Essential oils, new source of algicidal compounds

Abstract

The aim of this study was to find new compounds to control and suppress harmful algal blooms (HABs) through blasting algal cells in which prevent the development of red tide. The algicidal activity of three plants Satureja khuzistanica, Satureja rechingeri ,a ndZataria multiflora on the dinoflagellate Cochlodinium polykrikoides was evaluated by adding their essential oils and methanol extracts of several concentrations into the culture medium containing C. polykrikoides. The essential oils of S. khuzistanica, S. rechingeri ,a ndZ. multiflora were isolated by hydrodistillation and analyzed by means of gas chromatogra- phy (GC) and GC/mass spectroscopy (MS). A total of 17, 15, and 25 components were identified in the oils of S. khuzistanica, S. rechingeri ,a ndZ. multiflora ,r espectively. The major constituents of the essential oil of plants were carvacrol, thymol, and p-cymene. The half-lethal concentra- tions at 24 h (LC50, 24 h) of the essential oils were 2.12, 1.37, and 1.35 μ gm L �1 ,a nd LC50 of methanol extracts were 5.35, 5.55, and 5.29 μ gm L �1 for the three plants above, respective- ly, showing that both essential oils and methanol extracts of the plants strongly inhibited the growth of C. polykrikoides. However, essential oils showed better LC50 in comparison with the methanol extracts. In addition, the red tide inhibitors made with these higher plants had the merit of low concen- tration, fast reaction time as well as low stability in seawater and demonstrated a promising future for use in the control of red tides.