Synthesis and metabolism of vertebrate-type steroids by tissues of insects: a critical evaluation

This review covers the synthesis and the metabolism of vertebrate-type steroids (progesterone, testosterone, estradiol, corticosteroids) by insect tissues and discusses the significance of the reactions for insect physiology. Biosynthesis of vertebrate-type steroids from cholesterol hitherto has been demonstrated in only two insect species, i.e. the water beetle Acilius sulcatus (Coleoptera) and the tobacco hornworm Manduca sexta (Lepidoptera). In Acilius, steroid synthesis is associated with exosecretion (chemical defense). Nothing, however, is known about a physiological role of the C21 steroid conjugate present in ovaries and eggs of Manduca. No synthesis of vertebrate-type steroids was observed in any other insect investigated to date. Most metabolic conversions of steroids by insects concerned oxidoreduction of oxygen groups (hydroxysteroid dehydrogenase activity) and (polar and apolar) conjugate formation. All important enzymatic steps involved in synthesis and catabolism, as known from studies with tissues of vertebrates, were not, or hardly observed. The conclusion is drawn that typical vertebrate-type (C21, C19 and C18) steroids probably do not act as physiologically active substances in insects.     

Insect antifeedant properties of withanolides and related steroids from Solanaceae

Summary Physalis peruviana shrubs were not attacked by larvae ofSpodoptera littoralis. It was demonstrated that withanolide E, a steroid isolated fromP. peruviana, as well as several related steroids, have insect antifeedant properties.     

Der Einfluss einiger C21-Steroide auf die Wassereinlagerung in wachsenden embryonalen Knorpeln in vitro

Summary Embryonic chick cartilages were cultivated in a synthetic nutrient medium. In this experimental procedure cortisol is known to reduce the water uptake of the cartilages. It was found that some C₂₁-steroids exert a similar activity. Those of the steroids investigated, which inhibit water uptake, have in common a ⁴-3-keto group, an 11-hydroxy group, and a keto group in position 20; oxygen functions in positions 21 and 17 seem to be of minor importance for this activity. The possibility of these steroids being inactivated by cellular enzymes is discussed.     

Vincanorin und Vincarein,zwei neue Alkaloide ausVinca minor L.

Summary The isolation of two new alkaloids fromVinca minor L. (Apocynaceae) is described. Vincarein, C₂₁H₂₄N₂O₄, and Vincanorin, C₁₉H₂₂N₂O, both probably belong to the group of indol alkaloids.     

Neuartige Umwandlungen bei den Steroiden

Summary The problem of an efficient partial synthesis of the important corticosteroidal hormone, aldosterone, involves the ability to obtain steroids with functional groups at C-18. Thus, naturally occuring steroid alkaloids, holarrhimine and conessine, were degraded to nitrogen-free 18-hydroxysteroids.In order to find other more efficient methods of synthesis, attempts were made to effect direct functionalization of the unactivated angular methyl group 18 in steroids. This was achieved by known and by novel intramolecular substitution procedures.In the course of these investigations, conessin-type compounds, novel pentacarbocyclic steroids with four-and five-membered E ring as well as novel 18,20-oxido steroids were synthesized from pregnane derivatives. The lead tetraacetate oxidation of 20-hydroxypregnanes, leading to ether formation between C-18 and C-20, ultimately provided the key step for the first partial synthesis ofnat.-aldosterone. The latter work was carried out in close collaboration with the research group of the Pharmaceutical Department of CIBA Ltd., Basle.

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Erweiterte Fassung eines am 6. 5. 59 in der Zürcher Chemischen Gesellschaft sowie am 11. 6. 59 in der CIBA AG., Basel, vom Seniorautor gehaltenen Vortrages.     

