Synthesis, molecular structure, DFT calculations and biological activity of acetoxy linearol

Abstract

Acetoxy linearol (ent-3 beta,7 alpha,18-triacetoxykaur-16-ene), a natural compound was synthesized from linearol isolated from endemic Sideritis species and structurally characterized using diverse spectroscopic techniques such as H-1, C-13 NMR and FT-IR. The geometrical parameters, vibrational frequencies and gauge including atomic orbital (GIAO) H-1 and C-13 NMR chemical shift values of acetoxy linearol (1) in the ground state have been calculated using the density functional theory (DFT) method at the B3LYP and X3LYP with the 6-31+G (d) basis set. The calculated vibrational frequencies and H-1 and C-13 NMR chemical shifts have been compared with that of obtained experimental values. A combined study based on NMR data and theoretical calculations using DFT/GIAO indicate that (1) is the correct structure of title molecule. The experimental and theoretical results confirmed the proposed molecular structure of the synthesized (1) compound. Weak inhibitory activity of linearol and acetoxy linearol against acetyl- and butyryl-cholinesterase was determined. Also, the antioxidant capacity of the title molecule was determined by DPPH free radical scavenging and beta-carotene linoleic acid assays.