Acyl-CoA: cholesterol acyltransferase inhibitory activities of fatty acid amides isolated from Mylabris phalerate Pallas

Unsaturated fatty acid amides, 9(Z)-octadecenamide (2) and 9(Z),12(Z)-octadecadienamide (4) as inhibitors of acyl-CoA: cholesterol acyltransferase (ACAT) were isolated from the ethyl acetate extracts of the insect, Mylabris phalerate Pallas, and elucidated by their spectroscopic data analysis. Compounds 2 and 4 inhibited rat liver microsomal ACAT, hACAT-1, and hACAT-2 with IC(50) values of 170, 85, and 63 microM for 2 and of 151, 53, and 45 microM for 4, respectively.     

Fatty acid constituents of Peganum harmala plant using Gas Chromatography–Mass Spectroscopy

Fatty acid contents of the Peganum harmala plant as a result of hexane extraction were analyzed using GC–MS. The saturated fatty acid composition of the harmal plant was tetradecanoic, pentadecanoic, tridecanoic, hexadecanoic, heptadecanoic and octadecanoic acids, while the saturated fatty acid derivatives were 12-methyl tetradecanoic, 5,9,13-trimethyl tetradecanoic and 2-methyl octadecanoic acids. The most abundant fatty acid was hexadecanoic with concentration 48.13% followed by octadecanoic with concentration 13.80%. There are four unsaturated fatty acids called (E)-9-dodecenoic, (Z)-9-hexadecenoic, (Z,Z)-9,12-octadecadienoic and (Z,Z,Z)-9,12,15-octadecatrienoic. The most abundant unsaturated fatty acid was (Z,Z,Z)-9,12,15-octadecatrienoic with concentration 14.79% followed by (Z,Z)-9,12-octadecadienoic with concentration 10.61%. Also, there are eight non-fatty acid compounds 1-octadecene, 6,10,14-trimethyl-2-pentadecanone, (E)-15-heptadecenal, oxacyclohexadecan-2 one, 1,2,2,6,8-pentamethyl-7-oxabicyclo[4.3.1]dec-8-en-10-one, hexadecane-1,2-diol, n-heneicosane and eicosan-3-ol.     

Fatty acid amides from freshwater green alga Rhizoclonium hieroglyphicum

Freshwater green algae Rhizoclonium hieroglyphicum growing in the Ural Mountains were examined for their fatty acid amides using capillary gas chromatography-mass spectrometry (GC-MS). Eight fatty acid amides were identified by GC-MS. (Z)-9-octadecenamide was found to be the major component (2.26%).     

Macamides and their synthetic analogs: Evaluation of in vitro FAAH inhibition

Maca (Lepidium meyenii), a traditional food crop of the Peruvian Andes is now widely touted as a dietary supplement. Among the various chemical constituents isolated from the plant are a unique series of non-polar, long-chain fatty acid N-benzylamides known as macamides. We have synthesized 11 of the 19 reported macamides and have tested each as potential inhibitors of the human enzyme, fatty acid amide hydrolase (FAAH). The five most potent macamides were FAAH inhibitors (IC₅₀ = 10–17 μM). These amides were derivatives of oleic, linoleic and linolenic acids and benzylamine or 3-methoxybenzylamine. Of the three compounds evaluated in a pre-incubation time study, two macamides were not irreversible inhibitors of FAAH. The third, a carbamate structurally related to macamides, was shown to be an irreversible inhibitor of FAAH (IC₅₀ = 0.153 μM).     

Solid-phase extraction and HPLC-MS profiling of pyrrolizidine alkaloids and their N-oxides: a case study of Echium plantagineum

Pyrrolizidine alkaloids and their N-oxides can be extracted from the dried methanolic extracts of plant material using dilute aqueous acid. The subsequent integration of solid-phase extraction (with a strong cation exchanger) of the alkaloids and N-oxides from the aqueous acid solution, together with analysis using HPLC-ESI/MS, provides a method for the simultaneous profiling of the pyrrolizidine alkaloids and their N-oxides in plant samples and the collection of useful structural data as an aid in their identification. The N-oxide character of the analytes may be confirmed by treating analytical samples with a redox resin and observing the formation of the corresponding parent pyrrolizidine alkaloids. The present case study of Echium plantagineum highlighted a higher ratio of N-oxides to the parent tertiary bases than has been previously reported. Furthermore, a higher proportion of acetylated pyrrolizidine-N-oxides was observed in the flower heads relative to the leaves. Six pyrrolizidine alkaloids or pyrrolizidine-N-oxides, not previously reported from E. plantagineum, were tentatively identified on the basis of MS and biogenetic considerations. Three of these, 3'-O-acetylintermedine/lycopsamine, leptanthine-N-oxide and 9-O-angelylretronecine-N-oxide, have been reported elsewhere, whilst three others, 3'-O-acetylechiumine-N-oxide, echimiplatine-N-oxide and echiuplatine-N-oxide, appear unreported from any other source.     

