. "pyrroloquinoline quinone" . . "Pyrroloquinoline quinone" . . "pyrroloquinoline" . . . . . . . . . . "Pyrrolo-quinoline quinon" . "Pyrroloquinoline quinone" . . . . "PQQ" . . . . "4,5-Dioxo-4,5-dihydro-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid" . . .