RESUMO
Bioactivity-directed separation of a foliage extract from the New Zealand shrub Pseudowintera axillaris led to a compound with fungicidal activity against the plant pathogen Phytophthora infestans. This was identified as a new sesquiterpene dialdehyde cinnamate named paxidal. Two 6-hydroxy derivatives were present at lower levels in the extract. A further nine derivatives were synthesized from these natural products for a structure-activity study against a range of important food crop pathogens. The cinnamate group was important for fungicidal effects, and protection of the dialdehyde as a dimethyl acetal gave more potent, broader spectrum activity.
Assuntos
Cinamatos/análise , Fungicidas Industriais/análise , Pseudowintera/química , Sesquiterpenos/análise , Cinamatos/química , Cinamatos/farmacologia , Fungicidas Industriais/farmacologia , Modelos Moleculares , Nova Zelândia , Phytophthora/efeitos dos fármacos , Extratos Vegetais/farmacologia , Folhas de Planta/química , Sesquiterpenos/química , Sesquiterpenos/farmacologiaRESUMO
NMR studies have shown that seven new sesquiterpenoids, 3, 4, 5a, and 7-10, isolated from dried samples of the New Zealand liverwort Lepidolaena hodgsoniae have the same substituted cyclopentapyran ring system as the previously described insecticidal sesquiterpene diene hodgsonox (1), which has been reported only from this plant. In all but one compound, 10, the 1,1-disubstituted double bond of hodgsonox has migrated into an endocyclic position, but only two, 5a and 9, have the double bonds in conjugation. These seven new compounds represent a variety of different oxidation levels. Two of the new derivatives, 9 and 10, were isolated only from an aged sample and are presumably artifacts. The only other terpenoid isolated in significant quantity was (7R,10R)-calamenene (2).
Assuntos
Hepatófitas/química , Inseticidas/isolamento & purificação , Plantas Medicinais/química , Piranos/isolamento & purificação , Sesquiterpenos/isolamento & purificação , Compostos de Vinila/isolamento & purificação , Inseticidas/química , Inseticidas/farmacologia , Conformação Molecular , Estrutura Molecular , Nova Zelândia , Ressonância Magnética Nuclear Biomolecular , Sesquiterpenos Policíclicos , Piranos/química , Piranos/farmacologia , Sesquiterpenos/química , Sesquiterpenos/farmacologia , Estereoisomerismo , Terpenos/química , Terpenos/isolamento & purificação , Compostos de Vinila/química , Compostos de Vinila/farmacologiaRESUMO
The incorporation of [1-13C] labelled glucose into hodgsonox, a sesquiterpene epoxide with a unique, doubly allylic ether functionality has been studied in axenic cultures of the liverwort Lepidolaena hodgsoniae. Quantitative 13C NMR spectroscopic analysis showed that the isoprene units are derived exclusively from the methylerythritol phosphate pathway.
Assuntos
Hepatófitas/metabolismo , Sesquiterpenos/metabolismo , Isótopos de Carbono , Técnicas de Cultura/métodos , Glucose/química , Glucose/metabolismo , Hepatófitas/crescimento & desenvolvimento , Nova Zelândia , Ressonância Magnética Nuclear Biomolecular/métodos , Sesquiterpenos/química , Fosfatos Açúcares/química , Fosfatos Açúcares/metabolismoRESUMO
A bioactivity-directed investigation of an extract of the New Zealand clubmoss, Lycopodium varium, collected on subantarctic Campbell Island, has led to the isolation of the alkaloid huperzine A (1) as the major antifeedant and insecticidal component. Huperzine A showed insecticidal activity against the Australian carpet beetle, Anthrenocerus australis (LD(50) = 110 ppm), the Australian sheep blowfly, Lucilia cuprina (LD(50) = 2380 ppm), and the webbing clothes moth, Tineola bisselliella (LD(50) = 630 ppm). Feeding by A. australis was reduced by 97% at 63 ppm.
