Sesquiterpene Aldehydes Research Articles

Substances of Milky Juice of Genus Lactarius Fungi: Chemical and Toxicological Characteristics

Background: Fungi of the genus Lactarius Pers. before the maturation of spores are not damaged by microorganisms, insects, mollusks, and animals. Such resistance correlates with the period when the basidiomes of these fungi are filled with milky juice, which contains substances of various chemical nature that provide their protection. Objective: The aim of our work is to present the results of our recent and previously published studies on the identification and toxicological characteristics of substances available in the milky juice of fungi of the genus Lactarius Pers and used for protection against predator and parasite organisms. The possibility of using these substances to suppress tumor cells is also discussed. Methods: The biological effect of the juice of L. pergamenus, L. quietus, and L. volemus, as well as methylene chloride, extracts obtained from fresh, frozen and dried basidiomes of L. pergamenus was studied. Purification of individual fractions of hexane extract from the basidiomes was performed by chromatography on a silica gel column and their analysis by done by thin layer chromatography and gas chromatography mass spectrometry. Results: The sesquiterpene aldehydes were shown to be the main component of the chemical protection system of Lactarius. These agents are present in the milky juice of the Lactarius fungi, and they are easily oxidized by oxygen in the air. The milky juice of these mushrooms is also rich in higher fatty acids and phthalates. Phthalates possess an insecticidal effect, while higher fatty acids are capable of forming adducts with sesquiterpenes that provide emulsion stability. Water-soluble substances, in particular, the polyphenol oxidase enzyme, whose activity correlates with the content of milky juice in basidiomes, also play a protective role. Conclusion: Milky juice of mushrooms of Lactarius Pers. genus is a stable balanced emulsion containing a large number of substances. One part is responsible for the toxic effects on other organisms, while the other part determines the chemical stability of the emulsion. Altogether, they create an effective system of protection of fungi of the Lactarius genus against microorganisms, insects, mollusks, and animals.

Drimane Sesquiterpene Aldehydes Control Candida Yeast Isolated from Candidemia in Chilean Patients.

Drimys winteri J.R. (Winteraceae) produce drimane sesquiterpenoids with activity against Candida yeast. In this work, drimenol, polygodial (1), isotadeonal (2), and a new drimane α,β-unsaturated 1,4-dialdehyde, named winterdial (4), were purified from barks of D. winteri. The oxidation of drimenol produced the monoaldehyde drimenal (3). These four aldehyde sesquiterpenoids were evaluated against six Candida species isolated from candidemia patients in Chilean hospitals. Results showed that 1 displays fungistatic activity against all yeasts (3.75 to 15.0 µg/mL), but irritant effects on eyes and skin, whereas its non-pungent epimer 2 has fungistatic and fungicide activities at 1.9 and 15.0 µg/mL, respectively. On the other hand, compounds 3 and 4 were less active. Molecular dynamics simulations suggested that compounds 1–4 are capable of binding to the catalytic pocket of lanosterol 14-alpha demethylase with similar binding free energies, thus suggesting a potential mechanism of action through the inhibition of ergosterol synthesis. According to our findings, compound 2 appears as a valuable molecular scaffold to pursue the future development of more potent drugs against candidiasis with fewer side effects than polygodial. These outcomes are significant to broaden the alternatives to treat fungal infections with increasing prevalence worldwide using natural compounds as a primary source for active compounds.

A Sesquiterpene Aldehyde Isolated From Ethyl Acetate Extract of Lansium Domesticum Fruit Peel

