The antioxidant activity of wild medlar (Mespilus germanica L.) fruit, stem bark and leaf
The medlar is an edible fruit. Modern medicine has recognized its healing properties in the treatment of some diseases. There is no scientific data in the literature about the antioxidant activity of methanol or aqueous extract of medlar fruit, leaf or stem bark. Antioxidant activities of these parts were evaluated by employing six test systems. Stem bark extract (aqueous and methanol) showed best activity in 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity with IC50 = 10.7 ± 0.6 and 11.4 ± 0.8 μgml-1, respectively. All extracts showed weak Fe2+ chelating ability. Methanol extract of fruit had better activity in nitric oxide scavenging model than others (IC50 = 247 ± 12.2 μgml-1). The leaves and bark extracts showed good reducing power than fruit extract. In reducing powers, there were no significant differences (p > 0.05) among the stem bark and leaves extracts that were comparable with vitamin C (p< 0.05). Extracts exhibited good antioxidant activity in the ferric thiocyanate (FTC) method. They manifested almost the same pattern of activity as vitamin C and butylated hydroxyanisole (BHA) at different incubation times (until 72nd hour) but stem bark extract showed higher peroxidation inhibition than vitamin C and BHA at the 96th hour (p < 0.05). The extracts were capable of scavenging H2O2 in a concentration-dependent manner. Leaves methanol extract showed good activity that was comparable with quercetin (p > 0.05). Bark and leaf extracts had higher total phenolic and flavonoid contents than fruit.
Keywords: Antioxidant activity, free radical scavenging, Mespilus germanica, medlar, phenolic contents, flavonoids contents