Sterols names

Sterols are minor components of milk lipids, which make up just 0.3% of the total fat (Table 1.1). The principal component is cholesterol, which accounts for over 95% of the total about 10% of the cholesterol is present in the esterified form. Small amounts of other sterols, namely campesterol, stigmasterol and (3-sitosterol, have also been identified in milk fat (Mincione et al., 1977). 

Recently, 24- and 25-methylated sterols were isolated from sponges by Djerassi s group. GC/MS analysis of X. muta from Barbados showed that at least 18 sterols were present, the main sterol being 24(28)-dehydroaplysterol (19). In addition, 24-isopropenylcholesterol (29), verongulasterol (26), and a new sterol named mutasterol (30) were identified [21] (Fig. 3). 

Capillary GC analysis of the sterols of the Caribbean Xestospongia species, containing predominantly xestosterol (27), indicated a new sterol, xestospongesterol (31) which was separated by reversed-phase HPLC [22]. The structure was determined by mass spectrometry and NMR as a hitherto unprecedented quadruply biomethylated sterol. From the Indopacific sponge Strongylophora durissima, which has been reported to contain over 90% of strongylosterol, a new sterol named... 

The most notable sterol isolated by Kobayashi from the soft coral S. glaucum was a new C27-sterol named glaucasterol (57) [62], shown to have the same structure as papakusterol isolated from deep sea gorgonians [63]. The 245, 25S stereochemistry of this sterol has been established by synthesis [64] and correlation with occelasterol... 

The unsaponifiable material (1-3%) consists mainly of sterols, tocopherols and sesame lignans. For four cultivated species of S. indicum, the level of unsaponifiable material has been reported to be 1.4—1.8% (Kamal-Eldin and Appelqvist 1994b). The sesame oils from these species contained total sterols (0.51-0.76%), including desmethyl sterols (85-89%), monomethyl sterols (9-11%) and triterpene alcohols (dimethyl sterols) (2-4%) respectively. (1-Sitosterol (62-67%), campesterol (15-20%), stigmasterol (5-8%) and A5-avenasterol (7-10%) are the major sterols present in both free and esterified forms. The monomethyl sterols, namely gramisterol, citrostadienol and obtusi-foliol, were present mainly as esters. The total sterols contained 65% in free and 35% in esterified form. Composition (% wt) data of the desmethyl sterols, monomethyl sterols and dimethyl sterols (tritepene alcohols) of four Sesamum species are listed in Table 11.4. Tocopherols of crude sesame oils are generally... 

Cyclic alcohols are sulfated by reaction with chlorosulfonic acid or pyridine-sulfur trioxide complex. The former reagent, in the presence of iV,A/-dimethylani-line in chloroform at —12 to 20 °C, converted cyclohexanol into sodium cyclohexyl sulfate after neutralization with aqueous sodium hydroxide. The latter reagent was successfully applied to the sulfation of sterols, namely cholesterol, ergosterol and lanosterol " however, later studies (see p 158) showed that chlorosulfonic acid could also be used. 

Shyadehi AZ, DC Lamb, SL Kelly, DE Kelly, W-H Schunck, JN Wright, D Corina, M Akhtar (1996) The mechanism of the acyl-carbon bond cleavage reaction catalyzed by recombinant sterol 14a-demethyl-ase of Candida albicans (other names are lanosterol 14a-demethylase, P-450]4p, and CYP51). J Biol Chem 271 12445-12450. 

Brand Name(s) DHT, DFIT Intensol, Hytakerol Chemical Class Sterol derivative... 

A Japanese species of Epipolasis contained five sterol sulfates named halistanol sulfates A-E (536-540), which differ from the original halistanol sulfate (532) from Halichondria moorei [449]. Structures were elucidated by spectroscopic and chemical techniques. Halistanol sulfates F-H (541-543) are three additional sterol sulfates from Pseudaxinyssa digitata that inhibit HIV in vitro [450]. 

The rearrangement of this initially created C-20 carbocation to lanosterol (Fig. 22-6, step c) is also a remarkable reaction that requires the shift of a hydride ion and of two methyl groups, as indicated by the arrows in the figure. In addition, a hydrogen at C-9 (sterol numbering) is lost as a proton. Lanosterol is named for its occurrence in lanolin, the waxy fat in wool. Although the principal component of lanolin is cholesterol, lanosterol is its precursor both in sheep and in all other animals. Cholesterol is in turn the precursor to other animal sterols. The cholesterol biosynthetic pathway also provides cells with a variety of important signaling molecules.1603... 

Most steroids are alcohols, and accordingly are named as sterols. Important examples include cholesterol, ergosterol, estradiol, stigmasterol, and other representative sterols given in Table 30-2. As you can see from their structures, most possess the same ring skeleton but vary considerably in their peripheral structural features, stereochemistry, and in the degree of ring unsaturation. 

The lipids of the external tear film namely, neutral oils, phospholipids, sterol esters, various waxes, and other lipids are requisite for regulation of evaporation. These lipids are produced by the Meibomiam and other glands. The ability of the glandular structures situated in the conjunctiva and the lid propia to produce the tear film may be impaired due to exposure to pollutants and irritants or as a result of age-related dysfunction. 

The method applied consists in a prior, basic hydrolysis (saponification) of the oil sample, followed by thin layer chromatography (TLC) fractionation of the classes of compounds, namely hydrocarbons, tocopherols, long-chain aliphatic alcohols, triterpenic alcohols, methyl sterols, sterols and triterpenic dialcohols. This procedure loses all information about the combination of polycyclic triter-penes with fatty acids. 

Second-Step Reaction Methanolysis of TAGs After the first-step reaction, immobilized lipase was removed and the oil fraction recovered. MeOH and water in the oil fraction were then removed by evapolation. The resulting mixture was named dehydrated first-step product, which was composed of 80wt% FAMEs, 2wt% FFAs, 10wt% acylglycerols, lwt% sterols, 2wt% FAStEs, 5wt% unknown lipophilic compounds. The second-step reaction is methanolysis of acylglycerols in the dehydrated first-step product. 

Figure 2-12B. The ring junction between rings A and B is trans in some steroids, cis in others. The junctions between B and C and C and D are normally trans. Substituents that lie above the plane, as drawn in Figure 2— 12C, are named p, those below the plane, a. The 3-OH group in cholesterol (Figure 2-12C) is the -configuration, and it is this group that may form ester linkages. The composition of the plant sterols is given in Figure 2-13. Part of the sterols in natural...

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