9 pentose phosphate pathway (7). 1  1. Pentose Phosphate PathwayThree main functions:1) Supply the cell with NADPH in order to: a) provide reducing power for biosynthetic reactions.2  b) serve as a biochemical reductant (e.g., maintain glutathione levels).3  c) be utilized by the cytochrome P450 monooxygenase system. 1. Pentose Phosphate PathwayThree main functions:1) Supply the cell with NADPH in order to: a) provide reducing power for biosynthetic reactions. 2  b) serve as a biochemical reductant (e.g., maintain glutathione levels). 3  c) be utilized by the cytochrome P450 monooxygenase system.