Metabolic profile study of 7, 8-dihydroxyflavone in monkey plasma using high performance liquid chromatography-tandem mass spectrometry

- Quantification of 7, 8-DHF and methylated metabolites in monkey plasma.
- The method did not require conjugated standards, and showed two pretreatments to obtain free/total 7, 8-DHF and methylated 7, 8-DHF.
- The main position of methylation for 7, 8-DHF in mammal was identified for the first time.

7, 8-Dihydroxyflavone, as a high-affinity tropomyosin-receptor-kinase B agonist, can mimic the physiological actions of brain-derived neurotrophic factor and exert a variety of neurological actions in numerous models including Parkinsońs disease, depression, learning and memory. Nonetheless, a limited number of studies have been focused on its metabolism in mammal and no methodology has been reported for the determination of 7, 8-DHF and its metabolites. Herein, we developed a rapid, sensitive and accurate method using high performance liquid chromatography-tandem mass spectroscopy for the determination of 7, 8-DHF and its metabolites in monkey plasma. The lower limits of quantification for analytes were 0.4-2.0 ng mL−1. The intra-day and inter-day precisions (relative standard deviation, %) of analytes were within 11.83%, and the accuracy (relative error, %) ranged from −6.86 to 14.00%. The mean extraction recoveries for analytes were more than 89.14%. This validated method was successfully applied to the metabolic profile study of 7, 8-DHF in monkey plasma. The results indicated that 7, 8-DHF undergoes methylation, glucuronidation and/or sulfation, and the conjugated forms are the main metabolites in monkey plasma. We further demonstrated that methylated 7, 8-DHF can be also conjugated with glucuronidation/sulfation, and the methylation occurs mainly in the 8 position.