Contribution to the Ethnobotanical, Phytochemical, Antimicrobial and Antioxidant Study of the Leaves’ Aqueous Extract of the Common Walnut "<i>Juglans regia</i> L."

Abstract

This work has focused on phytochemical screening of the Common WalnutJuglans regiaL. leaves, and biological tests: antioxidant and antimicrobial effects of the aqueous extracts (infusion, crude) of the common walnuts leaves that we’ve picked, dried and preserved. An ethnobotanical survey in Blida region has been achieved, where it has been concluded that the inhabitants of this region use the common walnuts leaves in their daily care, and the various organs of the Common walnut are widely used as well. The phytochemical screening based on specific tests helped to highlight the presence of the main secondary metabolites such as tannins, flavonoids, alkaloids, free quinones, anthocyanins and saponins, which could be responsible for the biological properties. The antimicrobial study was conducted on bacterial strains and a yeast showed that both aqueous (infusion, crude) extracts have antibacterial effect against certain bacterial strains:Staphylococcus aureus(40.43 mm),Staphylococcus epidermidis(35.36 mm),Sarcina lutea(31, 17 mm), respectively, and an inhibitory effect only for the crude aqueous extract ofEschirichia coli(12 mm),Klebsiella pneumoniae(12 mm), for against these two extracts were proved to be inactive forCandida albicans.In addition, the study of antioxidant activity by the method of reduction of iron (FRAP) and the method of reduction of free radical (DPPH) has revealed an average rate of aqueous extract (infusion) compared with that of ascorbic acid and rutin respectively. With an EC50 of the aqueous extract and rutin which equal to 0.18 and 0.017 mg/ml respectively. According to these results we confirm some information obtained during the ethnobotanical survey and thatJuglans regiaL. is endowed with an antimicrobial and antioxidant power.