Conformational fidelity and hydrogen bond associability of L-histidine with sulfamate anion studied through XRD, quantum chemical, spectroscopic and molecular docking simulation as a cdk-4 inhibitor against retinoblastoma

Abstract

L-histidinium sulfamate, (C6H10N3O2)+.SO3NH2−,crystallizes in the orthorhombic space group, P212121, with four molecules per unit cell. The asymmetric part of unit cell comprises a diprotonated monovalent histidinium cation and a sulfamate anion. The amino nitrogen of the cation is deviated from the carboxylate group plane. The backbone conformations are observed to be cis and trans conformations. The side chain conformations are witnessed to be gauche I / gauche II / gauche I rotomers. The conformations of the cation are dominated by the three dimensional intermolecular hydrogen bonding network in the crystal packing. The classical hydrogen bonds are observed in the crystalline landscapes categorically cation-cation, anion-anion and cation-anion interactions leading to chain C(4), C(5) and C(7) motifs and ring R33(10), R33(14), R33(21) and R55(30) motifs. The molecular structure, FT-IR, FT-Raman, Frontier Molecular Orbitals (FMO), Natural Bond Orbital (NBO) analysis Mulliken charge analysis, Electrostatic potential analysis (ESP), Non-Linear Optical (NLO) properties of L-histidinium sulfamate have been evaluated using the (DFT) calculations with B3LYP/6‒311++G (d, p) basis set. TD-DFT in gas phase with the same basis set was used to analyze electronic parameters such as excitation energy, wavelength, band gap, and oscillator strength from the theoretical UV–Visible spectrum. The Fukui function was also used to investigate the molecule's local reactivity. The contribution of distinct interactions within the molecule and the strength of molecular packing in the compound have been evaluated through Hirshfeld surface (HS) analysis .Retinoblastoma is the most well-known pediatric malignant development of the eye. The protein cyclin dependent kinase (Cdk) plays a role in the phosphorylation process; its inhibition triggers the retinoblastoma protein's suppressor function, which stops tumor development. Molecular docking simulation has been performed through PyRx software and the new single crystal L-histidinium sulfamate showed effective binding to the Cdk-4 protein with the binding score of -6.7 Kcal/mol and pharmacokinetic studies showed a good safety profile of L-histidinium sulfamate.