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Histamine (HIST) and other biogenic amines found in fish and fishery products accumulated by the action of bacterial amino acid decarboxylase cannot be decomposed and eliminated by heating or other chemical methods. A simple method for HIST elimination is proposed by a coupling reaction of the fungal amine oxidase (FAO) and bacterial aldehyde oxidase (ALOX) of acetic acid bacteria. As a model reaction, FAO oxidized benzylamine to benzaldehyde, which in turn was oxidized spontaneously to benzoic acid with ALOX. Likely, in HIST elimination, FAO coupled well with ALOX to produce imidazole 4-acetic acid from HIST with an apparent yield of 100%. Imidazole 4-acetaldehyde was not detected in the reaction mixture. In the absence of ALOX, the coupling reaction was incomplete given a number of unidentified substances in the reaction mixture. The proposed coupling enzymatic method may be highly effective to eliminate toxic amines from fish and fishery products.

d-Mannose isomerase (EC 5.3.1.7) catalyzing reversible conversion between d-mannose and d-fructose was found in acetic acid bacteria. Cell fractionation confirmed the enzyme to be a typical membrane-bound enzyme, while all sugar isomerases so far reported are cytoplasmic. The optimal enzyme activity was found at pH 5.5, which was clear contrast to the cytoplasmic enzymes having alkaline optimal pH. The enzyme was heat stable, and the optimal reaction temperature was observed at around 40-60 °C. Purified enzyme after solubilization from membrane fraction showed the total molecular mass of 196 kDa composing of identical 4 subunits of 48 kDa. Washed cells or immobilized cells were well functional at nearly 80% of conversion ratio from d-mannose to d-fructose and reversely 20%-25% of d-fructose to d-mannose. Catalytic properties of the enzyme were discussed with respect to the biotechnological applications to high fructose syrup production from konjac taro.

Due to the indigestibility, utilization of konjac taro, Amorphophallus konjac has been limited only to the Japanese traditional konjac food. Koji preparation with konjac taro was examined to utilize konjac taro as a source of utilizable carbohydrates. Aspergillus luchuensis AKU 3302 was selected as a favorable strain for koji preparation, while Aspergillus oryzae used extensively in sake brewing industry was not so effective. Asp. luchuensis grew well over steamed konjac taro by extending hyphae with least conidia formation. Koji preparation was completed after 3-day incubation at 30°C. D-Mannose and D-glucose were the major monosaccharides found in a hydrolyzate giving the total sugar yield of 50 g from 100 g of dried konjac taro. An apparent extent of konjac taro hydrolysis at 55°C for 24 h seemed to be completed. Since konjac taro is hydrolyzed into monosaccharides, utilization of konjac taro carbohydrates may become possible to various products of biotechnological interest. Fil: Adachi, Osao. Yamaguchi University; Japón Fil: Hours, Roque Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Akakabe, Yoshihiko. Yamaguchi University; Japón Fil: Arima, Hideyuki. Yamaguchi Prefectural Industrial Technology Institute; Japón Fil: Taneba, Rie. Yamaguchi Prefectural Industrial Technology Institute; Japón Fil: Tanaka, Junya. Yamaguchi Prefectural Industrial Technology Institute; Japón Fil: Kataoka, Naoya. Yamaguchi University; Japón Fil: Matsushita, Kazunobu. Yamaguchi University; Japón Fil: Yakushi, Toshiharu. Yamaguchi University; Japón

