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Understanding of lipid oxidation mechanisms (e.g., auto-oxidation and photo-oxidation) in foods and cosmetics is deemed essential to maintain the quality of such products. In this study, the oxidation mechanisms in foods and cosmetics were evaluated through analysis of linoleic acid hydroperoxide (LAOOH) and linoleic acid ethyl ester hydroperoxide (ELAOOH) isomers. Based on our previous method for analysis of LAOOH isomers, in this study, we developed a new HPLC-MS/MS method that enables analysis of ELAOOH isomers. The HPLC-MS/MS methods to analyze LAOOH and ELOOH isomers were applied to food (liquor) and cosmetic (skin cream) samples. As a result, LAOOH and ELAOOH isomers specific to photo-oxidation, and ELAOOH isomers characteristic to auto-oxidation were detected in some marketed liquor samples, suggesting that lipid oxidation of marketed liquor proceeds by both photo- and auto-oxidation during the manufacturing process and/or sales. In contrast, because only LAOOH and ELAOOH isomers specific to auto-oxidation were detected in skin cream stored under dark at different temperatures (−5 °C–40 °C) for different periods (2–15 months), auto-oxidation was considered to be the major oxidation mechanism in such samples. Therefore, our HPLC-MS/MS methods appear to be powerful tools to elucidate lipid oxidation mechanisms in food and cosmetic products.

A thermophilic bacterium Thermosporothrix hazakensis NBRC 105916 which belongs to the class Ktedonobacteria was investigated to explore its biosynthetic potential of secondary metabolites. UV-guided fractionation led to the identification of a new benzenoid metabolite designated ktedonoketone (6) and an α-diketone metabolite 2’-oxosattabacin (7) along with five known compounds. Compound 7 was previously described as a synthetic compound, but this is the first finding as a natural product. Compound 7 induced adipocyte differentiation at 10–20 μM and autophagy at 1–10 μM. Compound 6 showed weak inducing activity of adipocyte differentiation. The biosynthetic origin of hazakacin (3), an acyloin-type compound, was elucidated by 13C-labeled precursor-feeding experiments.

γ-Oryzanol (OZ), which has a lot of beneficial effects, is a mixture of ferulic acid esters of triterpene alcohols (i.e., triterpene alcohol type of OZ (TTA-OZ)) and ferulic acid esters of plant sterols (i.e., plant sterol type of OZ (PS-OZ)). Although it has been reported that OZ is found in several kinds of cereal typified by rice, TTA-OZ (e.g., 24-methylenecycloartanyl ferulate (24MCA-FA)) has been believed to be characteristic to rice and has not been found in other cereals. In this study, we isolated a compound considered as a TTA-OZ (i.e., 24MCA-FA) from barley and determined the chemical structure using by HPLC-UV-MS, high-resolution MS, and NMR. Based on these results, we proved for the first time that barley certainly contains 24MCA-FA (i.e., TTA-OZ). During the isolation and purification of 24MCA-FA from barley, we found the prospect that a compound with similar properties to OZ (compound-X) might exist. To confirm this finding, the compound-X was also isolated, determined the chemical structure, and identified as a caffeic acid ester of 24-methylenecycloartanol (24MCA-CA), which has rarely been reported before. We also quantified these compounds in various species of barley cultivars and found for the first time the existence of 24MCA-FA and 24MCA-CA in various barley. Through these findings, it opens the possibility to use barley as a new source of 24MCA-FA and 24MCA-CA.

The elucidation of lipid oxidation mechanisms of food is vital. In certain lipids, characteristic lipid hydroperoxide isomers are formed by different oxidation mechanisms ( i.e ., photo-oxidation or auto-oxidation). For example, linoleic acid is photo-oxidized to 13-9 Z , 11 E -hydroperoxyoctadecadienoic acid (HPODE), 12-9 Z ,13 E -HPODE, 10-8 E ,12 Z -HPODE and 9-10 E ,12 Z -HPODE, whereas 13-9 Z , 11 E -HPODE, 13-9 E ,11 E -HPODE, 9-10 E ,12 Z -HPODE and 9-10 E ,12 E -HPODE are formed by auto-oxidation. Therefore, we considered that oxidation mechanisms could be evaluated by analyzing these characteristic positional and cis/trans lipid hydroperoxide isomers. In this study, we developed a novel chiral stationary phase LC-MS/MS (CSP-LC-MS/MS) method to analyze the positional and cis/trans isomers of HPODE, with the use of a chiral column and sodium ion. Also, as an application of the method, either light-exposed or heated edible oils were treated with lipase to hydrolyze triacylglycerols. The resultant fatty acids including HPODE isomers were analyzed with the developed method. As a result, HPODE isomers characteristic to photo-oxidation were certainly detected in light-exposed edible oils. On the other hand, in heated edible oils, the HPODE isomers characteristic to auto-oxidation were largely increased. Thus, the combination of the developed CSP-LC-MS/MS method with lipase proves to be a powerful tool to evaluate the involvement and mechanisms of lipid oxidation in the process of food deterioration.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.An amendment to this paper has been published and can be accessed via a link at the top of the paper.

An efficient and stereoselective syntheses of all the possible stereoisomers of coronafacic acid (CFA) has been developed. The stereochemistries of C3a and C7a were controlled in a diastereoselective Diels‐Alder type cycloaddition using a chiral auxiliary. CFA and 6‐epi‐CFA were synthesized by hydrogenation of a common intermediate. During the synthesis of 6‐epi‐CFA, we established that its cis‐fused configuration is important for the introduction of C4‐C5 double bond by dehydration. This report is the first practical synthesis of both 6‐epi‐CFA, and its enantiomer. An efficient and stereoselective syntheses of all the possible stereoisomers of coronafacic acid (CFA) has been developed. The stereochemistries of C3a and C7a were controlled in a diastereoselective Diels‐Alder type cycloaddition using a chiral auxiliary. CFA and 6‐epi‐CFA were synthesized by hydrogenation of a common intermediate. During the synthesis of 6‐epi‐CFA, we established that its cis‐fused configuration is important for the introduction of C4‐C5 double bond by dehydration. This report is the first practical synthesis of both 6‐epi‐CFA, and its enantiomer.

