Abstract: Compounds that can be used to increase NAD levels are described by inhibiting NAD+ degrading enzymes such as CD38 are described. The compounds have a structure according to formula I or Formula II, as described herein, or pharmaceutically acceptable salts thereof, wherein the attached groups are as defined in the specification. Methods of increasing intracellular NAD+ levels in a subject by administering an effective amount of a compound according to formula I or formula II to the subject are also described.