Recent studies on the nucleic acid-cleaving reaction and in vitro virus-inactivating action of 1, 2-enediol reductones and some reducing carbohydrate derivatives are reviewed. After a brief discussion on the mechanism of oxygen radical formation from 1, 2-enediols, works on the autoxidation of reducing sugars are reviewed, followed by the demonstration of examples of nucleic acid cleavages by reductones, sugar phosphates, aldopentoses, pyranosiduloses and synthetic and natural oxidized polysaccharides. In vitro inactivation of viruses by ascorbic acid, triose reductone, aldopentoses and partially substituted reducing sugars including some new types of synthetic polysaccharides in the presence or absence of Cu2+ are discussed. A table of compounds with DNA cleaving ability and recent reviews on nucleic acid breakage by oxygen radicals are included with 138 cited literatures.