Screening of Flowers Essential Oil and Hexane Extract of Rheum ribes L. from Iran- Chemical Composition, Antioxidant and Antimicrobial Activities

Abstract

The hexane extract of the flowers of Rheum ribes L. which was collected from north-western Iran,<br />was obtained by Soxhlet apparatus and the essential oil composition was obtained by hydro distillation<br />and analyzed by using GC-GC/MS. The extract from the flowers was characterized by a high amount<br />of unsaturated fatty acids (UFA) (66.0%) and some of long chain hydrocarbon compounds. The main<br />components of the hexane extract were 9-octadecenoic acid(ω-9) (42.8%), 9, 12- octadecadienoic acid<br />(linoleic acid or ω - 6) (19.6%), hexadecanoic acid, (palmitic acid) (8.6%), 1,2-benzenedicarboxylic<br />acid diisooctyl (5.7%), dodecane (3.7%) and γ- linolenic acid (3.6%). The hexane extract from Rheum<br />ribes flowers detected as an important source of ω-6 and ω-9 compounds. This study reveals that the<br />flowers of this plant are attractive sources of oily components, especially the essential ones, as well as of<br />effective natural sources of unsaturated fatty acids. Twenty three compounds representing 97.5% of the<br />distilled oil of R. ribes flowers were identified, among them germacrene-d (22.3%), α-pinene (13.5%),<br />terpinolene (12.4%), p-cymene (10.6%), bicyclogermacrene (9.6%) and limonene (8.6%) were the major<br />constituents. The antimicrobial activity of the essential oil and hexane extract were determined against<br />some bacteria and both samples had a moderate effect on the some Gram-positive and Gram-negative<br />bacteria. The antioxidant activity of the extract and essential oil were evaluated by DPPH method. The<br />results indicate that hexane extract of this plant flowers possess considerable antioxidant activity.