Chemical defense in the three European species ofCrematogaster ants

The composition of the Dufour gland of the antC. scutellaris has been reinvestigated by gas chromatography/mass spectrometry. The major components of the gland are (2E,5E,12Z)-4-oxoheneicosa-2,5,12-trien-1-ol acetate (1a) its ¹⁴ and ¹⁶ double bond isomers (1b and1c), and the corresponding (Z,Z)-dienes5a and5b, all containing an acetylated C₂₁ chain. The previously proposed structures1d, 1e, and5c, which are based on an homologous acetylated C₂₃ chain, correspond to minor derivatives present in the gland. Traces of acetylated C₁₉ homologs, tentatively identified as1g-1i, have also been found. The Dufour gland contents of the two other EuropeanCrematogaster species have also been studied.C. auberti is very similar toC. scutellaris in producing mainly1a, 1b and1c, together with the same higher and lower homologs, but it lacks the dienic derivatives5, whereasC. sordidula contains essentially the acetylated C₁₉ compounds1g, 1h, and1i, accompanied by acetylated C₁₇ homologs.     

Effects of feeding on healthy and diseased corn plants on a vector and on a non-vector insect

Insect-transmitted plant pathogens can have positive, negative or no effects on the vector insect. Effects could be direct (caused by the pathogen) or indirect (mediated by changes in the plant). Pathogen effects on non-vector insects are less well known.Peregrinus maidis (Ashmead) (Homoptera: Delphacidae), an insect that is not a vector of the corn stunt spiroplasma (CSS), weighed less 15 days after feeding on CSS-infected corn plants relative to insects feeding on healthy corn plants. Fecundity of non-vector insects that were removed from diseased plants was higher than for insects coming from healthy plants. ForDalbulus maidis (DeLong & Wolcott) (Homoptera: Cicadellidae), an insect that transmits CSS, there were no differences in weight, longevity, eggs per day, weekly or total fecundity after feeding on healthy or on CSS-infected corn plants. Significant differences in some phloem amino acids were detected between healthy and CSS-infected plants. Infected plants also showed an increased phloem acidity as disease symptoms progressed. Feeding on CSS-infected corn plants by an insect that does not vector the pathogen infecting the plant can have favorable consequences as evidenced by an increased fecundity.Scientific aritcle no. 8819, contribution no. A-6605 of the Maryland Agricultural Experiment Station.     

Aberrant,canavanyl protein formation and the ability to tolerate or utilize L-canavanine

Summary L-Canavanine, 2-amino-4-(guanidinooxy)butyric acid, and L-arginine incorporation into de novo synthesized proteins was compared in six organisms. Utilizing L-[guanidinooxy¹⁴C]canavanine and L-[guanidino¹⁴C]arginine at substrate saturation, the canavanine to arginine incorporation ratio was determined in de, novo synthesized proteins.Caryedes brasiliensis andSternechus tuberculatus, canavanine utilizing insects;Canavalia ensiformis, a canavanine storing plant; and to a lesser extentHeliothis virescens, a canavanine resistant insect, failed to accumulate significant canavanyl proteins. By contrast,Manduca sexta, a canavanine-sensitive insect, andGlycine max, a canavanine free plant, readily incorporated canavanine into newly synthesized proteins. This study supports the contention that the incorporation of canavanine into proteins in place of arginine contributes significantly to canavanine's antimetabolic properties.     

Hep27, a member of the short-chain dehydrogenase/reductase family, is an NADPH-dependent dicarbonyl reductase expressed in vascular endothelial tissue

