Sterols marine algae

Based on the apparent occurrence of 24-n-prop-24(28)-enylcholesterol (a C30 sterol) only in certain extant marine members of the chrysophytes (order Sarcinochrysidales Bdlard et al. 1990), the presence of the corresponding 24-n-propylcholestanes in oils and ancient sediments is considered to indicate a contribution from marine algae (Moldowan et al. 1990). Low levels of these C30 steranes have been detected in some coals, in which they can be interpreted as resulting from a marine transgression, and are often accompanied by other signs of marine contributions (e.g. lower relative abundance of C29 steranes and elevated chedanthane content Kdlops et al. 1994). 

Cholesterol, with a C27 carbon skeleton (Figure 6.1), is a sterol characteristic for higher animals. It is a steroid that is present in all animal tissues as a major structural component of cellular membranes. It is the precursor of bile acids, provitamin B, and the steroid hormones. Cholesterol can be present in the free form or esterified at the hydroxyl group with fatty acids of various chain length and saturation. Cholesterol also occurs in plants, usually in very small quantities, and marine algae. 

Sterols also can be found in marine algae. It has been reported that brovm algae (Phaeophyceae) contain mainly fucosterol and fucosterol derivatives, red algae (Rhodophyceae) contain mainly cholesterol and cholesterol derivatives, and green algae (Chlorophyceae) contain mainly... 

POTENTIAL HEALTH BENEFITS OF STEROLS FROM MARINE ALGAE... 

It is a plant sterol (phytosterol) present in canola oils and rape seed but is also found in some marine algae, diatoms and shellfish (oysters). It inhibits the enzyme A24-sterol reductase that is involved in mammalian cholesterol biosynthesis pemandez et al. Biochem J 336 109 2002], Brassino steroids have plant growth regulating activities [Anastasia et al. J C S Perkin 1379 7982.]... 

Avenastarol, ZS-isofucosteroh an isomer of Fuco-sterol (see) found in green marine algae (see Sterols). 

G. W. Pattersoni Sterols of Algae Proceedings of International Symposium on Marine Algae of the Indian Ocean Region, Bhavnagar, India, 9-12 January, 1979, pp 37. 

In marine algae, sterols are usually esterified, and free sterols exist only in small quantities, even in trace amounts the study of algal sterols therefore involves a saponification of the total lipid extract. Broadly speaking, the sterols of Chlorophyceae are numerous and have 27-29 carbons, that is, side-chains of 8-10 carbons. Currently, all sterols isolated from green algae have the usual tetra-cydic system of cholesterol (Kerr and Baker, 1991 Patterson, 1991). An examination of the sterol composition of about 50 species revealed the following trends ... 

Siddiqui, S., Usmanghani, K., and Shamed, M. (1994) Sterol and fatty add composition of a marine alga Bryopsis permata (Bryopsiphyceae, Chlorophyta). Pak.J. Pharm. Sci., 7, 73-82. 

Many reports have been devoted to the sterols of marine algae (e.g.. Idler and Wiseman, 1970 Fattorusso et al., 1975 Goad, 1978 Kerr and Baker, 1991 Patterson, 1991 D Auria, Minale, and Riccio, 1993 Rizk, Al Easa, and Kornprobst, 1999 El-Hattab et al., 2006). 

Framvaren has a well documented history of environmental change from fjord to lake and then back to a fjord. Sediment cores from both oxic and anoxic past environments contain organic carbon contents of 6-18% and reveal complex distributions of lipid compounds, the dominant classes being n-alkanes, n-alcohols, sterols and long-chain alkenones (Ficken Farrimond, 1995). The alkenones, which are predominantly produced by marine prymnesiophyte algae, are most abundant in the fjord facies of both cores, but are also detectable in the lacustrine sediments, albeit in much lower concentrations. The dramatic increase in abundance of these compounds is interpreted to record the change in environment from lake to fjord. 

In 1970, a new C26-sterol was first isolated from Placopecten magellanicus by Idler [126], and its structure was determined as (22 )-24-norcholesta-5,22-dien- -ol (83). Subsequently Cj -sterols were found in many marine sources. These sterols may be of dietary origin from algae, but the mode of biosynthesis is still unknown. (22Z)-Cholesta-5,22-dien-3j8-ol was reported from several molluscs [127]. 

Many additional steroid compounds are encountered in relatively complex mixtures. An increasing use of GC for the separation of biological sterols has been noticed during the last decade. The materials of interest may include bacteria, algae, various plants, marine animals, mammalian tissues, etc. Various dietary aspects of sterols and their metabolites, including bile acids, have recently been studied to a large extent. 

---