Therefore the novelity and for a better understanding of potential new sources of bioactive compounds of leaves of apple, pear, and quince it is important in this context to investigate the contents of some bioactive and nutritional compounds and their enzymatic in vitro inhibitory activity against hyperglycemic (α-glucosidase, and α-amylase), obesity (pancreatic lipase), lipoxygenase, cholinesterase (acetylcholinesterase and butylcholinesterase), inflammatory (cyclooxygenase 1 and 2) and antioxidant capacity (ORAC, FRAP, ABTS). This evidence concerns the gene PTGS1 and obesity due to melanocortin 4 receptor deficiency.