the production of thymoquinone from thymol and carvacrol

Monoterpenes are widely used in pharmaceutical, cosmetic and food industries
as active components. Some reactions of considerable commercial importance are
epoxidation of alfa pinene to alfa pinene oxide, which is an intermediate used in the
synthesis of several sandalwood fragrances; epoxidation of limonene to limonene oxide,
used to treat rhinitis; oxidation of carvacrol or thymol to thymoquinone, which has
antitumor and hepatoprotective effects (Skrobot et al. 2003).
5.2. Chemical Composition of Essential Oils
Different molecules in the same essential oil can exert different effects. This is
because the chemical structure of an essential oil determines its function. For example,
the phenols generally create antibacterial activity. Carvacrols have anti-inflammatory
activity and Limonines are antiviral (Monteiro et al. 2004).
The chemical composition of essential oils depends on climatic, seasonal, and
geographic conditions, harvest period, and distillation technique (Baydar et al. 2003). In
literature, the chemical composition of the some essential oils was studied by gas
chromotography (GC).
The aerial parts of wild oregano (Origanum minutiflorum) (endemic in Turkey),
oregano (Origanum onites), black thyme (Thymbra spicata) and wild savory (Satureja
cuneifolia) were collected wild during the flowering stage from the south western part
of Turkey. The major constituent of the oils determined by GC was carvacrol (85.9% in
O. onites, 84.5% in O. minutiflorum, 75.5% in T. spicata and 53.3% in S. cuneifolia)
(Baydar et al. 2003). The essential oil components identified are given in Table 5.1.
Eight major constituents were determined representing 97.4% in wild oregano, 97.1% in
oregano, 99.0% in black thyme and 93.1% in wild savory (Baydar et al. 2003).
The chemical composition Thymus revolutus, an endemic plant of Turkey, were
analyzed by GC. Twenty-two components were identified, and carvacrol was found as a
predominant compound in the oil. Twenty-two components were identified in the oil,
representing 98.15% of the total oil. The major components were carvacrol (43.13%),
alfa-terpinene (20.85%), p-cymene (13.94%), caryophyllene (5.40%) and thymol
(4.52%) (Karaman et al. 2001).Several earlier studies on another Turkish Thymus
showed that the main components of the oils were carvacrol and thymol in Thymus
(Tumen et al. 1994).
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