Biosynthetic pathways of the sex pheromone components and substrate selectivity of the oxidation enzymes working in pheromone glands of the fall webworm, Hyphantria cunea

The fall webworm, Hyphantria cunea Drury (Lepidoptera: Arctiidae), is a harmful polyphagous defoliator. Female moths produce the following four pheromone components in a ratio of about 5:4:10:2; (9Z,12Z)-9,12-octadecadienal (I), (9Z,12Z,15Z)-9,12,15-octadecatrienal (II), cis-9,10-epoxy-(3Z,6Z)-3,6-henicosadiene (III), and cis-9,10-epoxy-(3Z,6Z)-1,3,6-henicosatriene (IV). Although ¹³C-labeled linolenic acid was not converted into trienal II at the pheromone glands of H. cunea females, GC-MS analysis of an extract of the pheromone gland treated topically with ¹³C-labeled linolenyl alcohol showed the aldehyde incorporating the isotope. Other C₁₈ and C₁₉ fatty alcohols were also oxidized to the corresponding aldehydes in the pheromone gland, indicating a biosynthetic pathway of IIvia linolenyl alcohol and low substrate selectivity of the alcohol oxidase in the pheromone gland. On the other hand, epoxydiene III was expected to be produced by specific 9,10-epoxidation of the corresponding C₂₁ trienyl hydrocarbon, which might be biosynthesized from dietary linolenic acid in oenocytes and transported to the pheromone gland. The final biosynthetic step in the pheromone gland was confirmed by an experiment using deuterated C₂₁ triene, which was synthesized by the chain elongation of linolenic acid and LiAlD₄ reduction as key reactions. When the labeled triene was administered to the female by topical application at the pheromone gland or injection into the abdomen, deuterated III was detected in a pheromone extract by GC-MS analysis. Furthermore, the substrate selectivity of epoxidase and selective incorporation by the pheromone glands were examined by treatments with mixtures of the deuterated precursor and other hydrocarbons such as C₁₉-C₂₃ trienyl, C₂₁ dienyl, and C₂₁ monoenyl hydrocarbons. The 9,10-epoxy derivative of each alkene was produced, while the epoxidation of the C₂₁ monoene was poorer than those of the trienes and diene. The low selectivity indicated that the species-specific pheromone of the H. cunea female was mainly due to the critical formation of the precursor of each component.     

CYP341B14: A cytochrome P450 involved in the specific epoxidation of pheromone precursors in the fall webworm Hyphantria cunea

Two of the four sex pheromone components in the fall webworm Hyphantria cunea (Lepidoptera: Arctiidae), cis-9,10-epoxy-(3Z,6Z)-3,6-henicosadiene and cis-9,10-epoxy-(3Z,6Z)-1,3,6-henicosatriene, possess an epoxy ring within their molecules. These compounds have been suggested to be biosynthesized from dietary linolenic acid via the following enzymatic reactions; chain elongation, terminal desaturation (in the case of the latter component), decarboxylation, and epoxidation. The last step of this biosynthesis, epoxidation, is known to occur specifically in the sex pheromone gland of females. We identified the enzyme involved in the epoxidation of pheromone precursors by focusing on cytochromes P450, which are known to catalyze the oxidation of various compounds. Three P450-like sequences (Hc_epo1, Hc_epo2, and Hc_epo3) were identified in the cDNA library prepared from the sex pheromone gland of H. cunea. Among these clones, only Hc_epo1 was specifically expressed in the pheromone gland. The full-length sequence of Hc_epo1 contained an ORF of 1527 bp, which encoded a protein of 509 amino acids with a predicted molecular weight of 57.9 kDa. The deduced Hc_epo1 amino acid sequence possessed the characteristics of P450. A phylogenetic analysis of the sequence indicated that Hc_epo1 belonged to the CYP341B clade in the CYP341 family. Therefore, it was named CYP341B14. A subsequent functional assay using Sf-9 cells transiently expressing CYP341B14 demonstrated that this P450 protein was able to specifically epoxidize a (Z)-double bond at the 9th position in the pheromone precursor, (3Z,6Z,9Z)-3,6,9-henicosatriene.     