Gluconobacter frateurii CHM 43 have D-mannitol dehydrogenase (quinoprotein glycerol dehydrogenase) and flavoprotein D-fructose dehydrogenase in the membranes. When the two enzymes are functional, D-mannitol is converted to 5-keto-D-fructose with 65% yield when cultivated on D-mannitol. 5-Keto-D-fructose production with almost 100% yield was realized with the resting cells. The method proposed here should give a smart strategy for 5-keto-D-fructose production., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Mitochondria, which evolved from a free-living bacterial ancestor, contain their own genomes and genetic systems and are produced from preexisting mitochondria by binary division. The mitochondrion-dividing (MD) ring is the main skeletal structure of the mitochondrial division machinery. However, the assembly mechanism and molecular identity of the MD ring are unknown. Multi-omics analysis of isolated mitochondrial division machinery from the unicellular alga Cyanidioschyzon merolae revealed an uncharacterized glycosyltransferase, MITOCHONDRION-DIVIDING RING1 (MDR1), which is specifically expressed during mitochondrial division and forms a single ring at the mitochondrial division site. Nanoscale imaging using immunoelectron microscopy and componential analysis demonstrated that MDR1 is involved in MD ring formation and that the MD ring filaments are composed of glycosylated MDR1 and polymeric glucose nanofilaments. Down-regulation of MDR1 strongly interrupted mitochondrial division and obstructed MD ring assembly. Taken together, our results suggest that MDR1 mediates the synthesis of polyglucan nanofilaments that assemble to form the MD ring. Given that a homolog of MDR1 performs similar functions in chloroplast division, the establishment of MDR1 family proteins appears to have been a singular, crucial event for the emergence of endosymbiotic organelles.

A novel oxidation of D-pentonates to 4-keto-D-pentonates was analyzed with Gluconobacter Thailandicus NBRC 3258. D-Pentonate 4-dehydrogenase activity in the membrane fraction was readily inactivated by EDTA and it was reactivated by the addition of PQQ and Ca2+. D-Pentonate 4-dehydrogenase was purified to two different subunits, 80 and 14 kDa. The absorption spectrum of the purified enzyme showed no typical absorbance over the visible regions. The enzyme oxidized D-pentonates to 4-keto-D-pentonates at the optimum pH of 4.0. In addition, the enzyme oxidized D-fructose to 5-keto-D-fructose, D-psicose to 5-keto-D-psicose, including the other polyols such as, glycerol, D-ribitol, D-arabitol, and D-sorbitol. Thus, D-pentonate 4-dehydrogenase was found to be identical with glycerol dehydrogenase (GLDH), a major polyol dehydrogenase in Gluconobacter species. The reaction versatility of quinoprotein GLDH was notified in this study., Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales

Eight-carbon (C8) volatiles, such as 1-octen-3-ol, octan-3-one, and octan-3-ol, are ubiquitously found among fungi and bryophytes. In this study, it was found that the thalli of the common liverwort Marchantia polymorpha, a model plant species, emitted high amounts of C8 volatiles mainly consisting of (R)-1-octen-3-ol and octan-3-one upon mechanical wounding. The induction of emission took place within 40min. In intact thalli, 1-octen-3-yl acetate was the predominant C8 volatile while tissue disruption resulted in conversion of the acetate to 1-octen-3-ol. This conversion was carried out by an esterase showing stereospecificity to (R)-1-octen-3-yl acetate. From the transgenic line of M. polymorpha (des6(KO)) lacking arachidonic acid and eicosapentaenoic acid, formation of C8 volatiles was only minimally observed, which indicated that arachidonic and/or eicosapentaenoic acids were essential to form C8 volatiles in M. polymorpha. When des6(KO) thalli were exposed to the vapor of 1-octen-3-ol, they absorbed the alcohol and converted it into 1-octen-3-yl acetate and octan-3-one. Therefore, this implied that 1-octen-3-ol was the primary C8 product formed from arachidonic acid, and further metabolism involving acetylation and oxidoreduction occurred to diversify the C8 products. Octan-3-one was only minimally formed from completely disrupted thalli, while it was formed as the most abundant product in partially disrupted thalli. Therefore, it is assumed that the remaining intact tissues were involved in the conversion of 1-octen-3-ol to octan-3-one in the partially disrupted thalli. The conversion was partly promoted by addition of NAD(P)H into the completely disrupted tissues, suggesting an NAD(P)H-dependent oxidoreductase was involved in the conversion.