Lansium domesticum (fam. Meliaceae) contains various compounds with various biological activities. Based on the previous research, extracts from several parts of the plant have biological activity. This study aimed to isolate a compound from the fruitpeel of L. domesticum and evaluate cytotoxic activity against T47D, WiDr and HepG2 cell lines. Powdered peels were macerated with ethyl acetate and the filtrate was evaporated to give EtOAc extract. Dried extract was triturated with n-hexane to give n-hexane soluble fraction (A) and insoluble fraction (B). The fraction B was separated using vacuum column chromatography (VLC) with mobile phase n-hexane: ethyl acetate and given 5 fractions. Fractions B3-B5 were combined and separated using VLC with n-hexane and ethyl acetate as mobile phase. This VLC separation gave 18 subractions, subfractions 6-9 with the similar TLC profile were combined. This subfraction was separated further using preparative thin layer chromatography to give compound 1. The Isolated compound (1) appeared as liquid. The chemical structure of 1 was identified acoording to spectroscopic data and comparison with literature. Cytotoxic bioassay was performed on T-47D, WiDr and Hep G2 cell lines in a series of concentrations at 50, 40, 30, 20, 10 and 5µg/mL, with Doxorubicine used as positive control. According to spectroscopic data, compound 1 was identified as 2-ethyl,3-(1’-hydroxy-2’-menthene) propenal, and demonstrate the strongest cytotoxicity against T-47D cell lines (IC50=39.18+1.54 µg/mL).

Characterization of gossypol biosynthetic pathway

Gossypol and related sesquiterpene aldehydes in cotton function as defense compounds but are antinutritional in cottonseed products. By transcriptome comparison and coexpression analyses, we identified 146 candidates linked to gossypol biosynthesis. Analysis of metabolites accumulated in plants subjected to virus-induced gene silencing (VIGS) led to the identification of four enzymes and their supposed substrates. In vitro enzymatic assay and reconstitution in tobacco leaves elucidated a series of oxidative reactions of the gossypol biosynthesis pathway. The four functionally characterized enzymes, together with (+)-δ-cadinene synthase and the P450 involved in 7-hydroxy-(+)-δ-cadinene formation, convert farnesyl diphosphate (FPP) to hemigossypol, with two gaps left that each involves aromatization. Of six intermediates identified from the VIGS-treated leaves, 8-hydroxy-7-keto-δ-cadinene exerted a deleterious effect in dampening plant disease resistance if accumulated. Notably, CYP71BE79, the enzyme responsible for converting this phytotoxic intermediate, exhibited the highest catalytic activity among the five enzymes of the pathway assayed. In addition, despite their dispersed distribution in the cotton genome, all of the enzyme genes identified show a tight correlation of expression. Our data suggest that the enzymatic steps in the gossypol pathway are highly coordinated to ensure efficient substrate conversion.

Essential oil composition of seven populations belonging to two Nepeta species from Northwestern Iran

ABSTRACTEssential oils from the aerial parts of three populations of Nepeta crassifolia (Lamiaceae), which are Iranian endemic species and four populations of N. nuda grown in northwestern Iran were obtained by hydro-distillation and examined by gas chromatography (GC) and GC–mass spectrometry (GC/MS). Overall, 37 compounds were identified in the essential oils from different populations of N. crassifolia and N. nuda. The essential oils consisted mainly of oxygenated monoterpenes and sesquiterpene aldehydes. The major components in the oils of three populations of N. crassifolia were 4aβ, 7α, 7aβ-nepetalactone (16.46–27.45%), 4aα, 7α, 7aβ-nepetalactone (13.45–17.54%), 1,8-cineole (8.15–9.70%) and elemol (14.38–22.14%), while 7aβ-nepetalactone (61–72.21%), 4aα, 7α, 7aβ-nepetalactone (8.72–12.63%), pulegone (7.36%) and piperitenone oxide (4.12%) were identified as the main constituents in the oils of four populations of N. nuda. The essential oils from the aerial parts of two species of Nepeta sourced in northwestern Iran were rich in oxygenated monoterpenes. In conclusion, the present study indicated the essential oil components of wild populations of both Nepeta species varied with chemotypes, environmental conditions, and geographic origin.

Cytochrome P450 CYP6DA2 regulated by cap 'n'collar isoform C (CncC) is associated with gossypol tolerance in Aphis gossypii Glover.

