In vitro antioxidant and antibacterial activity of various extracts from exocarps and endocarps of walnut

Juglans regia seed has been used in traditional medicines as antimicrobial, antihelmintic and anti-diarrhoeal. In the present study, the antibacterial capabilities dichloromethane, ethyl acetate, methanol and aqueous extracts of endocarp and exocarp of walnut were determined against two Gram-positive bacteria and one Gram-negative bacteria. The antioxidant activity was screened by 2, 2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays. The highest antioxidant activity was observed for methanol extract of endocarp in both methods and it was stronger than positive control butylated hydroxy toluene (BHT). The total phenolic contents were ranging between 34.59 to 68.34mg GAE/g DW. The results revealed that all extracts had antibacterial activity against selected bacteria except aqueous extract. The methanol extract of endocarp presented the highest zone of inhibition against tested pathogens (9-21mm). From the results it is conclude that the methanol extract from endocarp of walnut could be used as a natural preservative ingredient in food and pharmaceutical industries.