Production of 4-keto-D-arabonate (4KAB) was confirmed in a culture medium of Gluconacetobacter liquefaciens strains, newly isolated from water kefir in Argentina. The strains rapidly oxidized D-glucose, Dgluconate (GA), and 2-keto-D-gluconate (2KGA), and accumulated 2,5-diketo-D-gluconate (25DKA) exclusively before reaching the stationary phase. 25DKA was in turn converted to 4KAB, and 4KAB remained stable in the culture medium. The occurrence of 4KAB was assumed by Ameyama and Kondo about 50 years ago in their study on the carbohydrate metabolism of acetic acid bacteria (Bull. Agr. Chem. Soc. Jpn., 22, 271-272, 380-386 (1958)). This is the first report confirming microbial production of 4KAB., Centro de Investigación y Desarrollo en Fermentaciones Industriales

The citrus fruit Setomi is a hybrid of Yoshiura ponkan (Citrus reticulate Blanco) and Kiyomi (Citrus unshiu Mrcov. x Citrus sinensis Osbeck). The essential oils from the peel of Setomi and its parent cultivars were obtained by a simultaneous distillation extraction technique. Comparing the essential oils of Setomi and its parent cultivars, it was found that the oil in the peel of Setomi consisted of characteristic aroma components from each parent cultivar. The principal component analysis of data, obtained with an electronic nose, indicated that the odor quality of Setomi was different from those of the parent cultivars.

2E-Nonenal and n-hexanal are the major and minor flavor compounds in the edible brown alga, Laminaria angustata, respectively. They are believed to characterize the flavor of this alga. However the metabolism of the two compounds is not precisely known. The pathways were clarified by elucidation of the intermediate structure through purification of the intermediate compounds from an enzymatic reaction and identification using HPLC and GC-MS techniques. Formation of n-hexanal, 3Z-nonenal and 2E-nonenal are proposed to be via two cascades from unsaturated fatty acids. They are C18:2(n-6), linoleic acid cascade and C20:4(n-6), arachidonic acid cascade through their hydroperoxides as intermediates by the lipoxygenase/fatty acid hydroperoxide lyase pathway.

Plant fatty acid alpha-dioxygenases (DOXs) catalyze the stereospecific conversion of fatty acids into the corresponding (R)-2-hydroperoxy fatty acids. In several plant species the corresponding gene was shown to be induced by pathogen infection, herbivore attack and environmental stresses. The precise signaling pathway accountable for the induction remains unidentified. In the present study, the effects of bacterial infection, oxidative- and heavy metal-stresses, and plant signaling molecules such as jasmonate, salicylic acid (SA), and ethylene (ET) on expression of a fatty acid alpha-DOX (OsDOX) gene in rice seedlings were investigated. The rice blight bacteria, Xanthomonas oryzae, elicited the accumulation of OsDOX transcripts in the leaves in both the incompatible and compatible interactions. Treating the seedling with CuSO4 also significantly enhanced the OsDOX expression. The degree of induction was shown to be mostly parallel to the level of endogenous jasmonic acid (JA) in the leaves. In contrast, SA was little effective and ET down-regulated not only the OsDOX expression but also the endogenous level of JA in rice seedlings. These results suggested that the OsDOX gene expression by a variety of stress-related stimuli was activated through jasmonate signaling and was negatively regulated by ET.

D-Ribose and 2-deoxy-D-ribose were oxidized to 4- keto-D-ribonate and 2-deoxy-4-keto-D-ribonate respectively by oxidative fermentation, and the chemical structures of the oxidation products were confirmed to be as expected. Both pentoses are important sugar components of nucleic acids. When examined, purine nucleosidase activity predominated in the membrane fraction of acetic acid bacteria. This is perhaps the first finding of membrane-bound purine nucleosidase., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Long-chain fatty acids can be metabolized to C n −1 aldehydes by α-oxidation in plants. The reaction mechanism of the enzyme has not been elucidated. In this study, a complete nucleotide sequence of fatty acid α-oxygenase gene in rice plants (Oryza sativa) was isolated. The deduced amino acid sequence showed some similarity with those of mammalian prostaglandin H synthases (PGHSs). The gene was expressed in Escherichia coli and purified to apparently homogenous state. It showed the highest activity with linoleic acid and predominantly formed 2-hydroperoxide of the fatty acid (C n ), which is then spontaneously decarboxylated to form corresponding C n −1 aldehyde. With linoleic or linoleic acids as a substrate, rice α-oxygenase formed no product having aλ max at approximately 234 nm, which indicated that the enzyme could not oxygenize the pentadiene system in the substrate. The spectroscopic feature of the purified enzyme in its ferrous state is similar to that of mammalian PGHS, whereas that of dithionite-reduced state showed significant difference. Site-directed mutagenesis revealed that His-158, Tyr-380, and Ser-558 were essential for the α-oxygenase activity. These residues are conserved in PGHS and known as a heme ligand, a source of a radical species to initiate oxygenation reaction and a residue involved in substrate binding, respectively. This finding suggested that the initial step of the oxygenation reaction in α-oxygenase has a high similarity with that of PGHS. The rice α-oxygenase activity was inhibited by imidazole but hardly inhibited by nonsteroidal anti-inflammatory drugs, such as aspirin, ibuprofen, and flurbiprofen, which are known as typical PGHS inhibitors. In addition, peroxidase activity could not be detected with α-oxygenase when palmitic acid 2-hydroperoxide was used as a substrate. From these findings, the catalytic resemblance between α-oxygenase and PGHS seems to be evident, although there still are differences in their substrate recognitions and peroxidation activities.