Cotton plants accumulate phytotoxins, such as gossypol and related sesquiterpene aldehydes, to resist insect herbivores. The survival of insects exposed to toxic secondary metabolites depends on the detoxification metabolism mediated by limited groups of cytochrome P450. Gossypol has an antibiotic effect on Aphis gossypii, and as the concentrations of gossypol were increased in the present study, the mortality of cotton aphids increased from 4 to 28%. The fecundity of the cotton aphids exposed to gossypol was also significantly reduced compared with the control. The transcriptional levels of CYP6DA2 in cotton aphids were significantly induced when exposed to gossypol, and knockdown of the CYP6DA2 transcripts by RNA interference (RNAi) significantly increased the toxicity of gossypol to cotton aphids. To further understand the gossypol regulatory cascade, the 5'-flanking promoter sequences of CYP6DA2 were isolated with a genome walker, and the promoter was very active and was inducible by gossypol. Co-transfection of the cap 'n' collar isoform C (CncC) and CYP6DA2 promoters dramatically increased the expression of CYP6DA2, and suppression of the CncC transcripts by RNAi significantly decreased the expression levels of CYP6DA2, and significantly increased the toxicity of gossypol to cotton aphids. Thus, the transcriptional regulation of CYP6DA2 involved the transcriptional factor CncC.

Gossypol: phytoalexin of cotton.

Sesquiterpenoids are a class of 15-carbon secondary metabolites that play diverse roles in plant adaptation to environment. Cotton plants accumulate a large amount of sesquiterpene aldehydes (including gossypol) as phytoalexins against pathogens and herbivores. They are stored in pigment glands of aerial organs and in epidermal layers of roots. Several enzymes of gossypol biosynthesis pathway have been characterized, including 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and farnesyl diphosphate synthase (FPS) that catalyze the formation of the precursor farnesyl diphosphate (FPP), (+)-δ-cadinene synthase (CDN) which is the first enzyme committed to gossypol biosynthesis, and the downstream enzymes of CYP706B1 and methyltransferase. Expressions of these genes are tightly regulated during cotton plants development and induced by jasmonate and fungi elicitors. The transcription factor GaWRKY1 has been shown to be involved in gossypol pathway regulation. Recent development of new genomic platforms and methods and releases of diploid and tetraploid cotton genome sequences will greatly facilitate the elucidation of gossypol biosynthetic pathway and its regulation.

Effects of cotton cultivars differing in gossypol content on the quality of Aphis gossypii as prey for two species of Coccinellidae

Plants can have detrimental effects on biological control agents by affecting their prey or host quality. Thus, it is important to understand the tri-trophic interactions between plants, herbivores and natural enemies when implementing biological control programmes. Studies have shown that both morphological and chemical traits of host plants can affect the third trophic level. Cotton plants are known to produce alkaloids such as gossypol, a sesquiterpene aldehyde that can confer resistance against herbivorous arthropods. Nevertheless, little is known about the effect of gossypol on biological control agents. In this study, we investigated how three cotton cultivars (BRS Rubi, BRS Safira and BRS Verde) differing in gossypol content affect development and growth of predatory coccinellids, Eriopis connexa and Harmonia axyridis, feeding on the cotton aphid Aphis gossypii reared on those cultivars. The results show that the cultivar BRS Rubi (highest gossypol content) had a sub-lethal effect on the development and growth of both Coccinellidae species compared with the other cultivars. Overall, the cultivar BRS Rubi reduced slightly fecundity, net reproductive rate and intrinsic rate of natural increase for both Coccinellidae species. However, because aphid populations stay short periods of time in the field, and adult coccinellids may supplement its diet with alternative prey and plant material this sub-lethal indirect effect of gossypol may not have a detrimental effect on field biological control of cotton aphid by either E. connexa or H. axyridis, thus suggesting a compatibility between plant resistance and biological control agents.

Isolation and characterization of terpene synthases in cotton (Gossypium hirsutum)

