RESUMEN
Six new highly oxygenated grayanane diterpenoids, neopierisoids G-L, 1-6, together with 10 known related compounds, 7-16, were identified from the flowers of the poisonous plant Pieris japonica. The structures were elucidated on the basis of comprehensive NMR spectroscopy and mass analysis. The relative configurations of 1-6 were elucidated by analysis of ROESY spectra and comparison of NMR data with the analogues. The absolute configurations of 1-6 were established by the X-ray diffraction analysis of 1 and comparison of the CD spectra of 1-6. Compared with the skeleton of the normal grayanane diterpenoids, compounds 1-6 shared an unusual seco A ring moiety. The antifeedant activities of compounds 1-16 against Pieris brassicae were evaluated by using a dual-choice bioassay, and compounds 1-10 with a normal grayanane skeleton showed potent antifeedant activity against P. brassicae. The structure-activity relationships of antifeedant activities of 1-16 against P. brassicae are discussed.
Asunto(s)
Mariposas Diurnas/efectos de los fármacos , Diterpenos/química , Diterpenos/farmacología , Ericaceae/química , Extractos Vegetales/química , Extractos Vegetales/farmacología , Animales , Mariposas Diurnas/fisiología , Conducta Alimentaria/efectos de los fármacos , Flores/química , Estructura Molecular , Relación Estructura-ActividadRESUMEN
Two new chlorinated multiacylated 3,4-seco-grayanane diterpenoids, neopierisoids A and B (1 and 2), were isolated from flowers of the poisonous plant Pieris japonica and were identified from spectroscopic analysis and X-ray diffraction data. Both compounds showed obvious antifeedant activity against Pieris brassicae with an EC50 of 10.07 µg/cm(2) for 1 and 5.33 µg/cm(2) for 2, indications of toxic properties. Chlorinated 3,4-seco-grayanane diterpenoids in P. japonica may play a defensive role against herbivores.