4-Keto-D-arabonate (D-threo-pent-4-ulosonate) and 4-keto-D-ribonate (D-erythro-pent-4-ulosonate) were prepared from D-arabinose and D-ribose by two successive reactions of membrane-bound enzymes, D-aldopentose 4-dehydrogenase and 4-keto-D-aldopentose 1-dehydrogenase of Gluconobacter suboxydans IFO 12528. Alternatively, they were prepared from D-arabonate and D-ribonate with another membrane-bound enzyme, D-pentonate 4-dehydrogenase. Analytical data confirmed the chemical structures of the 4-pentulosonates prepared. This is the first report of successful enzymatic synthesis of 4-pentulosonates.

SUMMARY: When long-chain saturated and unsaturated fatty acids were incubated with crude enzyme of marine green alga Ulva pertusa, the corresponding (R)-2-hydroperoxy acids were found to have high enantiomeric excess (> 99%). In a similar administration experiment, the (R)-2-hydroperoxy acid was obtained from the incubation of palmitic acid with crude enzymes of a variety of marine algae. Thus, we found that not only green algae but also brown and red algae are capable of enantioselective 2-hydroperoxylation of palmitic acid.

Genes encoding an alpha-oxygenase, in Nicotiana tabacum and Arabidopsis thaliana, have been recently isolated. However, the reaction mechanism of the enzyme has not so far been elucidated. In this study, a cDNA encoding the fatty acid alpha-oxygenase gene in rice plants was isolated. The deduced amino acid sequence showed high similarity (63.6%) to that of N. tabacum. The gene was cloned into an expression vector system, pQE-30, and expressed in Escherichia coli as a host cell. Palmitic acid as a substrate was incubated with the lysate of the cells, and the products were analysed by HPLC. A compound formed predominantly by the recombinant enzyme was shown to be n-pentadecanal. By incubating the mixture at 0 degrees C, 2-hydroperoxypalmitic acid was detected as a primary product and little formation of n-pentadecanal was detected. Furthermore, uptake of molecular oxygen was observed with an oxygen electrode. This indicated that the gene in rice plants encodes the alpha-oxygenase.

Neodictyoprolenol [(-)-(S)-(1,5Z,8Z)-undecatrien-3-ol], dictyoprolenol [(-)-(S )-(1,5Z)- undecadien-3-ol] and their acetates neodictyoprolene [(+)-(5)-3-acetoxy-(1,5Z,8Z)-undecatriene] and dictyoprolene [(+)-(S)-3-acetoxy-(1,5Z)-undecadiene], which are interesting as possible biosynthetic intermediates of the sex pheromones (dictyopterene B, C′ and D′) of brown algae, were synthesized by chemo-enzymatic methods through optical resolution of racemic neodictyoprolenol and dictyoprolenol using two lipases; Amano PS (Pseudom onas sp.) and Novozym 435® (Candida sp.). A combination of acylation of the alcohols and hydrolysis of the acetates by Novozym 435® produced neodictyoprolenol, neodictyoprolene, dictyoprolenol and dictyoprolene with high optical purities over 99% enantiomeric excess (e.e.). This snythetic methods will make it easier to search these compounds in marine algae and to study their biosynthesis.

