Catalyzes the NADPH-dependent reduction of L-xylulose, D-xylulose, L-(+) erythrulose, D-erythrose, D-threose, L-ribulose, 1,4-dibromo-2,3-butanedione and 2,3-heptanedione (PubMed:21477590). Also active against isatin, 9,10-phenanthrenequinone, menadione, 2,3-hexaenadione and 3,4-hexahenadione (PubMed:21300042). No activity observed when tested using NADH rather than NADPH (PubMed:21300042). NADP(+) + xylitol = H(+) + L-xylulose + NADPH Strongly inhibited by 10% dimethyl sulfoxide. The KM value for isatin is approximate as substrate saturation was not reached. Homotetramer. Detected on the cell membrane of spermatids. Expressed in intestine, gonad and spermatids (at protein level). Expressed in intestine, uterine seam, gonadal sheath cells, spermathecal-uterus valve and spermatids. Detected at the two-fold embryo stage. Expressed in the intestine during L1 to L3, followed by expression in uterine seam, gonadal sheath cells and spermathecal-uterus valve at L4. Reduced life span and impaired egg-laying function resulting in the retention of eggs. Exogenous addition of serotonin, which triggers vulval muscle contraction, or imipranine, a serotonin uptake inhibitor, rescues the ability to lay eggs, showing that the morphology of the vulva muscles and HSN neurons is normal. Belongs to the short-chain dehydrogenases/reductases (SDR) family.