Carvacrol, derivatives

When distilled with phosphorus pentoxide, camphor yields cymene, and with iodine, carvacrol. Both of these bodies are para-derivatives of benzene. On oxidation with nitric acid camphor yields many acids, of which the chief are camphoric acid, CjgHjgO, camphanic acid, CjoHj O, and camphoronic acid, CgHj Og. The constitution of these acids has an important bearing on that of camphor. Many formulae have been suggested for camphor during the past few years, but that of Bredt is now universally accepted, and has received complete confirmation by Komppa s synthesis of camphoric acid. This synthesis confirms the formula for camphoric acid as—... 

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). 

The importance of MP can be related to the physical state of the substance under the conditions of Draize test. In this study, it was assumed that chemicals with a MP less than or equal to 37°C would exist as liquids in the test procedure and that, in general, liquids would be more likely than solids to cause corrosion and irritation. The results confirm that there is indeed a relationship between physical state and the potential for acute skin toxicity. The fact that some solids are corrosive or irritant may relate to the fact that their MPs are not much higher than 37°C and that they exist as wax-like substances, which are more capable of penetrating into the skin than are solids with higher MPs. For example, carvacrol, and thymol, which are both irritant and corrosive, have predicted MPs of 38°C and 38.1°C, respectively. In the case of other solids, such as benzene sulfonyl chloride (MP = 61°C), the corrosive response may be due to a more toxic derivative (e.g., benzene sulfonic acid). 

Eugenol (4-allyl-2-methoxyphenol) Eugenol is not actually derived from a terpene molecule (as opposed to carvacrol and thymol) but it is a phenol and is found in essential oils of clove, cinnamon leaf, pimento, ylang ylang and rose. It has a spicy, pungent odour typical of clove. 

Phenylpropane derivatives The name given to compounds of phenol that have a three-carbon-atom (propyl) chain attached those most commonly found in essential oils are thymol, carvacrol, chavicol (see Phenols). 

Mexican oregano is used in the USA, and derives from various Lippia species, especially Lippia graveolens (Verbenaceae) its taste is reported to be less fresh and pleasant [190[. Main constituents are thymol, carvacrol, p-cymene [191 [. 

Complex phenols are widespread in nature, although the simple ones are relatively uncommon. Phenol is particularly found in mammalian urine, pine needles and oil tobacco leaves. Abundant natural substances such as thymol (1) and carvacrol (2) are derivatives of phenols. 

Carvacrol and Thymol, CH3.C3H7.C6H3.OH, are phenols derived from cymene (p-methyl-isopropylbenzene). In carvacrol the hydroxyl group is ortho to the methyl radical this is shown by the fact that carvacrol is converted into o-cresol and propylene when heated with phosphorus pentoxide. In thymol the hydroxyl group is ortho to isopropyl. 

The aCD, pCD, and HPpCD were used to increase the solubility of a range of plant-derived EO compounds (carvacrol = Carv, eugenol = Eng (EG), linalool = Lin and 2-pentanoylfuran = Pentfuran) and its influence on the antimicrobial activity of EO components on a range of microorganisms was tested. 

Phytochemistry Abovegroundparts containphenolcarbonicacids and their derivatives(caffeic,rosemarinic,l-caffeoylquinic, and 5-caffeoylquinic acids), flavonoids (luteolin, apigenin, scutellarein, and anthocyans) and essential oil (containing thymol, carvacrol, a-pinene, camphene, sabinene, n-thymol, isobomeol, boroneol, undecanoic add, and amyl alcohol Plant Resonrces of the USSR 1991 Kolesnikov and Gins 2001 Stahl-Biskup 2002). 

Austgulen, L. T., E. Solheim, and R. R. Scheline, 1987. Metabolism in rats of p-cymene derivatives Carvacrol and thymol. 98-102. 

Tyler VE (1999) Phytomedicines back to the future. J Nat Prod 62 1589-1592 Ultee A, Kets EP, Smid EJ (1999) Mechanisms of action of carvacrol on the food-borne pathogen Bacillus cereus. Appl Environ Microbiol 65 4606-4610 Ushida K, Jouany JP (1996) Methane production associated with rumen-ciliated protozoa and its effect on protozoan activity. Lett Appl Microbiol 23 129-132 Van Nevel CJ, Demeyer DI (1988) Manipulation of rumen fermentation. In Hobson PN (ed) The rumen microbial ecosystem. Elsevier Apphed Science, New York Varel VH, Miller DN (2001) Plant-derived oils reduce pathogens and gaseous emissions from stored cattle waste. Appl Environ Microbiol 67 1366-1370 Vidal F, Vidal JC, Gadelha APR, Lopes CS, Coelho MGP, Monteiro-Leal LH (2007) Giardia lamblia the effect of extracts and fractions from Mentha x piperita Lin. Lamiaceae) on trophozoites. Exp Parasitol 115 25-31... 

Simple alkyl phenols derived from phenol, found as constituents of essential oils, include two major monoterpenes with a similar odour, carvacrol (5-isopropyl-2-methylphenol, 8-119) and thymol (2-isopropyl-5-methylphenol, 8-119). These phenols occur, for example, in the essential oil of thyme. Chavicol, also known as 4-prop-2-en-l-ylphenol or 4-aUylphenol (8-119) is a component of the essential oil of basil. A number of other phenols are derived from guaiacol. Isoeugenol also occurs in the essential oil of basil as the (T)-isomer, (E)-2-methoxy-4-(prop-l-en-l-yl)phenol (8-119),... 

Many naturally occurring phenols are derived from nonaromatic precursors through rearrangements driven by the aromaticity of the final product. For example, carvone (see Real Life 5-1) undergoes an acid-catalyzed reorganization to carvacrol [2-methyl-5-(l-methylethyl)phenol], a component of the herbs oregano, thyme, and marjoram that contrihutes to their charactaistic odor. Formulate a mechanism. 

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