Hexyl Esters Research Articles

Fatty acid hexyl esters: Influence of the reaction parameters on the synthesis and diesel-biodiesel-1-hexanol blend composition on the application properties

The matter of this study is the influence of reaction parameters – temperature (40–80 °C), time (2–60 min), molar ratio of 1-hexanol to waste cooking oil (5:1–12:1), and mass fraction of KOH catalyst (1–3 wt%) – on the synthesis, i.e. reaction conversion, of fatty acid hexyl esters (FAHE). Afterward, larger amounts of biodiesel were synthesized, purified, and blended with 1-hexanol and non-additized mineral diesel, to assess blends’ application properties, as possible transportation fuels used in diesel engines. An increase in biodiesel’s volume fraction up to 20 vol% in blends led to an increase in their densities, viscosities, as well as surface tension values. On the contrary, adding 1-hexanol up to 15 vol% resulted in a decrease in these values. Low-temperature properties of diesel–biodiesel blends, e.g. pour point and cloud point and heat of combustion were the same or very close to those of mineral diesel, whereas FAHE significantly improved lubricating properties of diesel. Altogether, application property values of the prepared blends fell within the corresponding guidelines set by the standard EN 590.

Changes in the VOC of Fruits at Different Refrigeration Stages of 'Ruixue' and the Participation of Carboxylesterase MdCXE20 in the Catabolism of Volatile Esters.

Aroma is a crucial quality attribute of apple fruit, which significantly impacts its commercial value and consumer choice. Despite its importance the volatile aroma substances produced by the new variety 'Ruixue' after harvest remain unclear. In this study, we utilized headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) to investigate the changes in volatile substances, fruit hardness, crispness, and related aroma synthase activity of commercially mature 'Ruixue' apples during cold storage. Our findings revealed a gradual decline in fruit firmness and brittleness of 'Ruixue' apples during cold storage, with hexyl acetate, hexyl caproate, and hexyl thiocyanate being the main hexyl esters detected. To gain a better understanding of the metabolic pathway of esters, we identified 42 MdCXE gene members that are associated with ester degradation. Through RT-qPCR analysis, we discovered that carboxylesterase MdCXE20 exhibited higher expression levels compared to other MdCXE genes during cold storage. To confirm the role of MdCXE20, we conducted a transient injection of apple fruits and observed that overexpression of MdCXE20 led to the degradation of esters such as hexyl hexanoate, butyl hexanoate, butyl 2-methylbutyrate, hexyl butyrate, and hexyl 2-methylbutyrate. The results of the study showed that the virus-induced gene silencing of MdCXE20 found the opposite results. Additionally, the esters of OE-MdCXE20 callus showed a lower content of ester VOC than the control callus, according to the homologous stable transformation of 'Wanglin' callus. Overall, these findings suggest that the MdCXE20 gene plays a crucial role in the decrease of esters in 'Ruixue' apples, which ultimately affects their flavor.

Benzoic Acid Derivatives as Prodrugs for the Treatment of Tuberculosis.

One interesting approach to fight tuberculosis is the use of prodrugs that often have shown improved biological activities over drugs with poor absorption or difficulty to cross membranes. Previous studies demonstrate that weak acids such as benzoic acid, present antimycobacterial activity. Moreover, esters of those acids revealed to be a viable alternative since they may diffuse more easily through the cell membranes. Previously we showed that mycobacteria can easily activate benzoic acid esters by conversion to the corresponding acid. Since Zhang postulated that the activity of the acids can be dependent on their pKa, we set up to synthesize a library of benzoates with different electron withdrawing groups (4-chloro, 2,6-dichloro, 3,5-dichloro, 4-nitro, and 3,5 dinitro), to modulate pKa of the liberated acid and different alkoxy substituents (propyl, hexyl, and phenyl) to modulate their lipophilicity, and tested the activity of the esters and the corresponding free acids against mycobacteria. We also studied the activation of the esters by mycobacterial enzymes and the stability of the compounds in buffer and plasma. We concluded that all the benzoates in our study can be activated by mycobacterial enzymes and that the phenyl and hexyl esters presented higher activity than the corresponding free acids, with the nitrobenzoates, and especially the dinitrobenzoates, showing very interesting antitubercular activity that deserve further exploration. Our results did not show a correlation between the activity and the pKa of the acids.

