Chemical Composition, Algicidal, Antimicrobial, and Antioxidant Activities of the Essential Oils of Gaussen.

) Gaussen is a precious wood in the family Taxodiaceae. This study investigated the chemical components of the essential oil from the stem bark of and its algicidal, antifungal, and antioxidant properties. Sixty-nine compounds representing 89.70% of the stem bark essential oil were identified by GC-MS. The essential oil showed strong anti-algae, anti-bacteria, and anti-fungus activities against the tested species, and antioxidant activities. The IC values of the essential oil against chlorophyll a, chlorophyll b, and the total chlorophyll of (a species of algae), 24-96 h after the treatment, ranged from 31.77 to 84.92 μg/mL, while the IC values of butachlor ranged from 40.24 to 58.09 μg/mL. Ultrastructure changes revealed by the transmission electron microscopy indicated that the main algicidal action sites were the chloroplast and cell wall. The essential oil showed antifungal activities on (EC = 287.94 μg/mL) and (EC = 378.90 μg/mL). It also showed bactericidal activities on and , with zones of inhibition (ZOIs) being 18.66 and 16.75 mm, respectively at 40 μg/disk. Additionally, the essential oil possessed antioxidant activity estimated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method (IC = 33.51 μg/mL; IC value of the positive control ascorbic acid was 7.98 μg/mL). Thus, the essential oil of this plant might be used as a possible source of natural bioactive molecules in agrochemical industry as well as in food and cosmetic industries.