A growing body of evidence shows that pharmacological agents used for the treatment of type-2-diabetes such as dipeptidyl peptidase-4 inhibitors have become valuable candidates as disease modifying agents in the treatment of Alzheimer's disease. This book deals with a study investigates the neuroprotective roles of Pterocarpus marsupium and Eugenia jambolana as dipeptidyl peptidase-4 inhibitors in streptozotocin induced Alzheimer's disease. Our finding suggests that Pterocarpus marsupium and Eugenia jambolana are the potential cognitive enhancers against streptozotocin induced Alzheimer's disease by dipeptidyl peptidase-4 inhibitory action and their neuroprotective action attributed through increase in active glucagon-like peptide-1 levels.