Indanone-based Mannich bases: Design, synthesis, in-silico molecular docking, ADME predictions and biological evaluation including carbonic anhydrases, acetylcholinesterase inhibition and cytotoxicities

This study examined the rational design, synthesis, carbonic anhydrases (CAs), acetylcholinesterase (AChE) inhibitory effects, and cytotoxicity of 2-(2-hydroxy-3-(aminomethyl))benzylidene)-2,3-dihydro-1H-inden-1-one (1–6) and 2-(2-hydroxy-3,5-bis(aminomethyl))benzylidene)-2,3-dihydro-1H-inden-1-one (7–11). All compounds exhibited significant inhibitory activity against hCA I, hCA II, and AChE enzymes. Among them, compound 9 demonstrated potent inhibition of hCA I (Ki = 46.828 ± 11.32 nM) and AChE (Ki = 0.9820 ± 0.402 nM), while compound 11 showed strong inhibition against hCA II (Ki = 24.683 ± 6.216 nM). For comparison, the reference compound acetazolamide (AZA) inhibited hCA I and hCA II with Ki values of 183.390 ± 19.71 nM and 104.60 ± 27.60 nM, respectively. Regarding AChE inhibition, the reference drug Tacrine exhibited a Ki value of 58.85 ± 12.1 nM. These results indicate that compound 9 is significantly more potent than AZA against hCA I and markedly outperforms tacrine in inhibiting AChE. Similarly, compound 11 shows superior inhibitory activity compared to AZA against hCA II. The compounds' cytotoxicity against four human oral squamous cell carcinoma (OSCC) cell lines was compared to that of three normal oral cells. The compound 3, 2-(2-hydroxy-3-(piperidin-1-ylmethyl)benzylidene)-2,3-dihydro-1H-inden-1-one, stood out for its promising selectivity in cytotoxicity, demonstrating the highest SI (9.5 toward HSC-2), TS1 (4.8), and PSE (4.8) compared to other studied compounds. Compound 3 showed 5-fold higher tumor specificity than 5-FU when using epithelial normal (human oral keratinocyte) and four human OSCC cell lines. Molecular docking results demonstrated that molecule 9 exhibited a strong binding affinity to AChE (−12.3 kcal/mol) with a remarkably low inhibition constant (Ki = 0.963905 nM), suggesting its potential as a potent inhibitor despite the absence of conventional hydrogen bonding. Conversely, molecule 11 showed enhanced selectivity toward hCAII, forming two hydrogen bonds and displaying a binding affinity of 10.4 kcal/mol. These findings indicate that both molecules possess promising inhibitory potential and can serve as valuable candidates for further experimental validation. Overall, this study highlights the effectiveness of molecular docking as a predictive tool in drug discovery and supports the further development of these lead compounds for therapeutic applications. SAR-based structural changes of compounds 3, 9, and 11 have the potential to generate novel, highly effective molecules, providing alternative treatments for a wide range of therapeutic areas, including cancer and neurological illnesses.