Volatile composition changes of fruits in a biopolymer-coated polyethylene active packaging: Effects of modified atmosphere and packaging-shaped bacterial community

The potential impacts of active packaging on the volatile composition of fruits during preservations largely associated with consumers’ acceptance, yet was barely investigated. In this work, a biopolymer-coated polyethylene active film was developed and its effects on qualities and volatile compositions of fruits with different respiration rates were comprehensively investigated. Underlying reasons for the effect of active packaging on volatile composition change of fruits were elucidated through revealing ternary relationship among the packaging-shaped bacterial community, modified atmosphere and volatiles. Off-flavor production was reduced and more sesquiterpenes (α-cubebene, copaene, β-caryophyllene, α-caryophyllene, d-amorphene) were reserved for longan packaged with active film, due to its antimicrobial and moisture absorption ability, as leading contributors to the selective inhibition on spoilage bacteria genera including Zymobacter, Gluconobacter and Pantoea. Whereas volatile profile of strawberry with high respiration rate was more actively affected by the modified atmosphere induced by packaging, instead of the bacterial community, where hypoxia (<2% O2) led to the accumulation of ethyl esters (0.154–0.184 μg/g) that conferred off-flavor but decreased production of methyl (0.172–0.367 μg/g) and hexyl esters (1.26–1.89 × 10−2 μg/g) that represented typical fruity aroma. This work adds new knowledges on impacts of active packaging on the volatile profile of fruits and would provide guidance to smart design of active packaging for preservation of aromatic fruits.

Odor-contributing volatile compounds of a new Brazilian tabasco pepper cultivar analyzed by HS-SPME-GC-MS and HS-SPME-GC-O/FID

The cultivar BRS Avai was originated from recurrent phenotypic selection in the original American cultivar Tabasco Macllhenny™, used in the worldly famous Tabasco pepper (Capsicum frutescens L.) sauce. The determination of the aroma profile of this new cultivar could reveal important qualitative descriptors that will help in future crosses and in the improvement of the desirable characteristics. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry and gas chromatography-olfactometry techniques were used to analyze the volatile compounds from a new Brazilian cultivar, estimating the most powerful odor-active compounds. In the volatile fraction of BRS Avai pepper, esters were the predominant chemical class and major compounds were isohexyl and hexyl esters. Thirty-five odorants were detected and sixteen were considered as having moderate to high intensity, with hexyl 2-methylbutanoate, α-pinene, hexyl butanoate and hexyl 3-methylbutanoate contributing the most to the typical sweet, herbal and pepper-like aroma of this cultivar.

Experimental investigation of a combinational iron chelating protoporphyrin IX prodrug for fluorescence detection and photodynamic therapy

Photodynamic therapy (PDT) is an oxygen-dependent, light-activated, and locally destructive drug treatment of cancer. Protoporphyrin IX (PpIX)-induced PDT exploits cancer cells’ own innate heme biosynthesis to hyper-accumulate the naturally fluorescent and photoactive precursor to heme, PpIX. This occurs as a result of administering heme precursors (e.g., aminolevulinic acid; ALA) because the final step of the pathway (the insertion of ferrous iron into PpIX by ferrochelatase to form heme) is relatively slow. Separate administration of an iron chelating agent has previously been demonstrated to significantly improve dermatological PpIX-PDT by further limiting heme production. A newly synthesized combinational iron chelating PpIX prodrug (AP2-18) has been assessed experimentally in cultured primary human cells of bladder and dermatological origin, as an alternative photosensitizing agent to ALA or its methyl or hexyl esters (MAL and HAL respectively) for photodetection/PDT. Findings indicated that the technique of iron chelation (either through the separate administration of the established hydroxypyridinone iron chelator CP94 or the just as effective combined AP2-18) did not enhance either PpIX fluorescence or PDT-induced (neutral red assessed) cell death in human primary normal and malignant bladder cells. However, 500 µM AP2-18 significantly increased PpIX accumulation and produced a trend of increased cell death within epithelial squamous carcinoma cells. PpIX accumulation destabilized the actin cytoskeleton in bladder cancer cells prior to PDT and resulted in caspase-3 cleavage/early apoptosis afterwards. AP2-18 iron chelation should continue to be investigated for the enhancement of dermatological PpIX-PDT applications but not bladder photodetection/PDT.

