a reduced electron donor

A reduced electron donor is a molecule or compound that has gained one or more electrons, making it more negatively charged and therefore able to donate electrons to another molecule. Reduction is a chemical reaction that involves the gain of electrons, and a reduced molecule is one that has undergone this process. In biological systems, common examples of reduced electron donors include NADH (reduced form of nicotinamide adenine dinucleotide) and FADH2 (reduced form of flavin adenine dinucleotide), which are involved in redox reactions in cellular respiration and other metabolic processes. These molecules act as electron donors, providing electrons to other molecules that are being oxidized, and then accepting those electrons back as they are being reduced.