Fluorescence formation from the interaction of DNA with lipid oxidation degradation products

To clarify the mechanism of fluorescence formation between DNA and lipid degradation products in the presence of ferric chloride and ascorbic acid, a number of carbonyl compounds and decomposition products of pure methyl linolenate hydroperoxides were examined. Keto derivatives of methyl ricinoleate, linoleate, and oleate, alkanals and 2-alkenals produced little or no fluorescence with DNA in the presence of ferric chloride-ascorbic acid. 2,4-Alkadienals were more active and 2,4,7-decatrienal was the most active. Mixtures of volatile aldehydes prepared from linolenate hydroperoxide decomposed either thermally or with iron and ascorbate had the same activity as 2,4,7-decatrienal. Higher molecular-weight products from the decomposition of methyl linolenate hydroperoxides showed relatively low activity. beta-Carotene, alpha-tocopherol and other antioxidants effectively reduced the amount of fluorescence formed by linolenate hydroperoxides. The results suggest that, in addition to hydroperoxide decomposition products, singlet oxygen and/or free radical species contribute significantly to the fluorescence formed from the interaction of methyl linolenate hydroperoxides with DNA in the presence of ferric chloride and ascorbic acid.     

国产松露乙醚提取物的GC-MS分析

采用气相色谱-质谱(GC-MS)法分析我国云南产黑松露(Tuber indicum)乙醚提取物的化学成分.从中鉴定了56个化合物,占提取物总含量的87.37％,化合物组成特征:以脂肪酸类化合物为主,占59.98％,其中含亚油酸达26.51％;醇、酯、醛和烃类化合物分别占7.96％、2.79％、2.44％和13.12％,另外还含有少量的苯衍生物,占1.08％.     

Regulation of oxylipin synthesis

Two very common groups of oxylipins formed in plants involve the conversion of fatty acid hydroperoxides, such as hydroperoxy-octadecatrienoic acid, into further metabolites by allene oxide synthase and hydroperoxide lyase. Both of these oxylipin branch pathways appear to be ubiquitous or nearly so in plants, but the relative activities of these two branches vary among plant species. In most plants examined, including Arabidopsis, product formation from either of these pathways is minimal until elicited by wounding or some other means, upon which products from both pathways, such as jasmonic acid and C(6) aldehydes and alcohols, can increase by orders of magnitude. In some plant species such as Artemisia and Jasminum spp. oxylipin product formation is heavily skewed towards allene oxide synthase products. Others such as watermelon (Citrullus lanatus) produce 10-fold higher amounts or more of hydroperoxide lyase than allene oxide synthase products. Arabidopsis and tobacco are intermediate between these extremes. Artemisia and Jasminum are also unusual in that they do not require wounding or other types of induction for high oxylipin product formation. Release of non-esterified fatty acids appears to be correlated with oxylipin formation, but phospholipase A(2) appears not to be involved with oxylipin production, at least in the case of Artemisia leaves.     

Volatile compounds from triticum aestivum

Volatile compounds were isolated from aerial parts (foliage and culms) of wheat plants by reduced pressure steam distillation-extraction and identified by gas chromatography-mass spectrometry and co-chromatography with authentic compounds. Infrared spectra were also obtained on some constituents. Compounds identified included nonanal and related unsaturated C₉ aldehydes and alcohols as major components and some additional aldehydes, alcohols and a ketone.     

Traumatin- and Dinortraumatin-containing Galactolipids in Arabidopsis: THEIR FORMATION IN TISSUE-DISRUPTED LEAVES AS COUNTERPARTS OF GREEN LEAF VOLATILES*

Green leaf volatiles (GLVs) consisting of six-carbon aldehydes, alcohols, and their esters, are biosynthesized through the action of fatty acid hydroperoxide lyase (HPL), which uses fatty acid hydroperoxides as substrates. GLVs form immediately after disruption of plant leaf tissues by herbivore attacks and mechanical wounding and play a role in defense against attackers that attempt to invade through the wounds. The fates and the physiological significance of the counterparts of the HPL reaction, the 12/10-carbon oxoacids that are formed from 18/16-carbon fatty acid 13-/11-hydroperoxides, respectively, are largely unknown. In this study, we detected monogalactosyl diacylglycerols (MGDGs) containing the 12/10-carbon HPL products in disrupted leaf tissues of Arabidopsis, cabbage, tobacco, tomato, and common bean. They were identified as an MGDG containing 12-oxo-9-hydroxy-(E)-10-dodecenoic acid and 10-oxo-7-hydroxy-(E)-8-decenoic acid and an MGDG containing two 12-oxo-9-hydroxy-(E)-10-dodecenoic acids as their acyl groups. Analyses of Arabidopsis mutants lacking HPL indicated that these MGDGs were formed enzymatically through an active HPL reaction. Thus, our results suggested that in disrupted leaf tissues, MGDG-hydroperoxides were cleaved by HPL to form volatile six-carbon aldehydes and non-volatile 12/10-carbon aldehyde-containing galactolipids. Based on these results, we propose a novel oxylipin pathway that does not require the lipase reaction to form GLVs.     

