Chemical composition and antimicrobial activity of the essential oils from the aerial parts of Astragalus hamzaoglui extracted by hydrodistillation and microwave distillation

Abstract

The essential oils from the areal parts (flower, leaf and stem) of Astragalus hamzaoglui were isolated by hydrodistillation (HD) and a microwave distillation (MD) process. The composition of the volatiles was analysed by GC-FID and GC-MS and screened for their in vitro antimicrobial activity. Totals of 68/64, 65/64, and 68/67 compounds were identified in the flower, leaf, and stem oils of A. hamzaoglui accounting for 92.9- 95.0% in HD and 87.4-90.7% in MD, respectively. The essential oils consisted mainly of oxygenated monoterpenes (flower, HD: 33.3% vs. MD: 2.3%, leaf, HD: 8.0% vs. MD: 2.7%, stem, HD: 10.8% vs. MD: 4.7%), alcohols (flower, HD: 13.6% vs. MD: 10.4%, leaf, HD: 51.6% vs. MD: 3.6%, stem, HD: 35.4% vs. MD: 7.6%) and aldehydes (flower, HD: 15.5% vs. MD: 27.9%, leaf, HD: 10.0% vs. MD: 14.8%, stem, HD: 17.2% vs. MD: 24.5%). The major component of the oils of A. hamzaoglui was 1-octene-3-ol (flower, HD: 11.3% vs. MD: 8.8%, leaf, HD: 45.50% vs. MD: 3.3%, stem, HD: 32.6% vs. MD: 6.9%). Oxygenated sesquiterpenes were the minor constituents in all parts (flower, HD: 0.8% vs. MD: 0.4%, leaf, HD: 0.2% vs. MD: 0.4%, stem, HD: 0.4% vs. MD: 0.4%). of the A. hamzaoglui. Comparative study showed that the amount of total volatiles (flower, 95.0%, leaf, 92.9%, and stem, 95.0%) and the major constituent for the low molecular weight of essential oils were found to be better in HD of A. hamzaoglui. The oils were screened for antimicrobial activity against 12 microorganisms and showed antibacterial and antifungal activities against Escherichia coli, Staphylococcus aureus, Bacillus cereus 702 Roma, Mycobacterium smegmatis, and Saccharomyces cerevisiae. The antifungal activity was observed for the all tested oils against S. cerevisiae except stem oil of HD.