Sex pheromone of the cloaked pug moth,Eupithecia abietaria (Lepidoptera: Geometridae), a pest of spruce cones

The sex pheromone of the cloaked pug moth, Eupithecia abietaria Götze, an important cone‐feeding pest in spruce seed orchards in Europe, was investigated. Chemical and electrophysiological analyses of pheromone gland extracts of female moths and analogous analyses of synthetic hydrocarbons and epoxides of chain length C₁₉ and C₂₁ revealed (3Z,6Z,9Z)‐3,6,9‐nonadecatriene (3Z,6Z,9Z‐19:H) and 3Z,6Z‐cis‐9,10‐epoxynonadecadiene (3Z,6Z‐cis‐9,10‐epoxy‐19:H) as candidate pheromone components, which were found in a gland extract in a ratio of 95 : 5. In field trapping experiments, conspecific males were only attracted to a combination of 3Z,6Z,9Z‐19:H and the (9S,10R)‐enantiomer of 3Z,6Z‐cis‐9,10‐epoxy‐19:H. The (9R,10S)‐enantiomer was not attractive, which is in agreement with studies on other Eupithecia species, for which males have only been attracted by the (9S,10R)‐enantiomer of epoxides. Subsequent experiments showed that E. abietaria males were attracted to a wide range of ratios of the two active compounds and that trap catches increased with increasing dose of the binary blend. A two‐component bait containing 300 μg 3Z,6Z,9Z‐19:H and 33 μg of the (9S,10R)‐enantiomer of 3Z,6Z‐cis‐9,10‐epoxy‐19:H was efficient for monitoring E. abietaria in spruce seed orchards in southern Sweden, where this species has probably been overlooked as an important pest in the past. With sex pheromones recently identified for two other moths that are major pests on spruce cones, the spruce seed moth, Cydia strobilella L., and the spruce coneworm, Dioryctria abietella Denis & Schiffermüller, pheromone‐based monitoring can now be achieved for the whole guild of cone‐feeding moths in European spruce seed orchards.     

Sex pheromone composition of Ascotis selenaria (Lepidoptera: Geometridae) and its regional variation in Korea

This study was conducted to investigate sex pheromone composition of Ascotis selenaria (Lepidoptera: Geometridae) in Korea. Two sex pheromone compounds such as (Z,Z)-6,9-cis-3,4-epoxynonadecadiene (6Z,9Z-cis-3,4-epoxy-19:H) and (Z,Z,Z)-3,6,9-nonadecatriene (3Z,6Z,9Z-19:H) were identified in the glands of A. selenaria females by gas chromatography–mass spectrometry analysis. However, the component 3Z,6Z,9Z-19:H neither elicited an electroantennogram response nor increased the attractiveness for A. selenaria males in the field. The role of 3Z,6Z,9Z-19:H seems to be as an antagonistic signal for mating behavior of A. selenaria males.The blend ratios of two 6Z,9Z-cis-3,4-epoxy-19:H isomers such as, 6Z,9Z-cis-3R,4S-epoxy-19:H and 6Z,9Z-cis-3S,4R-epoxy-19:H, were critical to attract A. selenaria males. The blend ratios of the two isomers showing peak catch of A. selenaria males had large variations among the locations investigated. A. selenaria populations in Gunwi showed peak activity at ratios of 0.9:0.1 and 0.8:0.2, whereas the populations in Goheung, Yeongam, and Jeju (Aewol and Harye) showed peak activity at a 0.5:0.5 ratio. In Changnyeong, the peak activity occurred in a bimodal form at ratios of 0.7:0.3 and 0.4:0.6. Such variation was partially explained by geographical isolation due to mountain ranges. Consequently, the results of our study should be useful for designing a region-specific pheromone lure for successful A. selenaria monitoring.     