Differential metabolisms of green leaf volatiles in injured and intact parts of a wounded leaf meet distinct ecophysiological requirements

Almost all terrestrial plants produce green leaf volatiles (GLVs), consisting of six-carbon (C6) aldehydes, alcohols and their esters, after mechanical wounding. C6 aldehydes deter enemies, but C6 alcohols and esters are rather inert. In this study, we address why the ability to produce various GLVs in wounded plant tissues has been conserved in the plant kingdom. The major product in completely disrupted Arabidopsis leaf tissues was (Z)-3-hexenal, while (Z)-3-hexenol and (Z)-3-hexenyl acetate were the main products formed in the intact parts of partially wounded leaves. (13)C-labeled C6 aldehydes placed on the disrupted part of a wounded leaf diffused into neighboring intact tissues and were reduced to C6 alcohols. The reduction of the aldehydes to alcohols was catalyzed by an NADPH-dependent reductase. When NADPH was supplemented to disrupted tissues, C6 aldehydes were reduced to C6 alcohols, indicating that C6 aldehydes accumulated because of insufficient NADPH. When the leaves were exposed to higher doses of C6 aldehydes, however, a substantial fraction of C6 aldehydes persisted in the leaves and damaged them, indicating potential toxicity of C6 aldehydes to the leaf cells. Thus, the production of C6 aldehydes and their differential metabolisms in wounded leaves has dual benefits. In disrupted tissues, C6 aldehydes and their α,β-unsaturated aldehyde derivatives accumulate to deter invaders. In intact cells, the aldehydes are reduced to minimize self-toxicity and allow healthy cells to survive. The metabolism of GLVs is thus efficiently designed to meet ecophysiological requirements of the microenvironments within a wounded leaf.     

Conversion of Some Saturated Fatty Acids,Aldehydes, and Alcohols into γ- and δ-Lactones

A series or γ- and δ-lactones could be found in the thermal oxidative products of normal saturated acids, aldehydes, and alcohols (C₉, C₁₀, and C₁₂, respectively) heated at 180°C in the presence of 0.1% KMnO₄. Their lactones were identified by gas chromatography, infrared spectroscopy, and mass spectroscopy. And they could be detected also in the volatile compounds occurred by heating of C₁₀ acid, aldehyde, and alcohol mixed with pork fat. So it was expected that lactones in meat fat flavor described in the earlier papers could be secondary products converted from saturated acids, aldehydes, and alcohols formed by oxidative degradation of meat fats. This process was presumed to be one of the mechanisms of the lactone formation.

It was discussed that lactones might be derived through mono or dihydroperoxides of acids, aldehydes, and alcohols.     

固相微萃取结合GC/MS联用技术研究野松茸干品的挥发性成分

采用顶空固相微萃取结合气相色谱-质谱联用技术分析鉴定了野松茸干品中的挥发性风味成分.鉴定出48种风味化合物,占挥发性成分总量的91.44％,其中酸类9种、酯类6种、含氮杂环化合物11种、醇类3种、醛类5种、酮类10种、其他类4种.野松茸干品中主要的芳香成分是桂酸甲酯(42.99％)、3-甲基丁酸(8.56％)、2,6-二甲基吡嗪(8.36％)、2,5-二甲基吡嗪(2.46％)和1-辛烯-3-醇(2.06％).     

Metabolism of toluene and xylenes by Pseudomonas (putida (arvilla) mt-2: evidence for a new function of the TOL plasmid.