When palmitic acid was incubated with crude enzyme of marine green alga Ulva pertusa, (R)-2-hydroperoxyhexadecanoic acid was formed in high enantiomeric purity (>99%ee).

Long-chain aldehydes (LCA), such as pentadecanal (PD), (8Z,11Z)-heptadecadienal (HDD) and (8Z,11Z,14Z)-heptadecatrienal (HDT), were identified in the essential oils obtained from fresh green tobacco leaves (Nicotiana tabacum cv. BY2 and N. tabacum cv. MC). PD, HDD and HDT were found to be produced enzymatically from palmitic acid (PA), linoleic acid and α-linolenic acid, respectively. LCA-forming activity for PA changed during growth of tobacco leaves and was highest at flowering time.

A growth-promoting substance (GPS) for methylotrophic yeasts was purified from yeast extract. The purified GPS showed growth promotion by reducing the lag time of the growth of methylotrophic Candida boidinii, while the growth rate at the exponential phase was the same as that of growth without GPS. GPS was finally identified to be L-proline by the criteria of instrumental analysis and chemical shift assignments.

(−)-( 3R,4R )-3-Butyl-4-vinylcyclopentene [(−)- 1 ] was synthesized via (+)-( 1S,5R )-3-oxabicyclo [3,3,0] oct-6-en-2-one. Synthetic (−)- 1 coincided with the peak with later retention time of racemic (±)- 1 in a chiral GC (CP-Cyclodex 236M), while the natural 1 in essential oils from the marine brown algae, Dictyopteris prolifera and D . sp. was identical with the earlier retention time peak. Thus, the absolute configuration of the natural product in Dictyopteris oils was determined as (+)-( 3S,4S ) with ca 100% enantiomeric excess.

Eikenella corrodens produces autoinducer-2 (AI-2) in the mid log phase, and AI-2 activity decreases dramatically during the stationary phase. We investigated the mechanism underlying this decrease in AI-2 activity. To analyze the mechanism, we extracted and purified AI-2 from the supernatant of mid-log-phase culture. Simultaneously, the stationary-phase culture supernatant was fractionated by ammonium sulfate precipitation. On incubating purified AI-2 and 4-hydroxy-5-methyl-3(2H)-furanone (MHF) with each fraction, the 30% fraction decreased both AI-2 and MHF activities. The data suggest that AI-2 and MHF were rendered inactive in the same manner. Heat and/or trypsin treatment of the 30% fraction did not completely arrest AI-2 inactivation, suggesting that partially heat-stable proteins are involved in AI-2 inactivation. We observed that an enzyme converted MHF to another form. This suggests that E. corrodens produces an AI-2 inactivating enzyme, and that AI-2 can be degraded or modified by it.

In order to confirm the biosynthetic pathway to 1-octen-3-ol from linoleic acid, a crude enzyme solution was prepared from the edible mushroom, Lentinus decadetes. When the reaction was performed in the presence of glutathione peroxidase, which can reduce organic hydroperoxide to the corresponding hydroxide, the amount of 1-octen-3-ol formed from linoleic acid was decreased. At the same time, an accumulation of linoleic acid 10-hydroxide could be detected. The 10-hydroperoxide therefore seems to be an intermediate on the biosynthetic pathway.

Immobilized cells of Daucus carota transformed acetophenone into (S)-α-phenethyl alcohol by a stereoselective reduction pathway. Immobilized cells of Nicotiana tabacum also transformed the same substrate into the (S)-alcohol, but neither stereoselective reduction nor stereoselective oxidation was observed in the biotransformation process. (R)- and (S)-α-phenethyl alcohol of a high enantiomeric purity of > 99% ee can be prepared by the biotransformation of acetophenone with immobilized cells of Gardenia jasminoides and Daucus carota.

