oxidoreductase activity, acting on the CH-CH group of donors, NAD or NADP as acceptor 7-dehydrocholesterol reductase activity sterol delta7-reductase activity sterol Delta(7)-reductase activity Catalysis of the reaction: cholesterol + NADP+ = cholesta-5,7-dien-3-beta-ol + NADPH + H+. 7-DHC reductase activity cholesterol:NADP+ delta7-oxidoreductase activity