A Selective Method of Estimation of Bacitracin in the Presence of Other Antibiotics and Growth Factors

The plum cankerworm moth, Cystidia couaggaria couaggaria (Geometridae: Ennominae), is a defoliator of Chinese plum trees (Prunus mume). The pheromone components of the female were analyzed by gas chromatography (GC) with an electro-antennographic (EAG) detector and GC coupled with mass spectrometry. The crude pheromone extract included several EAG-active components, i.e., trienyl, dienyl, and saturated hydrocarbons, with a C₂₁–C₂₅ straight chain. The characteristic mass spectra indicated the unsaturated hydrocarbons to be (3Z,6Z,9Z)-3,6,9-trienes and (6Z,9Z)-6,9-dienes. In the fields, mixtures of the synthetic C₂₁ and C₂₃ trienes in a ratio of 2:3 and 1:4 successfully attracted males of this diurnal species during daytime. While the male antennae responded to the C₂₅ triene and saturated hydrocarbons, their synergistic effects were not observed on the male attraction in the fields. Addition of the C₂₁ diene interestingly inhibited the activity of the triene mixture. Males of Cystidia truncangulata, a sympatric diurnal congener of C. c. couaggaria, showed similar EAG responses to the unsaturated hydrocarbons, but no C. truncangulata males were attracted by the lures tested for C. c. couaggaria males, indicating that the identified hydrocarbons comprised the species-specific pheromone of C. c. couaggaria females.     

Female sex pheromone of a lichen moth Eilema japonica (Arctiidae, Lithosiinae): Components and control of production

Seven candidates for components of the female sex pheromone of Eilema japonica (Arctiidae, Lithosiinae) were detected in an extract of pheromone glands with a gas chromatograph-electroantennographic detector. The compounds were identified as (Z,Z)-6,9-icosadiene (D20), (Z,Z)-6,9-henicosadiene (D21), (Z,Z,Z)-3,6,9-henicosatriene (T21), (Z,Z)-6,9-docosadiene (D22), (Z,Z,Z)-3,6,9-docosatriene (T22), (Z,Z)-6,9-tricosadiene (D23), and (Z,Z,Z)-3,6,9-tricosatriene (T23). Assays using synthetic lures in a wind tunnel showed that D21 (proportion, 0.39), T21 (0.08), D22 (0.27), and T22 (0.26) are important for evoking full behavioral responses from the males. Titers of the pheromone components did not show clear temporal fluctuations. Moreover, decapitation of the female moth had no effect on the titers of pheromone components in the pheromone gland, suggesting that cephalic endocrine factors such as pheromone biosynthesis activating neuropeptide (PBAN) are not involved in the control of pheromone biosynthesis in this species.     

Ring A-stereoisomers of 1-hydroxyvitamin D3 and their relative binding affinities for the intestinal 1α,25-dihydroxyvitamin D3 receptor protein

A set of eight 1-hydroxyvitamin D₃ compounds comprising the four possible (5Z)-1,3-diol stereoisomers and the corresponding (5E)-double bond isomers, has been prepared in order to assess the effect of 1,3-diol stereochemistry and 5,6-double bond geometry on binding affinity for the intestinal 1,25-(OH)₂D₃-receptor protein. The compounds were synthesized from either vitamin D₃ or 3-epivitamin D₃ via 3,5-cyclovitamin D intermediates. Competitive receptor binding assays establish that all changes from the natural ring A-configuration (1S, 3R, 5Z) lead to decreased binding affinity, and confirm the importance of the 1-hydroxy function since the conversion of stereochemistry at that center from 1α(S) to 1β(R) has the most pronounced effect on binding affinity (attenuation by more than three orders of magnitude). Other modifications (i.e., conversion at C-3, or cis to trans isomerization of the 5,6-double bond) decrease binding affinity by more moderate (ca. 10-fold) but cumulative factors.     

