Identification of Walnut Tree Leaves Extractives Chemical Composition and the Effect of Growth Time

Plant extractives show unique properties. They impart colors and change the color of wood and generates attractive appearance. Since early days, societies have been utilizing plant extractives in industrial, medical and even as fungicides and biocides. In early times this application was based on the professional experiences, but as the sciences were advanced, then the technical and experimental identification and utilization was employed. In general, people look at walnut tree wood and fruit as its economic values. However, scientific research has proved the values of walnut tree extractives. In this study the chemical composition of walnut tree extractives and its variation in two periods of spring and summer as well as the impact of the drying on quantity and quality of the extractive components are investigated.

Walnut tree leaves from a selected location of an old walnut tree (100 years old) in mountain region of Karaj were collected in spring and summer. One part of the samples was air dried and another portion was used at green moisture condition. Totally four samples were obtained. Ethanol-acetone extraction was according to Tappi T204-05 procedure. The extractive was identified using GC-MASS spectroscopy and the chemical components in the extractives were identified and tabulated. 

The results revealed that the dried leaves contain fewer chemical compounds compared to green samples which can be an indication that some of the compounds in green sample are volatile and vaporize upon drying. Furthermore, the extractives chemical composition and content varies between spring and summer samples. The major chemical compounds identified were 2-methylneptaline, tri-decan, tetradecan, 2,3-dimethyl naptaline and methylcyclobenzen.

The results indicated the seasonal variation of walnut tree extractives. These is also considerable variation in wet and dry samples which can be attributed to the presence of volatile compounds. The odor of walnut leaves is the consequence of existence of such volatile extractives. The absence of some of the compounds in summer samples indicate the seasonal changes of the extractives.