Insect Pigments Research Articles

Syntheses in enantiopure form of four diastereoisomeric naphthopyranquinones derived from aphid insect pigments

The first syntheses are described of the four enantiopure naphthopyranquinones (1R,3R,4S)- and (1R,3R,4R)-3,4-dihydro-4,7,9-trihydroxy-1,3-dimethylnaphtho[2,3-c]pyranquinone (quinone A 1 and quinone A' 2) and their two C-3 epimers, the (1R,3S,4S)- and (1R,3S,4R)-diastereoisomers 5 and 6, using enantiopure lactate as the source of asymmetry. Key factors in these syntheses are the maintenance of stereochemical integrity throughout the sequences and intramolecular diastereoselective cyclisations of the titanium phenolates of phenolic lactaldehydes. For these cyclisations the differing degree of diastereoselectivity is explained as are the stereochemistries of the product 2-benzopyran-4,5-diols.

Syntheses of 2,5-dimethyl-4-naphth-2'-yldioxolanes and their stereoselective isomerization to naphtho[1,2-c]pyrans, angular analogues of glucoside B, a cleavage product of the aphid insect pigments the protoaphins

Benzynes were generated selectively through loss of ortho-bromotosylate from 1,2-dibromo-3- tosylates. Thus when treated with bu tyl lithium in the presence of furan rel -(2 R ,4 S ,5 R )-4-(2',3'- dibromo-5'-methoxy-4'-toluene- p -sulfonyloxyphenyl)-2,5-d imethyl-1,3-dioxolane 21 was converted in two steps into rel -(2 R ,4 S ,5 R )-4-(1'-bromo-4'-methoxynaphthalen-2'-yl)-2,5- dimethyl-1,3-dioxolane 8 in good yield. Attempted stereoselective isomerization of dioxolane 8 with titanium(IV) chloride at low temperature led to the recovery, almost exclusively, of starting material. The debrominated analogue rel -(2 R ,4 S ,5 R )-4-(1'-methoxynaphthalen-3'-yl)-2,5- dimethyl-1,3-dioxolane 31 , on the other hand, isomerized readily to give rel -(1 R ,3 R ,4 S )- and rel - (1 S ,3 R ,4 S )-3,4-dihydro-4-hydroxy-6-met hoxy-1,3-dimethylnaphtho[1,2- c ]pyrans 32 and 34 in a ratio (~1:3) that did not vary with reaction temperature.

The Diastereoselective Syntheses of Enantiopure Benzo- and Naphtho-pyrans Related to the Aphid Insect Pigments

An overview is presented of synthetic endeavours directed towards the assembly of the enantiopure quinone A and quinone A′, natural derivatives of the aphid insect pigments protoaphin-fb and protoaphin-sl. These are achieved through intramolecular diastereoselective cyclization of tethered phenolic lactaldehydes. The conformational implications of the cyclization process are discussed. Model reactions allow the formulation of a more concise, convergent route to these natural derivatives through the corresponding intermolecular reactions, in which the required complementary diastereoselectivity is provided by the choice of either titanium or magnesium phenolates for reaction with the ethoxyethyl-protected asymmetric lactaldehyde.

ChemInform Abstract: Asymmetric Diastereoselective Syntheses of the Aphid Insect Pigment Derivatives Quinone A and Quinone A′.

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Characterization of the kynurenine 3-monooxygenase gene corresponding to the white egg 1 mutant in the silkworm Bombyx mori.

Kynurenine 3-monooxygenase (KMO, EC 1.14.13.9), which catalyzes the oxidation of kynurenine to 3-hydroxykynurenine, is involved in the synthesis of ommochrome pigments in insects. A silkworm mutant, white egg 1 ( w-1), has been shown to be deficient in this enzyme activity. The mutant is characterized morphologically by its white eyes and the fact that the females lay white eggs. To analyze the relationship between the KMO gene and the mutation, we first determined the entire sequence of a full-length 2.0-kb cDNA and examined its expression pattern in the wild type. The cDNA sequence contains one ORF encoding a polypeptide of 456 amino acids, and transcripts were detected in the larval Malpighian tubules and the pupal ovaries, but not in other tissues. Southern analysis and nucleotide sequencing showed that the KMO gene is present in a single copy and consists of ten exons distributed over a 16-kb region. Comparison of the transcripts between the wild type and mutant silkworms showed that the wild type expressed a single transcript, whereas the mutant exhibited markedly reduced amounts of two transcripts with sizes of 2.0 kb and 1.8 kb. Nucleotide sequence analysis of these mutant transcripts indicated that sequences corresponding to the ninth and tenth exons were missing. Inverse PCR and Southern analysis of the mutant gene demonstrated that the corresponding genomic region was deleted in the w-1 mutant.