Cotton plants accumulate gossypol and related sesquiterpene aldehydes, which function as phytoalexins against pathogens and feeding deterrents to herbivorous insects. However, to date little is known about the biosynthesis of volatile terpenes in this crop. Herein is reported that 5 monoterpenes and 11 sesquiterpenes from extracts of a glanded cotton cultivar, Gossypium hirsutum cv. CCRI12, were detected by gas chromatography-mass spectrometry (GC-MS). By EST data mining combined with Rapid Amplification of cDNA Ends (RACE), full-length cDNAs of three terpene synthases (TPSs), GhTPS1, GhTPS2 and GhTPS3 were isolated. By in vitro assays of the recombinant proteins, it was found that GhTPS1 and GhTPS2 are sesquiterpene synthases: the former converted farnesyl pyrophosphate (FPP) into β-caryophyllene and α-humulene in a ratio of 2:1, whereas the latter produced several sesquiterpenes with guaia-1(10),11-diene as the major product. By contrast, GhTPS3 is a monoterpene synthase, which produced α-pinene, β-pinene, β-phellandrene and trace amounts of other monoterpenes from geranyl pyrophosphate (GPP). The TPS activities were also supported by Virus Induced Gene Silencing (VIGS) in the cotton plant. GhTPS1 and GhTPS3 were highly expressed in the cotton plant overall, whereas GhTPS2 was expressed only in leaves. When stimulated by mechanical wounding, Verticillium dahliae (Vde) elicitor or methyl jasmonate (MeJA), production of terpenes and expression of the corresponding synthase genes were induced. These data demonstrate that the three genes account for the biosynthesis of volatile terpenes of cotton, at least of this Upland cotton.

Chemical variability and antioxidant activity of Eryngium maritimum L. essential oils from Corsica and Sardinia

ABSTRACTThe chemical compositions of Corsican and Sardinian Eryngium maritimum L. essential oils were investigated using column chromatography, gas chromatography with flame ionization detection and gas chromatography–mass spectrometry in electron impact mode. Sixty‐three compounds were identified accounting for 85.8–95.7% of the total amount. With germacrene D (13.7–45.9%), three uncommon oxygenated sesquiterpenes, 4βH‐cadin‐9‐en‐15‐al (18.4–27.6%), 4βH‐cadin‐9‐en‐15‐ol (2.2–14.3%) and 4βH‐muurol‐9‐en‐15‐al (4.3–9.3%), were identified as main components of the essential oils obtained from the plant aerial parts. Relative to these, essential oils from the roots differed drastically with high contents of 2,4,5‐trimethylbenzaldehyde (39.8%), 2,3,6‐trimethylbenzaldehyde (29.0%) and α‐muurolene (23.5%). The chemical variability of Corsican and Sardinian E. maritimum essential oils was studied using statistical analysis. A direct correlation between the island of origin of the sample essential oils and their chemical compositions was assessed. Corsican essential oils exhibited higher amounts of hydrocarbon terpenes than Sardinian samples. Relative to other Eryngium species, Corsican and Sardinian E. maritimum essential oils exhibited original compositions with sesquiterpene aldehydes. These compounds, together with total essential oil, were tested for antioxidant properties using the DPPH and ABTS radical‐scavenging activity tests. No meaningful activity could be attributed to sesquiterpene aldehydes and the corresponding alcohols but the total essential oil and the oxygenated fraction of E. maritimum both demonstrated strong antioxidant properties. Copyright © 2013 John Wiley & Sons, Ltd.

Base‐Induced Decarboxylation of Polyunsaturated α‐Cyano Acids Derived from Malonic Acid: Synthesis of Sesquiterpene Nitriles and Aldehydes with β‐, φ‐, and ψ‐End Groups

AbstractCatalytic base‐induced decarboxylation of polyunsaturated α‐cyano‐β‐methyl acids derived from malonic acid led to the corresponding nitriles 3 (Schemes 2 and 3), 6 (Scheme 5), and 9 (Scheme 6). This decarboxylation occurred with previous deconjugation of the α,β‐alkene moiety of the α‐cyano‐β‐methyl acid, leading to an α‐cyano‐β‐methylene propanoic acid which was easily decarboxylated (see Scheme 2). β‐Methylene intermediates, in some cases, could be isolated; mechanistic pathways are proposed. The nitriles 3, 6, and 9 were reduced to the sesquiterpene aldehydes 4 (β‐end group), 7 (φ‐end group), and 10 (ψ‐end group), respectively.

