Antioxidant potential of some natural and semi-synthetic flavonoid derivatives and the extracts from Maclura pomifera (Rafin.) Schneider (osage orange) and its essential oil composition / Ilkay Erdogan Orhan, Fatma Sezer Senol, Betül Demirci, Margita Dvorská, Karel Smejkal, Milan Žemlička KE304