Relationship Between Chemical Functional Groups on Eucalyptus Secondary Metabolites and their Effectiveness as Marsupial Antifeedants

Eucalyptus displays strong intraspecific variation in resistance to browsing by marsupial folivores that can be attributed to variation in the concentration and type of diformylphloroglucinol compounds (DFPCs) in the foliage. In this study, we ask which functional groups of diformylphloroglucinol compounds determine their effectiveness in deterring feeding. We used a simple and highly deterrent compound, jensenone, as a model DFPC and compared its activity to structural variants that differ in the types of functional groups on the phloroglucinol molecule. Torquatone, a naturally occurring compound in the steam volatile fraction of Eucalyptus torquata foliage, has neither the aldehyde nor phenol groups that are believed to contribute to the antifeedant actions of jensenone. From the naturally occurring compounds we have synthesized two intermediates, a capped phenol/free aldehyde compound (acetyl-jensenone) and a free phenol/no aldehyde compound (demethyl-torquatone). Addition of jensenone and acetyl-jensenone to diets of common ringtail possums (Pseudocheirus peregrinus) substantially reduced their food intakes. Torquatone showed less activity, and there was little reduction in food intake when demethyl-torquatone was added to the diet. We conclude that at least the aldehyde groups attached to the aromatic nucleus are important in determining whether these compounds deter feeding by common ringtail possums, whereas the phenol groups may play only a minor role.     

Antiherbivore Chemistry of Eucalyptus--Cues and Deterrents for Marsupial Folivores

Formylated phloroglucinol compounds (FPCs) are the single most important factor determining the amount of foliage that marsupial folivores eat from individual Eucalyptus trees. Folivores need to recognize which trees contain FPCs if they are to avoid them and forage efficiently, they are challenged by great diversity in the types and quantities of FPCs present, even within eucalypt species. We investigated the relationship between FPCs and terpenoids in species with both simple and complex FPC profiles and found strong positive correlations between terpenes generally, and several monoterpenes in particular, and FPCs. Terpene cues also indicated qualitative differences in trees' FPC profiles. We describe significant qualitative and quantitative variation in FPCs in several species that are important food sources for marsupial folivores. New discoveries include the fact that macrocarpals occur as two major, distinct groups and several new dimeric acylphloroglucinols from Eucalyptus strzeleckii. These patterns add to the chemical complexity of the foraging environment for folivores.     

Fish protein concentrate: A new source of dietary protein

The concept of fish protein concentrate (FPC) is based on the more efficient use of our fishery resource by converting under-utilized fish to acceptable products for human consumption. FPC is not a single product. It is rather a family of products produced by different processes. Each member in the family of products has different characteristics and can be used for different purposes. Although a variety of processes has been developed, most have been based on solvent extraction of whole fish to remove lipids and water. FPC produced by solvent extraction of fish of several different species contains between 75% and 95% protein, which is particularly high in quality. This type of product can be used in foods to improve markedly their nutritional quality without significantly changing their other characteristics. FPC produced by some solvent extraction methods, however, has limited functional properties. New processes are being developed which use enzymes, various solvents, or a combination of enzymes and solvents. Products from some of these processes have improved functional properties and these FPCs appear to be particularly promising for use in foods for their functional attributes. Several problems still remain to be solved and research is needed to determine how FPCs can be produced and utilized most efficiently and effectively. There is, however, a commercial industry emerging and indications are that FPCs will find a significant place in the market. One of 16 papers being published from the Symposium, “Oilseed Processors Challenged by World Protein Needs,” presented at the ISF-AOCS World Congress, Chicago, September 1970. National Marine Fisheries Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce.     

Controlled Hydrolysis of Odorants Schiff Bases in Low-Molecular-Weight Gels

Imines or Schiff bases (SB) are formed by the condensation of an aldehyde or a ketone with a primary amine, with the removal of a water molecule. Schiff bases are central molecules in several biological processes for their ability to form and cleave by small variation of the medium. We report here the controlled hydrolysis of four SBs that may be applied in the fragrance industry, as they are profragrances all containing odorant molecules: methyl anthranilate as primary amine, and four aldehydes (cyclamal, helional, hydroxycitronellal and triplal) that are very volatile odorants. The SB stability was assessed over time by HPLC-MS in neutral or acidic conditions, both in solution and when trapped in low molecular weight gels. Our results demonstrate that it is possible to control the hydrolysis of the Schiff bases in the gel environment, thus tuning the quantity of aldehyde released and the persistency of the fragrance.     

