Xu H, Delling M, Jun JC, Clapham DE. Oregano, thyme and clove-derived flavors and skin sensitizers activate specific TRP channels. Nat Neurosci. 2006 May; 9(5):628-35. PMID: 16617338.
University of California San Francisco 
Oregano, thyme and clove-derived flavors and skin sensitizers activate specific TRP channels