Chemical Composition of Ruta chalepensis Leaves Essential Oil and Variation in Biological Activities between Leaves, Stems and Roots Methanolic Extracts

To our knowledge, this study is the first to investigate the biological activities of the methanolic extracts of leaves, roots and stems of Ruta chalepensis L. (Rutaceae) in Tunisia. The chemical composition of the essential oil extracted from R. chalepensis leaves was determined by GC-MS. The antioxidant activities of tested essential oil and the methanolic extracts of leaves, stems and roots of R. chalepensis were evaluated using DPPH and ABTS radicals scavenging tests. Their antimicrobial activities were achieved by disc diffusion method and broth dilution assay. The main components of the selected essential oil were menthol (43.92 %) and linalool (42.10 %). Significant differences were found between the total phenol contents and biological activities of the different parts of R. chalepensis. In addition, significant correlations were observed between antioxidant activities and phenolic contents for methanol extracts. In fact, leaves extract presented higher total phenol content than stems and roots extracts. The tested oil showed better antioxidant activity than methanolic extracts. The highest antioxidant activity was recorded in leaves methanolic extract. The latter showed strong antibacterial activity against tested microorganisms, whereas the evaluated oil remained almost inactive. The inhibition zones diameters and minimal inhibitrice concentration values for tested bacteria, which were sensible to different methanolic extracts, were in the range of 8-35 mm and 0.78-25 mg/ml, respectively. This study demonstrated that the R. chalepensis extract can be regarded as promising candidate for natural plant source of antioxidant and antimicrobial agents.