Cyanogenic polymorphism in Eucalyptus polyanthemos Schauer subsp vestita L. Johnson and K. Hill (Myrtaceae)

Plant cyanogenesis, the release of cyanide from endogenous cyanide-containing compounds, is an effective herbivore deterrent. This paper characterises cyanogenesis in the Australian tree Eucalyptus polyanthemos Schauer subsp. vestita L. Johnson and K. Hill for the first time. The cyanogenic glucoside prunasin ((R)-mandelonitrile beta-D-glucoside) was determined to be the only cyanogenic compound in E. polyanthemos foliage. Two natural populations of E. polyanthernos showed quantitative variation in foliar prumasin concentration, varying from zero (i.e. acyanogenic) to 2.07 mg CN g(-1) dry weight in one population and from 0.17 to 1.98 mg CN g(-1) dry weight in the other. No significant difference was detected between the populations with respect to the mean prunasin concentration or the degree of variation in foliar prunasin, despite significant differences in foliar nitrogen. Variation between individuals was also observed with respect to the capacity of foliage to catabolise prunasin to form cyanide. Moreover, variation in this capacity generally correlated with the amount of prunasin in the tissue, suggesting genetic linkage between prunasin and beta-glucosidase. (C) 2002 Elsevier Science Ltd. All rights reserved.

Cyanogenic polimorphysm in brackens, Pteridium arachnoideum and P. caudatum, from the northern Andes

Cyanogenesis in Pteridium caudatum and P. arachnoideum has been examined. Samples of the Andes of South America furnished from 0 to 4.63 mg of prunasin g-1 of frond dry weight (dw) in P. caudatum and from 0 to 103 mg of g-1 dw in P. arachnoideum. In both fern species the continuous distribution of prunasin suggested cyanogenic polymorphism. The frequency of cyanogenic morphs was 84.7% for P. caudatum and 98.6% for P. arachnoideum. Cyanogenic activity was highest in the young crozier and waned rapidly with frond growth. The crozier head was found to yield HCN much more than the stipe.

Estudo químico e das atividades citotóxica, antioxidante e antifúngica de Prunus myrtifolia L. (Urban.) (ROSACEAE)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)