NADPH 

The coenzyme NADPH differs from nicotinamide adenine dinucleotide (NADH) only by the presence of a phosphate group on one of the ribose units (Fig. 1).
This seemingly small change in structure allows NADPH to interact with NADPH-specific enzymes that have unique roles in the cell. For example, in the cytosol of hepatocytes, the steady-state NADP+/NADPH ratio is ~0.1, which favors the use of NADPH in reductive biosynthetic reactions. This contrasts with the high NAD+/NADH ratio (~1,000), which favors an oxidative role for NAD⁺.
This section summarizes some important NADPH-specific functions in reductive biosynthesis and detoxification reactions.

Figure 1:  Structure of reduced nicotinamide adenine dinucleotide phosphate (NADPH).