Antidiabetes and antioxidant potential of Schiff bases derived from 2-naphthaldehye and substituted aromatic amines: Synthesis, crystal structure, Hirshfeld surface analysis, computational, and invitro studies

Three Schiff bases were synthesised by the condensation reaction between 2-napthaldehyde and aromatic amines to afford (E)-N-mesityl-1-(naphthalen-2-yl)methanimine (L1), (E)-N-(2,6-dime-thylphenyl)-1-(naphthalen-2-yl)methanimine (L2) and (E)-N-(2,6-diisopropylphenyl)-1-(naph-thalen-2-yl)methanimine (L3). The synthesised compounds were characterised using UV-visible, NMR (13C & 1H), and Fourier transform infrared spectroscopic methods while their purity was ascertained by elemental analysis. Structural analysis revealed that the naphthalene ring is almost coplanar with the imine functional group as evident by C1-C10-C11-N1 torsion angles of 176.4 (2)degrees and 179.4(1)degrees in L2 and L3, respectively. Of all the various intermolecular contacts, HMIDLINE HORIZONTAL ELLIPSISH interactions contributed mostly towards the Hirshfeld surfaces of both L2 (58.7 %) and L3 (69.7 %). Quantum chemical descriptors of L1 -L3 were determined using Density Functional Theory (DFT) and the results obtained showed that the energy band gap (Delta E) for L1, L2 and L3 are 3.872, 4.023 and 4.004 eV respectively. The antidiabetic potential of the three compounds were studied using alpha-amylase and alpha-glucosidase assay. Compound L1 showed very promising antidiabetic activities with IC50 values of 58.85 mu g/mL and 57.60 mu g/mL while the reference drug (Acarbose) had 405.84 mu g/mL and 35.69 mu g/mL for alpha-amylase and alpha-glucosidase respectively. In-silico studies showed that L1 docking score as well as binding energies are higher than that of acarbose, which are recognized inhibitors of alpha-amylase together with alpha-glucosidase. Further insight from the RMSF, RMSD and RoG analysis predicted that, throughout the simulation L1 showcased evident influence on the structural stability of alpha-amylase. The antioxidant potential of the compounds was carried out using nitric oxide (NO), ferric reducing ability power (FRAP) and 2,2-diphenyl-1- picrylhydrazyl (DPPH) assays. The compounds exhibited good to fairly antioxidant properties with L1 as well as L3 having IC50 values of 70.91 and 91.21 mu g/mL respectively for NO scav-enging activities assay, which comparatively outshined acarbose (reference drug) with IC50 value of 109.95 mu g/mL. Pharmacology and pharmacokinetics approximations of L1 - L3 showed min-imal violation of Lipinski's Ro5 and this projects them to be less toxic and orally bioavailable as potential templates for the design of therapeutics with antioxidant and antidiabetic activities.