RESUMO
The Japanese beetle (JB), Popillia japonica, exhibits rapid paralysis after consuming flower petals of zonal geranium, Pelargonium x hortorum. Activity-guided fractionations were conducted with polar flower petal extracts from P. x hortorum cv. Nittany Lion Red, which led to the isolation of a paralysis-inducing compound. High-resolution-MS and NMR ((1)H, (13)C, COSY, heteronuclear sequential quantum correlation, heteronuclear multiple bond correlation) analysis identified the paralytic compound as quisqualic acid (C(5)H(7)N(3)O(5)), a known but rare agonist of excitatory amino acid receptors. Optical rotation measurements and chiral HPLC analysis determined an L-configuration. Geranium-derived and synthetic L-quisqualic acid demonstrated the same positive paralytic dose-response. Isolation of a neurotoxic, excitatory amino acid from zonal geranium establishes the phytochemical basis for induced paralysis of the JB, which had remained uncharacterized since the phenomenon was first described in 1920.
Assuntos
Besouros/efeitos dos fármacos , Aminoácidos Excitatórios/toxicidade , Flores/química , Geranium/química , Ácido Quisquálico/toxicidade , Animais , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Agonistas de Aminoácidos Excitatórios/química , Agonistas de Aminoácidos Excitatórios/toxicidade , Aminoácidos Excitatórios/química , Aminoácidos Excitatórios/isolamento & purificação , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Ácido Quisquálico/química , Ácido Quisquálico/isolamento & purificação , EstereoisomerismoRESUMO
A new acylglycosyl sterol (4) was isolated from the MeOH extract of Quisqualis Fructus together with four known compounds. On the basis of spectroscopic data, their structures were elucidated as clerosterol (1), betulinic acid (2), methylursolate (3), 3-O-[6'-O-(8Z-octadecenoyl)-beta-D-glucopyranosyl]-clerosterol (4) and alpha-xylofuranosyluracil (5).