When linoleic and linolenic acid were incubated with a crude enzyme of marine green alga Ulva conglobata, the corresponding (R)-9-hydroperoxy-(10E, 12Z)-10, 12-octadecadienoic acid [(R)-9-HPODE] and (R)-9-hydroperoxy-(10E, 12Z, 15Z)-10, 12, 15-octadecatrienoic acid [(R)-9-HPOTrE] were formed with a high enantiomeric excess (>99%), respectively.

In our previous study, a new microbial reaction yielding 4-keto-D-arabonate from 2,5-diketo-D-gluconate was identified with Gluconacetobacter liquefaciens RCTMR 10. It appeared that decarboxylation and dehydrogenation took place together in the reaction. To analyze the nature of the reaction, investigations were done with the membrane fraction of the organism, and 4-keto-D-arabinose was confirmed as the direct precursor of 4-keto-D-arabonate. Two novel membrane-bound enzymes, 2,5-diketo-D-gluconate decarboxylase and 4-keto-D-aldopentose 1-dehydrogenase, were involved in the reaction. Alternatively, D-arabonate was oxidized to 4-keto-D-arabonate by another membrane-bound enzyme, D-arabonate 4-dehydrogenase. More directly, D-arabinose oxidation was examined with growing cells and with the membrane fraction of G. suboxydans IFO 12528. 4-Keto-D-arabinose, the same intermediate as that from 2,5-diketo-D-gluconate, was detected, and it was oxidized to 4-keto-D-arabonate. Likewise, D-ribose was oxidized to 4-keto-D-ribose and then it was oxidized to 4-keto-D-ribonate. In addition to 4-keto-D-aldopentose 1-dehydrogenase, the presence of a novel membranebound enzyme, D-aldopentose 4-dehydrogenase, was confirmed in the membrane fraction. The formation of 4-keto-D-aldopentoses and 4-keto-D-pentonates (4-pentulosonates) was finally confirmed as reaction products of four different novel membrane-bound enzymes., Centro de Investigación y Desarrollo en Fermentaciones Industriales

A total of 39 aroma compounds were detected in the essential oil of Citrus nagato-yuzukichi Tanaka (nagato-yuzukichi) by gas chromatography-mass spectrometry (GC-MS). The essential oil was characterized by a high percentage of monoterpene hydrocarbons (12 components, 90.52%). The composition pattern of essential oil in C. nagato-yuzukichi was fairly similar to that of Citrus sudachi Hort. ex Shirai (Sudachi). Principal component analysis (PCA) of data obtained with an electronic nose indicated a variation of each oil along PC1. The oils of Citrus junos Tanaka (Yuzu) and Citrus sphaerocarpa Tanaka (Kabosu) showed a clear upward displacement as compared with those of C. nagato-yuzukichi and C. sudachi. However, in PC2, the oils of C. nagato-yuzukichi and C. sudachi showed a displacement in a negative direction and a positive one respectively.

Chlorogenate hydrolase (EC 3.1.1.42, CHase) was highly induced in mycelia of Aspergillus sojae AKU 3312 grown in Czapek medium containing either instant coffee powder or coffee pulp as inducer. No CHase formation was observed in the mycelia when cultivated without the inducer. CHase was purified readily from CHase-induced mycelia to high homogeneity, and the purified CHase revealed the molecular weight of 180,000 consisting of two identical subunits of 88 kDa. Equimolar quinate (QA) and caffeate (CA) were confirmed on hydrolysis of chlorogenate (CGA). The purified CHase was only useful for a laboratory scale hydrolysis of CGA. For practical QA and CA production using scaled up hydrolysis of vegetable extracts of natural CGA resources, the enzyme activity of purified CHase decreased and denatured irreversibly. Preparation of coffee pulp koji and its application to QA and CA production were proposed instead of purified CHase. When coffee pulp koji was heated at 60 degrees C for 30 min, CHase survived without any appreciable loss of enzyme activity while vegetative mycelial growth and spore germination were terminated. The heated coffee pulp koji thus prepared was effective itself as stable immobilized catalyst of CHase for QA and CA production from vegetable CGA resources such as coffee powders, coffee pulp, and others.

