Comparison of bioactive compounds and health promoting properties of fruits and leaves of apple, pear and quince

This paper presents characterization of healthy potential new sources of functional constituents with reference to basic plant sources. In this study, the phenolics, triterpene, isoprenoids (chlorophylls and carotenoids), amino acids, minerals, sugars and organic acids of different cultivars of pome species—apple, pear, quince—leaves vs. fruits and their enzymatic in vitro enzyme inhibition of hyperglycemic (α-glucosidase, α-amylase), obesity (pancreatic lipase), cholinesterase (acetylcholinesterase, butylcholinesterase), inflammatory (15-LOX, COX-1 and -2) and antioxidant capacity (ORAC, FRAP, ABTS) were evaluated. Leaves of pome species as a new plant sources were characterized by higher content of bioactive and nutritional compounds than basic fruits. The dominant fraction for quince, pear, and apple fruits was polymeric procyanidins. In quince and pear leaves flavan-3-ols, and in apple dihydrochalcones dominated. Triterpene was present in equal content in leaves and fruits. Leaves are excellent sources of amino acids and minerals (especially Ca, Mg, Fe, and K), with high content of organic acids and low content of sugars compared to fruits of pome species. Leaves of apples and pears most effectively inhibited COX-1, COX-2, α-amylase, and α-glucosidase enzyme but quince leaves showed the most effective inhibition of pancreatic lipase, AChE and BuChE, 15-LOX, and antioxidant capacity, which particularly correlated with bioactive compounds. Present study shows that leaves are promising sources of valuable compounds and may be used to produce functional foods as well as for medical purposes.