Monoenyl hydrocarbons in female body wax of the yellow peach moth as synergists of aldehyde pheromone components

The non-polar components of female body wax and pheromone gland extracts of the yellow peach moth synergistically enhanced male behavioral responses from close to pheromone sources in wind tunnel tests when mixed with an aldehyde pheromone blend. When the non-polar fractions (NPFs) of female body wax were further separated by column chromatography, synergistic activities were found in the 3 and 50% ether in hexane fractions, and they additively increased male responses. The main components of the first fraction were (Z)-9-tricosene, (Z)-9-pentacosene, (Z)-9-heptacosene, (Z)-9-nonacosene and (Z)-9-hentriacontene. Only (Z)-9-heptacosene showed a significant synergistic effect in enhancing male responses, but the other components had no effect. A mixture of the five monoenyl hydrocarbons lost activity at lower doses than 5 ng. Natural ratios of these hydrocarbons in the female body wax and pheromone gland extracts were similar, but the amount of (Z)-9-heptacosene in the female body wax was significantly higher than in the pheromone gland extracts. We conclude that (Z)-9-heptacosene increases male responses to aldehyde pheromones, and unknown component(s) in the 50% ether in the hexane fraction are required for full synergistic enhancement by the NPFs of the female body wax and the pheromone gland extracts.     

Research of the (E/Z)-isomerization of carotenoids in Pécs since the 1970s

Geometrical configuration of the polyene chain of approximately 40 mono- and di-cis carotenoids was determined from 1970 through 1990. Subsequently, the kinetic, equilibrium and thermodynamic parameters (k, K, A, E_A, ΔH^#, ΔG^#, ΔS^#) of the reversible thermal isomerization of several symmetrical and unsymmetrical carotenoids were calculated. The rate of the iodine-catalyzed photoisomerization of (all-E)-, (9Z)- and (13Z)-zeaxanthin was compared and the ‘specific rate’ (per unit light energy at given wavelengths) of the iodine-catalyzed photoisomerization for several (13Z)-carotenoids was investigated. As the missing links of the biosynthetic pathway of paprika-carotenoids, carotenoids containing new end groups were isolated; their sterically unhindered mono-cis isomers were also prepared and their geometrical configuration was determined. The investigation concentrated on the substrate specificity of the enzyme violaxanthin-deepoxidase, the light-induced formation of (13Z)-violaxanthin in green leaves, the binding of xanthophylls to the bulk light-harvesting complex (LHC) of photosystem II in higher plants, the biochemical basis of color as an aesthetic quality in Citrus-fruits and the (9Z)-epoxycarotenoid cleavage enzyme activity for ABA biosynthesis. Recently (9Z)-capsanthin-5,6-epoxide and capsoneoxanthin, two novel carotenoids have been isolated from natural sources.     

The volatile Dufour's gland components of the harvester ants Pogonomyrmex rugosus and P. barbatus

The volatile Dufour's gland components of Pogonomyrmex rugosus and P. barbatus have been examined and found to be hydrocarbons. Homologous families of alkanes from this gland consisted of normal hydrocarbons ranging from n-dodecane to n-pentadecane and three types of methyl-branched homologues of the general formula C_nH_2n+1CH(CH₃)C_mH_2m+1, where n is 2, 4, or 5 and the sum of n and m is 10, 11, 12, or 13. The dimethyl-branched hydrocarbons 3,5-dimethyldodecane and 3,4-dimethyltridecane were also observed.     

Alkenyl sex pheromone analogs in the hemolymph of an arctiid Eilema japonica and several non-arctiid moths

The majority of moth species utilize compounds derived from de novo synthesized fatty acids as their sex pheromones (type I). In contrast, species belonging to two recently diverged moth families, Arctiidae and Geometridae, utilize alkenes and their epoxides, which are derived from dietary essential fatty acids (EFAs), as their sex pheromones (type II). In the latter species, EFAs are considered to be converted into alkenes, often after chain elongation, in specialized cells called oenocytes. These alkenes are transported through the hemolymph to the pheromone gland, from which they are secreted with or without further modifications. We confirmed that the appearance of EFA-derived alkenes in the hemolymph was closely associated with the completion of pheromone gland formation in an arctiid moth Eilema japonica. Analyses of the hemolymph of several moth species utilizing type-I sex pheromones demonstrated the occurrence of (Z,Z,Z)-3,6,9-tricosatriene (T23), a typical type-II component, in the hemolymph of a noctuid Mamestra brassicae and two crambids Ostrinia furnacalis and Ostrinia scapulalis. Our results demonstrated that moths utilizing type-I pheromones have the ability to synthesize type-II sex pheromones, and suggested that recently diverged groups of moths may have secondarily exploited EFA-derived alkenes as sex pheromones.     

