Two new quinolinone alkaloids and 13 known compounds were isolated from chestnut (Castanea crenata Sieb) honey. Two new compounds were determined to be 3-dihydro-spiro[2(1H),3'(1'H)-diquinoline]-3',4,4'-trione (spirodiquinolinone) and 3-(2'-piperidine)-kynurenic acid. In addition, 2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-one was identified for the first time from nature. In addition, 2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-one was newly identified from chestnut honey, although this compound has been synthesized before. The structures were determined by the NMR and electrospray ionization-mass spectroscopy (ESI-MS). Three compounds were qualified and quantitated in chestnut honey by selective multiple reaction monitoring (MRM) detection of LC-ESI-MS using the isolated compounds as external standards.
Keywords: Castanea crenata; alkaloid; chestnut honey; kynurenic acid; quinolinone.