Charles F. Cohen

Ecdysones and Analogs: Effects on Development and Reproduction of Insects

Ingestion of certain synthetic ecdysone analogs inhibited larval growth and development in several species of insects, whereas 20-hydroxyecdysone was inactive or considerably less active. Natural 20-hydroxyecdysone and ponasterone A, and a synthetic ecdysone analog inhibited ovarian maturation and egg production in the adult housefly. These effects appeared to be related to hormonal activity.

Sensitivity of Visual Receptors of Carotenoid-Depleted Flies: A Vitamin A Deficiency in an Invertebrate

House flies (Musca domestica) raised under sterile conditions on a diet lacking carotenoids and retinol (vitamin A) have visual receptor sensitivities —as assessed electroretinographically—which average more than 2 log units below normal, both in the near ultraviolet (340 m�) and visible (500 m�) regions of the spectrum. Loss of sensitivity can be prevented by the addition of β-carotene to the larval food. Flies reared for several generations on a carotenoid-free diet, but under conditions where the adults are not kept sterile, do not show a further loss of sensitivity. It is suggested that carotenoid stored in the egg prevents complete blindness in the first generation, and that microorganisms can supply small amounts of carotenoid and thereby prevent complete blindness in the second and successive generations.

14α-methyl-5α-ergost-8-en-3β-ol and 14α-methyl-5α-ergosta-8,24(28)-dien-3β-ol from triparanol-treated Chlorella emersonii☆

Abstract From triparanol-treated cultures of Chlorella emersonii , two new sterols, 14α-methyl-5α-ergost 8-en-3β-ol and 14α-methyl-5α-ergosta-8,24(28)-dien-3β-ol were isolated and identified. These two sterols represent 7 and 3 per cent, respectively, of the total sterols from treated cultures, though only the former was discernible in gas chromatograms of non-treated cultures. The triparanol-treated cultures also contained the naturally occurring sterols, ▵ 7 -ergostenol, ▵ 7 -chondrillastenol and chondrillasterol, but at concentrations less than that present in control cultures. The synthesis of 14α-methyl-5α-ergost-8-en-3β-ol is described.

Photoflashes: A Potential New Tool for Control of Insect Populations

Imported cabbageworms, Pieris rapae (L.), were reared in cans exposed to light from fluorescent lamps for 10 hours daily. When larvae were exposed to daily electronic photoflashes scheduled 3 to 4 hours after the fluorescent lamp was turned off, pupae failed to diapause. Effective wavelengths are lower than those controlling photoperiodism in plants. The effective energies are about 1 joule per square centimeter.

Nonsteroidal secondary and tertiary amines: Inhibitors of insect development and metamorphosis and Δ24-sterol reductase system of tobacco hornwormreductase system of tobacco hornworm

Several new branched and straight chain secondary and tertiary amines were shown to have inhibitive effects upon development and metamorphosis and the Δ24-sterol reductase system in larvae of the tobacco hornworm similar to those previously observed with a number of azasteroids. Certain of the amines which are related structurally to compounds with juvenile hormone activity in insects also blocked development and metamorphosis in three other species of insects. These compounds are lethal or inhibit development in all larval stages and thus differ in action from compounds with juvenile hormone activity where the principal effect is to block the penultimate or ultimate molt.

Two novel sterols from inhibited Chlorella ellipsoidea

Abstract The biosynthesis of the normal Δ 5 -sterols of Chlorella ellipsoidea was completely inhibited by AY-9944 at a concentration of 4 ppm in the medium. From AY-9944-inhibited Chlorella ellipsoidea , two sterols previously unidentified from biological material, namely, (24 S )-5 a -ergosta-8,14-dien-3β-ol and (24 S )-5 a -stigmasta-8,14-dien-3β-ol were isolated. They represented 26 and 43%, respectively, of the total sterols isolated from treated cultures. If these sterols are normal intermediates in the biosynthetic sequence for sterols in this alga, then AY-9944 appears to inhibit the reduction of the 14(15) double bond. The syntheses of both sterols are described.

Synthesis of analogs of α-ecdysone. A simplified synthesis of 2β,3β,14α-trihydroxy-7-en-6-one-5β-steroids

Abstract Several compounds that contain the steroid nucleus of α-ecdysone were synthesized, namely; 2β,3β,14α-trihydroxy-5β-cholest-7-en-6-one, 2β,3β,14α-trihydroxy-27-nor-5β-cholest-7-en-6-one, 2β,3β,14α-trihydroxy-(24R)-5β-ergost-7-en-6-one, and 2β,3β,14α-trihydroxy-(24R)-5β-stigmast-7-en-6-one, and their mass spectral data and that of their 5α-isomers are presented. Also 11 derivatives of the 2β,3β,14α-trihydroxy-5β-cholest-7-en-6-one were prepared as were additional compounds with specific structural features that would help to better define the relationship of structure to biological activity in insects.

Brassicasterol and 22,23-dihydrobrassicasterol from ergosterol via i-ergosterol

Abstract Since the method most commonly employed for the preparation of brassicasterol gave brassicasterol acetate in an overall 4% to 5% yield, an alternate method for the preparation of gram quantities of brassicasterol and 22,23-dihydrobrassicasterol was investigated. The partial syntheses of brassicasterol and 22,23-dihydrobrassicasterol are described. Brassicasterol and 22,23-dihydrobrassicasterol were obtained in an overall yield of 25% and 20%, respectively, from ergosterol via i -ergosterol.

Synthesis and biological activity of 5β-hydroxy analogs of α-ecdysone

Abstract Two 5β-hydroxy analogs of α-ecdysone — 2β,3β,5β,14α-tetrahydroxy-5β-cholest-7-en-6-one and 3β,5β,14α-trihydroxy-5β-cholest-7-en-6-one were synthesized and their mass spectra obtained. The biological activity of these two compounds was compared with that of the most active synthetic ecdysone analog previously tested in insects, and the presence of the 5β-hydroxyl group generally enhanced the inhibitive activity.

Synthesis of Δ7-coprostenol and its identity with the sterol foemed by the reduction of 7-dehydrocholesterol by intestinal microorganisms

Abstract A method for the preparation of Δ 7 -coprostenol and the confirmation of its identity as the sterol formed by the reduction of 7-dehydrocholesterol by intestinal microorganisms has been presented. The Δ 8 (14)- and Δ 14 -coprostenols were also prepared. Comparative gas-liquid Chromatographic and thin-layer Chromatographic data on the 5α and 5β Δ 7 -, Δ 8 (14)- and Δ 14 -cholestenols and their acetates are also given.