Tribological Properties of 10-Undecenoic Acid-Derived Schiff Base Lubricant Additives

Four 10-undecenoic acid-based Schiff bases were synthesized by condensation of methyl 11-(2-aminoethylthio) undecanoate with various aromatic aldehydes. Synthesized compounds were characterized by spectral techniques and evaluated for their tribological and antioxidant performances in biolubricant base oil, namely epoxy 2-ethyl hexyl esters of karanja fatty acids. The tribological test results indicate that all the synthesized thioethers containing Schiff bases act as good antiwear and extreme pressure additives. A significant reduction in wear scar diameter was observed at a very low concentration (0.6 wt%), whereas, at 1 wt% concentration, weld point enhancement observed from 160 to 230 kg. Quantum chemical calculations based on density functional theory for the interactions of Schiff bases with surfaces correlated with experimental wear data. Overall, the dimethoxy-substituted phenyl ring containing Schiff base was more effective in enhancing the antiwear and extreme pressure performance of base oil, whereas dihydroxy-substituted phenyl ring containing Schiff base exhibited good antioxidant property.

Synthesis and evaluation of stearic acid based heterocyclic Schiff bases as biolubricant additives in epoxy karanja fatty acid 2-ethyl hexyl esters base oil

Four novel stearic acid derived Schiff bases containing heterocyclic aromatic groups (furan, thiophene, pyrrole and pyridine) were synthesized in a three step reaction procedure. All the products were characterized by FT-IR, NMR and ESI-MS. The lubricity and antioxidant properties of synthesized Schiff bases were evaluated with 4-ball machine and differential scanning calorimeter. The morphologies and composition of elements on the worn surfaces were studied by using scanning electron microscope and energy-dispersive X-ray spectroscopy. Results show that these stearic acid based derivatives possess good tribological properties and antioxidant performance. The difference in the additive performance of the derivatives is closely related to the difference in their molecular structure. Pyridine containing Schiff base was more effective as both antiwear and extreme pressure additive while thiophene derivative exhibited higher efficacy as antioxidant.

Odorant-Based Detection and Discrimination of Two Economic Pests in Export Apples.

Detection of pest infestations in fresh produce traded internationally could offer improved prospects for reducing the movement of unwanted pests. Because immature stages of some pests can be difficult to find visually, other cues such as herbivore-induced volatiles that can potentially be detected at the early stages of infestation are worth investigating. In this study, we artificially infested postharvested apples (Malus × domestica 'Royal Gala') with two economic apple pests, the specialist codling moth (CM, Cydia pomonella Linnaeus, Lepidoptera: Tortricidae) and the generalist Queensland fruit fly (QFF, Bactrocera tryoni, Froggatt, Diptera: Tephritidae) and collected volatile organic compounds (VOCs) over time (days 0, 6, and 14-15). In both infestation experiments, we found a strong and significant interaction between time and treatment. Apples infested with the QFF emitted lower total amounts of VOCs than uninfested apples, whereas apples infested with the CM released similar total amounts of VOCs. Apples infested with CM had increases in several hexyl and butyl esters, which were particularly noticeable after 15 d. In contrast, changes in ethyl esters were characteristics of QFF infestation and could be detected from day 6. Our multilevel and multivariate statistical analysis identified specific volatile biomarkers for each species at each sampling time that can be used to design a new tool for remote detection and surveillance of these invasive pests in harvested apples. Nevertheless, other information such as the cultivar as well as the storage condition needs to be taken into consideration to increase accuracy of future odorant-based sensors for pest identification.

Diethyl-Ether Flower Washings of Dianthus cruentus Griseb. (Caryophyllaceae): Derivatization Reactions Leading to the Identification of New Wax Constituents.

Some carnation species (Dianthus spp., Caryophyllaceae) exhibit a strong resistance to drought stress that is connected with the increased surface wax formation. Wax composition is unknown for the majority of Dianthus spp. Herein, mass spectral and gas chromatographic data, in combination with synthesis and chemical transformations (transesterification and synthesis of dimethyl disulfide adducts), enabled the identification of 151 constituents of diethyl-ether washings of fresh flowers of Dianthus cruentus Griseb. from Serbia. The flower wax contained, along with the dominant ubiquitous long-chain n-alkanes, homologous series of n- and branched (iso- and anteiso-) long-chain hexyl alkanoates/alkenoates and alkyl/alkenyl benzoates. The branching position in the mentioned hexyl esters was probed by synthesis of esters of three isomeric hexanols that were spectrally characterized (1 H- and 13 C-NMR, IR, MS). The washings also contained long-chain (Z)- and (E)-alkenes (C23 -C35 ) with several different double bond regiochemistries. Fifty-five of these constituents (eight hexyl esters, two benzoates, and forty-five alkenes) were detected for the first time in Plantae, while ten of these represent completely new compounds. The rare occurrence of these wax constituents makes them possible chemotaxonomic markers of this particular Dianthus sp.