Effects of the aphid Rhopalosiphum padi on the leafhopper Psammotettix alienus under laboratory conditions

The Japanese giant looper, Ascotis selenaria cretacea, is a serious defoliator of tea gardens in Japan. The females produce racemic (Z,Z)-6,9-cis-3,4-epoxynonadecadiene (epo3,Z6,Z9-19:H, main component) and (Z,Z,Z)-3,6,9-nonadecatriene (Z3,Z6,Z9-19:H, minor component). The orientation of the males to the synthetic pheromone placed in a trap was strongly disrupted by Z3,Z6,Z9-19:H or a mixture of its monoepoxy derivatives (epoxydiene mixture, EDM) impregnated in septa and placed around the trap. Based on this result, polyethylene tubes containing Z3,Z6,Z9-19:H or EDM were prepared and effect of these dispensers was examined in a field. Disruption of male orientation to synthetic pheromone traps was achieved in orchards permeated with Z3,Z6,Z9-19:H at dispenser density of 3000 and 5000 tubes ha^–1 (release rate: 0.55–0.61 mg day^–1 tube^–1) and with EDM at every tested dose, 250–5000 tubes ha^–1 (release rate: 0.25–0.39 mg day^–1 tube^–1). Furthermore, disruption of mating in tethered females was observed in these orchards; particularly, the mating was perfectly inhibited in the areas treated with EDM at 3000 and 5000 tubes ha^–1. This is the first formulation for the mating disruption of a geometrid pest.     

Cloning and functional characterization of a fatty acid transport protein (FATP) from the pheromone gland of a lichen moth, Eilema japonica, which secretes an alkenyl sex pheromone

Sex pheromones of moths are largely classified into two types based on the presence (Type I) or absence (Type II) of a terminal functional group. While Type-I sex pheromones are synthesized from common fatty acids in the pheromone gland (PG), Type-II sex pheromones are derived from hydrocarbons produced presumably in the oenocytes and transported to the PG via the hemolymph. Recently, a fatty acid transport protein (BmFATP) was identified from the PG of the silkworm Bombyx mori, which produces a Type-I sex pheromone (bombykol). BmFATP was shown to facilitate the uptake of extracellular fatty acids into PG cells for the synthesis of bombykol. To elucidate the presence and function of FATP in the PG of moths that produce Type-II sex pheromones, we explored fatp homologues expressed in the PG of a lichen moth, Eilema japonica, which secretes an alkenyl sex pheromone (Type II). A fatp homologue cloned from E. japonica (Ejfatp) was predominantly expressed in the PG, and its expression is upregulated shortly after eclosion. Functional expression of EjFATP in Escherichia coli enhanced the uptake of long chain fatty acids (C₁₈ and C₂₀), but not pheromone precursor hydrocarbons. To the best of our knowledge, this is the first report of the cloning and functional characterization of a FATP in the PG of a moth producing a Type-II sex pheromone. Although EjFATP is not likely to be involved in the uptake of pheromone precursors in E. japonica, the expression pattern of Ejfatp suggests a role for EjFATP in the PG not directly linked to pheromone biosynthesis.     

Structure and biosynthesis of malloprenols from Mallotus japonicus

The mallo prenol isolated from the leaves of Mallotus japonicus was elucidated to be a mixture of (2Z,6Z, 10Z, 14Z, 18Z, 22Z, 26E, 30E, 34E)-3,7,11,15,19,23,27,31,35,39-decamethyl-2,6,10,14,18,22,26,30,34,38-tetracontadecaen-1-ol and its C₄₅- and C₅₅-homologues and not the previously reported structure. The malloprenols were demonstrated to be biosynthesized by successive cis condensation of isoprene residues with (2E, 6E, 10E)-geranylgeranyl pyrophosphate.     