Female sex pheromone of Athetis lepigone (Lepidoptera: Noctuidae): Identification and field evaluation

Athetis lepigone has been recorded in many countries in Europe and Asia, but it had never been documented as an agricultural pest until 2005. For the purpose of using the sex pheromone to control this pest, we conducted a study to identify the sex pheromone of A. lepigone by gas chromatography with an electroantennographic detector (GC‐EAD) and GC coupled with mass spectrometry (GC/MS) analyses. Three pheromone candidates were detected by GC‐EAD analysis in the extracts of the female sex pheromone gland, and two candidates were identified as (Z)‐7‐dodecenyl acetate (Z7‐12:OAc) and (Z)‐9‐tetradecenyl acetate (Z9‐14:OAc) in a ratio of 1:5 by mass spectral analysis of natural pheromone components and dimethyl disulphide adducts. In the field male trapping test, the traps baited with the binary blend captured high number of males, while traps with single component hardly caught males, indicating that the two components are essential for the male attractiveness. In addition, the optimum ratios of Z7‐12:OAc and Z9‐14:OAc were determined as 3:7–7:3, and the best doses for the binary blend (at ratio of 3:7 between Z7‐12:OAc and Z9‐14:OAc) were 0.25–0.5 mg/trap, based on the number of male catches. The identification of a highly attractive sex pheromone will help in developing efficient strategies for monitoring and control of A. lepigone.     

Specific adduction of plant lipid transfer protein by an allene oxide generated by 9-lipoxygenase and allene oxide synthase

Lipid transfer proteins (LTPs) are ubiquitous plant lipid-binding proteins that have been associated with multiple developmental and stress responses. Although LTPs typically bind fatty acids and fatty acid derivatives in a non-covalent way, studies on the LTPs of barley seeds have identified an abundantly occurring covalently modified form, LTP1b, the lipid ligand of which has resisted clarification. In the present study, this adduct was identified as the alpha-ketol 9-hydroxy-10-oxo-12(Z)-octadecenoic acid. Further studies on the formation of LTP1b demonstrated that the ligand was introduced by nucleophilic attack of the free carboxylate group of the Asp-7 residue of the protein at carbon-9 of the allene oxide fatty acid 9(S),10-epoxy-10,12(Z)-octadecadienoic acid. This reactive oxylipin was produced in barley seeds by oxygenation of linoleic acid by 9-lipoxygenase followed by dehydration of the resulting hydroperoxide by allene oxide synthase. The generation of protein-oxylipin adducts represents a new function for plant allene oxide synthases, enzymes that have earlier been implicated mainly in the biosynthesis of the jasmonate family of plant hormones. Additionally, the LTP-allene oxide synthase interaction opens new perspectives regarding the roles of LTPs in the signaling of plant defense and development.     

Quantification by ELISA of Cytokinins in Root-Pressure Exudates of Urtica dioica Plants Grown under Different Nitrogen Levels

ELISAs for [9R]iP, [9R]Z and (diH) [9R]Z have been worked out which, in combination with HPLC., allow the quantitative determination of cytokinins of the isopentenyladenin-, zeatin- and dihydrozeatin-type in samples of plant material. The three ELISAs are optimally applicable in the range from 0.5 to 20 pmoles of cytokinins per assay but reliable measurements can still be performed down to 0.05 pmoles. The assay has been applied to root pressure exudates obtained from Urtica dioica plants grown under controlled conditions and at different nitrogen (nitrate) levels. The predominant cytokinins of the xylem exudate were Z, Z-nucleotide, iP, [9R]iP and iP-nucleotide, while (diH)Z was present to a minor extent. The concentrations of these compounds were found to range between 0.2 and 3 pmoles per ml exudate. Interestingly, no effect of the different nitrogen nutrition on the pattern and concentration of cytokinins in the xylem exudate could be established.     

