Sterol peroxide

The detection limits per chromatogram zone are 50 ng substance for sterol peroxides [1], 20-100 ng for nitrate esters [3] and 5-25 ng for aromatic amines [5]. 

Guyot, M., and M. Durgeat Occurrence of 9(11)-Unsaturated Sterol Peroxides in Tunicates. Tetrahedron Lett. 22, 1391 (1981). 

One aspect of LC-MS which is rapidly being developed is the HPLC-MS and has great promise for the analysis of many compounds. The primary obstacle to easy coupling of HPLC to MS arises from the fact that the flow for conventional HPLC columns is approximately an order of magnitude greater than can be accommodated by the commonly used ion sources and pumping systems. The requirement for a transfer of a maximal quantity of sample and a minimal amount of solvent into the ion source of the mass spectrometer has necessitated the development of different interfaces. The need for introduction of smaller amounts of HPLC effluents into a mass spectrometer has stimulated the development of narrow bore columns. The application of HPLC-MS with a direct liquid introduction has been applied to the identification of marine sterol peroxides by Djerassi and Sugnaux in 1982. An ultrasphere ODS column of i.d. 5 ixm and methanol-water (99 1, v/v) solvent system were used. 

Fattorusso, E., Magno, S., Santacroce, C., and Sica, D. (1974a) Sterol peroxides from the sponge Axinella cannabina. Gazz. Chim. Ital, 104, 409-413. 

Findlay, J.A. and Patil, A.D. (1984) A novel sterol peroxide from the sea anemone Metridium senile. Steroids, 44, 261—265. 

A symbolizes the triplet state intermediate formed, as in fluorescence quenching, by interaction with oxygen. In this way transannular peroxides of biochemical interest can be formed. Well-known examples, shown in Fig. 1, are ascaridole, isolated from chenopodium oil (Nelson, 1913), sterol peroxides (Windaus and Drunken, 1928), and a-phillandrene peroxide (Schenk, 1948, and Schenk et al., 1953). 

Fig. 1. The first row shows examples of natural transannular peroxides ascari-dole and a-phillandrene peroxide. The former can be obtained from terpene by diensynthesis with Oj and with chlorophyll or eosin as a photosensitizer. The second row shows sterol peroxide (Windaus and Brunken, 1928) and pentacene (Dufraisse, 1939). The last row illustrates the reversibility of oxygen addition in some cases (Dufraisse and Etienne, 193S).

Sterol Peroxides from the Sponge Axinella cannabina. Gazz. Chim. it. 104,... 

There are many endogenous substrates, of widely different chemical structure, that are metabolized through oxidative, peroxidative, and reductive changes introduced by P450 enzymes. These include saturated and unsaturated fatty acids, eicosanoids, sterols and steroids, bile acids, vitamin D derivatives, retinoids, and uroporphyrinogens (Tables 9.4 and 9.5). 

Rietveld A, Neutz S, Simons K, Eaton S. Association of sterol-and glycosylphosphatidyUnositol-linked proteins with Drosophila raft lipid microdomains. J. Biol. Chem. 1999 274 12049-12054. Subbaiah PV, Subramanian VS, Wang K. Novel physiological 51. function of sphingomyebn in plasma. Inhibition of lipid peroxidation in low density hpoproteins. J. Biol. Chem. 1999 274 36409-36414. 52. 

Animal fats are subjected to deodorization when a very bland or essentially flavorless fat is desired, such as in margarines or cooking fats. The fats are heated at 200°C to 260°C in the absence of air (to prevent oxidation) and treated with dry steam under a vacuum of 5-10 milliatmospheres. Off-flavor compounds are volatile under these conditions and are captured and removed in the steam stream. In addition to flavor components, free fatty acids, which can also contribute undesirable flavors, and other minor constituents such as peroxides, sterols, sterol esters, toco-pherols, and other natural antioxidants are partially or completely removed from the fat by this treatment. 

Total sterol levels are affected by cultivar and region of cultivation. The ripening causes a slow continuous decrease of these compounds. Tocopherols are influenced by genetic and environmental factors, conditions of post-harvest fruit transportation and storage, and oil conservation. The smallest quantities were found in oil samples with high acidity and peroxide values. 

One of the main functions of peroxisomes is to detoxify the cell by splitting hydrogen peroxide. They contain the enzyme catalase. Catalase converts H2O2 (hydrogen peroxide, a toxic by-product of cellular metabolism) to H2O and O2, with 4H202 4H2O-I-2O2. Peroxisomes also degrade fatty acids and toxic compounds and catalyze the first two steps required in the synthesis of ether-linked phospholipids (which are later used to build membranes) and sterols. In addition, it plays a role in isoprenoid biosynthesis and amino acid metabolism. 

Cholesterol, on reaction with dibenzoyl peroxide followed by trichloroacetic acid, gave a blue colour attributed to cations with conjugated unsaturated structures. Cholesta-2,4,6-triene and 3-(cholest-5-en-3/8-yl)cholesta-2,4,6-triene were isolated from the product mixture. Some other sterols gave diverse colours.The coloured solutions formed from cholesterol or oestrone with antimony trichloride give e.s.r. spectra suggesting the presence of radical-cations. Cholesta-3,5-diene and 3,3 -bicholesta-2,4-diene were isolated from the reaction of cholesterol, and the hexaene (131) from oestrone. Dimeric and trimeric products have been... 

During their studies of the biochemical role of peroxidation, Blondin et al. (B15) developed a method for distinguishing between steroidal peroxides and other sterols. By using a flash heater at 350°C, it was foimd that steroidal 5,8-peroxides decomposed to give a number of peaks, whereas a single peak was obtained with most sterols under the same conditions. 

The Codex Alimentarius standard includes limits for acidity, volatile matter, insoluble impurities, peroxide value, colour, odour, taste, iron, copper, K27o, AK, permitted additives, contaminants (lead, arsenic, halogenated solvents), refractive index, saponification value, iodine value and unsaponifiable matter. Physical and chemical constants, such as iodine value and saponification value, are not found in the EU regulation. This is explained by the fact that more definite information is obtained by determining fatty acid composition, sterol and wax composition, trans fatty acid content, stigmastadiene, and so on. 

Intermediate cases can happen, when blocks of variables are present. As an example, take the case of olive oil samples, on each of which the following analyses have been run a titration for acidity, the analysis of peroxides, a UV spectroscopy for AK, a GC for sterols, and another GC for fatty acids. In such a situation what counts is not the final number of variables, but the number of analyses one can save. 

---