The essential oil from the shoots of the marine embryophyte, Zostera marina was prepared by simultaneous distillation-extraction. Volatile compounds in the oil were identified by GC and GC-mass spectrometry. The major constituents were phytol, hexadecanamide, octadecanamide, pentadecane, heptadecane, nonadecane, (8 Z , 11 Z )-heptadecadienal (HDD), (8 Z )-heptadecenal (HD), (9 Z , 12 Z , 15 Z )-octadecatrienal and (9 Z , 12 Z )-octadecadienal. HDD and HD were shown to be formed enzymatically from linoleic acid and oleic acid, respectively.

Bamboo vinegar solutions had pHs of 2.5 to 2.8, and the amounts of organic constituents were estimated to be 2.3 to 4.6% (w/w). Volatile organic compounds (28 components) were detected by GC-MS, and among of these, 11 compounds were common to three samples of bamboo vinegar. Perhaps acetic acid, 3-methyl-1,2-cyclohexadione, guaiacol, p-cresol, and syringol contributed to the characteristic odors (sour, smoky, and medicinal note) in bamboo vinegar.

Linoleic acid (LA) incubated with a homogenate of Lentinula edodes or Tricholoma matsutake mushroom significantly increased the amount of (R)-1-octen-3-ol. The alcohol was identified as (S)-10-HODE with 90-87% and >99% enantiomeric excess (ee), respectively. During the incubation of LA with these homogenates in the presence of glutathione-glutathione peroxidase (GSH-GPx), which can reduce hydroperoxy fatty acids to the corresponding hydroxy acids, the formation of (R)-1-octen-3-ol was significantly inhibited, whereas the amount of 10-hydroxy-(8E,12Z)-8,12-octadecadienoic acid (10-HODE) was significantly increased. The acid was identified as (S)-10-HODE with 92-88% ee and >99% ee, respectively. The decrease in the amount of alcohol was approximately the same as the increase in amount of HODE in both mushrooms. These results indicate a stereochemical correlation between (R)-1-octen-3-ol and (S)-10-hydroperoxy-(8E,12Z)-8,12-octadecadienoic acid [(S)-10-HPODE] in both mushrooms.

The long-chain aldehydes, (8Z,11Z,14Z)-8,11,14-heptadecatrienal, (7Z,10Z,13Z)-7,10,13-hexadecatrienal, and (8Z,11Z)-8,11-heptadecadienal, were concisely synthesized by using Grignard coupling, catalytic hydrogenation with the Lindlar catalyst, and oxidation with Dess–Martin periodinane as the key steps. Particularly, (8Z,11Z,14Z)-8,11,14-heptadecatrienal and (7Z,10Z,13Z)-7,10,13-hexadecatrienal both possessed a seaweed-like odor.

Marine green alga Ulva conglobata was investigated for the biogeneration of oxygenated products from exogenously added arachidonic acid (ARA). A crude enzyme from the alga afforded the detectable amount of a hydroperoxyicosatetraenoic acid (HPITE), which was identified as (R)-11-HPITE by HPLC and GC-MS. Headspace-SPME method indicated that ARA was selectively used to form 2,4-decadienals. These results showed that 2,4-decadienals are produced via (R)-11-HPITE from ARA exclusively.

In higher plants, C6 and C9 aldehydes are formed from C18 fatty acids, such as linoleic or linolenic acid, through formation of 13- and 9-hydroperoxides, followed by their stereospecific cleavage by fatty acid hydroperoxide lyases (HPL). Some marine algae can also form C6 and C9 aldehydes, but their precise biosynthetic pathway has not been elucidated fully. In this study, we show that Laminaria angustata, a brown alga, formed C6 and C9 aldehydes enzymatically. The alga forms C9 aldehydes exclusively from the C20 fatty acid, arachidonic acid, while C6 aldehydes are derived either from C18 or from C20 fatty acid. The intermediates in the biosynthetic pathway were trapped by using a glutathione/glutathione peroxidase system, and subjected to structural analyses. Formation of (S)-12-, and (S)-15-hydroperoxy arachidonic acids [12(S)HPETE and 15(S)HPETE] from arachidonic acid was confirmed by chiral HPLC analyses. These account respectively for C9 aldehyde and C6 aldehyde formation, respectively. The HPL that catalyzes formation of C9 aldehydes from 12(S)HPETE seems highly specific for hydroperoxides of C20 fatty acids.