Human Hep27 was originally isolated from growth-arrested HepG2 cells and identified as a member of the superfamily of short-chain dehydrogenases/reductases (SDR). Its substrate specificity has not been determined, but a cross-species comparison suggests that it occurs in widely divergent species, such as human, Cenorhabditis elegans, Drosophila and Arabidopsis thaliana. In this study, Hep27 was expressed as a His₆ fusion protein, and subjected to a substrate screen, using a compound library of SDR substrates, comprising steroids, retinoids, sugars and carbonyl compounds. Whereas no steroid dehydrogenase or retinoid activity was detected, it was found that Hep27 catalyzed the NADPH-dependent reduction of dicarbonyl compounds, like 3,4-hexanedione and 1-phenyl-1,2-propanedione with similar turnover numbers as DCXR (a mitochondrial dicarbonyl reductase/xylulose reductase). In contrast, Hep27 does not convert sugar substrates like xylulose or threose. Based on its substrate specificity and expression in endothelial tissues, it is suggested that Hep27 functions as a dicarbonyl reductase in enzymatic inactivation of reactive carbonyls, involved in covalent modification of cellular components. Received 16 January 2006; received after revision 28 February 2006; accepted 31 March 2006     

Squalene and other unsaturated hydrocarbons,inBryocladia cuspidata

Summary By gas chromatography-electron impact mass spectrometry the red algaBryocladia cuspidata, was found to contain n-pentadecane and n-heptadecane. Gas chromatography-chemical ionization mass spectrometry indicated the presence of squalene as well as a C₂₁ pentaene and a C₂₁ hexaene, tentatively identified as 1,6,9,12,15-heneicosapentaene and 1,6,9,12,15,18-heneicosahexaene.Acknowledgments. This study was supported in part by a grant (AI 04769) from the National Institute of Allergy and Infectious Diseases. S.C. on leave of absence from the University of Catania, thanks the National Research Council of Italy for a Fellowship (1974–1975).     

Die α-Glycerophosphat-Oxydation des Heuschreckenbrustmuskels (Locusta migratoria)

Summary The conditions were studied for the glycerophosphate oxidation by homogenate from locust flight muscle, and the O₂-consumption was measured. Maximal oxidation rates were found with 0.087m glycerophosphate, 8 × 10^–6 m cytochromec, 7 × 10^–6 m DPN and pH 7.5. The production of dihydroxyacetone phosphate is followed by further oxidation steps, as could be shown by estimation of the different fractions of acid-soluble phosphate. Comparative studies were made on different insects and vertebrates. The rate of succinate oxidation by insect muscle was found to be ten times higher than that of vertebrate muscle. The relation of glycerophosphate oxidation to succinate oxidation is quite different in insects and vertebrates, but no difference could be detected between the two types of muscle metabolism of insects: the carbohydrate and the fatutilizing type.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Nematicidal activity of secondary and tertiary alkyl amides and amines

Summary Several C₁₁ to C₁₅ amides and amines that disrupt growth in certain insects showed high nematicidal activity in direct contact tests. Two amides and 9 amines killedPanagrellus at 5–10 ppm. Of these, 1 amide and 3 amines killedMeloidogyne larvae at 20 ppm.Nematology Laboratory.Insect Physiology Laboratory.     

The synthesis of corticosteroids methylated at C21

Zusammenfassung Die Darstellung der beiden epimeren C₂₁-Methylderivate des 9-Fluorprednisolons wird beschrieben. 9-Fluor-21-methyl-1, 4-pregnadien-11, 17, 21B-triol-3, 20-dion-21-azetat ist ein hochwirksames entzündungshemmendes Steroid, vollkommen frei von Nebenwirkungen der Natrium- und Wasserretention des C₂₁-unsubstituierten 9-Fluorprednisolons.     

A reinvestigation of the chemistry of the Dufours gland of the formicine ant,Anoplolepis custodiens

The components of individual Dufours glands excised fromAnoplolepis custodiens workers were analysed by GC-MS. In addition to then-alkanes andn-alkenes previously reported² in these glands, primary alcohols (C₁₉-C₂₂), secondary alcohols (C₂₀-C₂₃), 2-ketones (C₂₀-C₂₃) and possibly carboxylate ethyl esters (C₁₉ and C₂₁) were identified as components of these glands. It seems possible that these high-boiling compounds are used by the workers in laying trails on the hot sandy surfaces of their characteristic habitat and in lining of the inner walls of nests, but no standard compounds have been available to us for any behavioral studies.     

