Design and synthesis of quinoline-derived thioureas as potential antihyperglycemic, anti-Alzheimer, and antioxidant agents.

A library of quinoline-based thiourea hybrids 1-41 was synthesized via a single-step reaction scheme. All compounds were evaluated for their inhibitory potential against α-amylase, α-glucosidase, AChE, and BChE enzymes as well as for DPPH radical scavenging activity. Among forty-one compounds, 27-31 and 33-37 showed excellent inhibition against α-amylase (IC50 = 18.36-28.21 µM) and α-glucosidase (IC50 = 17.77-29.31 µM) compared to the standard acarbose (IC50 = 16.98 ± 0.12, 14.19 ± 0.06 µM). Moreover, compounds 27, 28, 30, 31, 34, 35, and 37 inhibited AChE (IC50 = 5.60-14.97 µM) and BChE (IC50 = 6.99-15.70 µM) with greater potency than the standard donepezil chloride (IC50 = 1.49 ± 0.13, 2.39 ± 0.06 µM). Kinetic analyses were conducted for the most active compounds to elucidate their modes of enzyme inhibition. Furthermore, molecular docking studies were conducted to explore ligand binding interactions within the enzyme active site. All synthesized derivatives were further evaluated for their DPPH radical scavenging activity, among which compounds 27, 28, 30, 31, 34, and 35 exhibited significant to moderate antioxidant potential (SC50 = 23.92-34.73 µM) compared with the reference standard ascorbic acid (SC50 = 18.28 ± 0.15 µM). Among this library, compound 31, with a difluoro group on the phenyl ring, was identified as the most potent inhibitor against all enzymes. Thus, this study suggests that the reported compounds hold the potential to be further advanced as lead anti-Alzheimer and anti-diabetic agents.