H. W. A. Biessels

Quantitative determination of the juvenile hormones in the haemolymph of Locusta migratoria during normal development and after implantation of corpora allata

Simultaneous quantitative determination of the three naturally occurring juvenile hormones in insects (JH-I, JH-II and JH-III) was performed on haemolymph samples of both normally developing locusts and locusts implanted with active corpora allata, using capillary gas chromatography with electron capture detection. In fourth instar female larvae, 24–48 hr after the third ecdysis, as well as in adult females, 18 days after the imaginal ecdysis, only JH-III was detected. In fifth instar female larvae JH-III was present in very low concentrations, if at all. After implantation of four pairs of corpora allata taken from young fourth instar female larvae or one pair or corpora allata taken from adult females into fifth instar female larvae 0–24 hr after ecdysis, an elevation of the JH-III titre was observed. Neither JH-I nor JH-II could be detected. The amount of JH-III, already elevated 2 hr after implantation, remained high for several days in comparison to that of control insects. On the third day after the subsequent moult the JH-III level was comparable to that of normally developing fifth instar larvae. Factors involved in the achievement of the haemolymph JH-titre are discussed.

Triterpenes of Prunus serotina and P. lusitanica

Abstract The leaves of Prunus serotina and P. lusitanica contain a new triterpene, 2α,3α-dihydroxyurs-12-en-28-oic acid, isolated in form of its methyl ester. Other triterpenes present in these species are ursolic acid and ursol aldehyde. P. lusitanica also yields friedeline.

Glass capillary column gas chromatographic method for simultaneous quantitative determination of insect juvenile hormones at the picogram level: A comparitive study of various halogenated derivatives

A gas chromatographic method has been developed for the simultaneous quantitative determination of the juvenile hormones I, II and III (JH-I, JH-II and JH-III) in insects. After extraction and partial purification the hormones are converted into their 10-heptafluorobutyryl-11-methoxy derivatives and analysed as such by gas chromatography. The gas chromatographic system consists of an all-glass moving needle injector, a glass capillary column and an electron-capture detector. JH-I, JH-II and JH-III can be determined simultaneously in amounts as low as 0.5, 0.3 and 0.2 ng, respectively, per sample. The 10-heptafluorobutyryl-11-methoxy derivatives were selected after an extensive comparative study of potentially suitable halogenated derivatives. Geometrical stereoisomers of the juvenile hormones are used as internal standards.

Constituents of Papaver bracteatum: O-methyl-α-thebaol and 10-n-nonacosanol. Lanthanide-induced chemical shifts in 1H NMR and 13C NMR☆

Abstract Two non-alkaloidal constituents were identified in Papaver bracteatum: O-methyl-α-thebaol and 10-n-nonacosanol. O-Methyl-α-thebaol is a new natural compound. The presence of isothebaine is confirmed. Lanthanide-induced chemical shifts can be used for the assignments of the 13C NMR chemical shifts of isothebaine and phenanthrenes. The use of lanthanide-induced chemical shifts in the identification of methoxyl resonances in 1H NMR is discussed.

A new rearrangement product of thebaine, isolated from Papaver bracteatum Lindl. Structural assignment of thebaine N-oxides

From Papaver bracteatum an unusual alkaloid is isolated: 6,7,8,9,10,14-hexadehydro-4,5-epoxy-3,6-di-methoxy-17-methylthebinan (1). This alkaloid is also obtained from the mixture of rearrangement products of one of the thebaine N-oxides. The structure of another constituent of the latter mixture is deduced to be 6,7,8,9,10,14-hexadehydro-3,6-dimethoxythebinan-4-ol (15). The presence of both thebaine N-oxides in Papaver bracteatum is confirmed, and their structures are revised on chemical and spectroscopic grounds.

FISSION OF AS-AS BONDS IN ELEMENTAL ARSENIC BY ALKALI METALS IN LIQUID AMMONIA. A ROUTE TO MONOALKYL ARSINES

Abstract Addition of two mol equivalents of t-butyl alcohol to a mixture of powdered arsenic and three mol equivalents of lithium in liquid ammonia gives a suspension of lithium arsenide LiAsH2. Subsequent addition of a large excess of t-butyl alcohol and n-octyl iodide at very low temperatures affords n-octyl arsine in -65% yield.