Gossypol‐enhanced P450 gene pool contributes to cotton bollworm tolerance to a pyrethroid insecticide

Cotton plants accumulate phytotoxins, including gossypol and related sesquiterpene aldehydes, to resist insect herbivores and pathogens. To counteract these defensive plant secondary metabolites, cotton bollworms (Helicoverpa armigera) elevate their production of detoxification enzymes, including cytochrome P450 monooxygenases (P450s). Besides their tolerance to phytotoxin, cotton bollworms have quickly developed resistance to deltamethrin, a widely used pyrethroid insecticide in cotton field. However, the relationship between host plant secondary metabolites and bollworm insecticide resistance is poorly understood. Here, we show that exogenously expressed CYP6AE14, a gossypol-inducible P450 of cotton bollworm, has epoxidation activity towards aldrin, an organochlorine insecticide, indicating that gossypol-induced P450s participate in insecticide metabolism. Gossypol-ingested cotton bollworm larvae showed higher midgut P450 enzyme activities and exhibited enhanced tolerance to deltamethrin. The midgut transcripts of bollworm larvae administrated with different phytochemicals and deltamethrin were then compared by microarray analysis, which showed that gossypol and deltamethrin induced the most similar P450 expression profiles. Gossypol-induced P450s exhibited high divergence and at least five of them (CYP321A1, CYP9A12, CYP9A14, CYP6AE11 and CYP6B7) contributed to cotton bollworm tolerance to deltamethrin. Knocking down one of them, CYP9A14, by plant-mediated RNA interference (RNAi) rendered the larvae more sensitive to the insecticide. These data demonstrate that generalist insects can take advantage of secondary metabolites from their major host plants to elaborate defence systems against other toxic chemicals, and impairing this defence pathway by RNAi holds a potential for reducing the required dosages of agrochemicals in pest control.

Effect of gossypol on survival and reproduction of the zoophytophagous stinkbug Podisus nigrispinus (Dallas)

Effect of gossypol on survival and reproduction of the zoophytophagous stinkbug Podisus nigrispinus (Dallas). Gossypol is a sesquiterpene aldehyde found in cotton plants conferring resistance against herbivory. Although the effect of this sesquiterpenoid on insect pests of cotton is known, the interaction of this compound with zoophytophagous predators such as Podisus nigrispinus (Dallas) (Hemiptera, Pentatomidae) has not been studied so far. Thus, the objective of this study was to evaluate the effect of the purified gossypol on nymphs and adults of P. nigrispinus. Nymphs and adults of this predator were fed on Tenebrio molitor pupae and supplemented with solutions of gossypol at concentrations of 0.00, 0.05, 0.10, and 0.20% (w/v) during the nymphal and adult stages or, only during the adult stage of P. nigrispinus. The nymphal stage of the predator was, on average, two days longer when suplemmented with gossypol. Emerged adults had lower fecundity and egg hatching, especially at the highest gossypol concentration (0.20%) ingested during the nymphal and adult stages. However, this predator was not affected when it ingested the compound only during the adult stage. P. nigrispinus can have delayed nymphal development and lower reproductive performance when ingesting the gossypol during the nymphal and adult stages, but only at higher concentrations of gossypol than that produced by cotton plants.

Highly Efficient Stereocontrolled Total Synthesis of (+)‐Upial

Dual benefit:(+)-Upial, isolated from the sponge Dysidea fragilis (Kaneohe Bay, Hawaii), as a nonisoprenoid sesquiterpene aldehyde lactone, was efficiently synthesized. The key step involved an intramolecular carbonyl–ene reaction, in which the stereocontrolled construction of a bicyclo[3.3.1]nonane ring with five asymmetric carbon centers and the facile introduction of the exo-methylene unit were achieved in a single step (see scheme).

Pubescenone, a New Marasmane Sesquiterpenoid from the Mushroom Lactarius pubescens.

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Pubescenone, a New Marasmane Sesquiterpenoid from the Mushroom Lactarius pubescens

A new marasmane sesquiterpenoid, named pubescenone (1), was isolated from the fruiting bodies of the basidiomycete Lactarius pubescens together with a known sesquiterpene aldehyde, lactaral (2). The structure of pubescenone (1) was elucidated on the basis of extensive spectral methods (MS, IR, 1D and 2D NMR experiments).