Some marine algae can form volatile aldehydes such as n-hexanal, hexenals, and nonenals. In higher plants it is well established that these short-chain aldehydes are formed from C18 fatty acids via actions of lipoxygenase and fatty acid hydroperoxide lyase, however, the biosynthetic pathway in marine algae has not been fully established yet. A brown alga, Laminaria angustata, forms relatively higher amounts of C6- and C9-aldehydes. When linoleic acid was added to a homogenate prepared from the fronds of this algae, formation of n-hexanal was observed. When glutathione peroxidase was added to the reaction mixture concomitant with glutathione, the formation of n-hexanal from linoleic acid was inhibited, and oxygenated fatty acids accumulated. By chemical analyses one of the major oxygenated fatty acids was shown to be (S)-13-hydroxy-(Z, E)-9, 11-octadecadienoic acid. Therefore, it is assumed that n-hexanal is formed from linoleic acid via a sequential action of lipoxygenase and fatty acid hydroperoxide lyase (HPL), by an almost similar pathway as the counterpart found in higher plants. HPL partially purified from the fronds has a rather strict substrate specificity, and only 13-hydroperoxide of linoleic acid, and 15-hydroperoxide of arachidonic acid are the essentially suitable substrates for the enzyme. By surveying various species of marine algae including Phaeophyta, Rhodophyta and Chlorophyta it was shown that almost all the marine algae have HPL activity. Thus, a wide distribution of the enzyme is expected.

Long-chain fatty acids can be metabolized to Cn−1 aldehydes by α-oxidation in plants. The reaction mechanism of the enzyme has not been elucidated. In this study, the gene encoding rice α-oxygenase was expressed in E. coli and purified to apparently homogenous state. Site-directed mutagenesis revealed that His-158, Tyr-380, and Ser-558 were essential for the α-oxygenase activity. These residues are conserved in prostaglandin H synthases (PGHS) and known as a heme-ligand, a source of a radical species to initiate oxygenation reaction, and a residue involved in substrate binding, respectively. The rice α-oxygenase activity was inhibited by imidazole but hardly inhibited by nonsteroidal anti-inflammatory drugs, which are known as typical PGHS inhibitions. In addition, peroxidase activity could not be detected with α-oxygenase when palmitic acid 2-hydroperoxide was used as a substrate. From these findings catalytic resemblance between α-oxygenase and PGHS seems to be evident although there still are differences in their substrate recognitions and peroxidation activities.

Immobilized cells of Gardenia jasminoides enantioselectively transformed acetophenone into the corresponding ( R )-alcohol by a two-step pathway involving initial reduction of the aromatic ketone to produce a mixture of ( R )- and ( S )-α-phenethyl alcohol followed by stereoselective oxidation of the ( S )-aromatic alcohol to produce acetophenone.

Immobilized cells of Daucus carota enantioselectively transformed aromatic ketones such as acetophenone and propiophenone, into the corresponding ( S )-alcohols with an optical purity of 89–99% ee in a chemical yield of 54–70%. Immobilized Gardenia jasminoides cells yielded the ( R )-alcohols with a 63–91% ee.

After the formation of dianions of a carboxylic acid with lithium diisopropylamide, oxygen was bubbled into the solution to produce 2-hydroperoxy acid. Then the reaction mixture was acidified with a 2 N HCl solution and subsequently elevated to 50 degrees C to afford the aldehyde with the loss of one carbon atom. Even saturated (C(10)-C(20)) and unsaturated (C(18:1)) carboxylic acids were converted into the odd aldehydes (C(9)-C(19), C(17:1)) in high yields. This conversion was found to be an efficient method for the preparation of carboxylic acids (Cn) to one-carbon degraded aldehydes (Cn-1) via 2-hydroperoxy acids.

When long-chain unsaturated fatty acids such as oleic, linoleic, and linolenic acid were incubated with crude enzymes from the marine green alga Ulva pertusa, the corresponding (R)-2-hydroperoxy acids were formed with a high enantiomeric excess (>99%).