Seasonal impact on the yield, chemoprofiling, antibacterial and antioxidant activities of the essential oil of Juglans Regia

The essential oil from the leaves of Juglans regia L. (Juglandaceae) growing wild in Kashmir (India) was obtained by hydro-distillation and analysed during different stages of growth ranging from April to October. The analysis was carried out by a combination of capillary GC-FID and GC-MS analytical techniques. Both qualitative and quantitative differences were observed in the essential oil collected at different developmental stages in which the sample Jr-3 exhibited the presence of thirty eight (38) molecules, followed by Jr-4 (32), Jr-6 (30), Jr-2 (29), Jr-7 (26), Jr-5 (25) and Jr-1 (18) constituents. The essential oil yield varied from 0.020 % to 0.035 % in fresh leaves of the different samples of J. regia. The Jr-1, Jr-2, Jr-3, Jr-4  and Jr-6 oil samples exhibited the dominance of monoterpene hydrocarbons constituting 61.0 %, 56.4%, 39.8%, 55.9%  and 29.0%  of the total oil composition respectively, where as sesquiterpene hydrocarbons form the major portion of oil samples of Jr-5 (40.4% ) & Jr-7(38.9%). Major constituents like α-Pinene, β -Pinene, Germacrane-D, β -Caryophyllene, Methylsalicylate, α-Humulene though present in all samples exhibit significant quantitative variation. The various oil samples possess varying degrees of antioxidant and antimicrobial properties which shows decreasing order with the decreasing number of constituents. The current study is the first attempt that reports the seasonal impact on the essential oil composition, antioxidant and antimicrobial activities of J. regia growing in Kashmir valley.