Sex pheromone precursors in Spodoptera littoralis (Lepidoptera: Noctuidae)

Female pheromone gland extracts of Spodoptera littoralis were analyzed for pheromone precursors. Large amounts of fatty methyl esters were found and a positive relationship between the methyl esters and the pheromonal components was observed. The esters were identified on the basis of capillary gas chromatography, coupled gas chromatography with mass spectroscopy and dimethyl disulfide derivatization, and subsequent gas chromatography with mass spectrometry. The characteristic fatty esters of S. littoralis are methyl (Z)-9-tetradecenoate, (E)- and (Z)-11-tetradecenoate, (Z,E)-9,12-tetradecadienoate, (Z,E)-9,11-tetradecadienoate, and (Z)-11-hexadecenoate. The biosynthesis of the monosaturated acids involves probably the common E11 and Z11 desaturases and chain shortening. For the biosynthesis of the novel diene acids, we propose a second, specific desaturation of (Z)-9-tetradecenoate by an E11 desaturase to produce (Z,E)-9,11-tetradecadienoate or by an E12 desaturase to produce (Z,E)-9,12-tetradecadienoate.     

Discovery of a disused desaturase gene from the pheromone gland of the moth Ascotis selenaria, which secretes an epoxyalkenyl sex pheromone

Female Ascotis selenaria (Geometridae) moths use 3,4-epoxy-(Z,Z)-6,9-nonadecadiene, which is synthesized from linolenic acid, as the main component of their sex pheromone. While the use of dietary linolenic or linoleic fatty acid derivatives as sex pheromone components has been observed in moth species belonging to a few families including Geometridae, the majority of moths use derivatives of a common saturated fatty acid, palmitic acid, as their sex pheromone components. We attempted to gain insight into the differentiation of pheromone biosynthetic pathways in geometrids by analyzing the desaturase genes expressed in the pheromone gland of A. selenaria. We demonstrated that a Δ11-desaturase-like gene (Asdesat1) was specifically expressed in the pheromone gland of A. selenaria in spite of the absence of a desaturation step in the pheromone biosynthetic pathway in this species. Further analysis revealed that the presumed transmembrane domains were degenerated in Asdesat1. Phylogenetic analysis demonstrated that Asdesat1 anciently diverged from the lineage of Δ11-desaturases, which are currently widely used in the biosynthesis of sex pheromones by moths. These results suggest that an ancestral Δ11-desaturase became dysfunctional in A. selenaria after a shift in pheromone biosynthetic pathways.     

Modifications at C-3 and C-4 of 2-amino-2-deoxy-d-glucose

Modifications at C-3 and C-4 of 2-amino-2-deoxy-d-glucose have been developed. A 3,4-double bond was introduced into benzyl 2-acetamido-2-deoxy-3,4-di-O-Methylsulfonyl-α-d-glucopyranoside by treatment with NaI and Zn. Epoxidation of the double bond with m-chloroperoxybenzoic acid gave an exo-epoxide exclusively. The stereochemistry of the epoxidation product has been confirmed by an alternative synthesis. An analysis of the ¹H-n.m.r. spectra indicates that both the 3,4-unsaturated derivatives and the epoxide exist in the °H₁ (d) conformation. Nucleophilic reagents (F^?, I^?) opened the 3,4-epoxide to give 4-substituted derivatives having the d-gulo configuration. Thus, 2-acetamido-1,3,6-tri-O-acetyl-2,4-dideoxy-4-iodo-α-d-gulopyranose and 2-acetamido-1,3,6-tri-O-acetyl-3,4-dideoxy-4-fluoro-α-d-gulopyranose have been synthesized. Reduction of the double bond in the key intermediate and deprotection gave 2-acetamido-2,3,4-trideoxy-d-glucopyranose. Some of the derivatives were active as inhibitors of growth of mouse, mammary adenocarcinoma cells in culture.     

