Screening of the Essential Oil, Hexane Extract, Chemical Composition, Antioxidant Activity, andAntimicrobial Acitivity of the Flower Rheum ribes L. from Iran

Abstract

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