Phytochemical Analysis and Biological Activities of Essential Oils of the Leaves and Flowers of Ageratum houstonianum Mill. Cultivated in Egypt

Abstract

The essential oils of Ageratum houstonianum Mill grown in Egypt were obtained and studied for the first time. The essential oils of leaves (0.1 % v/w) and flowers (0.06 % v/w) of A. houstonianum Mill. (Asteraceae) were comparatively analyzed by GC/MS using non polar column Rtx-5MS. A total of 11-32 components were identified, 7 being common in both samples. The main constituents of both leaves-and flowers-derived oil samples were precocene I (22.4-34.6 %), β-caryophyllene (63.9-13.7 %), and precocene II (10.8-29.6 %) respectively. The principle difference was a considerably more pronounced sesquiterpenes presence in the leaves-oil, amounting to 65.8 %, than in the flowers counterpart (32.4 %). Caryophyllene (63.9 %) was the major sesquiterpenes detected in leaves-oil, while flowers-oil showed less amounts of sesquiterpenoid hydrocarbons (32.4 %) and represented by caryophyllene (13.5 %). Chromenes was prevailed major constituents of flowers derived oil (64.8 %) nearly double its percent in the leaves derived oil (33.3 %). In vitro screen of antimicrobial and cytotoxic activities was determined against positive control. No antifungal activity was experiential on the tested fungi for all tested samples in the used concentration. Flowers-oil sample is being mostly efficient as antibacterial against Bacillus subtilis and Staphylococcus aureus with potency 50 % compared to gentamicin. The essential oil samples revealed marked in vitro cytotoxicity against colon (HCT-116) carcinoma cell line with IC50 (11.1 %, 14.2 %) μg/ml for the leaves-, flowers-derived oil sample, respectively. The antibacterial effect of the essential oil of the flowers of A.houstonianum Mill can be credited to chromenes. As well as the leaves derived oil prevailed caryophyllene as a major constituents which may justify its observed cytotoxic activity.