Lipids phytosterols

M. Hossen and E. Hernandez Phospholipase D-catalyzed synthesis of novel phospho-lipid-phytosterol conjugates. Lipids 39 (2004) 777-782. 

Moreau RA, Whitaker BD and Hicks KB. 2002. Phytosterols, phytostanols, and their conjugates in foods structural diversity, quantitative analysis, and health-promoting uses. Prog Lipid Res 41 457-500. 

Cardiolipin or diphosphatidyl glycerol is one of the most ancient membrane phospholipids from phylogenic aspects. It is surprising for such a complex molecule as cardiolipin to have evolved as one of the major membrane lipids in prokaryotics, when steroids such as cholesterol and phytosterols did not. In eukaryotic cells, cardiolipin is exclusively localized within the mitochondria where it is particularly emiched in the outer leaflet of the inner membrane. Even though a molecular structure of cardiolipin has been conserved in entire organisms, its biological significance has escaped attention except in the case of anti-cardiolipin auto-antibodies which are clinically associated with the Wasserman reaction. 

Wqsowicz, E. (2002). Cholesterol and phytosterols, in Sikorski, Z.E. and Kolakowska, A., eds.. Chemical and Functional Properties of Food Lipids, CRC Press, Boca Raton, 93-107. 

Noguchi, S. Fujioka and A. Sakurai. Identification of teasterone and phytosterols in the lipid fraction from seeds of Cannabis sativa L. Nihon Yukagakkaishi 1997 46(12) 1499-1504. 

Wang, Y.W., P.J. Jones, I. Pischel, and C. Fairow. Effects of policosanols and phytosterols on lipid levels and cholesterol biosynthesis in hamsters. Lipids 2003 38(2) 165-170. 

Ostlund, R.E. (2004). Phytosterols and cholesterol metabolism. Current Opinion in Lipid-ology, 15, 37 U. 

Jones, P. J. H., Raeini-Sarjaz, M., Ntanios, F.Y., Vanstone, C.A., Feng, J.Y., and Parsons, W.E. 2000. Modulation of plasma lipid levels and cholesterol kinetics by phytosterol versus phytostanol esters. J. Lipid Res. 41, 697-705. 

Mel nikov, S.M., Seijen ten Hoorn, J.W., and Eijkelenboom, A.P. 2004a. Effect of phytosterols and phytostanols on the solubilization of cholesterol by dietary mixed micelles An in vitro study. Chem. Phys. Lipids 127, 121-141. 

Jones, P.J., Howell, T., MacDougall, D.E., Feng, J.Y., and Parsons, W. 1998. Short-term administration of tall oil phytosterols improves plasma lipid profiles in subjects with different cholesterol levels. Metabolism 47, 751-756. 

The range of food components now considered as bioactives include vitamins, minerals, functional lipids, probiotics, amino acids, peptides and proteins, phytosterols, phytochemicals and antioxidants (Wildman 2001). Their structure and function vary widely and are important considerations when adding them to food. The health aspects of bioactive ingredients and functional foods are not covered here as they are beyond the scope of this chapter. 

Extraction of free phytosterols and steryl conjugates In principle, sterols are extracted with common organic solvents like hexane, heptane, methanol, and chloroform, but the more polar conjugates (SFs, SGs, and ASGs) require more polar extraction solvents to be quantitatively extracted from plant sample materials. Therefore, if only selected class(s) of steryl conjugates with similar polarity are analyzed, one solvent extraction can be sufficient. However, for a total lipid extraction for a later fractionation to the individual classes of phytosterol conjugates, one must utilize combinations of extraction solvents to ensure maximum recovery. 

Moreau, R.A. Powell, M.J. Hicks, K.B. Norton, R.A. 1998. A Comparison of the levels of ferulate-phytosterol esters in com and other seeds. In Advances in Plant Lipid Research ( Sanchez, J. Cerda-Olmedo, E. Martinez-Force, E.,Eds.) Uni-versidad de Sevilla, Spain, pp. 472 74. 

A concern has been raised that phytosterol doses that are effective for cholesterol reduction may impair the absorption and lower blood concentrations of fat-soluble vitamins and antioxidants. A number of studies showed that phytosterols had no effect on plasma concentrations of vitamin D, retinol, or plasma-lipid-standardized alpha-tocopherol. Moreover, the reports of the effect of phytosterols on concentrations of blood carotenoids (lutein, lycopene, and alpha-carotene) are controversial. There seems to be general agreement that phytosterol doses >1 g/d significantly decrease LDL-C standardized beta-carotene concentrations however, it remains to be determined whether a reported 15-20% reduction in beta-carotene due to phytosterol supplementation is associated with adverse health effects. Noakes et al. found that consumption of one or more carotenoid-rich vegetable or fruit servings a day was sufficient to prevent lowering of plasma carotenoid concentrations in 46 subjects with hypercholesterolemia treated with 2.3 g of either sterol or stanol esters. 

