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Insecticidal Alkaloids against Drosophila melanogaster from Nuphar japonicum DC.

1998; American Chemical Society; Volume: 46; Issue: 3 Linguagem: Inglês

10.1021/jf9701547

1520-5118

Mitsuo Miyazawa, Kimio Yoshio, Yukio Ishikawa, Hiromu Kameoka,

Fungal Plant Pathogen Control

In the course of screening for novel naturally occurring insecticides from Chinese crude drugs, MeOH extract of rhizomes of Nuphar japonicum DC. was found to give an insecticidal activity against larvae of Drosophila melanogaster Meigen. Four alkaloids, (−)-7-epi-deoxynupharidine (1), (−)-castoramine (2), (−)-nupharolutine (3), and (−)-nupharmine (4), were isolated by bioassy-guided fractionation from the extract. Insecticidal activity against larvae of D. melanogaster was demonstrated; 2 and 1 showed LC50 values of 1.00 and 4.33 μmol/mL of diet concentration, respectively. Acute toxicity against adults of D. melanogaster was also found; 1 had the most potent activity, with an LD50 value of 0.86 μg/adult. 1, 2, and 3 caused acetylcholinesterase inhibitions, at 0.5 mmol/L, of 99.6, 65.0, and 59.7%, respectively; however, 4 had only slight activity in this study. Therefore, 1 and 2 were identified as insecticidal compounds from rhizomes of N. japonicum DC. Structure−bioactivity relationship study indicated the importance of the position of the hydroxyl group and the piperizine skeleton for enhanced activity. Keywords: Nuphar japonicum DC.; Nymphaeaceae; rhizomes; Drosophila melanogaster Meigen; sesquiterpene alkaloids; (−)-7-epi-deoxynupharidine; (−)-castoramine; (−)-nupharolutine; (−)-nuphamine; insecticidal activity; structure−activity relationship