed by compound 10. As compared to the standard inhibitor donepezil both compounds revealed greater stabilities and higher binding affinities for both acetylcholinesterase and butyrylcholinesterase.
A series of fifteen hybrid analogs (1-15) based on benzimidazole bearing triazole skeleton were synthesized and were evaluated for in vitro AChE and BuChE inhibition profile. All the newly afforded scaffolds showed moderate to good AChE and BuChE activity having IC 50 values ranging from 0.40 ± 0.05 to 19.60 ± 0.40 μM against AChE and 1.50 ± 0.10 to 23.30 ± 0.50 μM against BuChE in comparison to Donepezil (IC 50 = 0.016 ± 0.12 μM for AChE), (IC 50 = 4.5 ± 0.11 μM for BuChE) as reference drug. It was concluded from structure-activity relationship (SAR) studies that scaffolds bearing groups of strong e-withdrawing nature (-NO 2 , -F and -Cl) at different position of aryl ring were found to be potent inhibitors of both targeted AChE and BuChE enzymes. Therefore, compounds 7 (bearing para-NO 2 ), 2 (bearing para-fluoro), 6 (bearing meta-NO 2 ) and 8 (bearing meta-fluoro) were identified as the most active on screening against
The 7-quinolinyl-bearing triazole analogs were synthesized (1d-19d) and further assessed in vitro for their inhibitory profile against α-amylase andαglucosidase. The entire analogs showed a diverse range of activities having IC 50 values between 0.80 ± 0.05 µM to 40.20 ± 0.70 µM (α-amylase) and 1.20 ± 0.10 µM to 43.30 ± 0.80 µM (α-glucosidase) under the positive control of acarbose (IC 50 = 10.30 ± 0.20 µM) (IC 50 = 9.80 ± 0.20 µM) as the standard drug. Among the synthesized scaffolds, seven scaffolds 12d, 10d, 8d, 9d, 11d, 5d, and 14d showed excellent α-amylase and α-glucosidase inhibitory potentials with IC 50 values of 4.
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