Composition of Turkish Lemon and Grapefruit Peel Oils

Lemon [Citrus limon (L.) Burm. f.] and grapefruit (Citrusparadisi Macf.) peel oils were obtained by cold-pressing lemon and grapefruit peels. The oils were analyzed by high-resolution gas chromatograph (HRGC) and high-resolution gas chromatography/mass spectrometer (HRGC/MS). In total, 42 and 27 components have been identified in lemon and grapefruit oils, respectively. Lemon oil showed a high content of monoterpene hydrocarbons (89.9%) with limonene (61.8%), γ-terpinene (10.6%) and β-pinene (8.1%) being the first three major components. Similarly, grape-fruit oil was characterized by its higher content of monoterpene hydrocarbons (96.4%) of which limonene (92.5%) and myrcene (2.6%) were the first two major components. Grapefruit oil contained a lower amount of sesquiterpene hydrocarbons, aldehydes, alcohols and esters than that in lemon oil.

GC/MS Analysis of the Volatile Constituents of Corymbia citriodora Hook. from Réunion Island

A hydrodistilled oil from Corymbia citriodora Hook. produced from leaves harvested in the Réunion Island was analyzed by GC and GC/MS on nonpolar and polar columns, respectively. Nearly 100 constituents were identified. The major constituents were citronellal (63.6%), α-citronellol (7.3%), isopulegol isomers (6.5%), citronellyl acetate (2.6%), p-cymene (2.5%), citronellal dimmers (2.5%), α-pinene (2.1%) and β-caryophyllene (1.2%). Several esters of isobutyric acid (4), monoterpene- (18), and sesquiterpene (15) hydrocarbons, oxides (6), monoterpene alcohols (10), esters (8) and aldehydes (4), (Z)-jasmone, citronellyl citronellate, citronellic acid, eugenol, and some aliphatic and alicyclic derivatives, were presented in trace amounts. On the polar column, further constituents were identified, including menthone, isomenthone, 4-vinylguiacol, and two heavy aliphatic acids: myristic and palmitic acids.

Two new irregular acyclic sesquiterpenes aldehydes from Santolina corsica essential oil.

Two isomeric irregular sesquiterpene aldehydes, namely 3,9-dimethyl-6-isopropyl-2(E),7(E),9-decatrienal and 3,9-dimethyl-6-isopropyl-2(Z),7(E),9-decatrienal, were isolated from the essential oil of Santolina corsica and their structures were elucidated by 1D and 2D NMR spectroscopy.

Characterization of GaWRKY1, a cotton transcription factor that regulates the sesquiterpene synthase gene (+)-delta-cadinene synthase-A.

The cotton (+)-delta-cadinene synthase (CAD1), a sesquiterpene cyclase, catalyzes a branch-point step leading to biosynthesis of sesquiterpene phytoalexins, including gossypol. CAD1-A is a member of CAD1 gene family, and its promoter contains a W-box palindrome with two reversely oriented TGAC repeats, which are the proposed binding sites of WRKY transcription factors. We isolated several WRKY cDNAs from Gossypium arboreum. One of them, GaWRKY1, encodes a protein containing a single WRKY domain and a putative N-terminal Leu zipper. Similar to genes encoding enzymes of cotton sesquiterpene pathway, GaWRKY1 was down-regulated in a glandless cotton cultivar that contained much less gossypol. GaWRKY1 showed a temporal and spatial pattern of expression comparable to that of CAD1-A in various aerial organs examined, including sepal, stigma, anther, and developing seeds. In suspension cells, expression of both GaWRKY1 and CAD1-A genes and biosynthesis of sesquiterpene aldehydes were strongly induced by a fungal elicitor preparation and methyl jasmonate. GaWRKY1 interacted with the 3x W-box derived from CAD1-A promoter in yeast (Saccharomyces cerevisiae) one-hybrid system and in vitro. Furthermore, in transgenic Arabidopsis plants, overexpression of GaWRKY1 highly activated the CAD1-A promoter, and transient assay in tobacco (Nicotiana tabacum) leaves demonstrated that W-box was required for this activation. These results suggest that GaWRKY1 participates in regulation of sesquiterpene biosynthesis in cotton, and CAD1-A is a target gene of this transcription factor.