Inhibition of Lipopolysaccharide‐Induced Nitric Oxide Production by Antofine and Its Analogues in RAW 264.7 Macrophage Cells

Based on the anti‐inflammatory activity of phenanthroindolizidine alkaloids, the inhibitory effect of antofine and its analogues on lipopolysaccharide (LPS)‐induced nitric oxide (NO) production was examined, and structure–activity relationships are discussed. Antofine and several analogues suppressed NO production in LPS‐stimulated RAW 264.7 cells. The MeO group at C(2), and the bulkiness of the substituents at C(3) and C(6) in the phenanthrene ring might be critical for this effect. Besides, regulation of iNOS expression might be involved in the inhibitory effect of antofine on LPS‐induced NO production in macrophage cells.     

Responses of male California red scale to sex pheromone isomers

The California red scale, Aonidiella aurantii (Maskell), sex pheromone components were previously identified as two independently attractive norsesquiterpenes. The four possible optical isomers of one and the four possible geometric and optical isomers of the other were synthesized and tested for male California red scale attractiveness in field tests and greenhouse bioassays. The results showed that there was enantiomeric and geometric specificity and only 1 isomer of each component was significantly more active than the others. The active isomers were (3S,6R)-3-methyl-6-isopropenyl-9 decen-1-yl acetate and (3Z,6R)-3-methyl-6-isopropenyl-3,9-decadien-1-yl acetate. The presence of other isomers, including the synthetic analogue 3-methyl-6-isopropylidene-9-decen-1-yl acetate, had no effect on trap catch.     

No inhibitory effect on receptor neurone activity by sulphur analogues of the sex pheromone component (Z)-5-decenyl acetate in the turnip moth, Agrofis segetum (Lepidoptera: Noctuidae)

Abstract. Olfactory responses from the entire antenna and from single antennal sensilla of the male turnip moth, Agrotis segetum (Lepidoptea: Noctuidae Schiff.), were recorded after stimulation of the antenna with the sex pheromone component, (Z)-5-decenyl acetate (Z5-10:OAc), and three sulphur analogues of this compound. Adaptation of olfactory receptor neurones tuned to Z5-10:OAc was investigated after pre-exposure of these receptor neurones to the key stimulus and to the three sulphur analogues. Both electro-antennographic and single sensillum recordings revealed that the sulphur analogues had a significantly decreased effect compared to the natural stimulus. The pre-exposure experiments demonstrated that no further inhibition of neural activity was observed than could be expected from receptor neurone adaptation. Earlier reports, describing sulphur analogues as possible hyperagonists acting on moth pheromone receptor neurones, are not supported by the present study.     

Homocholine and Short-Chain N-Alkyl Choline Analogues as Substrates for Torpedo Choline Acetyltransferase

Abstract: The kinetic parameters, K_m and V_max, for the acetylation of choline and several close analogues were determined by using (a) purified choline acetyltransferase and (b) a hypotonically lysed synaptosomal extract prepared from the electric organ of Torpedo marmorata. Whereas the K_m for choline was similar in both cases (0.51 and 0.42 m m ), the crude enzyme showed a three- to fivefold greater affinity for its analogues than the purified enzyme, the activity decreasing rapidly with increased N -alkyl substitution. Homocholine was a poor substrate, but was clearly acetylated by both preparations. The effect of salt on analogue acetylation by the crude enzyme was studied by increasing NaCl concentration from zero to 150 m m . There was an increase in both K_m and V_max for all substrates; choline, N,N,N -dimethylmonoethylaminoethanol, -monomethyldiethylaminoethanol and -dimethylmonobutylaminoethanol showed the greatest changes, whilst N,N,N -triethylaminoethanol and -dimethylmonopropylaminoethanol and homocholine were much less affected. However, in all cases, the kinetic parameter V_max / K_m remained unchanged. The maximal velocities of the different substrates varied more under conditions of high than of low salt. Sodium chloride up to 300 m m had no effect on the amount of enzyme which was bound to membranes in the synaptosomal extract. It is concluded that choline acetyltransferase has a high degree of substrate specificity, which is slightly altered by purification. The effects of salt cannot be explained as a consequence of nonspecific ionic association with membranes.     

Inhibition of flowering by hexahydrofluorene-9-carboxylic acids related to allogibberic acid

1,2,3,4,4a,9a-hexahydrofluorene-9-carboxylic acid isomers have been prepared by reduction of fluorene-9-carboxylic acid. Hexahydrofluorene-9-carboxylic acid (5) produce inhibition of flowering and vegetative frond development in Lemna perpusilla 6746 similar to that observed with allogibberic acid. The stereochemical requirements for this type of biological activity in allogibberic acids and hexahydrofluorene-9-carboxylic acids are considered.