Test method for determination of different biodiesels (fatty acid alkyl esters) content in diesel fuel using FTIR-ATR

Abstract A novel procedure that uses FTIR-ATR C O signal area (1690–1800 cm−1) and a standard test method that is used for determination of fatty acid methyl ester in diesel were applied for the quantification of ethyl, propyl, butyl, isobutyl, pentyl, isopenyl, hexyl, heptyl, octyl, decyl, and dodecyl fatty acid esters in diesel. These methods were examined in the range from 0.0 to 30.0 vol% of biodiesel in diesel. The obtained correlation between concentration and FTIR absorption was highly linear (R2 above 0.993, in most cases 0.999). Considering that diesel blends with butanol or higher alcohols with their corresponding fatty acid alkyl ester can satisfy the requirements for use in diesel engines, we tested if such blending would influence the results of those two methods. The results indicate that biodiesel can be quantified for blends with alcohol content up to 9 vol% of the total volume when signal area calibration is used.

Synthesis and physical-chemical properties of functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid

Introduction. Synthetic research of new biologically active compounds occupies an important place in modern pharmaceutical science.Thus it is important to develop techniques for the biologically active substances functionalization. Esters and amides take special place among the variety of functional derivatives of organic acids,. These fragments are well-known pharmacophores and could be found in a wide range of drugs. Thus, the nootropic agent pyracetam is 2-oxo-1-pyrolidineacetamide, and is the selective antagonist of β-adrenoreceptores; atenolol is a derivative of benzeneacetamide. Substituted acetamide and ester fragments are also present in the structures of aprofen, spasmolitin, acetylidine and β-lactam cephalosporins and penicillins antibiotics. Aim of our research was the synthetic method development for functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid and the study of their physical-chemical properties. Materials and methods. Melting points were determined using capillary method on DMP (M). 1 Н NMR-spectra were recorded by Varian Mercury VX-200 device (company «Varian» – USA) solvent – (DMSO- d 6 ), internal standard – ТМS. Elemental analysis of obtained compounds was produced on device Elementar Vario L cube. Chemical shifts were reported in ppm (parts per million) values. Infrared (IR) spectra were measured on a Bruker Alpha instrument using a potassium bromide (KBr) disk, scanning from 400 to 4000 cm -1 . Results and discussion. We selected 3-benzyl-8-propylxanthinyl-7-acetic acid as initial compound for our study. For synthesis of hexyl, heptyl, octyl, nonyl, decyl and benzyl esters of 3-benzyl-8-propylxanthinyl-7-acetic acid we used alternative method, that included alkylation of sodium salts of acids with alkyl halogens. Reaction was made at DMF medium by reflux of reagents. Next stage of our research was the synthesis of amides of 3-beznyl-8-propylxanthinyl-7-acetic acid by the reaction of ethyl or propyl esters with butylamine, benzylamine, p-methylbenzylamine or p-fluorobenzylamine. It should be noted that we conducted reaction without solvent in the medium of amine and reagents were not reflux but heated at 80 о С. The structures of all obtained compounds were proved by the elemental analysis, IR- and 1 H NMR-spectroscopy. Conclusions . Obtained results of our work can be used for further search of biological active compounds among functional derivatives of xanthinyl-7-alkanyl acids

Chain Length of Amphipathic-Type Thioesters Dramatically Affects Reactivity in Aqueous Amidation Reactions with Cysteine Esters

The reaction of five amphipathic-type thioesters, CH3(CH2) m COS(CH2) n COONa (m + n = 12), with cysteine hexyl, butyl, and ethyl esters were studied in aqueous medium. Compounds with the thioester group in close proximity to the carboxylate moiety (m = 10, n = 2) afforded amides in almost quantitative yield, whereas no reaction proceeded by using compounds with the thioester group distant from the carboxylate. In contrast, no clear difference in yield was observed among the five amphipathic-type thioesters upon reaction with valine hexyl ester. The results indicate that the reaction is affected by both the position of the thioester group and the hydrophilic/hydrophobic properties of the amino acid side chain.