To elucidate the role of enzymatic lipid peroxidation in disease pathogenesis and in food deterioration, we recently achieved stereoselective analysis of phosphatidylcholine hydroperoxide (PCOOH) possessing 13 S -hydroperoxy-9 Z ,11 E -octadecadienoic acid (13( S )-9 Z ,11 E -HPODE) using HPLC-MS/MS with a CHIRALPAK OP (+) column. Because enzymatic oxidation progresses concurrently with auto-oxidation, we need to distinguish them further. Here, we attempted such an analysis. First, we used lipoxygenase, linoleic acid, and lysophosphatidylcholine (LPC) to synthesize the enzymatic oxidation product 13( S )-9 Z ,11 E -HPODE PC, and the auto-oxidation products 13( RS )-9 Z ,11 E -HPODE PC and 13( RS )-9 E ,11 E -HPODE PC, which were used as standards to test the ability of various columns to separate the enzymatic oxidation product from auto-oxidation products. Separation was achieved by connecting in series two columns with different properties: CHIRALPAK OP (+) and CHIRALPAK IB-3. The CHIRALPAK OP (+) column separated 13( R )-9 Z ,11 E -HPODE PC and 13( S )-9 Z ,11 E -HPODE PC, whereas CHIRALPAK IB-3 enabled separation of 13( S )-9 Z ,11 E -HPODE PC and 13( RS )-9 E ,11 E -HPODE PC. The results for the analysis of both enzymatically oxidized and auto-oxidized lecithin (an important phospholipid mixture in vivo and in food) indicate that our method would be useful for distinguishing enzymatic oxidation and auto-oxidation reactions. Such information will be invaluable for elucidating the involvement of PCOOH in disease pathogenesis and in food deterioration.

Amphirionin‐5, derived from dinoflagellates of the genus Amphidinium , exhibits a unique biological activity whereby trace amounts can lead to potent proliferation of osteoblasts, making it a promising candidate for regenerative therapy of bone and treatment of osteoporosis. However, the relative configuration of amphirionin‐5 has only been partially determined. Herein, the total synthesis of amphirionin‐5 is undertaken to establish its overall stereochemistry. Synthesized C16‐C28 model with the proposed relative configuration of C19‐C23 shows significant discrepancies between its NMR spectroscopic data around C19 and those of the corresponding substructures of the natural amphirionin‐5, suggesting of necessity for reconsideration of the relative configuration of C19. Two further 19 S ‐type C11‐C28 models are synthesized, and detailed NMR analysis reveals that the 13 C NMR of (19 S ,26 R )‐C11‐C28 models show the best agreement with those in the corresponding substructure of the natural product; thus, the relative configurations from C19 to C26 of amphirionin‐5 are proposed as 19 S *, 20 S *, 23 S *, and 26 R *. Coupling of the C1‐C16 segment, synthesized from an optically active α ‐silyloxy pentanolide as a common intermediate, and the (19 S ,26 R )‐C17‐C28 segment is achieved under intermolecular Stetter reaction conditions, enabling the convergent total synthesis of the candidate diastereomer of amphirionin‐5. Ultimately, the overall stereochemistry of amphirionin‐5 is fully assigned.

A sex pheromone component of Pseudococcus cryptus has been isolated and identified. The crude pheromone extract obtained by airborne collection was fractionated by liquid chromatography (LC) on Florisil, and further purified by high performance liquid chromatography and preparative Gas Chromatography (GC). The pheromone component was shown to be an ester, the alcohol part of which was identical to the known alcohol moiety of the pheromone of Planococcus citri. The chemical structure was determined to be 3-isopropenyl-2,2-dimethylcyclobutylmethyl 3-methyl-3-butenoate by MS and 1H NMR analyses. The absolute configuration of the pheromone was assigned as (1R,3R) by comparison of the retention time of the alcohol derived from the P. cryptus pheromone with those of the alcohol derived from P. citri pheromone, and a synthetic sample of alcohol enriched in the (1R,3R)-enantiomer, using a chiral GC stationary phase. The structure of the pheromone was confirmed by synthesis, and by bioassays in a glasshouse.

Male-released semiochemicals of the stink bug Piezodorus hybneri (Heteroptera: Pentatomidae) elicit attraction of male and female bugs and homosexual behavior in males. Three active components were isolated from the airborne volatiles of males by flash chromatography, with the activity-monitored by GC-EAD and behavioral bioassay. The pheromone system was characterized as a mixture of beta-sesquiphellandrene, (R)-15-hexadecanolide. and methyl 8-(Z)-hexadecenoate (ratio: 10:4:1), and the activity of the semiochemicals was assessed with authentic samples. Enantiomerically pure samples of the R and S macrolactones were obtained by Yamaguchi's and Mitsunobu's macrolactonization of a key intermediate. (R)-15-hydroxyhexadecanoic acid. The nonnatural S stereoisomer was neither a beneficial nor a behavioral antagonist. Individual constituents or binary mixtures were active, but the optimal male response was elicited only by the full mixture. Behavioral observation and the fact that the onset of pheromone production is coincident with ovarian development strongly suggest that these semiochemicals are, in fact, sex pheromones.