Carvacrol, structure

Aromatic monoterpenes such as p-cymene 9 and its hydroxylated derivatives thymol 12 and its isomer carvacrol 13 always occur along with a-terpinene 23, y-terpinene 25 and terpinen-4-ol 29 (Structure 4.8). Metabolites, likep-cymene-8-0I 30 and cuminyl alcohol 31 may also be derived from p-cymene (Fig. 4.4). 

Other phenolic compounds have also been shown to cause similar changes in conformation and physical properties of PAn/HCSA salts.24-28 Most of these, for example, m-cresol, are highly corrosive and toxic, limiting their desirability for processing and enhancing the electrical conductivity of PAn s. However, we have recently found that the structurally related molecules thymol 2 and carvacrol 3, which are much less toxic than m-cresol, can also function as effective secondary dopants for PAn/(+)-HCSA films and increase the electrical conductivity by up to two orders of magnitude.28... 

Phenols Phenols that occur in essential oils usually contain an aliphatic side chain for example, thymol, eugenol, and carvacrol, whose structures are shown in Figure 8. 

Ben Arfa, A. Combes, S. Preziosi-Belloy, L.N. Gontard, N. Antimicrobial activity of carvacrol related to its chemical structure. Lett. Appl. Microbiol. 2006, 43 (2), 149-154. 

The relationship between the pharmacological effects elicited by menthol and ion channel dysfunction depends on the interaction of this monoterpene with distinct types of ion channels. In this way, the reported local anesthetic effects attributed to menthol and for some of its structural chemical homologues, such as thymol, carvacrol, and carveol, might be caused by a blockade of voltage-gated sodium channels [21, 25, 26]. On the other hand, a pronounced cytotoxic effect of menthol is correlated with the action of menthol in TRPM8 channels [22, 27]. At this point, we will make a short introduction to TRPM8 channels to further discuss the putative cytotoxic effects of menthol in various cell types. 

Carvacrol possesses antibacterial, antifungal, and anti-insecticidal effects that are worth noting. The antibacterial potential of this substance has been ascribed to its effect on the structural and functional integrity of the cytoplasmic membrane. Due to this effect, carvacrol is used to extend the time before food becomes spoiled by bacteria [101]. For example, carvacrol inhibited, in sub-lethal concentrations, the virulence of Salmonella typhimurium by reducing the motility and invasion in porcine epithelial cells, which is an important finding inasmuch as carvacrol is commonly used in sub-lethal concentrations [102]. 

Thymol (26) and carvacrol (27), isolated from herbs such as thyme and savory, are members of the menthane family in which the cyclohexane structure has been oxidized to an aromatic (phenolic) ring. Oils containing these phenolic terpenes have been shown to be particularly effective as antibacterial agents (Kalemba and Kimicka 2003). 

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