Structure and synthesis of atalaphylline and related alkaloids

The structure of atalaphylline, (1; 1,3,5-trihydroxy-4-(γ,γ-dimethylallyl)acridone an alkaloid of Atalantia monophylla, was confirmed by oxidative degradation and by total synthesis. The synthesis involved the preparation of 1,3,5-trihydroxy-9-acridone followed by direct prenylation to give atalaphylline and a monoprenylated product.     

The alkaloids of Aspidosperma cuspa: 16-epi-isositsirikine,a new indole base

Aspidosperma cuspa Blake contains kopsanone, epikopsanol, kopsanol, aspidodasycarpine and 16-epi-isositsirikine. Both chemical and botanical data support the allocation of this species to a unique series within the genus.     

Alkaloid biosynthesis in Croton linearis

The ability of Croton linearis to form crotonosine from linearisine has been demonstrated; the extent of this conversion appears to vary according to the sex of the plant.     

Experience influences gustatory responsiveness to pyrrolizidine alkaloids in the polyphagous caterpillar,Estigmene acrea

Electrophysiological recordings from taste sensilla of the caterpillar Estigmene acrea with the pyrrolizidine alkaloid, seneciphylline N-oxide, demonstrated that prior feeding on plants with pyrrolizidine alkaloids caused an increase in responsiveness of the PA-sensitive cells in two sensilla, relative to feeding on plants without such chemicals. Rearing on synthetic diet without pyrrolizidine alkaloids for up to seven generations caused a continuous decline in responsiveness, that could be reversed by experience with powdered Crotalaria pumila in the diet or by pure pyrrolizidine alkaloid, monocrotaline, in the diet. Response to the cardiac glycoside, ouabain, that stimulates one of the two pyrrolizidine alkaloid-sensitive cells, showed a similar decline. Pyrrolizidine alkaloids had no measurable effect on growth and development. Responses in all other taste cells were unaffected. The data are discussed in relation to the possible adaptive significance and the possible mechanisms involved.R.F. Chapman has died since this article was written     

Oriciopsin,a new ring-D cleaved tetranortriterpenoid,and flindersiamine from Oriciopsis glaberrima

A novel ring-D cleaved tetranortriterpenoid, oriciopsin and flindersiamine have been isolated from the whole plant extracts of Oriciopsis glaberrima. The structure of the new limonoid was determined from its ¹H NMR and ¹³C NMR spectra and by mass spectrometry.     

Effects of histidine decarboxylase inhibitors on the production of an aberrant alkaloid in Dolichothele sphaerica

Attempts at regulating the production of the aberrant alkaloid 4(5)-[N-isovalerylaminomethyl]imidazole were initiated by pretreating Dolichothele sphaerica plants with Known histidine decarboxylase inhibitors. Larger quantities of the unnatural precursor, 4(5)-aminomethylimidazole, were converted to the corresponding aberrant alkaloid when the cactus plants were pretreated with α-methylhistidine or α-hydrazinohistidine. These compounds appeared to be successful in inhibiting the formation of histamine from histidine, thereby limiting the availability of the natural precursor.     

The structure of alkaloid Y from Schefferomitra subaequalis

Alkaloid Y has been shown by direct comparison of samples to be identical with Aristolactam BII, the lactam of 10-amino-3,4-dimethoxyphenanthrene-1-carboxylic acid.