Pseudomonas putida (arvilla) mt-2 carries genes for the catabolism of toluene, m-xylene, and p-xylene on a transmissible plasmid, TOL. These compounds are degraded by oxidation of one of the methyl substituents via the corresponding alcohols and aldehydes to benzoate and m- and p-toluates, respectively, which are then further metabolised by the meta pathway, also coded for by the TOL plasmid. The specificities of the benzyl alcohol dehydrogenase and the benzaldehyde dehydrogenase for their three respective substrates are independent of the carbon source used for growth, suggesting that a single set of nonspecific enzymes is responsible for the dissimilation of the breakdown products of toluene and m- and p-xylene. Benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase are coincidently and possible coordinately induced by toluene and the xylenes, and by the corresponding alcohols and aldehydes. They are not induced in cells grown on m-toluate but catechol 2,3-oxygenase can be induced by m-xylene.     

Volatile components of sugar beet leaves

Extracts of both young and old sugar beet plants were obtained using a modified Likens and Nickerson apparatus. Constituents were identified by GC/MS, and using selected ion monitoring it was shown that the previously determined phenylacetonitrile was probably not of glucosinolate origin. Some unsaturated aldehydes, alcohols and derivatives (enzymic lipid degradation products) were formed to greater extents by the younger leaves, but otherwise such quantitative differences were relatively few and generally random. An interesting range of chlorinated compounds was obtained only from the older plants; a pesticide origin is suggested.     

Anisaldehyde production and aryl-alcohol oxidase and dehydrogenase activities in ligninolytic fungi of the genus Pleurotus.

A variety of simple aromatic compounds were identified in liquid cultures of the basidiomycetes Pleurotus cornucopiae, P. eryngii, P. floridanus, P. pulmonarius, P. ostreatus, and P. sajor-caju by using gas chromatography-mass spectrometry. Such compounds were detected in fungal cultures on lignin- and straw-containing media, but it was found that they were also produced in the absence of aromatic precursors. Anisylic and hydroxybenzylic compounds (such as alcohols, aldehydes, and acids) were identified, p-anisaldehyde being the most characteristic extracellular metabolite synthesized by these ligninolytic fungi. Small amounts of 3-chloro-p-anisaldehyde were also detected in several species. It is postulated that the balance between the more-or-less-oxidized aromatic compounds can be explained in terms of the activity of fungal enzymes, including aryl-alcohol oxidase and dehydrogenase. The former enzyme shows high affinity for p-anisyl alcohol, which is oxidized to p-anisaldehyde with production of H2O2. The aryl-alcohol dehydrogenase was detected only in the mycelium, where it reduces aromatic aldehydes in the presence of NADPH. Both enzymes could be involved in the redox cycling of these aromatic compounds, providing H2O2 to ligninolytic peroxidases.     

Seed Dormancy in Red Rice : VII. Structure-Activity Studies of Germination Stimulants

Many chemically dissimilar substances break dormancy of seeds, but the relationship between chemical structure and physiological activity is unknown. In this study, the concentrations of organic acids, esters, aldehydes, alcohols, and inorganic weak acids required to elicit 50% germination of initially dormant, dehulled red rice seeds (Oryza sativa) were determined. The activity of most substances was very highly and inversely correlated to lipophilicity as measured by octanol/water partition coefficients; chemicals with the highest partition coefficients required the lowest concentrations to elicit the germination response. Relative efficacy was also dependent upon the functional group; generally, monocarboxylic acids were more effective than aldehydes, esters, hydroxyacids, and alcohols. Relative hydrophobicity plots supported a modulating role of the functional group. Dormancy-breaking activity of methyl formate, formic acid, nitrite, azide, and cyanide was higher than predicted based on lipophilicity and apparently was related to molecular size; compounds with smaller molecular widths were required at lower concentrations to achieve the 50% germination response.     

