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.

Kaliziri extract upregulates tyrosinase, TRP-1, TRP-2 and MITF expression in murine B16 melanoma cells.

BACKGROUND: Kaliziri extract (KZE) is a traditional Uyghur medicine (TUM), used by traditional hospitals in China as an injection for treatment of vitiligo for more than 30 years. Clinical application has shown that this medicine has obvious therapeutic effects. However, its phytochemical analysis and mechanism have not been examined. METHODS: KZE was extracted from seeds of Kaliziri [Vernonia anthelmintica (L.) Willd.] in ethanol-water (80:20, v/v), its components were identified by LC-MS/MS, and the signaling pathway of melanin synthesis in KZE treated murine B16 melanoma cells was examined by western blotting. RESULTS: Liquid chromatography-mass spectrometry analysis confirmed that the main components of KZE are flavonoids. KZE increased the tyrosinase activity and melanin content in a dose-dependent manner at concentrations of 5-40 µg/ml, and treatment with 20 µg/ml of KZE enhanced the expression of tyrosinase in B16 cells in a time-dependent manner. CONCLUSIONS: KZE induced melanogenesis by increasing the expression of TYR, TRP-1, TRP-2 and MITF in B16 cells.