神黄豆化学成分研究

对神黄豆Cassia agnes Brenan茎部的化学成分进行了研究。从其甲醇提取物的乙酸乙酯萃取部分分离得到了10个化合物,根据理化性质和波谱数据鉴定其结构分别为:(–)-表阿夫儿茶精(1)、12,13-dihydromicromeric acid(2)、白桦脂醇(3)、8(17),12E,14-labdatrien-19-ol(4)、β-谷甾醇(5)、胡萝卜苷(6)、二十四烷酰单甘油酯(7)、sitoindoside I(8)、9Z,12Z-octadecadienoic acid(9)和间苯三酚(10)。以上化合物均为首次从神黄豆中发现。     

The Macamide N-3-Methoxybenzyl-Linoleamide Is a Time-Dependent Fatty Acid Amide Hydrolase (FAAH) Inhibitor

The Peruvian plant Lepidium meyenii (Maca) has been shown to possess neuroprotective activity both in vitro and in vivo [1–3]. Previous studies have also demonstrated the activity of the pentane extract and its macamides, the most representative lipophilic constituents of Maca, in the endocannabinoid system as fatty acid amide hydrolase (FAAH) inhibitors. One of the most active macamides, N-3-methoxybenzyl-linoleamide [4, 5], was studied to determine its mechanism of interaction with FAAH and whether it has inhibitory activity on mono-acyl glycerol lipase (MAGL), the second enzyme responsible for endocannabinoid degradation [6]. Macamide concentrations from 1 to 100 μM were tested using FAAH and MAGL inhibitor assay methods and showed no effect on MAGL. Tests with other conditions were performed in order to characterize the inhibitory mechanism of FAAH inhibition. N-3-methoxybenzyl-linoleamide displayed significant time-dependent and dose-dependent FAAH inhibitory activity. The mechanism of inhibition was most likely irreversible or slowly reversible. These results suggest the potential application of macamides isolated from Maca as FAAH inhibitors, as they might act on the central nervous system to provide analgesic, anti-inflammatory, or neuroprotective effects, by modulating the release of neurotransmitters.     

Allene oxide cyclase: a new enzyme in plant lipid metabolism

The mechanism of the biosynthesis of 12-oxo-10,15(Z)-phytodienoic acid (12-oxo-PDA) from 13(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid in preparations of corn (Zea mays L.) was studied. In the initial reaction the hydroperoxide was converted into an unstable allene oxide, 12,13(S)-epoxy-9(Z),11,15(Z)-octadecatrienoic acid, by action of a particle-bound hydroperoxide dehydrase. A new enzyme, allene oxide cyclase, catalyzed subsequent cyclization of allene oxide into 9(S),13(S)-12-oxo-PDA. In addition, because of its chemical instability, the allene oxide underwent competing nonenzymatic reactions such as hydrolysis into alpha- and gamma-ketol derivatives as well as spontaneous cyclization into racemic 12-oxo-PDA. (+/-)-cis-12,13-Epoxy-9(Z)-octadecenoic acid and (+/-)-cis-12,13-epoxy-9(Z),15(Z)-octadecadienoic acid, in which the epoxy group was located in the same position as in the allene oxide substrate, served as potent inhibitors of corn allene oxide cyclase. On the other hand, the isomeric (+/-)-cis-9,10-epoxy-12(Z)-octadecenoic acid had little inhibitory effect. Allene oxide cyclase was present in the soluble fraction of corn homogenate and had a molecular weight of about 45,000 as judged by gel filtration. The enzyme activity was detected in several plant tissues, the highest levels being observed in potato tubers and in leaves of spinach and white cabbage.     

Large-scale preparation of (9Z,12E)-[1-(13)C]-octadeca-9,12-dienoic acid, (9Z,12Z,15E)-[1-(13)C]-octadeca-9,12,15-trienoic acid and their [1-(13)C] all-cis isomers

Several grams of labelled trans linoleic and linolenic acids with high chemical and isomeric purities (>97%) have been prepared for human metabolism studies. A total of 12.5 g of (9Z, 12E)-[1-(13)C]-octadeca-9,12-dienoic acid and 6.3 g of (9Z,12Z, 15E)-[1-(13)C]-octadeca-9,12,15-trienoic acid were obtained in, respectively, seven steps (7.8% overall yield) and 11 steps (7% overall yield) from 7-bromo-heptan-1-ol. The trans bromo precursors used for the labelling were synthesised by using copper-catalysed couplings. The trans fatty acids were then obtained via the nitrile derivatives. A total of 23.5 g of (9Z,12Z)-[1-(13)C]-octadeca-9, 12-dienoic acid and 10.4 g of (9Z,12Z,15Z)-[1-(13)C]-octadeca-9,12, 15-trienoic acid were prepared in five steps in, respectively, 32 and 18% overall yield. Large quantities of bromo and chloro precursors were synthesised from the commercially available acid according to Barton's procedure. In all cases, the main impurities (>0.5%) of each labelled fatty acid have been characterised.     