Chemical Defence in a Millipede: Evaluation and Characterization of Antimicrobial Activity of the Defensive Secretion from Pachyiulus hungaricus (Karsch, 1881) (Diplopoda, Julida, Julidae).

The chemical defence of the millipede Pachyiulus hungaricus is reported in the present paper, in which a chemical characterization is given and antimicrobial activity is determined. In total, independently of sex, 44 compounds were identified. All compounds belong to two groups: quinones and pentyl and hexyl esters of long-chain fatty acids. The relative abundances of quinones and non-quinones were 94.7% vs. 5.3% (males) and 87.3% vs. 12.7% (females), respectively. The two dominant quinones in both sexes were 2-methyl-1,4,-benzoquinone and 2-methoxy-3-methyl-1,4-benzoquinone. Antibacterial and antifungal activity of the defensive secretion was evaluated in vitro against seven bacterial strains and eight fungal species. With the aid of a dilution technique, the antimicrobial potential of the secretion and high sensitivity of all tested strains were confirmed. The lowest minimum concentrations of these compounds (0.20–0.25 mg/mL) were sufficient for inhibition of Aeromonas hydrophila, Listeria monocytogenes and Methicillin resistant Staphylococcus aureus (MRSA). The growth of eight tested fungal species was inhibited by slightly lower concentrations of the secretion, with Fusarium equiseti as the most sensitive fungus and Aspergillus flavus as the most resistant. Values of MIC and MFC in the employed microdilution assay ranged from 0.10 to above 0.35 mg/mL. The given extract contains antimicrobial components potentially useful as therapeutic agents in the pharmaceutical and agricultural industries.

Role of Ethylene in the Biosynthetic Pathway of Related-aroma Volatiles Derived from Fatty Acids in Oriental Sweet Melon

The catabolism of fatty acid (FA) is regarded as a key pathway of aroma volatile compounds in oriental sweet melon (Cucumis melo var. makuwa). In our research, two cultivars of oriental sweet melon, Caihong7 and Tianbao, were employed to illuminate which step of the biosynthetic pathway of aroma compounds could be regulated by ethylene (ETH). The role of ETH in determining the profiles of straight-chain aroma volatile compounds, levels of FA as aroma precursors, activities of aroma-related enzymes derived from FA pathway, and expression patterns of key enzymes were investigated. Overall, exogenous application of ETH increased the production rates of endogenous ETH and levels of FA. Compared with control, the level of straight-chain esters, especially the acetate, hexanoate, and hexyl esters, was significantly increased by ETH, whereas the content of alcohol and aldehyde reduced. In addition, the metabolism of free FA included linoleic acid (LA), linolenic acid (LeA), and oleic acid (OA) appeared to be ETH-dependent. The activities of lipoxygenase (LOX), alcohol dehydrogenase (ADH), and alcohol acetyltransferase (AAT) as well as the expression patterns of Cm-ADH1, Cm-ADH2, Cm-AAT1, and Cm-AAT4 were positively regulated by ETH. In contrast, hydroperoxide lyase (HPL) and Cm-AAT2 and Cm-AAT3 seemed to be independent of ETH modulation. These results suggested that the dissimilation of FA included LA, LeA, and OA into the acetate, hexanoate, and hexyl esters mainly through ETH regulating the LOX pathway by enhancing the expression of particular members of aroma-related key enzyme gene families as well as the activities of dehydrogenation and esterification.

Ester Hydrogenation Catalyzed by CNN-Pincer Complexes of Ruthenium

Ruthenium complexes supported by two new CNN-pincer ligands were synthesized. Both were tested as catalysts for the hydrogenation of esters under mild conditions (105 °C, 6 bar H2). A striking dependence on ligand structure was observed, as a dimethylamino-substituted ligand gave a nearly inactive catalyst, while a diethylamino-substituted variant gave up to 980 catalytic turnovers for the hydrogenation of benzyl benzoate. This system catalyzes the hydrogenation of various substrates including ethyl, benzyl, and hexyl esters, but is surprisingly unreactive toward methyl esters. Experiments demonstrate that base-catalyzed transesterification is rapid under the reaction conditions and that methyl esters are effectively hydrogenated when benzyl alcohol is added to the reaction mixture. The reverse reaction, dehydrogenation of primary alcohols to give esters, was tested as well; up to 920 catalytic turnovers were observed for the dehydrogenation of 1-hexanol to hexyl hexanoate.