Insect antifeedant activity associated with compounds isolated from species ofLonchocarpus andTephrosia

The antifeedant activity of a series of 21 chalcones, flavanes, and flavanones isolated from the generaLonchocarpus andTephrosia (Leguminosae) was assessed by behavioral and electrophysiological bioassays against larvae ofSpodoptera littoralis andS. exempta. The antifeedant activity is related to the molecular structure of the compounds, and possible modes of interaction with the insect taste receptors are discussed.     

Syntheses and reactions of urethanes of cellobiose and cellulose-containing uretdione groups

Urethanes of cellobiose and cellulose-containing uretdione groups are synthesized by the reaction of aliphatic and aromatic diisocyanate uretdiones with the saccharides. The syntheses are performed as a heterogeneous reaction in dimethyl acetamide using dibutyl tin dilaurate as a catalyst, as well as a homogeneous reaction in dimethyl acetamide-lithium chloride. Thus, Semisynthetic prepolymers are formed that offer the reactivity of (blocked) isocyanate groups. To demonstrate their reactivity, ring opening of the uretdiones is performed by the addition of a secondary amine to yield the corresponding ureas.     

受阻胺类固化剂固化环氧树脂的固化过程研究

通过差示扫描量热法(DSC)研究了几种不同基团取代脂肪族二元胺中的一个氢原子所形成的三官能度脂肪胺类固化剂固化环氧树脂的过程。分别使用Kissinger模型和Flynn-Wall-Ozawa模型对三种固化剂固化环氧树脂的动力学参数进行了计算。结果表明,三种固化剂固化环氧树脂的反应活性大小比较为:N-乙基乙二胺≈N-甲基乙二胺>N-苯基乙二胺。这不仅与得到的固化度-时间曲线结果相符,并且可以从结构的角度以电子效应,共轭效应和位阻效应理论给予合理解释。N-苯基乙二胺中,由于苯环的刚性较大,空间位阻效应尤为明显,活化能(E a)在固化度(α)=0.5时为61.99 kJ/mol,而在α=0.9时达到97.63 kJ/mol,随着固化度的增加反应活性迅速下降,因此该类固化剂固化过程中更需要控制工艺。     

Magnetic-separable robust microbeads using a branched polymer for stable enzyme immobilization

Uniform magnetic separable robust microbeads using a branched polymer were successfully developed for stable enzyme immobilization. The changed morphology of the microbeads was shown by scanning electron microscopy (SEM) analysis. The aldehyde groups on the polymers and imine groups derived from the Schiff base reaction between the aldehyde and amine moiety were found as the evidence of these reactions based on Fourier transform infrared (FT-IR) spectroscopy. The amine groups of the enzyme react with the aldehyde groups on the glutaraldehyde polymer so that the stable conjugations are formed. The specific activity of the conjugated enzyme was found to be retained more than 50%, but the reaction rate constant, K_m value was not changed, compared to the free enzyme. In addition, the enzyme conjugated in the microbeads was found to be highly stable for more than 50 days, pertaining over 60% of its initial activity, even after being reused more than 15 times repeatedly. Furthermore, the magnetic-driven controllability provided facile separable characters for the repeated recycling. It is expected that these microbeads can be utilized as a key tool for successful realization not only in enzymatic conversion processes but also in extended fields; bio-based sensors or analytical devices, bioprocessing, bioremediation, to name only a few of numerous areas.     

A new method for fast isolation of insect antifeedant compounds from complex mixtures

Bioassay-guided isolation of bioactive natural substances requires monitoring of all fractionation and purification steps using a bioassay system. This is often a long and tedious process, especially with insect feeding bioassays. We report here a new method, based on the principle of bioautography, for a quick isolation of insect antifeedant compounds. TLC plates, after development, are coated with a thin layer of artificial diet and fed toSpodoptera litura larvae. The location of uneaten areas is then compared with theR _fvalues of the TLC spots, in order to determine rapidly the active fractions. This methods allows for a very fast determination of the most active antifeedant compounds in a complex mixture and considerably speeds up the isolation process. This new method was successfully applied in the study of antifeedant activity of several plant samples, and results are presented here for a model plant,Skimmia japonica (Rutaceae). Using this new method, the compounds responsible for the feeding-deterrent activity, three furanocoumarins (bergapten, xanthotoxin, and oxypeucedanin), were quickly and efficiently identified.     