Composition of the leaf, stem bark and root bark oils of Isolona cooperi investigated by GC (retention index), GC-MS and 13C-NMR spectroscopy

The leaf, stem bark and root bark oils of Isolona cooperi Hutchinson & Dalziel from the Ivory Coast have been analysed by GC (retention index), GC-MS and 13C-NMR spectroscopy. Two types of essential oil were produced by the plant. The leaf and stem bark oils were monoterpene-rich, containing principally (Z)-beta-ocimene and gamma-terpinene and three lactones, 5-[(E and Z)-hexylidene]-5H-furan-2-ones and massoia lactone, were present in appreciable amounts. Conversely, the root bark oil was dominated by 5-isopentenylindole and (E)-beta-caryophyllene. The strategy for the analysis of each oil was adapted according to the nature of the components.     

Glucosylation of (Z)‐3‐hexenol informs intraspecies interactions in plants: A case study in Camellia sinensis

Plants emit a variety of volatiles in response to herbivore attack, and (Z)‐3‐hexenol and its glycosides have been shown to function as defence compounds. Although the ability to incorporate and convert (Z)‐3‐hexenol to glycosides is widely conserved in plants, the enzymes responsible for the glycosylation of (Z)‐3‐hexenol remained unknown until today. In this study, uridine‐diphosphate‐dependent glycosyltransferase (UGT) candidate genes were selected by correlation analysis and their response to airborne (Z)‐3‐hexenol, which has been shown to be taken up by the tea plant. The allelic proteins UGT85A53‐1 and UGT85A53‐2 showed the highest activity towards (Z)‐3‐hexenol and are distinct from UGT85A53‐3, which displayed a similar catalytic efficiency for (Z)‐3‐hexenol and nerol. A single amino acid exchange E59D enhanced the activity towards (Z)‐3‐hexenol, whereas a L445M mutation reduced the catalytic activity towards all substrates tested. Transient overexpression of CsUGT85A53‐1 in tobacco significantly increased the level of (Z)‐3‐hexenyl glucoside. The functional characterization of CsUGT85A53 as a (Z)‐3‐hexenol UGT not only provides the foundation for the biotechnological production of (Z)‐3‐hexenyl glucoside but also delivers insights for the development of novel insect pest control strategies in tea plant and might be generally applicable to other plants.     

Microfluorimetric analysis of dynamics of genomic changes in Chinese hamster fibroblasts CHL V-79 RJK with multiple drug resistance

Results of a karyological analysis of cells CHL V-79 RJK selected for their resistance to ethidium bromide (EB) causing multidrug resistance (MDR) (subline Vebr-5) were compared with data from the microfluorimetric determination of the DNA content in individual chromosomes of the karyotype. The analysis was performed at the 11th and 88th passages. Karyotyping of Vebr-5 has shown the presence of an additional genetic material (AGM) in the form of homogenously or differentially stained regions (HSR or DSR, respectively) in two chromosomes (Z1 and Z6, loci 1p29-31 and 1q26, respectively). HSR in Z6, in the site of localization of the mdr gene of the wild type had unstable length and structure, which is characteristic of the morphological markers of the amplification of genes of the mdr family. During the long cultivation of Vebr-5 in the presence of EB (88 passages), the instability of HSR (DSR) in Z6 increased. Results of a microfluorimetric analysis of Vebr-5 at the 11th passage have shown a statistically significant increase of the DNA content not only in chromosomes Z1 and Z6 marked by HSR (DSR), but also in three chromosomes (Z5, Z12, and Z13) that have no visual morphological changes. The corresponding analysis at the 88th passage has also revealed nonrandom changes in the DNA content in four more chromosomes, including an increase in Z14 and a decrease in chromosomes 8, Z7, and Z9. A decrease in the DNA content in chromosomes is considered to be the result of a partial loss of genetic material, while its increase is considered to be the result of its translocation and/or amplification. While the coefficient of the variation of the DNA content changes about 9% for large chromosomes, it amounted to about 26% for the small ones, indicating that small chromosomes to have a greater potential for instability than large chromosomes. The obtained data not only confirm, but also enlarge, the concept of the directions and character of the destabilization of the cell genetic apparatus in the process of neoplastic transformation due to MDR acquisition by these cells.     