Jones, RJ. et al.. Modulation of plasma lipid levels and cholesterol kinetics by phytosterol versus phytostanol esters, J. Lipid Res., 41, 697, 2000. 

Howell, T.J., MacDougall, D.E., and Jones, P.J., Phytosterols partially explain differences in cholesterol metabolism caused by corn or olive oil feeding, J. Lipid Res., 1998 39, 892, 1998. 

Recent developments in the area of oils and fats has led to the production of specialty lipids from novel sources such as fruit seeds, nuts, and other minor plant sources. In addition, preparation of structured lipids for a myriad of applications has been of interest. Minor components of oils and fats may be isolated during processing and used as nutraceutical and functional food ingredients. Examples are lecithin, phytosterols, tocopherols, and tocotrienols, among others. Obviously, the health-promoting potential of such products is also of interest. 

A typical Western diet contains approximately 100-300 mg and 20-50 mg of plant sterol and plant stanol, respectively. The relationship between total dietary phytosterol content and the fatty acid composition of the diet decreases with increasing saturated fatty acids, whereas the total dietary phytosterol content increases with increasing PUFA (89). Fortification of lipid foods, such as margarine, with plant sterols will dramatically increase the daily intake of phytosterols and significantly lower serum cholesterol (90). The dietary consumption of large amounts of plant sterols will interfere with cholesterol absorption, thereby leading to an increased daily neutral steroid excretion. 

Tree nuts, tree nut oils, and tree nut byproducts (defatted meals and hulls) are known to contain several bioactive and health-promoting components. Epidemiological evidence indicates that the consumption of tree nuts may exert several cardioprotective effects, which are speculated to derive from their lipid component that includes unsaturated fatty acids, phytosterols, and tocols (4). Recent investigations... 

The proximate composition of almond includes 50.6% lipid, 21.3% protein, 19.7% carbohydrate, 5.3% water, and 3.1% ash (w/w) (1). The most common method for producing almond oil is hexane extraction that affords high oil yields, however, cold pressing is another commercially used procedure for almond oil production (8). Shi et al. (8) assessed the fatty acid composition of almond oil oleic acid was major fatty acid present (68%), followed by hnoleic acid (25%), palmitic acid (4.7%), and small amounts (<2.3%) of palmitoleic, stearic, and ara-chidic acids (Table 1). Almond oil is also a rich source of a-tocopherol (around 390 mg/kg) and contains trace amounts of other tocopherol isomers as well as phyl-loquinone (70pg/kg) (1). Almond oil contains 2.6g/kg phytosterols, mainly p-sitosterol, with trace amounts of stigmasterol and campesterol (1). 

The fatty acid composition of hazelnut oil is as follows 78-83% oleic acid, 9-10% linoleic acid, 4—5% palmitic acid, and 2-3% stearic acid as well as other minor fatty acids (Table 3) (1, 22). Parcerisa et al. (23) examined lipid class composition of hazelnut oil, showing that triacylglycerols constituted 98.4% of total lipids, glycolipids comprised 1.4% of total hpids, and trace amounts (<0.2%) of phosphatidylcholine and phosphatidylinositol were also present. Hazelnut oil contains 1.2-1.14 g/kg of phytosterols primarily in the form of p-sitosterol and is a very good source of a-tocopherol (382-472 mg/kg) (1, 22). The main odorant in... 

Walnuts contain about 65% lipids, however, considerable differences exist among varieties (range 52-70%, w/w) (1,40). Walnuts also contain 15.8% protein, 13.7% carbohydrate, 4.1% water, and 1.8% ash (w/w) (1). The fatty acid composition of walnut oil is unique compared with other tree nut oils for two reasons walnut oil contains predominantly linoleic acid (49-63%) and a considerable amount of ot-linolenic acid (8-15.5%). Other fatty acids present include oleic acid (13.8-26.1%), palmitic acid (6.7-8.7%), and stearic acid (1.4—2.5%) (Table 5) (40). The tocopherol content of walnut oil varies among different cultivars and extraction procedures and ranges between 268 mg/kg and 436 mg/kg. The predominant tocol isomer is y-tocopherol (>90%), followed by a-tocopherol (6%), and then (3- and 8-tocopherols (41). Nonpolar lipids have been shown to constitute 96.9% of total lipids in walnut oil, whereas polar lipids account for 3.1%. The polar lipid fraction consisted of 73.4% sphingolipids (ceramides and galactosylcera-mides) and 26.6% phospholipids (predominantly phosphatidylethanolamine) (42). Walnut oil contains approximately 1.8g/kg phytosterols (1), primarily p-sitosterol (85%), followed by A-5-avenasterol (7.3%), campesterol (4.6%), and, finally, cholesterol (1.1%) (42). 

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