Effects of aldehydes on CD36 expression

INTRODUCTION: During the oil frying process lipid peroxidation compounds are formed. These products can modulate gene expression and alter cellular behaviour. The cellular uptake of oxidized LDL, a key step in the development of atherosclerosis, is mediated by the CD36 scavenger receptor, whose expression is down-regulated by alpha-tocopherol.OBJECTIVE: To determine the effects of water-soluble aldehydes, obtained from thermally oxidized sunflower oil on the expression of CD36 scavenger receptor in human monocytes (THP-1 cells). We also wanted to study the effects of alpha-tocopherol on CD36 expression in the presence of water-soluble aldehydes.MATERIALS AND METHODS: Sunflower oil was heated in a frying pan, at 180--200 degrees C for 40 min, water-soluble aldehydes were isolated, and the content of thiobarbituric acid reacting substances (TBARS) was determined. THP-1 monocytes were cultured in RPMI medium during 24 h and incubated with increasing concentrations of the water-soluble aldehydes (ranging from 0.05 to 1 microM) and with or without 50 microM of alpha-tocopherol. In parallel, THP-1 cells were cultured with the same volume of an extract obtained from non-oxidized oil or distilled water. The CD36 expression at the cell surface was studied with fluorescence-activated cell sorting (FACS).RESULTS: Monocytes incubated in a medium containing water-soluble aldehydes, showed a dose dependent increase in the expression of the CD36 protein on the cell surface, compared to with the control groups. When the cells were treated simultaneously with 50 microM of alpha-tocopherol a significant reduction in the expression of the CD36 protein was observed.CONCLUSION: Water-soluble aldehydes, extracted from thermally oxidized culinary oil, increase the expression of CD36. This effect is partially decreased by the presence of alpha-tocopherol.     

The composition of volatile components of dry cepe and oyster mushroom

The composition of aroma compounds in dry cepe mushroom (Boletis edulis Fr.) and oyster mushroom (Pleurotus ostreatus Fr.) was studied using capillary gas chromatography and chromatography—mass spectrometry. In dry cepe, 53 volatile compounds were identified, and in dry oyster mushroom 41 compounds were identified. Volatile organic substances with various functional groups formed the flavor of dry mushrooms. Unsaturated alcohols and ketones with eight carbon atoms were responsible for the mushroom notes of products. Their content in dry cepe was much higher than in dry oyster mushroom. The specific aroma of dry cepe was formed by the complex mixture of methional, substituted furans, pyrazines, and pyrroles. The content of these compounds was higher in dry cepe than in dry oyster mushroom. The content of aromatic and aliphatic aldehydes with six, nine, and ten carbon atoms was higher in dry oyster mushroom. The differences in the qualitative and quantitative composition of volatile compounds are responsible for more intensive and pleasant aroma of dry cepe in comparison to that of dry oyster mushroom.     

Variation in volatile compounds from tansy (Tanacetum vulgare L.) related to genetic and morphological differences of genotypes

Air-dried flower heads of 20 Finnish tansy genotypes were extracted with petroleum ether and analyzed using GC-MS. A total of 55 volatile compounds were detected, and 53 were identified. Of the tansy genotypes studied, 15 were well defined and five were mixed chemotypes. Complete linkage analysis differentiated the populations into six clusters. The most frequently found monoterpene was camphor with or without several satellite compounds such as camphene, 1,8-cineole, pinocamphone, chrysanthenyl acetate, bornyl acetate and isobornyl acetate. In 13 genotypes, camphor concentration exceeded 18.5% and in seven genotypes, camphor was less than 7.2%. Other chemotypes rich in trans thujone, artemisia ketone, 1,8-cineole, or davadone-D were also identified. Davadone-D and a mixed chemotype, containing tricyclene and myrcene, were identified from a Finnish tansy for the first time. Geographically, most chemotypes containing camphor originated from Central Finland, whereas chemotypes without camphor such as artemisia ketone, davadone D and myrcene-tricyclene originated from South or Southwest Finland. Morphologically, the 20 tansy chemotypes based on the groups formed from complete linkage cluster analysis, were compared. The group containing the highest concentration of camphor chemotypes had the tallest shoots. The groups consisting from chemotypes containing davadone-D or artemisia ketone, which originated from Southwest Finland, produced the highest number of flower heads, had the tallest corymb, and were last to flower. Also, the group consisting from chemotypes with a high concentration of camphor and originated from South Finland started to flower late. The correlation between the genetic distance matrices based on RAPD patterns reported previously (Keskitalo et al., 1998. Theo. Appl. Genet. 96, 1141-1150.) and the chemical distance matrices of the present study of the same tansy genotypes was highly significant (0.41, P<0.0001).     

Volatiles from winter wheat: Identification of additional compounds and effects of tissue source

Sixteen volatile compounds have been identified in oil prepared from winter wheat by reduced pressure steam distillation-extraction. Most of these compounds were found in relatively small quatities (0.5%, or less) with the exception of pentadecanal. Comparisons were also made of the relative amounts of C₉ alcohols and aldehydes obtained from fresh versus frozen plants, cut versus intact plants and leaves versus culms.     

Formation of lipoxygenase-pathway-derived aldehydes in barley leaves upon methyl jasmonate treatment.