美花圆叶筋骨草化学成分研究

研究美花圆叶筋骨草Ajuga ovalifolia var.calantha的化学成分和生物活性。实验采用硅胶柱色谱、SephadexLH-20凝胶柱色谱、ODS柱色谱和半制备型高效液相色谱等分离纯化方法,从美花圆叶筋骨草全草70%丙酮提取物乙酸乙酯部位中分离得到了12个化合物,根据波谱学数据进行结构鉴定为:2-methoxy-4-(2-propenyl)-phenyl-β-D-glucopyranoside(1)、oct-1-en-3-yl-β-glucopyranoside(2)、异地黄苷(3)、20-羟基蜕皮素-20,22-单丙酮化合物(4)、n-辛基-β-D-吡喃葡萄糖苷(5)、(2S)-3-O-octadeca-9Z,12Z,15Z-trienoylglyceryl-O-β-D-galactopyranoside(6)、地黄苷(7)、乙酰哈巴苷(8)、水龙骨素B(9)、香草乙酮(10)、筋骨草内酯(11)、α-(9Z,12′Z,15′Z)-octadecatrienoicacidmonoglyceride(12),其中化合物1~6、8、12为首次从该属植物中分离得到,化合物1~9、11~12为首次从美花圆叶筋骨草中分离得到。运用脂多糖(LPS)诱导的小鼠巨噬细胞RAW264.7生成NO的细胞模型对化合物3、4、7、9、11进行抗炎活性筛选和磷酸甘油酸脱氢酶(PHGDH)活性测定。所筛化合物均无抗炎活性,化合物7对PHGDH具有一定的抑制作用。     

Properties of two multifunctional plant fatty acid acetylenase/desaturase enzymes.

The properties of the Delta6 desaturase/acetylenase from the moss Ceratodon purpureus and the Delta12 acetylenase from the dicot Crepis alpina were studied by expressing the encoding genes in Arabidopsis thaliana and Saccharomyces cerevisiae. The acetylenase from C. alpinaDelta12 desaturated both oleate and linoleate with about equal efficiency. The desaturation of oleate gave rise to 9(Z),12(E)- and 9(Z),12(Z)-octadecadienoates in a ratio of approximately 3 : 1. Experiments using stereospecifically deuterated oleates showed that the pro-R hydrogen atoms were removed from C-12 and C-13 in the introduction of the 12(Z) double bond, whereas the pro-R and pro-S hydrogen atoms were removed from these carbons during the formation of the 12(E) double bond. The results suggested that the Delta12 acetylenase could accommodate oleate having either a cisoid or transoid conformation of the C(12)-C(13) single bond, and that these conformers served as precursors of the 12(Z) and 12(E) double bonds, respectively. However, only the 9(Z),12(Z)-octadecadienoate isomer could be further desaturated to 9(Z)-octadecen-12-ynoate (crepenynate) by the enzyme. The evolutionarily closely related Delta12 epoxygenase from Crepis palaestina had only weak desaturase activity but could also produce 9(Z),12(E)-octadecadienoate from oleate. The Delta6 acetylenase/desaturase from C. purpureus, on the other hand, produced only the 6(Z) isomers using C16 and C18 acyl groups possessing a Delta9 double bond as substrates. The Delta6 double bond was efficiently further converted to an acetylenic bond by a second round of desaturation but only if the acyl substrate had a Delta12 double bond and that this was in the Z configuration.     

Facile syntheses for (5Z,9Z)-5,9-hexadecadienoic acid, (5Z,9Z)-5,9-nonadecadienoic acid, and (5Z,9Z)-5,9-eicosadienoic acid through a common synthetic route

The delta 5,9 fatty acids (5Z,9Z)-5,9-hexadecadienoic acid, (5Z,9Z)-5,9-nonadecadienoic acid, and (5Z,9Z)-5,9-eicosadienoic acid were synthesized for the first time in four steps (9-12% overall yield) starting from commercially available 2-(2-bromoethyl)-1,3-dioxolane. The synthetic approach provided enough material to corroborate the structure and stereochemistry of (5Z,9Z)-5,9-nonadecadienoic acid which was recently identified in the flowers of Malvaviscus arboreus (Malvaceae). The novel phospholipids 1-hexadecanoyl-2-[(5Z,9Z)-5,9-eicosadienoyl]-sn-glycer o-3-phosphocholine and 1-octadecanoyl-2-[(5Z,9Z)-5,9-eicosadienoyl]-sn- glycero-3-phosphocholine were also synthesized from commercially available L-alpha-phosphatidylcholine (egg yolk) and characterized by positive ion electrospray mass spectrometry. These are the first examples of unsymmetrical phospholipids with saturated fatty acids at the sn-1 position and delta 5,9 fatty acids at the sn-2 position.     

