Evolution of Polyphenols, Flavonoids, and Tannins Content in Walnut Leaves and Green Walnut Husk during Growing Season

The walnut leaves and the green walnut husk are been widely used in folk medicine. These vegetal materials have been reported as a source of bioactive molecules such as the phenolic compounds. In this research, there were analysed different quality parameters afferent to several walnut varieties, harvested from the germplasm collection located at S.C.D.P. Valcea, Romania. Romanian cultivars 'Jupanesti', 'Valrex' and 'Valmit' and French one 'Franquette' were analyzed. The variation in bioactive compounds content from the walnut leaves and walnut husk at different developmental stages (from June to September) was investigated. The results showed that the content in polyphenols, flavonoids and tannins has significantly increased until the ripening stage, after that a decrease of the values of these parameters follows. Greater values of the three parameters were also observed at walnut leaves and green walnut husk of cultivars attacked by walnut blight, caused by the bacterium Xanthomonas arboricola pv. juglandis (Xaj). The findings of this study reveal the mode of variation in the content of polyphenols, flavonoids and tannins during the growing season of the walnut leaves and green walnut husk, emphasizing also the influence of Xaj. The results obtained demonstrated the potential of the walnut leaves and the green walnut husk as an economical source of antioxidant and antimicrobial agents.