Asymmetric diastereoselective syntheses of the aphid insect pigment derivatives quinone A and quinone A′

Commercially available ( R)-lactate has been used to provide the chiral source for the asymmetric diastereoselective syntheses of all four stereoisomers of 3,4-dihydro-4,7,9-trihydroxy-1,3-dimethylnaphtho[2,3- c]pyran-5,10-quinone based on 3 R stereochemistry. The (1 R,3 R,4 S) and (1 R,3 R,4 R) stereoisomers were identical with the natural derivatives of the aphid insect pigments quinone A and quinone A′, while the (1 S,3 R,4 S) and (1 S,3 R,4 R) stereoisomers were found to be the enantiomers of two hitherto unreported naturally derived quinones from alternative aphid insect sources. A key-step is the titanium tetraisopropoxide-induced intramolecular diastereoselective cyclization of meta-hydroxybenzyl protected lactaldehydes to afford benzo[ c]pyran-4,5-diols.

Six opsins from the butterfly Papilio glaucus: molecular phylogenetic evidence for paralogous origins of red-sensitive visual pigments in insects.

It has been hypothesized that the UV-, blue-, and green-sensitive visual pigments of insects were present in the common ancestor of crustaceans and insects, whereas red-sensitive visual pigments evolved later as a result of convergent evolution. This hypothesis is examined with respect to the placement of six opsins from the swallowtail butterfly Papilio glaucus (PglRh1-6) in relationship to 46 other insect, crustacean, and chelicerate opsin sequences. All basal relationships established with maximum parsimony analysis except two are present in the distance and maximum likelihood analyses. In all analyses, the six P. glaucus opsins fall into three well-supported clades, comprised, respectively, of ultraviolet (UV), blue, and long-wavelength (LW) pigments, which appear to predate the radiation of the insects. Lepidopteran green- and red-sensitive visual pigments form a monophyletic clade, which lends support to the hypothesis from comparative physiological studies that red-sensitive visual pigments in insects have paralogous origins. Polymorphic amino acid sites (180, 197, 277, 285, 308), which are essential for generating the spectral diversity among the vertebrate red- and green-sensitive pigments are notably invariant in the Papilio red- and green-sensitive pigments. Other major tuning sites must be sought to explain the spectral diversification among these and other insect visual pigments.

Feeding of Anthrenus verbasci Linne on wool fabric dyed with insect pigment

Feeding of <i>Anthrenus verbasci Linne</i> on wool fabric dyed with insect pigment

The Apis mellifera pupal melanization program is affected by treatment with a juvenile hormone analogue

Apis mellifera treated during different developmental phases with pyriproxyfen, a juvenile hormone analogue, show profound alterations in cuticular pigmentation and sclerotization. When the treatment is effected during the feeding phase of the fifth larval instar (LF5), the pupal development is blocked and pigmentation does not occur. Treatment of older larvae, at the spinning phase of the fifth larval instar (LS5), of prepupae (PP) or pupae at the beginning of the pupal period (Pw, white-eyed, unpigmented cuticle pupae) does not impair pigmentation, but, instead, this process is accelerated, intensified and abnormal. Hormonal treatment during these developmental phases (LS5, PP and Pw) induces earlier activity of phenoloxidase, an enzyme of the reaction chain leading to melanin synthesis. Treated pupae have significantly higher enzymatic levels and show a graded response in phenoloxidase activity after treatment with 0.1, 1 or 5 μg pyriproxyfen. Besides pigmentation, other developmental events were also altered in treated bees: pupal development was shortened, and the expression of esterase-6 activity, the onset of which coincides with the beginning of pigmentation, was shifted with the precocious initiation of this process in treated pupae. The significance of these results is discussed in relation to the mode of hormonal action on cuticular pigmentation in insects.

A metal-mediated diastereoselective synthesis of precursors to the aphid pigment derivatives

Chiral compounds 16 and 17, precursors to the aphid insect pigment derivatives, have been prepared in good to high yield, with complete control of the diastereoselectivity at the newly-created chiral centre C-1, through the use of metal phenolates derived from naphthol 3.

The chemistry and systematic importance of the green wing pigment in emerald moths (Lepidopera: Geometridae, Geometrinae)

The green colour in the wings of Emerald Moths (Geometridae: Lepidoptera) was found to be caused by a single pigment, here termed geoverdin. Contrary to previous suggestions, it is not a bile pigment; there is some evidence that geoverdin is a derivative of chlorophyll. The pigment molecule is highly labile and eluded identification. However, after resolving problems of extracting this acid- and light-sensitive substance from the wing scales (inert, exocuticular structures), we found that profiling by thin layer pigment in a wide range of Lepidoptera. With the possible exception of two genera, geoverdin occurs s the primary pigment only within the Geometrinae, although it exists in trace quantities in certain other Lepidoptera. Our comparisons suggest that the presence of large quantities of geoverdin in Geometrinae is an apomorphic character for the subfamily, although its occurrence in two anomaloud genera suggests that it may not have evolved uniquely. More generally, we recommend the use of TLC profiling as an invaluable technique for systematic studies involving insect pigments.

