In recent years, considerable attention has been directed to the site of origin, pathways of biosynthesis, metabolism, and excretory routes of unusual bile acids in human, particulaly for patients with hepatobiliary disease and newborn infants and fetus. In addition to five common bile acids (cholic, chenodeoxycholic, deoxycholic, ursodeoxycholic, and lithocholic acids), patients with hepatobiliary disease and newborn infants and fetus excrete a number of unusual bile acids in human biological fluids (bile, serum, urine, feces, and meconium). The unusual bile acids include the stereoisomers of the common bile acids, bile acids having various functional groups at different positions or in greater number than found in the common bile acids, and “short-chain” and “long-chain” bile acids. In this review, we compiled a list of the unusual bile acids hitherto reported in literatures and give an outline of procedures for their syntheses.

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The effects of phospholipids on the oxidative dimerization of t-butylated hydroxyanisole (BHA) were investigated during the thermal oxidation of saturated and unsaturated triglycerides.
Glycerol trilaurate or glycerol trilinoleate, into which BHA and phospholipids (phosphatidyl choline and phosphatidyl ethanolamine) were previously dissolved, was oxidized by air at 150°C for 10h, and the concentrations of BHA monomer and its dimers in the reaction mixture were determined by HPLC.
In glycerol trilaurate, the formation of a diphenyl ether type dimer from BHA monomer was strongly suppressed by addition of phospholipids. The effect of phosphatidyl ethanolamine was in essentially the same as that of phosphatidyl choline. In glycerol trilinoleate, the stability of the BHA monomer was remarkably increased and the amounts of dimers formed in a reaction mixture decreased significantly by the addition of phospholipids. However, the total amount of the BHA monomer and its dimers showed little change. From these facts, it is clear that phospholipids inhibit the initial stage of the oxidation of BHA. When tri-η-octylamine and tri-η-butyl phosphate were added to a solution of BHA in glycerol trilinoleate, a little inhibition of the oxidative dimerization was seen. Thus, the prevention of the oxidative dimerization of BHA by phospholipids may not necessarily be due to the combined action of phosphate ester linkage and amine group in the phospholipid molecule. The effect of phosphatidyl ethanolamine on the oxidative dimerization of BHA in a mixture of glycerol trilaurate and glycerol trilinoleate (4:1) was essentially the same as that in glycerol trilinoleate alone.

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A mixture of malonaldehyde, an alkenal, an alkadienal and an organic hydroperoxide, as an oxidized lipid model, was made to react with thiobarbituric acid (TBA) in 4% acetic acid at 100°C for 20min. Amount of a red pigment, formed from the alkenal and the alkadienal, was greatly increased with the amounts of other components. A combination of that alkenal and alkadienal or that of two alkadienals synergistically enhanced the pigment formation. Organic hydroperoxides dramatically enhanced this formation from these aldehydes. Intermediary 1:1 adducts of the aldehydes with TBA were effectively converted to the pigment in the presence of hydroperoxides. Pigment yield was much greater than that of the malonaldehyde content in the mixture. Alkenals, alkadienals and hydroperoxides may contribute to formation of red pigment synergistically in TBA tests for oxidized lipids.

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The metabolism of lipids in the intestines was studied in vitro on their surface. Interfacial tension between lipids and water is depressed by adsorption of bile salts at the lipid-water interface. During triglyceride hydrolysis, the fraction of monoglyceride at this interface increases, leading to additional depression of interfacial tension and the formation of a fine lipid dispersion. The interfacial tension of lipid-water is minimum at optimum HLB (hydrophile lipophile balance) of mixed emulsifiers. With further hydrolysis, the monoglyceride fraction at the interface becomes larger, leading in turn to greater interfacial tension. Fine emulsion droplets produced on decreasing the interfacial tension to 0.50.3mN·m^-1, may be adsorbed on the intestinal wall when the HLB of the adsorbed amphiphile layer becomes lipophilic. This is because an amphiphile aggregate disperses water when it is hydrophilic, but forms an amphiphile phase when the hydrophile lipophile property is balanced or lipophilic. After absorption of emulsion droplets, triglyceride may form by esterification of glycerides. Thus, the HLB of mixed amphiphiles may become hydrophilic, and bile salts may dissolve into the blood and recirculate.

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The amino groups of lipase-P (Pseudomonas sp. lipase from Amano Pharmaceutical Ltd.) were modified with alkenyl succinic anhydride (ASA) that is used as a reactive sizing agent for paper making in industry. It was possible to N-acylate the amino groups smoothly up to 50% modification with little inactivation of the enzyme, using emulsified tetradecenyl succinic anhydride at 37°C, pH 7.5.
Ester-synthesis activity of the enzymes was estimated by using oleic acid and oleyl alcohol as substrates in cyclohexane. The enzymes were suspended in the substrate solution in powder form or in immobilized enzyme form (immobilized on celite and macroporous ion exchange resin). Both enzymes resulted in higher ester-synthesis activity. The initial ester-synthesis rate was 8.4 times that of either enzyme in its native form.

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The influence of cultural conditions, especially glucose concentration and C/N ratio, in a high concentration sugar medium on cell growth and lipid accumulation of Mortierella isabellina IFO 7884 fungus was investigated. M. isabellina was capable of growing in over a 200g/L glucose medium with little effect on cell growth. The high concentration of sugar in the medium accelerated lipid accumulation. The content of lipid cultivated in a high concentration sugar medium exceeded that in a low concentration sugar medium at the same C/N ratio. Maximum dry cell and total lipid weights of 156.4 and 83.1g/L were observed for a 390g/L glucose medium (C/N ratio=20). The highest lipid productivity, however, was found to be 0.69g/Lh for a 270g/L glucose medium (C/N ratio=20).

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Fatty acid compositions and physical characteristics of shortening were determined for 25 brands of products: for bread, whipped cream and frozen dessert, 5 brands each; 5 fluid brands; for cake; 4, and for pie crust, 1.
The investigation was conducted essentially the same as in the preceeding study on bakery margarines. [YUKAGAKU, in contribution]
1) Results of fatty acid analyses indicated the main material oil or fat to be a vegetable liquid oil in all brads of liquid shortening, a laurin oil in 2 types for frozen dessert and palm oil in the others for frozen dessert. Hardened marine oils were found to blend in 10 other types, as evident from the relatively high levels of long chain fatty acids with 20 or more carbon.
Trans-isomers of unsaturated fatty acids were detected in only a very few samples of fluid shortening and frozen dessert, but in all other types. Their levels averaged 11.4% for t-18:1, 3.8% for t-20:1 and 2.8% for t-22:1.
2) According to the SFC and hardness index curves, the frozen desserts, particularly those containing mainly laurin oil, tended to be harder than other solid products in a lower temperature region than 15°C, but they readily softened in a higher temperature region.
The SFC curve for fluid products indicated solid fat components to be comprised only of the emulsifiers added.
3) The hardness index was correlated to SFC for the shortening. The total % of unsaturated fatty acids, except trans-isomers, was also correlated to SFC at 20°C for all the products, and if products comprised mainly of laurin oil be not considered, the correlation was even better. However, no correlation was found between the total % and hardness index at 20°C for the shortening, even without this consideration.

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