Antiradical activity of different parts of Walnut (Juglans regia L.) fruit as a function of genotype

► We showed individual phenolic compounds in different genotypes by HPLC. ► We conclude that antiradical activity related to both content and type of phenol. ► We peruse the impact genotype and environmental factors on antiradical activity. ► We propose walnut fruit by-products phenolic extract for preventing of some diseases. The objective of this work was to analyse phenolic compounds and antiradical capacity of different parts of walnut fruit among six genotypes of Juglans regia L. Therefore, total phenolic and flavonoid content were determined and methanolic extracts of walnut genotypes were considered by the reducing power, DPPH (2,2-diphenyl-1-picrylhydrazyl), superoxide anion and nitric oxide radical scavenging. Significant differences were found in phenolic content and radical scavenging capacity of different parts of fruits and among various genotypes. High correlation coefficient (R2=0.81) was observed between phenol content and radical scavenging activity, but this was not always true (R2=0.01). These results demonstrated that walnut genotypes have different phenolic compounds and phenolic compounds have different radical scavenging power. The differences of phenolic compounds were confirmed by using high performance liquid chromatography (HPLC).