Abstract
Pyrroloquinoline quinone (PQQ) is a water-soluble, vitamin-like compound discovered in bacteria as the third redox coenzyme. PQQ is reportedly present especially in natto (fermented soybeans) and tea, and the compound has been reported to have physiological activities such as antioxidant effect and nerve protection. However, the distribution and physiological function of PQQ have been still unclear, probably due to limitation of its analytical method. In this study, we tried to develop a LC-MS/MS method of PQQ. By using a reverse-phase column with an ion-pair reagent (dibutylammonium acetate), PQQ standard could be analyzed at the sensitive order of picogram level. Furthermore, since PQQ could easily react with amino acids including Arg, Gln, Gly, His, Lys, and Phe, a LC-MS/MS method for analysis of PQQ-amino acid adducts was also developed. The developed method could be useful for not only investigation of distribution of PQQ and PQQ-amino acid adducts in nature, but also evaluation of their absorption, metabolism and physiological activities in vivo.
