Nakano Miho, Sakamoto Takuma, Itoh Yoshiyuki, Kitano Yoshikazu, Tsukakoshi Kaori, Bono Hidemasa, Tabunoki Hiroko
Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and System Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan.
Department of Science of Biological Production, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
PLoS One. 2025 Jul 23;20(7):e0321438. doi: 10.1371/journal.pone.0321438. eCollection 2025.
Host plant selection may depend on the metabolic system in herbivorous insects. Although oligophagous insects take up specific host plant components, how host plant components and their biological activities are altered through their metabolic systems remains unknown. Here, by examining gene expression of metabolic enzymes and components in the larval frass, we investigated the metabolic ability of Papilio memnon larvae fed with Citrus x paradisi (grapefruit) against host plant components. The gene expression levels of some metabolic enzymes were fluctuated between the larval midgut and the larval fat bodies. Furthermore, the chloroform extract from the larval frass, but not that from grapefruit leaves, inhibited cell viability of human pancreatic cancer cell line, MIA PaCa2. Finally, we identified two chlorophyll catabolites, pheophorbide-a and pyropheophorbide-a, in the larval frass extract. Pyropheophorbide-a reduces cell viability of and induces morphological changes in cells of MIA PaCa2; in addition, pheophorbide-a and pyropheophorbide-a inhibit the aggregation of amyloid β-protein (human, 1-42). Therefore, the chemical structure and biological activity of host plant components are affected by the P. memnon metabolic system. Our findings may contribute to the understanding of the process for producing pheophorbide-a and pyrophephorbide-a from chlorophyll, facilitated by the metabolic ability of P. memnon larvae.
寄主植物的选择可能取决于植食性昆虫的代谢系统。尽管寡食性昆虫摄取特定的寄主植物成分，但寄主植物成分及其生物活性如何通过它们的代谢系统发生改变仍不清楚。在这里，通过检测幼虫粪便中代谢酶和成分的基因表达，我们研究了取食葡萄柚（Citrus x paradisi）的美凤蝶（Papilio memnon）幼虫对寄主植物成分的代谢能力。一些代谢酶的基因表达水平在幼虫中肠和幼虫脂肪体之间波动。此外，幼虫粪便的氯仿提取物而非葡萄柚叶的氯仿提取物抑制了人胰腺癌细胞系MIA PaCa2的细胞活力。最后，我们在幼虫粪便提取物中鉴定出两种叶绿素分解代谢物，脱镁叶绿酸-a和焦脱镁叶绿酸-a。焦脱镁叶绿酸-a降低了MIA PaCa2细胞的活力并诱导其细胞形态发生变化；此外，脱镁叶绿酸-a和焦脱镁叶绿酸-a抑制了淀粉样β蛋白（人，1-42）的聚集。因此，寄主植物成分的化学结构和生物活性受到美凤蝶代谢系统的影响。我们的研究结果可能有助于理解在美凤蝶幼虫代谢能力的促进下从叶绿素产生脱镁叶绿酸-a和焦脱镁叶绿酸-a的过程。
