Keita Yunoki

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.

It is well known that sphingolipids specifically exist in the terrestrial mammal epidermis and correlate with skin barrier functions. However, the lipid properties of the marine mammal epidermis have not been examined in detail. We thus investigated the chemical composition of lipid components, especially sphingolipids, in the black epidermis (outer skin) of Antarctic minke whales (six mature and six immature specimens). Complex lipid fractions mainly contained cerebroside (CE), cholesteryl sulfate and sphingomyelin (SM), as well as two glycerophospholipids. Moreover, in the superficial layer of the black epidermis, CE was richly abundant but phospholipids were scarce. As component fatty acids, the non-hydroxy monounsaturated very long chain fatty acids (VLFA) within 34 carbons were generally present in CE and SM in the black epidermis. CE also consisted of alpha-hydroxy fatty acids with monounsaturation within C34 (17%) and a slight proportion of omega-hydroxy ones (32:1 and 34:1), the latter being probably derived from acyl-CE. Component sphingoid bases of both sphingolipids were predominantly 4-sphingenine (64%), followed by a C16 analogue (21%). When comparing these by different maturities, mature whales showed sphingolipid profiles with higher levels of unsaturated fatty acids and with shorter sphingoid base chains than those of immature ones. Component analysis revealed that CE sugars were 67% glucose and 33% galactose, and alpha-hydroxy fatty acids only bound to galactose.

Significant amounts of policosanol and very long-chain fatty acids (VLFAs) ranging in carbon length from 22 to 30 were found in the lipophilic fraction obtained from potato pulp fermented with Rhizopus oryzae. It is believed that these compounds would have originally been present as suberin-related compounds, but not as wax, in the periderm of potato tubers and concentrated into potato pulp during the process of starch production. Moreover, the policosanol and VLFAs extracted from potato pulp with organic solvents were found to have increased after fermentation.