Composition of epicuticular wax of rice,Oryza sativa

Summary The epicuticular wax of rice, varietyRibe, comprised n-alkanes, esters, aldehydes and free alcohols. The nalkanes contained 4 major chain lengths, C₂₇, C₂₉, C₃₁ and C₃₃. Triacontanal and dotriacontanal were the major aldehydes. Octacosanol comprised 89% of the free alcohols. The esters were mainly esters of C₁₆ to C₂₄ acids with C₂₂ to C₃₀ alcohols.This research was supported by the Consiglio Nazionale delle Ricerche, Rome.     

Physical characteristics of the cerebral big prothoracicotropic hormone fromManduca sexta

The prothoracicotropic hormones (PTTHs) are cerebral peptides that control insect postembryonic development by stimulating the prothoracic glands to synthesize ecdysteroids. InManduca sexta, the tobacco hornworm, two classes of PTTH are distinguished by their M_r, small (ca. 7 kDa) and big PTTH (ca. 25–30 kDa). Little is known about the physical nature of the PTTHs and this study takes a first step towards defining characteristics of theManduca big PTTH. The neurohormone has a Stokes radius of 2.59 nm and a sedimentation coefficient of 2.76 S. Based on these data, an M_r of 29,443.7 and anf/f ₀ of 1.27 were calculated. Combined, the physical data revealManduca big PTTH is an asymmetrical acidic homodimeric peptide with intra- and intermolecular disulfide bonds.     

Nest cell lining of the solitary beeHylaeus bisinuatus (Hymenoptera: Colletidae)

The nest cell lining ofHylaeus bisinuatus (Hymenoptera: Colletidae) was shown by high-resolution solidstate [¹³C]NMR to be composed of lipid polymer and protein. The lipid polymer was shown by reduction and subsequent GC/MS analysis to be comprised of -hydroxy fatty acids (C₂₀, C₂₂, C₂₄ and C₂₆) and fatty alcohols (C₁₆ to C₃₀). The protein portion of the lining had a silk-like amino acid composition.     

Über die Synthese einiger Polychlorpolyene und die Atropisomerie der Oktachlorhexatriene

Summary The synthesis of some unsaturated polychloro compounds, starting from the heptachloropropanes, octachloropropane and hexachloropropane, by means of aluminium in ether is described. For four compounds C₆Cl₈, subject to some conversions, the structure of octachlorohexatriene-(1, 3, 5) has been made probable, and the possibility of a special stereoisomerism is discussed.

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Mitteilung «über Polyhalogenverbindungen»; 1. Mitteilung siehe Chem. Ber.80, 206 (1947). Die ausführliche Veröffentlichung dieser Arbeit folgt ebendort.     

Insect hemolymph clotting

The clot’s appearance in different large-bodied insects has been described, but until recently, little was known about any insect clot’s molecular makeup, and few experiments could directly test its function. Techniques have been developed in Drosophila (fruit fly) larvae to identify clotting factors that can then be tested for effects on hemostasis, healing, and immunity. This has revealed unanticipated complexity in the hemostatic mechanisms in these larvae. While the clot’s molecular structure is not yet fully understood, progress is being made, and the loss of clotting factors has been shown to cause subtle immune defects. The few similarities between coagulation in different insect species and life stages, and the current state of knowledge about coagulation in insects are discussed.     

Über physiologische,durch einen Gehalt an verschiedenen Alkaloiden charakterisierte Rassen vonSedum acre L

Summary It is shown thatSedum acre L. collected near Darmstadt contains an alkaloid Sedridin C₈H₁₇ON, while in the literature a sample of the plant collected in Canada showed a content of Sedamin (C₁₄H₂₁ON) and Nicotine. The constitution of Sedridin has been proved and its biogenesis is discussed.