Fluorescence Localization and Comparative Ultrastructural Study of Periplocoside NW from Periploca sepium Bunge in the Midgut of the Oriental Amyworm, Mythimna separata Walker (Lepidoptera: Noctuidae)

Abstract

Periplocoside NW (PSNW) is a novel insecticidal compound isolated from the root bark of Periploca sepium Bunge and has potent stomach toxicity against some insect pests. Previous studies showed that the Mythimna separata larva is sensitive to PSNW, but the Agrotis ispilon larva is insensitive. In this study, preliminary target localization on the midgut of M. separata larvae was conducted via a fluorescence labeling technique. A comparative ultrastructural study on the effects of PSNW on the midguts of M. separata and A. ispilon larvae was performed. Symptom observation results showed that typical stomach toxicity was induced by PSNW in M. separata larvae. Fluorescence localization results showed that PSNW binds to the midgut cells of M. separata larvae. Ultrastructure observations showed destruction of the microvilli, organelle, and cytomembrane in the midgut cells of M. separata larvae, whereas no obvious changes were observed in midgut cells of A. ispilon larvae. These results were consistent with the insecticidal activity of PSNW. Therefore, PSNW might act on the midgut tissues of the insects, and one or more binding sites of PSNW may exist in M. separata larvae midgut cell cytomembranes.

Genus Periploca (Apocynaceae): A Review of Its Classification, Phytochemistry, Biological Activities and Toxicology

“…Periplocoside X ( 80 ) was confirmed to contain a 3,7-dioxy-heptulose group [46] according to its NMR spectroscopic data and by referring to periplocoside A. In Wu and co-workers’ search for insecticidal compounds from P. supium , they discovered two new glycosides, namely periplocoside P ( 81 ) and periplocoside NW ( 82 ) [47,48]. Compounds 83 – 86 are all newly found pregnane glycosides in recent ten years [18,40,43] which are different from 47 – 82 in terms of the length and constitution of the saccharide chain at C-3 or C-20.…”

Comparative Proteomic Analysis of the Effect of Periplocoside P from Periploca sepium on Brush Border Membrane Vesicles in Midgut Epithelium of Mythimna separata Larvae

“…Periplocoside P (PSP), a novel compound isolated from P. sepium has high insecticidal activity (LC 50 = 110 mg·L −1 ) against Mythimna separata [ 13 ]. To determine the specific mechanism of action of periplocosides against M. separata larvae, we performed systematic research and showed that putative targets of periplocosides may exist in the brush border membrane vesicles (BBMVs) of the larvae midgut [ 13 , 14 ]. Nevertheless, the specific site of action of periplocoside compounds remains unknown.…”

Isolation of the Binding Protein of Periplocoside E from BBMVs in Midgut of the Oriental Amyworm Mythimna separata Walker (Lepidoptera: Noctuidae) through Affinity Chromatography

“…These compounds possess a special mode of action that involves obvious swelling of the abdomen, and, thus far, no other modes of insecticidal action have been recorded [ 8 ]. Fluorescence localization analysis indicated that periplocoside NW (PSNW) can bind to the midgut cells of Mythimna separata larvae [ 9 ]. Ultrastructural observations showed that microvilli, organelle, and cytomembrane are destructed in the midgut cells of M. separata larvae [ 10 ].…”