Antifeedants against <Emphasis Type="Italic">Hylobius abietis</Emphasis> Pine Weevils: An Active Compound In Extract of Bark of <Emphasis Type="Italic">Tilia cordata</Emphasis> Linden

Linden (Tilia cordata) bark was shown to contain an antifeedant effective against the large pine weevil, Hylobius abietis. Soxhlet extraction of inner and outer bark resulted in an extract that showed antifeedant activity in a microfeeding assay. The extract was fractionated by chromatography on silica gel using gradient elution with solvents of increasing polarity. The content of the fractions obtained was monitored by thin layer- and gas chromatography. Fractions of similar chemical composition were merged. Two of the 17 fractions showed antifeedant activity in the microfeeding assay. Nonanoic acid was identified in both of these fractions. Subsequent testing in the microfeeding assay showed that nonanoic acid possessed strong antifeedant activity against H. abietis adults.     

GC/MS and PGC/MS analyses of plasma polymerization for benzaldehyde

Gas chromatography/mass spectrometry studies of gas condensates in plasma and pyrolysis products of plasma polymer for benzaldehyde were made. Both products' analyses indicate the significant presence of benzyl and carbonyl groups in plasma polymer samples. Infrared measurements were also used to correlate the structures suggested by GC/MS results. A radical mechanism, which involved hydrogen abstraction, aldehyde group abstraction, and benzyl fragmentation under plasma activation, was proposed. The highly crosslinked and branched structures of the plasma polymer were attributed to the subsequent reactivity of free radicals, formed as a result of the scission of the chemical bonds in the benzaldehyde molecules.     

Antifeedant and toxic effects of sesquiterpenes fromSenecio palmensis to colorado potato beetle

A bioassay-guided fractionation of the aerial parts ofSenecio palmensis resulted in the isolation of two sesquiterpenes, 2,10-bisaboladien-1-one and 11-acetoxy-5-angeloyloxy-silphinen-3-one. The bisabolene and the silphinene represented 0.012% and 0.024% of the plant dry weight, respectively. Both compounds showed antifeedant activity againstLeptinotarsa decemlineata larvae and adults in short-term choice and no-choice bioassays. Both compounds were also tested against different species of phytopathogenic fungi. The beetles were more sensitive to these compounds in choice than in no-choice assays, with a gradient of increasing sensitivity from second instars to adults. Bisabolene was 45 times less active as an antifeedant than juglone, which was tested as a positive control. The silphinen was more active than the bisabolene, with a range of activity similar to juglone. Furthermore, exposure of fourth instars to these compounds over a 24-hr period resulted in reduced feeding and growth rates. To distinguish between antifeedant and toxic effects, growth efficiencies were calculated as the slope of the regression of relative growth rate on relative consumption rate. The comparison of these results with those of antifeedant simulation and contact toxicity bioassays indicates that feeding inhibition is the primary mode of action of the bisabolene, while the silphinene shows both antifeedant and toxic effects.     

Antifeedant effects of proteinase inhibitors on feeding behaviors of adult western corn rootworm (Diabrotica virgifera virgifera)

Low-molecular-weight peptidyl proteinase inhibitors (PIs) including leupeptin, calpain inhibitor I, and calpeptin were found to be potent antifeedants for adult western corn rootworm (WCR) against the phagostimulation of cucurbitacin B (Cuc B) or a corn pollen extract (CPE). Leupeptin was the strongest (ED₅₀ = 0.36 and 0.55 nmol/disk for Cuc B and CPE, respectively) among PIs tested with an antifeedant potency much stronger than the steroid progesterone (ED₅₀ = 2.29 and 5.05 nmol/disk for Cuc B and CPE, respectively), but slightly less than the reference alkaloid, strychnine (ED₅₀ = 0.17 and 0.37 nmol/disk for Cuc B and CPE, respectively). All active PIs contain a di- or tripeptidyl aldehyde moiety, indicating that PIs exert their antifeedant effects by covalent interaction with putative sulfhydryl (SH) groups on taste receptors as do these PIs with cysteine proteinases. However, opposite inhibition potency against Cuc B versus CPE by two thiol-group reducing agents, DTT and L-cysteine, and the results with other cysteine-modifying reagents obscure the net functional role of SH groups at WCR taste chemoreceptors. Surprisingly, the model phagostimulant for diabroticites, Cuc B, was more easily counteracted by these feeding deterrents than the stimulants present in CPE. Three-dimensional structure–antifeedant relationships for the PIs suggest that a novel taste chemoreception mechanism exists for these peptidyl aldehydes or that they fit partially into a strychnine binding pocket on protein chemoreceptors. Favorable economic benefit may be achieved if PIs are discovered to be useful in adult WCR control, since both pre- and postingestive sites would be targeted.     

