Pyridoxamine (PM) could competitively protect amino groups in proteins from glycating agents. Although PM is expected to react with saccharides, available data therein are limited. In this study, a novel hydrophilic compound from a model reaction solution containing PM and xylose was isolated and identified as (6aR,9aR)-1,8,9-trihydroxy-2,6a-dimethyl-6a,9a-dihydrocyclopenta[5,6]pyrano[3,4-c]pyridin-7(5H)-one with a tricyclic structure. This compound appeared to be specifically formed from pentose via 1-deoxypentosone, and its formation was facilitated over a pH range of 7.0-8.0. After heating at 90 °C for 5 h in a reaction mixture containing 30 mM PM and pentose at pH 7.4, this compound was obtained at a yield of 6.95-8.53 mM.