Induction of female sex pheromone production in male houseflies by ovary implants or 20-hydroxyecdysone

Implanting ovaries or injecting 20-hydroxyecdysone into male houseflies induced sex pheromone production, including (Z)-9-tricosene (muscalure), 9,10-epoxytricosane and (Z)-14-tricosen-10-one, which normally occurs only in vitellogenic females. Control males did not produce detectable amounts of these compounds. Injection of 20-hydroxyecdysone (5 μg/insect per day) for 3 days resulted in the accumulation of 1.81 μg/insect of (Z)-9-tricosene, 0.97 μg/insect of 9,10-epoxytricosane and 0.12 μg/insect (Z)-14-tricosen-10-one. Multiple injections of 20-hydroxyecdysone at doses as low as 50 ng resulted in the accumulation of 23:1, C₂₃ epoxide and C₂₃ ketone; shifted the distribution of label within the alkenes from 27:1 to 23:1 and decreased the amount of label in the hydrocarbon fractions as alkenes. Structures of the C₂₃ alkene and epoxide produced by the males were verified by gas chromatography-mass spectrometry. Radioactivity from [1-¹⁴C] acetate was incorporated into the C₂₃ alkene, epoxide and ketone in male insects after ovaries were implanted or they were injected with 20-hydroxyecdysone. Synthesis of the C₂₃ pheromone components decreased rapidly within several days after the administration of 20-hydroxyecdysone ceased, indicating that the enzymes involved in sex pheromone production were not permanently induced by hormone treatment. Ecdysone was also effective in initianing pheromone production in males, whereas inokosterone and cholesterol were not effective. Data presented demonstrate that male houseflies possess the metabolic capability to produce the sex pheromone components, and this suggests that 20-hydroxyecdysone alters the production of cuticular hydrocarbons such that the C₂₃ sex pheromone components become major products.     

On the Specificity of a Fatty Acid Epoxygenase in Broad Bean (Vicia faba L.)

Seeds of broad bean (Vicia faba L.) contain a hydroperoxide-dependent fatty acid epoxygenase. Hydrogen peroxide served as an effective oxygen donor in the epoxygenase reaction. Fifteen unsaturated fatty acids were incubated with V. faba epoxygenase in the presence of hydrogen peroxide and the epoxy fatty acids produced were identified. Examination of the substrate specificity of the epoxygenase using a series of monounsaturated fatty acids demonstrated that (Z)-fatty acids were rapidly epoxidized into the corresponding cis-epoxy acids, whereas (E)-fatty acids were converted into their trans-epoxides at a very slow rate. In the series of (Z)-monoenoic acids, the double bond position as well as the chain length influenced the rate of epoxidation. The best substrates were found to be palmitoleic, oleic, and myristoleic acids. Steric analysis showed that most of the epoxy acids produced from monounsaturated fatty acids as well as from linoleic and α-linolenic acids had mainly the (R),(S) configuration. Exceptions were C₁₈ acids having the epoxide group located at C-12/13, in which cases the (S),(R) enantiomers dominated. 13(S)-Hydroxy-9(Z),11(E)-octadecadienoic acid incubated with epoxygenase afforded the epoxy alcohol 9(S),10(R)-epoxy-13(S)-hydroxy-11(E)-octadecenoic acid as the major product. Smaller amounts of the diastereomeric epoxy alcohol 9(R),10(S)-epoxy-13(S)-hydroxy-11(E)-octadecenoic acid as well as the α,β-epoxy alcohol 11(R),12(R)-epoxy-13(S)-hydroxy-9(Z)-octadecenoic acid were also obtained. The soluble fraction of homogenate of V. faba seeds contained an epoxide hydrolase activity that catalyzed the conversion of cis-9,10-epoxyoctadecanoic acid into threo-9,10-dihydroxyoctadecanoic acid.