Ecological Example of Conditioned Flavor Aversion in Plant–Herbivore Interactions: Effect of Terpenes of Eucalyptus Leaves on Feeding by Common Ringtail and Brushtail Possums

We investigated the hypothesis that feeding deterrence of common ringtail possums (Pseudocheirus peregrinus) and common brushtail possums (Trichosurus vulpecula) by Eucalyptus terpenes (in this case 1,8-cineole) is a result of a conditioned flavor aversion (CFA), due to the association of terpenes with postingestive effects of another group of Eucalyptus toxins, the diformylphloroglucinol compounds (DFPCs). Wild-caught common ringtail and common brushtail possums showed a dose-dependent reduction in food intake when 1,8-cineole was added to the diet. However, after continued exposure over 12 days to increasing amounts of cineole in the diet, both species substantially increased their intakes of cineole relative to control animals. This indicated that the aversion to cineole was a conditioned response rather than a physiological limitation in their ability to detoxify terpenes. Subsequent exposure to a diet including both cineole and jensenone (a simple DFPC also found in Eucalyptus and considered to cause postingestive emesis) in corresponding amounts was able to recondition the dose-dependent aversion. Consequently, animals that had been given jensenone showed an aversion to cineole-rich diets that matched the behavior of animals in the control group. This supported our hypothesis that the effect of terpenes on feeding of these marsupial folivores on Eucalyptus is due to a CFA. Possums can cope with levels of terpenes in the diet that far exceed those occurring naturally. The role of terpenes in marsupial folivore–Eucalyptus interactions appears to be to act as a cue to levels of toxic DFPCs in the leaves, rather than acting as toxins in their own right.     

Some chemical bases for gypsy moth,Lymantria dispar,larval rejection of green ash,Fraxinus pennsylvanica,foliage as food

Green ash is one of the few tree species rejected as food by larvae of the generalist gypsy moth,Lymantria dispar L. (Lepidoptera: Lymantriidae). Such rejection is based especially on chemicals present in green ash foliage. The gypsy moth larval feeding-inhibitory activity is contained in the ethyl acetate extractables of green ash foliage. Three representative columnchromatographed fractions of the extractables contained antifeedant activity. Individual fractions showed weaker antifeedant activity compared to the total ethyl acetate extractables. Acid hydrolysis of the extractables destroyed antifeedant activity and yielded feeding stimulant activity at higher concentrations. The aqueous extractables were not feeding-inhibitory. Compounds in the green ash extractables were separated by TLC, HPLC, CC, and GC.     

Antifeedant Effects of Some Novel Terpenoids on Chrysomelidae Beetles: Comparisons with Alkaloids on an Alkaloid-Adapted and Nonadapted Species

Structure–dose–feeding deterrency relationships were compared between the Colorado potato beetle, Leptinotarsa decemlineata (Say), and the western corn rootworm, Diabrotica virgifera virgifera LeConte, using 15 alkaloids, terpenoids, and phenolic derivatives. The former species, a specialist herbivore on selected alkaloid-rich Solanaceae species, was on average 100-times less sensitive to the antifeedant effects of alkaloids, but more similarly sensitive to the terpenoids and phenolics than the latter species, a generalist flower herbivore predominantly on Graminae, Cucurbitaceae, and Compositae species. Antifeedant ED₅₀ values for the potato beetle and corn rootworm, each from closely related subfamilies of Chrysomelidae, ranged over four orders of dose magnitude among the 15 compounds with major species differences in stereosensitivity to -hydrastines and analog sensitivity with the silphinenes. Extremes in sensitivity ranged from silphinene, a rare tricyclic sesquiterpene that is 53 times more active on the potato beetle to aconitine, which is 430 times more antifeedant to the corn rootworm. Among silphinene and its two hydrolysis derivatives, there was not a strong correlation between antifeedant potency and injected toxicity for the two beetle species, but there was correlation between behavioral activity and galeal taste cell electrophysiological threshold and frequency responses. That all of the established GABA- and glycinergic compounds tested were antifeedant for both species suggests a shared molecular mechanism for antifeedant taste chemoreception in these divergent Chrysomelidae species. Moreover, the wide differences in antifeedant sensitivities among these and other chrysomelids to a suite of ligand-gated ion channel antagonists implicate a common protein neuroreceptor type with extraordinary heterogeneity in beetle taste.     