Ein α‐Methylanthrachinon aus Streptomyceten

An α‐Methylanthraquinone from StreptomycetesFrom cultures of several streptomycete strains producing isochromanquinone antibiotics (4, 5), 3,8‐dihydroxy‐1‐methylanthraquinone‐2‐carboxylic acid (2b), one of the rare naturally occurring α‐methylanthraquinones, was isolated. Native compounds of this group became known only as insect pigments (e.g. 1d) and later on as constituents of a few plants. A common biosynthesis of benzoisochromanquinones and α‐methylanthraquinones is discussed.

Evolution of rhodopsin supergene family. Independent divergence of visual pigments in vertebrates and insects and possibly in mollusks.

Evolution of rhodopsin supergene family. Independent divergence of visual pigments in vertebrates and insects and possibly in mollusks.

Role of juvenile hormone in regulating tyrosine glucoside synthesis for pupal tanning in Manduca sexta (L.)

Tyrosine glucoside (α- d-glucopyranosyl- O- l-tyrosine) serves as a reservoir of tyrosine and glucose for pupal and adult cuticle formation, tanning, and pigmentation in several Lepidopteran insects. In the tobacco hornworm, Manduca sexta (L.), detectable quantities appear in the haemolymph 1–2 days after ecdysis of the fifth instar and very high concentrations accumulate between the fourth and eighth days of the stadium. If juvenile hormone II or a mimic (methoprene) is injected into fifth-instar larvae at 24-h intervals after ecdysis, tyrosine glucoside synthesis is almost completely suppressed. Temporary starvation of newly ecdysed larvae that results in the maintenance of a high endogenous juvenile hormone titre, also suppresses and delays the onset of tyrosine glucoside synthesis. The decrease and eventual disappearance of juvenile hormone after ecdysis of the last-larval instar appears to be a necessary prerequisite for the synthesis or activation of tyrosine glucoside synthetase along with the initiation of other metamorphic events.

Biliverdin IX γ in beetles (dytiscidae: laccophilinae)

1. 1. A bile pigment has been isolated from the green adults of the water beetle Laccophilus minutus and shown: to be biliverdin IX γ. Its identification is is based on co-chromatography with the four authentic biliverdin isomers, electronic spectra, mass spectra and chemical degradation. 2. 2. This is the first report on a bile pigment from a beetle and the first identification of biliverdin IX γ outside the lepidopteran order. 3. 3. Some of the carotenoids have been tentatively identified; astaxanthin diester represents the principal one. 4. 4. The distribution of bile pigments in insects and the chemotaxonomy of water beetles are discussed.

Ceroalbolinic Acid, a Common Body Pigment of Three Ceroplastes Scale Insects in Japan. Confirmation of Structure

Abstract The structure of ceroalbolinic acid, a widely occurring insect pigment, a common body pigment of three Japanese Ceroplastes scale insects, has been confirmed as 2 by 13C-NMR long-range selective proton decoupling (LSPD) experiments on its permethylated derivative 3. Full assignments of skeletal carbons for 3 were also obtained.

ChemInform Abstract: INTERMEDIATES IN THE 1‐2‐ADDITION OF 1,1‐DIETHOXYETHENE TO QUINONES‐ SYNTHESIS OF DEOXYERYTHROLACCIN

AbstractLl‐Diäthoxy‐äthylen (I) und 2,3‐Dimethyl‐p‐chinon (II) reagieren über eine Zwischenstufe (III) zum Diäthoxy‐naphthochinon (IV), wobei eine Hydrochinon‐Zwischenstufe (V) angenommen werden kann.

Intermediates in the 1:2-addition of 1,1-diethoxyethene to quinones: synthesis of deoxyerythrolaccin

Intermediate 1 : 2-adducts have been isolated from the reaction of 1,1-diethoxyethene with quinones, a process which has been extended to the synthesis of the insect pigment deoxyerythrolaccin.

ChemInform Abstract: ADDITION OF 1,1‐DIETHOXYETHENE TO QUINONES‐ SYNTHESIS OF ACETYLEMODIN

AbstractAddition von Diäthoxyäthylen (I) an 2,3‐Dimethyl‐l ,4‐benzochinon (II) liefert ein Gemisch aus 63% des Orthoesters (III) und 9% des Naphthochinons (IVa).

Addition of 1,1-diethoxyethene to quinones: synthesis of acetylemodin

Addition of 1,1-diethoxyethene to quinones involves concurrent 1:1- and 1:2-pathways, application of which has led to synthesis of the insect pigment acetylemodin (11).