Dietary sphingolipids (SL) inhibit colon carcinogenesis, reduce serum cholesterol, and improve skin barrier function and are considered to be "functional lipids". For comparative determination of the effects of SL with different chemical compositions on lipid metabolism and its related hepatic gene expression, Zucker fatty rats were fed pure sphingomyelin (SM) of animal origin and glucosylceramide (GC) of plant origin. After 45 days, the SM and GC diets led to significant reductions in hepatic lipid and plasma non-HDL cholesterol. Both SM and GC diets decreased plasma insulin levels, whereas only the GC diet increased the plasma adiponectin level. Hepatic gene expression analysis revealed increased expression of adiponectin receptor 2 (Adipor2), peroxisome proliferator-activated receptor alpha (PPARalpha), and pyruvate dehydrogenase kinase 4 (Pdk4). However, expression of stearoyl CoA desaturase (Scd1) was significantly decreased. These results suggest that dietary SL, even of different origins and chemical compositions, may prevent fatty liver and hypercholesterolemia through improvement of adiponectin signaling and consequent increases in insulin sensitivity.

The aim of this study was to evaluate the concentration of oleanolic acids (OA) in pomace, a winemaking byproduct, and its influence on the levels of plasma lipids in rats fed a high-fat diet and on hepatic gene expression using DNA microarray analysis in vivo. HPLC analyses of pomace ethanol extract (PEE) revealed a high amount of OA ranging from 4 to 11 g/100 g. Male Sprague-Dawley rats were fed a normal-fat diet (NF group), a high-fat diet with 21% lard (HF group), a high-fat diet with 0.05% OA (OA group, 50 mg/kg/day), or a high-fat diet with 0.45% PEE (PEE group, 450 mg/kg/day). Plasma triacylglycerol and phospholipid concentrations were significantly lower in the OA and PEE groups than in the HF group. The microarray analysis of hepatic mRNA revealed reduced expression levels of lipogenic genes including acetyl-CoA carboxylase and glycerol-3-phosphate acyltransferase, probably resulting from the suppression of transcription factor Srebf1 expression. Gene expression of gluconeogensis and inflammatory cytokines was also down-regulated in the OA and PEE groups, suggesting that administration of OA or PEE could ameliorate obesity-induced insulin resistance, as well as prevent hyperlipidemia.

Sphingolipids have attracted attention as physiologically functional lipids. We determined their class and content in Japanese meals that had been prepared by a nutritionist, mainly by using HPLC-ELSD. In all 12 meals tested, cerebroside and/or sphingomyelin were generally detected as the major sphingolipids. The total amounts of sphingolipids in typical high-and lowcalorie meal samples over 2 days were 292 and 128 mg/ day, and 81 and 45 mg/day, respectively. Key words: sphingolipid; cerebroside; sphingomyelin; ceramide; daily intake Sphingolipids are known to exist in eukaryotes as components of the biological membrane and are involved in cellular membrane traffic and signal transduction. 1,2) Moreover, sphingomyelin, glucosylceramide (cerebroside) and ceramide are abundantly present in an animal epidermis in spite of differences due to species. [3][4][5] Of these, free ceramide included in the human stratum corneum has the function of epidermal moisture retention or as a protection system against external irritation. 6,7) Various physiological functions of dietary sphingolipids, such as preventing early-stage colon cancer [8][9][10] and improving the skin barrier function, 11,12) have been demonstrated. The most common sphingolipid currently used as a foodstuff is cerebroside extracted from plants, which is mainly composed of sphingoid bases distinctive from those of mammals, the plant type being sphingadienine and phytosphingosine and the mammal type being 4-trans sphingenine (d18:1 4t ) as major sphingoid bases. However, apart from d18:1 4t , the sphingoid bases are hardly absorbed in the intestinal tract. 13,14) It is considered that the routinely ingested sphingolipids are mainly sphingomyelin from animal foodstuffs and mainly cerebroside from plant foodstuffs. 15,16) In reports concerning the intake of sphingolipids, Vesper et al. have summarized the amounts of sphingolipids in foods from estimated data in the available literature; 15) however, their class and how much sphingolipid is ingested daily have not been clarified. In addition, Sugawara and Miyazawa have reported the daily intake estimated from the contents of cerebroside in various plant foodstuffs. 16) The classes and contents of sphingolipids in certain meals for healthy energetic people cooked by a nutritionist were analyzed in the present study. Typical meals for older people, which are generally low-calorie, were also comparatively investigated.Six meal samples (breakfast, lunch and dinner) in 2 d for healthy energetic people were kindly donated by the Kushiro station of the Ground Self-Defense Force (Hokkaido, Japan). Six meal samples for 2 d prepared in a home for senior citizens in Nakasatsunai-mura (Kasaigun, Hokkaido, Japan) were used as low-calorie meals. The composition of food groups and calories in each meal are shown in Table 1. The energy content of the high-calorie (HC) meals from the Self Defense Force was approximately 3,000 kcal per day, exceeding the recommendations for regular Japanese men of 1,800 to 2,000 kcal; however, t...

Membrane lipids of photosynthetic organisms consist of glycerophospholipids and glyceroglycolipids. We investigated a method for the simultaneous quantitative analysis of neutral and acidic lipids using HPLC-ELSD, and quantified monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG) and sulfoquinovosyldiacylglycerol (SQDG). Ten complex lipid classes were separated with a binary gradient system consisting of chloroform and methanol-acetone-water-acetic acid (30:60:9:1, v/v/v/v) with 0.3% triethylamine (pH 4), and were eluted within 16 min. The contents of SQDG in ten edible plants ranged from 3 to 101 mg/100 g, and were positively correlated to the neutral glyceroglycolipids contents.

FA components of 11 musts made from grape cultivars grown for making red wine in various regions of Japan and of wines made from the musts were compared to elucidate variety-dependent characteristics and to clarify their effect on FA ethyl ester (FAEE) formation in wine. Sixteen FA with carbon chain lengths from 12 to 26 were detected in all musts, with palmitic, linoleic, and linolenic acids generally predominating. Higher levels of linoleic acid were found in musts from a cold region (Hokkaido), and higher levels of oleic acid occurred in musts from a warm region (Honshu). Moreover, the unsaturation indexes (1.31-1.56) of five grape musts from the cold region showed significant differences among varieties, corresponding to the grapevines' degree of cryotolerance. The FA levels (610-6,610 nmol/100 mL) of all wines were extremely low (1.2-12.8%) compared with those of must, but the FA compositions were similar to those of must. Additionally, significant amounts of FAEE, possibly derived from yeast activity, were found in wines by using a solid-phase extraction method. The amounts of FAEE in wine significantly differed among samples (245-904 nmol/100 mL) and were inversely correlated with the percentage of linoleic acid in musts (R = -0.883). Thus, higher linoleic acid levels in must may be related to lower FAEE formation by yeast.