Spectrophotometric determination of morin in strawberries and their antioxidant activity

Abstract

Morin is one of the flavonoids with intensive antioxidant activity. With the aim to use its benefits on human health, there is an increasing trend to pay attention to its content in food or supplements. The simplicity and low cost of spectrophotometric determination based on the formation of a morin complex with Zn2+ ion (stoichiometric ratio 1 : 1), at pH 7.98 and 392 nm, give it an advantage over other methods that can be used for morin quantification. The concentration range over which the response was linear was 0.151 – 4.533 mg L-1. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.030 mg L-1 and 0.091 mg L-1, respectively. The developed method was successfully applied for the determination of the morin content in strawberries. Additionally, the antioxidative abilities of strawberry extracts and morin, determined by DPPH and FRAP tests, were compared and discussed.

Morin je jedan od flavonoida sa vrlo izraženom antioksidantnom aktivnošću. Sa ciljem korišćenja njegovih pozitivnih efekata na ljudsko zdravlje, u porastu je trend interesovanja za njegov sadržaj u hrani ili suplementima. U radu je predstavljena jednostavna i pristupačna spektrofotometrijska metoda određivanja morina, zasnovana na formiranju kompleksa morina sa Zn2+ jonom (u stehiometrijskom odnosu 1 : 1, na pH 7,98 i 392 nm), što joj daje prednost u odnosu na druge metode koje se mogu koristiti za kvantifikaciju morina. Metoda pokazuje linearnost odgovora u koncentracionom opsegu 0,151 - 4,533 mg L-1, pri čemu limit detekcije (LOD) iznosi 0,030 mg L-1 a limit kvantifikacije metode (LOQ) je 0,091 mg L-1. Razvijena metoda je uspešno primenjena za određivanje sadržaja morina u jagodama. Takođe, prikazani su i komentarisani rezultati određivanja antioksidativne aktivnosti jagoda i morina, DPPH i FRAP testovima.