Terpenes from human

Vaddi, H.K., et al. 2003. Oxide terpenes as human skin penetration enhancers of haloperidol from ethanol and propylene glycol and their modes of action on stratum corneum. Biol Pharm Bull 26 220. 

Cal, K., S. Janicki, and M. Sznitowska. 2001. In vitro studies on penetration of terpenes from matrix-type transdermal systems through human skin. Int J Pharm 224 81. 

What is clean air Unpolluted air is a concept of what the air would be if humans and their works were not on earth, and if the air were not polluted by natural point sources such as volcanoes and forest fires. The true composition of unpolluted air is unknown because humans have been polluting the air for thousands of years. In addition there are many natural pollutants such as terpenes from plants, smoke from forest fires, and fumes and smoke from volcanoes. Table 4.1 lists the components that, in the absence of such pollution, are thought to constitute clean air. 

The ultimate precursor of all the carbon atoms in cholesterol and in the other steroids that are derived from cholesterol is the acetyl group of acetyl-GoA. There are many steps in the biosynthesis of steroids. The condensation of three acetyl groups produces mevalonate, which contains six carbons. Decarboxylation of mevalonate produces the five-carbon isoprene unit frequently encountered in the structure of lipids. The involvement of isoprene imits is a key point in the biosynthesis of steroids and of many other compounds that have the generic name terpenes. Vitamins A, E, and K come from reactions involving terpenes that humans cannot carry out. That is why we must consume these vitamins in our diets vitamin D, the remaining lipid-soluble vitamin, is derived from cholesterol (Section 8.8). Isoprene units are involved in the biosynthesis of ubiquinone (coenzyme Q) and of derivatives of proteins and tRNA with specific five-carbon units attached. Isoprene units are often added to proteins to act as anchors when the protein is attached to a membrane. 

Until rather recently, our choice among chemicals repellant to insects was very limited (9), and some of the available remedies seem to have been almost equally repellent to their human users. The most familiar of them undoubtedly is the classical oil of citronella, a mixture of plant terpenes which consists principally of geraniol, citronellol, and citronellal. It is a remarkable coincidence that at least one insect species, an ant discussed by Dr. Happ, also makes use of some of these same terpenes as repellents against other insects. It biosynthesizes them de novo rather than simply taking them from plant sources. Many other examples of insect repellency have been observed (9), and Roth and Eisner (28) list over 30 compounds which have been identified as defense substances of anthropods. 

A considerable number of mycotoxins that show high toxicity to vertebrates and/ or invertebrates are produced by organisms associated with crop plants (Flannigan 1991). There are many known cases of human poisoning caused by such compounds. There are three broad categories of mycotoxins represented here, based on the structures of the intermediates from which these secondary metabolites are derived. They are (1) compounds derived from polyketides, (2) terpenes derived from mevalonic acid, and (3) cyclic peptides and derivatives thereof. 

Participation of Br in marine terpene biosynthesis (Section II.C) is reflected in the impressive number (several hundred) of halogenated terpenes, some with useful biological activities, that have been identified. For example, the poly halogenated sesquiterpenes isoobtusol (14) and isoobtusol acetate (15), isolated from the red alga Laurencia obtussa, showed potent activity against HeLa 229 human carcinoma cells1011. 

Terpenic compounds are resorbed from the digestive tract and sue situated in the hepatie tissues. Thanks to their ability to dissolve fats, they prevent the formation of cholesterol gathering inside the liver and they also recover proper colloidal state to the bile. Terpenes also enhance the bile content in the hepatic cells and in the liver tracts. Terpenic hydrocarbons dilating the smooth muscles [78, 79] make the hepatic tracts more distended both inside and outside. It has been pointed out that the terpenes contained in Rowachol dissolve bile stones [87-89]. The meehanism of terpenes activity has not as yet been completely explained. It was explained that menthol and other monoterpenes inhibit the activity of the lecithin-cholesterol acyltransferase in the human serum [90]. They also lower the activity of the hepatic S-3-hydroxy-3-methylglutaryl-CoA reductase, which is responsible for the physiological inhibition of cholesterol synthesis in the liver [82, 91, 92]. 

Often, different research groups find conflicting results from similar experiments. In many of these instances, exposure mixtures have not been completely defined. For example, studies with human volunteers in test chambers showed much higher tolerances to formaldehyde (a hydrophile) with respect to dyspnea symptoms than to formaldehyde when exposure was concurrent with exposure to terpenes (lipophiles) by wood workers. I1718 ... 

The exposure of humans in the private bathroom or public beauty shops is often underestimated. The major sources of exposure to chloroform (CHCI3) in the United States are showers, boiling water and clothes washers. CHCI3 is formed from the chlorine used to treat water supplies (Ott and Roberts, 1998). Many cosmetic products contain a number of VOCs such as 2-phenoxyethanol, 2-butanone, acetone, terpenes, 2-hydroxy-4-meth-oxybenzophenone or phenylmethanol. However, in most product categories we are not selling a product, we are selling a proposition, as Selinger (1988) pointed out. 

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