Short-chain dehydrogenase/reductase; part of the gene cluster that mediates the biosynthesis of aspernidine A, a prenylated isoindolinone (PubMed:23706169). The starting point of the biosynthesis of aspernidin A is the production of orsellinaldehyde by the non-reducing polyketide synthase pkfA (PubMed:22510154). Hydroxylation, methylation of one of the phenol groups, and prenylation, presumably catalyzed by the prenyltransferase pkfE, would be needed to yield aspernidine D (Probable). Subsequently, the cytochrome P450 monooxygenase pkfB is responsible for hydroxylation of aspernidine D to yield aspernidine E (PubMed:23706169). The dehydrogenase pkfF may be responsible for further oxidation of aspernidine E to form a dialdehyde intermediate which is further transformed in a series of steps, some of which are enzyme-mediated, to generate aspernidine A (Probable). The possibility that additional enzymes outside of the cluster are involved in aspernidine A biosynthesis cannot be excluded (Probable). Secondary metabolite biosynthesis. Abolishes the production of Aspernidine A. Belongs to the short-chain dehydrogenases/reductases (SDR) family.