Although apples have been shown to have anti-cancer properties, the specific components responsible for this effect have not been identified until now. Using bioactivity-guided fractionation of apple peels, scientist have identified the chemical identity of bioactive constituents in apple peels, thirteen triterpenoids were isolated, most of which showed high potential anticancer activities against the three human cancer cell lines.

With higher antiproliferative activity toward HepG2 cancer cells:

• 2-hydroxyursolic acid
• 2-hydroxy-3-{[(2E)-3-phenyl-1-oxo-2-propenyl]oxy}olean-12-en-28-oic acid
• 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid

Higher antiproliferative activity against MCF-7 cancer cells:

• 2-hydroxyursolic acid
• 2-hydroxy-3-{[(2E)-3-phenyl-1-oxo-2-propenyl]oxy}olean-12-en-28-oic acid
• 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid

All triterpenoids tested showed antiproliferative activity against Caco-2 cancer cells, especially:

• 2-hydroxyursolic acid
• 2-hydroxy-3-{[(2E)-3-phenyl-1-oxo-2-propenyl]oxy}olean-12-en-28-oic acid
• 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid

The study has been published in the J. Agric. Food Chem.