Relationships between free and esterified fatty acids and LOX-derived volatiles during ripening in apple

Ripening in intact apple fruit is accompanied by an increase in the autonomous emissions of hexanol and esters derived from hexanol (hexyl esters). It is thought that these compounds are, to some extent, dependent upon hexanal synthesis by the action of lipoxygenase (LOX) on fatty lipids. To better understand the relationship between fatty acid substrates and their volatile products, we determined the content of oleic (18:1), linoleic (18:2), and linolenic (18:3) acids in free and polar (esterified) lipid fractions of the skin and subtending cortex of ‘Jonagold’ fruit throughout ripening. In the free fatty acid fraction, 18:1 and 18:2 content increased several-fold during ripening, but the 18:3 content remained low and unchanged. In the polar lipid fraction, ripening resulted in a modest increase in the 18:1 and 18:2 content and an extensive decline in the 18:3 content. The rise in 18:2 content of the free fatty acid fraction mirrored emissions of hexanol and hexyl esters in intact fruit and the decline in the 18:3 content of polar lipids reflected the drop in cis-3-hexenal emissions found for disrupted fruit tissue. For intact fruit, our results suggest that hexanal and its metabolites, hexanol and hexyl esters, may be derived from the action of LOX on 18:2 free fatty acid. For disrupted fruit tissue, the data suggest cis-3-hexenal and trans-2-hexenal are largely generated from the action of LOX on 18:3 in the polar lipid fraction. The mechanism whereby free 18:1 and 18:2 could accumulate without a concomitant increase in free 18:3 is not clear. To our knowledge, there is currently no synthetic or catabolic pathway characterized that might account for this finding.

Changes in the volatile composition and sensory properties of cheeses made with milk from commercial sheep flocks managed indoors, part-time grazing in valley, and extensive mountain grazing

Changes in the volatile composition and sensory profile of cheeses made from the milk of six commercial sheep flocks in different feeding seasons through lactation were studied. The abundance of straight-chain volatile acids, ethyl, propyl, hexyl and isobutyl esters, aldehydes, terpenes and other minor compounds was higher in cheeses made from the milk of mountain grazing sheep (mountain cheeses) than in those made from the milk of indoor feeding and part-time grazing sheep. In contrast, the abundance of 2-butanone and 2-methylpropanoic acid was lower in cheeses made with milk from grazing ewes. Mountain cheeses had lower overall intensity, buttery, toasty and nutty aroma, salty taste, and elasticity and moisture in mouth than cheeses made from milk of indoor feeding ewes. Stepwise discriminant analysis was able to robustly discriminate mountain cheeses from those made with the milk from indoor feeding sheep or those part-time grazing in valley.

Antiallergic activity of rosmarinic acid esters is modulated by hydrophobicity, and bulkiness of alkyl side chain.

Methyl, propyl and hexyl esters of rosmarinic, caffeic and p-coumaric acids were tested for antiallergic activity, and rosmarinic acid propyl ester exhibited the greatest β-hexosaminidase release suppression (IC50, 23.7 μM). Quadratic correlations between pIC50 and cLogP (r(2) = 0.94, 0.98, and 1.00, respectively) were observed in each acid ester series. The antiallergic activity is modulated by hydrophobicity, and alkyl chain bulkiness.

Male-specific epicuticular compounds of the sulfur butterfly Colias erate poliographus (Lepidoptera: Pieridae)

Adults of the sulfur butterfly Colias erate poliographus Motschulsky showed sexual dimorphism in their epicuticular composition, with octadecanal and hexyl myristate, palmitate, and stearate identified as male-specific compounds in 3-day-old adults. Since males of the closely related North American species Colias philodice Godart also have the 3 hexyl esters and utilize them as aphrodisiac pheromones toward conspecific females, these substances are likely to serve as pheromones for C. erate. These male-specific compounds were more abundant in wings, especially forewings, than in the body. Male wings lacked androconia but possessed characteristic intermembranous cells. These cells were present behind the base of the socket of ordinary scales and distributed from the basal to discal areas in the forewing costal region and hind wing inner-marginal region. The intermembranous cells were morphologically similar to the male-specific secretory organs of C. philodice and seemed to be the source of the male-specific compounds of C. erate. However, in the wing areas including these cells, the wing scales contained larger amounts of male-specific compounds than the wing membrane, suggesting that the male-specific compounds produced in the intermembranous cells were transferred to and disseminated from the wing scales.