alpha-oxidation of fatty acids in higher plants. Identification of a pathogen-inducible oxygenase (piox) as an alpha-dioxygenase and biosynthesis of 2-hydroperoxylinolenic acid.

A pathogen-inducible oxygenase in tobacco leaves and a homologous enzyme from Arabidopsis were recently characterized (Sanz, A., Moreno, J. I., and Castresana, C. (1998) Plant Cell 10, 1523-1537). Linolenic acid incubated at 23 degrees C with preparations containing the recombinant enzymes underwent alpha-oxidation with the formation of a chain-shortened aldehyde, i.e., 8(Z),11(Z), 14(Z)-heptadecatrienal (83%), an alpha-hydroxy acid, 2(R)-hydroxy-9(Z),12(Z),15(Z)-octadecatrienoic acid (15%), and a chain-shortened fatty acid, 8(Z),11(Z),14(Z)-heptadecatrienoic acid (2%). When incubations were performed at 0 degrees C, 2(R)-hydroperoxy-9(Z),12(Z),15(Z)-octadecatrienoic acid was obtained as the main product. An intermediary role of 2(R)-hydroperoxy-9(Z), 12(Z),15(Z)-octadecatrienoic acid in alpha-oxidation was demonstrated by re-incubation experiments, in which the hydroperoxide was converted into the same alpha-oxidation products as those formed from linolenic acid. 2(R)-Hydroperoxy-9(Z),12(Z), 15(Z)-octadecatrienoic acid was chemically unstable and had a half-life time in buffer of about 30 min at 23 degrees C. Extracts of cells expressing the recombinant oxygenases accelerated breakdown of the hydroperoxide (half-life time, about 3 min at 23 degrees C), however, this was not attributable to the recombinant enzymes since the same rate of hydroperoxide degradation was observed in the presence of control cells not expressing the enzymes. No significant discrimination between enantiomers was observed in the degradation of 2(R,S)-hydroperoxy-9(Z)-octadecenoic acid in the presence of recombinant oxygenases. A previously studied system for alpha-oxidation in cucumber was re-examined using the newly developed techniques and was found to catalyze the same conversions as those observed with the recombinant enzymes, i.e. enzymatic alpha-dioxygenation of fatty acids into 2(R)-hydroperoxides and a first order, non-stereoselective degradation of hydroperoxides into alpha-oxidation products. It was concluded that the recombinant enzymes from tobacco and Arabidopsis were both alpha-dioxygenases, and that members of this new class of enzymes catalyze the first step of alpha-oxidation in plant tissue.     

Envelope Membranes from Spinach Chloroplasts Are a Site of Metabolism of Fatty Acid Hydroperoxides

Enzymes in envelope membranes from spinach (Spinacia oleracea L.) chloroplasts were found to catalyze the rapid breakdown of fatty acid hydroperoxides. In contrast, no such activities were detected in the stroma or in thylakoids. In preparations of envelope membranes, 9S-hydroperoxy-10(E),12(Z)-octadecadienoic acid, 13S-hydroperoxy-9(Z),11(E)-octadecadienoic acid, or 13S-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid were transformed at almost the same rates (1-2 [mu]mol min-1 mg-1 protein). The products formed were separated by reversed-phase high-pressure liquid chromatography and further characterized by gas chromatography-mass spectrometry. Fatty acid hydroperoxides were cleaved (a) into aldehydes and oxoacid fragments, corresponding to the functioning of a hydroperoxide lyase, (b) into ketols that were spontaneously formed from allene oxide synthesized by a hydroperoxide dehydratase, (c) into hydroxy compounds synthesized enzymatically by a system that has not yet been characterized, and (d) into oxoenes resulting from the hydroperoxidase activity of a lipoxygenase. Chloroplast envelope membranes therefore contain a whole set of enzymes that catalyze the synthesis of a variety of fatty acid derivatives, some of which may act as regulatory molecules. The results presented demonstrate a new role for the plastid envelope within the plant cell.