Rapid detection and structural characterization of methysticin metabolites generated from rat and human liver microsomes and hepatocytes using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry.

RATIONALE: Methysticin is a naturally occurring ingredient isolated from Piper methysticum Forst. The metabolic profile of methysticin is unknown. The goal of this study was to elucidate the metabolism of methysticin using rat and human liver microsomes and hepatocytes. METHODS: The incubation samples were analyzed using ultra-high-performance liquid chromatography coupled with quadrupole/orbitrap high-resolution mass spectrometry (UHPLC-HRMS). The structures of the metabolites were characterized based on the elemental composition, exact mass, and product ions. RESULTS: A total of 10 metabolites were detected and identified. Among these metabolites, M4 (ring opening of 1,3-benzodioxole) was the predominant metabolite in rat and human liver microsomes. M4 and its glucuronide conjugate (M2) were the major metabolites in rat and human hepatocytes. The metabolic pathways of methysticin are summarized as follows: (a) oxidative ring opening of 1,3-benzodioxole forms the catechol derivative (M4), which subsequently undergoes glucuronidation (M1 and M2), methylation (M8), and sulfation (M7). (b) Demethylation to yield desmethyl methysticin (M6), followed by glucuronidation (M3 and M5). (c) Hydroxylation (M9 and M10). CONCLUSIONS: For the first time, this study provides new information on the in vitro metabolic profiles of methysticin, which facilitates an understanding of the disposition of this bioactive ingredient.

Publisher Correction: Juvenile Hormone Epoxide Hydrolase: a Promising Target for Hemipteran Pest Management.

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Juvenile Hormone Epoxide Hydrolase: a Promising Target for Hemipteran Pest Management.

Juvenile hormone epoxide hydrolase (JHEH) has attracted great interest because of its critical role in the regulation of juvenile hormone (JH) in insects. In this study, one JHEH gene from Apolygus lucorum (AlucJHEH) was characterized in terms of deduced amino acid sequence, phylogeny, homology modeling and docking simulation. The results reveals a conserved catalytic mechanism of AlucJHEH toward JH. Our study also demonstrates that the mRNA of AlucJHEH gene was detectable in head, thorax and abdomen from all life stages. To functionally characterize the AlucJHEH gene, three fragments of double-stranded RNAs (dsRNAs) were designed to target different regions of the sequence. Injection of 3rd nymphs with dsRNA fragments successfully knocked down the target gene expression, and a significantly decreased survival rate was observed, together with a molting block, These findings confirm the important regulatory roles of AlucJHEH in A. lucorum and indicate this gene as a promising target for future hemipterans pest control.