Relationship between structural properties and biological activity of (-)-menthol and some menthyl esters

Menthol is a naturally occurring cyclic terpene alcohol and is the major component of peppermint and corn mint essential oils extracted from Mentha piperita L. and Mentha arvensis L.. Menthol and its derivatives are widely used in pharmaceutical, cosmetic and food industries. Among its eight isomers, (-)-menthol is the most effective one in terms of refreshing effect. While the invigorating property of (-)-menthol is generally known, this claim is based on a substantial amount of literature and experience. (-)-Menthol has consistently been reported to possess better cooling and refreshing qualities in comparison to its isomers, making it the preferred choice in a broad range of applications such as personal care products, pharmaceuticals and food additives. Additionally, the (-)-menthol molecular structure allows it to have a tighter fitting with the thermoreceptors in the skin and mucous membranes, and thus to provide a more intense cooling feeling. Thus, although others have similar properties to a degree, (-)-menthol is the best compared to all in its refreshing capacity. This study focuses on menthol and some of its esters, viz. menthyl acetate, propionate, butyrate, valerate and hexanoate, with the purpose of establish a connection between structural, electrostatic and electronic characteristics and biological effects. The mostly favoured interactions of the esters with biotargets were investigated at a molecular level, offering a plausible foundation for their bioactivity elucidation. This study is conducted at a quantum mechanical and molecular docking level. The results may be of possible usefulness in areas of applications, such as pharmacological research and drug.