Fig. 1.

The intracellular metabolism of endogenous and exogenous D-ribose. Exogenous D-ribose primarily derives from food or drug, while endogenous D-ribose is mainly biosynthesized from glucose through the pentose phosphate pathway (PPP). The reversible transformation between D-ribose and R-5-P can be catalyzed by RBKS. When the intracellular D-ribose level increases, some of them may enter into the nonoxidative stage of PPP, ultimately generating F-6-P and G-3-P to produce ATP through anaerobic glycolysis or aerobic glucose oxidation; the other may be catalyzed to PRPP to participate in the nucleotide (including ATP) synthesis. Both of the above pathways can supply ATP for the cells to facilitate their growth. However, when excessive D-ribose is deposited in the cell, it can also initiate rapid nonenzymatic glycation reactions AGEs, which can cause damage to the cells