In barley leaves, the application of jasmonates leads to dramatic alterations of gene expression. Among the up-regulated gene products lipoxygenases occur abundantly. Here, at least four of them were identified as 13-lipoxygenases exhibiting acidic pH optima between pH 5.0 and 6.5. (13S,9Z,11E,15Z)-13-hydroxy-9,11,15-octadecatrienoic acid was found to be the main endogenous lipoxygenase-derived polyenoic fatty acid derivative indicating 13-lipoxygenase activity in vivo. Moreover, upon methyl jasmonate treatment > 78% of the fatty acid hydroperoxides are metabolized by hydroperoxide lyase activity resulting in the endogenous occurrence of volatile aldehydes. (2E)-4-Hydroxy-2-hexenal, hexanal and (3Z)- plus (2E)-hexenal were identified as 2,4-dinitro-phenylhydrazones using HPLC and identification was confirmed by GC/MS analysis. This is the first proof that (2E)-4-hydroxy-2-hexenal is formed in plants under physiological conditions. Quantification of (2E)-4-hydroxy-2-hexenal, hexanal and hexenals upon methyl jasmonate treatment of barley leaf segments revealed that hexenals were the major aldehydes peaking at 24 h after methyl jasmonate treatment. Their endogenous content increased from 1.6 nmol.g-1 fresh weight to 45 nmol.g-1 fresh weight in methyl-jasmonate-treated leaf segments, whereas (2E)-4-hydroxy-2-hexenal, peaking at 48 h of methyl jasmonate treatment increased from 9 to 15 nmol.g-1 fresh weight. Similar to the hexenals, hexanal reached its maximal amount 24 h after methyl jasmonate treatment, but increased from 0.6 to 3.0 nmol.g-1 fresh weight. In addition to the classical leaf aldehydes, (2E)-4-hydroxy-2-hexenal was detected, thereby raising the question of whether it functions in the degradation of chloroplast membrane constituents, which takes place after methyl jasmonate treatment.     

Improved identification of monomethyl paraffin chain branching (close to the methyl end) of long-chain compounds by gas chromatography and mass spectrometry

An improved method for the identification of monomethyl substituted paraffin chains (n?2, n?3 and n?4) by gas chromatography and mass spectrometry is presented. Fatty acids and sphingolipid long-chain bases were converted to their corresponding alcohols, which were analyzed as methyl ethers. These compounds were better separated on packed columns (XE-60) than other derivatives, and the low temperature of analysis minimized the bleeding of stationary phase into the mass spectrometer. Mass spectra of methyl ethers allowed a more conclusive identification of branches than of other derivatives. The method may be generally applied to fatty acids, aldehydes and alcohols.     

基于植物代谢组学方法的马钱子油炸炮制前后化学差异研究

为对马钱子油炸炮制前后提取物的差异进行定性、定量研究,实验采用超高效液相色谱-四级杆串联飞行时间质谱(UPLC-Q-TOF-MS)采集数据,结合Peak View软件、在线数据库等进行化学成分定性分析,并采用Analyst工作站进行主要化学成分的含量测定,将炮制前后离子数据导入SIMCA-P软件,建立OPLS-DA数学模型,进行差异性次生代谢产物分析。结果显示马钱子的成分类别主要包括生物碱、糖苷、脂肪酸酯和醇类,其中检测到已知成分共29个,未曾报道的化合物达13个;OPLS-DA分析中最显著的化合物是士的宁、麦芽糖、Dattelic acid和油酸;定量分析结果表明油炸炮制后马钱子碱和士的宁的含量有所降低,且士的宁的下降幅度略大于马钱子碱,均能达到《中国药典》2015年版马钱子项下要求。本研究通过多种手段探讨了油炸炮制前后马钱子化学成分变化情况,结果表明炮制方法、减毒效果及化学成分间存在相关性,为马钱子炮制机理解释及药效物质基础阐明提供新的思路和数据参考。     

An analysis of the volatile flavour compounds in a soft raw goat milk cheese

The major components of the musty cow rind cheeses were identified in a soft raw goat milk cheese as heptan-2-one, nonan-2-one, their corresponding secondary alcohols, some esters and sulfur compounds. Their production was associated with the manufacturing process and its influence on the microbial activity. However a specificity in goat cheese compounds was displayed concerning in particular limonene and some ketones, alcohols and aldehydes.