A variety of substances with proven antioxidant and radical scavenging activity, such as hydroxytyrosol (3,4-DHPEA), tyrosol (p-HPEA) and their secoiridoid derivatives (dialdheydic form of decarboxymethyl elenolic acid, 3,4-DHPEA-EDA or p-HPEA-EDA) as well as verbascoside, is also contained in OP