Where does NADP+ come from?
Niacin (better known as vitamin B3) and nicotinamide are both precursors of the coenzymes NAD and NADP in vivo. As you can see below, the biosynthesis of NADP+ proceeds as follows, when nicotinamide combines with a basic ingredient, a sugar phosphate:



The sugar phosphate precursor can also form AMP and GMP, also important molecules in the cell, when it reacts with the nucleobases adenine and guanine (A and G from the 'ladder' that bridges the DNA helix).

Just as an additional funfact, some bacteria such as Plasmodium falciparum and Toxoplasma gondii cannot synthesize nicotinamide themselves, because they lack the genes for it. Instead, they salvage the enzymes from eukaryotic hosts. This is an example of an incomplete biochemical toolkit giving rise to parasitism.