Structure-Odor Activity Studies on Derivatives of Aromatic and Oxygenated Monoterpenoids Synthesized by Modifying p-Cymene

J Nat Prod. 2020 Apr 24;83(4):834-842. doi: 10.1021/acs.jnatprod.9b00339. Epub 2020 Mar 20.

Abstract

Thymoquinone was recently reported as having a unique pencil-like odor and being the impact compound for the cedar-like and cedar wood-based product smell such as pencils. The compounds thymol and carvacrol are structurally related odorants commonly found in plants and foods such as thyme and oregano, also having a significant contribution to their overall aroma. However, a systematic elucidation of the sensory properties in this class of oxygenated, aromatic monoterpenoids has not been carried out. To close this gap and gain new insights into structure-odor relationships leading to pencil-like and woody odors, 19 structurally related derivatives of p-cymene starting from thymol and carvacrol were synthesized and characterized. The compounds had odor thresholds ranging from 2.0 ng/L air to 388.8 ng/L air, being lowest for thymol and carvacrol and highest for thymohydroquinone. The compounds smelled mostly thyme-like, oregano-like, and pencil-like with phenolic, earthy, and medicinal variations in their odor character, which could be successfully linked to structural motifs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cymenes / chemistry*
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Hydrocarbons, Aromatic / chemistry
  • Molecular Structure
  • Monoterpenes / chemical synthesis
  • Monoterpenes / chemistry*
  • Monoterpenes / pharmacology*
  • Odorants / analysis*
  • Oxygen / chemistry
  • Sensory Thresholds / drug effects
  • Structure-Activity Relationship

Substances

  • Cymenes
  • Hydrocarbons, Aromatic
  • Monoterpenes
  • 4-cymene
  • Oxygen