Sphingolipids ceramides

Sphingolipids (ceramids, sphingomyelin, cerebrosides, sulfatides, gangliosides) and lipids with secondary amines produce blue spots on a white backgound (CAUTION benzidine is a carcinogen)... 

Figure 12.12 Sphingomyelins. Sphingomyelins are esters of a ceramide and phospho-ryl choline. However, similar compounds are ceramide-1-phosphoryl ethanolamines and phosphono forms of sphingolipids. Ceramides W-acyl-sphingosines) are amides of a long chain di- or trihydroxy base containing 12 to 22 carbon atoms, of which sphingosine (4-sphingenine) is the commonest, and a long chain fatty acid whose acyl chain is shown by R1. This may contain up to 26 carbon atoms.

Ferrying of molecules into cells via entry through caveolae may represent a way to traffic specifically cytotoxic molecules to specific action sites. For example, elevating the intracellular level of the sphingolipid ceramide is known to exert antimitogenic and proapoptotic effects. While ceramide is cell-permeable and displays antiapoptotic properties in vitro, systemic in vivo use of ceramide is hampered by its hydrophobicity. Using a C6-ceramide formulation in pegylated liposomes was shown to elicit a sixfold reduction in solid phase tumors, when compared to unloaded liposomes in a mouse model of breast adenocarcinoma [68],... 

Recently, the sphingolipid ceramide, which is a product of fatty acyl CoA, has been identified as the link between excess nutrients (i.e., saturated fatty acids) and inflammatory cytokines (i.e., TNFa), to the induction of insulin resistance. Moreover, ceramide has been shown to be toxic to pancreatic P-cells, cardiomyocytes, and endothelial cells, which contributes to diabetes, hypertension, cardiac failure, and atherosclerosis (41). However, the role of ceramide in mediating insulin-resistance humans is still unclear (42). 

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). 

Figure 26.3 Synthesis of sphingolipids. Ceramide is the starting point for the formation of sphingomyelin and gangliosides.

Wooten, L.G. and Ogretmen, B. Spl/Sp3-dependent regulation of human telomerase reverse transcriptase promoter activity by the bioactive sphingolipid ceramide. J Biol Chem, 280, 2005, 28867-28876. 

Apoptosis Reduced sphingolipid ceramide Ceramide generation activator (e.g.,... 

---