Insecticidal Triterpenes in Meliaceae: Plant Species,Molecules and Activities: Part Ⅰ (Aphanamixis-Chukrasia)

Plant-originated triterpenes are important insecticidal molecules. The research on insecticidal activity of molecules from Meliaceae plants has always received attention due to the molecules from this family showing a variety of insecticidal activities with diverse mechanisms of action. In this paper, we discuss 102 triterpenoid molecules with insecticidal activity of plants of eight genera (Aglaia, Aphanamixis, Azadirachta, Cabralea, Carapa, Cedrela, Chisocheton, and Chukrasia) in Meliaceae. In total, 19 insecticidal plant species are presented. Among these species, Azadirachta indica A. Juss is the most well-known insecticidal plant and azadirachtin is the active molecule most widely recognized and highly effective botanical insecticide. However, it is noteworthy that six species from Cedrela were reported to show insecticidal activity and deserve future study. In this paper, a total of 102 insecticidal molecules are summarized, including 96 nortriterpenes, 4 tetracyclic triterpenes, and 2 pentacyclic triterpenes. Results showed antifeedant activity, growth inhibition activity, poisonous activity, or other activities. Among them, 43 molecules from 15 plant species showed antifeedant activity against 16 insect species, 49 molecules from 14 plant species exhibited poisonous activity on 10 insect species, and 19 molecules from 11 plant species possessed growth regulatory activity on 12 insect species. Among these molecules, azadirachtins were found to be the most successful botanical insecticides. Still, other molecules possessed more than one type of obvious activity, including 7-deacetylgedunin, salannin, gedunin, azadirone, salannol, azadiradione, and methyl angolensate. Most of these molecules are only in the primary stage of study activity; their mechanism of action and structure–activity relationship warrant further study.     

Patterns of Bioactivity and Herbivory on Nothofagus Species from Chile and New Zealand

Nothofagus species from Chile and New Zealand were surveyed in the field for invertebrate abundance and leaf feeding damage and in the laboratory for antifeedant activity against leafrollers (Ctenopsteustis obliquana, Epiphyas postvittana), deterrent activity against pea aphid (Acyrthosiphon pisum), insect growth regulatory activity (Oncopeltus fasciatus), nematicidal activity (Caenorhabditis elegans), antibiotic activity (Pseudomonas solanaciarium), and general toxicity. A data matrix indicated that N. alessandri and N. pumilio most likely have a chemical barrier to insect attack as leaves showed low faunal abundance, low herbivory, and activity in the leafroller antifeedant, aphid deterrent, and nematicidal assays. A chemical examination of N. alessandri that used the leafroller antifeedant test to guide the separation yielded an active fraction containing the flavonoid, galangin, and the stilbene, pinosylvin, which appear to act in concert to deter leafroller feeding. The discovery of the phytoalexin, pinosylvin, in the leaves, raises the possibility that Nothofagus in general, and N. alessandri in particular, may have induced chemical defense mechanisms.     

Novel detection of formylated phloroglucinol compounds (FPCs) in the wound wood of Eucalyptus globulus and E. nitens

This study characterized the chemical responses of Eucalyptus globulus and Eucalyptus nitens to artificial inoculation with a basidiomycete decay fungus. Nine-year-old trees responded to mechanical wounding or inoculation with the decay fungus by producing new wound wood characterized by the presence of dark extractives 17 months after wounding. Analysis of crude wound wood extracts by HPLC coupled to negative ion electrospray mass spectrometry revealed the presence of a complex mixture of many unidentified formylated phloroglucinol compounds (FPCs), in addition to a diverse range of other polyphenolic compounds (hydrolyzable tannins, proanthocyanidins, flavanone glycoside, stilbene glycosides). Prior to this study, FPCs have only been reported from leaves and buds of Eucalyptus spp. Unequivocal evidence for the presence of macrocarpal A and B, and sideroxylonal A and B in the crude extracts was obtained, as well as evidence for a wide range of as yet unreported FPCs. Subsequent preliminary in vitro fungal and bacterial bioassays did not support an antimicrobial role for FPCs in host-pathogen interactions in eucalypts.     

Biotransamination of Furan-Based Aldehydes with Isopropylamine: Enzyme Screening and pH Influence

Furan-based amines are highly valuable compounds which can be directly obtained via reductive amination from easily accessible furfural, 5-(hydroxymethyl)furfural (HMF) and 2,5-diformylfuran (DFF). Herein the biocatalytic amination of these carbonyl derivatives is disclosed using amine transaminases (ATAs) and isopropylamine (IPA) as amine donors. Among the different biocatalysts tested, the ones from Chromobacterium violaceum (Cv-TA), Arthrobacter citreus (ArS-TA), and variants from Arthrobacter sp. (ArRmut11-TA) and Vibrio fluvialis (Vf-mut-TA), afforded high levels of product formation (>80 %) at 100–200 mM aldehyde concentration. The transformations were studied in terms of enzyme and IPA loading. The pH influence was found as a key factor and attributed to the imine/aldehyde equilibrium that can arise from the high reactivity of the carbonyl substrates with a nucleophilic amine such as IPA.