| abstract |
The present invention relates to a compound represented by the formula (A) or (B), or a salt thereof capable of improving a red color of pyrroloquinoline quinone (PQQ) and obtaining functions of original PQQ, and to a method of efficiently manufacturing the compound. n n n n n n n n n n wherein R is an alkyl group, a hydroxyalkyl group, a dihydroxyalkyl group, or an alkoxyalkyl group. |