Antispasmodic activity of carnosic acid extracted from rosmarinus officinalis: Isolation, spectroscopic characterization, DFT studies, and in silico molecular docking investigations

Abstract

This research work focuses on the isolation, spectroscopic characterization (FT-IR, UV–vis, and NMR), density functional theory (DFT) studies, and the potential application of carnosic acid as an antispasmodic agent drug evaluated by molecular docking with various spasmolytic receptors proteins and the results compared with diazepam (DZP) and toleterodine (TTD) as standard drugs. All computational calculations of the isolated and spectroscopic determined structure was performed at the B3LYP/6–311++G(d,p) theoretical method within the framework of DFT approach. The theoretical vibrational assignments of the various functional groups along with the potential energy distributions (PEDs) were performed using the vibrational energy distribution analysis (VEDA) program and carefully compared with the experimental data. The natural bond orbital (NBO), nonlinear optics (NLO), and frontier molecular orbital (FMO) molecular electronic properties were also investigated and reported. While the binding affinity showed that carnosic acid has better interaction with the nicotinic acetylcholine receptor when compared to DZP and TTD, however, it is not a GABAa receptor agonist but a much better nicotinic acetylcholine receptor agent when juxtaposed with a similar agent like DZP and TTT as an antispasmodic agent as a smooth muscle relaxant.