NADPH is the reduced form of NADP+, meaning that the latter features an extra hydrogen ion in its chemical structure. In order for NADP+ to transform into NADPH, the former requires two electrons and two hydrogen ions. One of the hydrogen ions is included in the structure of NADPH, while the other is released as a product of reaction. This reaction is part of the photosynthesis process.
NADPH results after the reduction of NADP+, or nicotinamide adenine dinucleotide phosphate, a coenzyme that plays specific roles in a wide range of anabolic reactions. NADPH acts as a reducing agent during the synthesis of nucleic acids and lipids. It is also involved in the process of carbohydrate synthesis that takes place in plants. As a reduced compound, NADPH becomes a molecule with high energy, thus being especially useful in driving the Calvin cycle. It's also important during the process that transforms carbon dioxide into glucose.
A compound called ferredoxin-NADP+ reductase plays an important part during the photosynthesis process, being responsible for producing NADPH. NADPH is also involved in reactions that take place in animal organisms. Organisms that do not undergo photosynthesis produce NADPH through the pentose phosphate pathway. To act as a reducing agent, a molecule of NADPH releases a hydride ion (H-) and a NADP+ molecule.