Patent ID: 7671211

Claim:
A method for reduction of a substrate with thioredoxin reductase, comprising combining the thioredoxin reductase, the substrate and NADPH in an in vitro composition, wherein the composition does not include insulin, under conditions to reduce the substrate, the substrate comprising a substance selected from the group consisting of a compound represented by the following general formula (1) or (1′) and a physiologically acceptable salt thereof: wherein R 1 and R 2 independently represent a hydrogen atom, a halogen atom, a trifluoromethyl group, a nitro group, a C 1 -C 6 alkyl group, or a C 1 -C 6 alkoxyl group, or R 1 and R 2 may combine together to represent methylenedioxy group; R 3 represents an aryl group, an aromatic heterocyclic group, a 5- to 7-membered cycloalkyl group, or a 5- to 7-membered cycloalkenyl group, and the aryl group, the aromatic heterocyclic group, the cycloalkyl group, and the cycloalkenyl group may be substituted with one or more substituents; R 4 represents a hydrogen atom, a hydroxyl group, a —S-glutathione group, a —S-α-amino acid group, or an aralkyl group whose aryl moiety may be substituted with one or more substituents; R 5 represents a hydrogen atom or a C 1 -C 6 alkyl group, or R 4 and R 5 may combine together to represent single bond; Y represents oxygen atom or sulfur atom; n represents an integer of from 0 to 5; and the selenium atom may be oxidized.