Effects of gelsemine on oxidative stress and DNA damage responses of <i>Tetrahymena thermophila</i>

Abstract

Gelsemine is an important toxic substance extracted from <i>Gelsemium elegans</i>, which has a lot of biological functions in cells and organisms, but its toxicity has been rarely reported in <i>Tetrahymena thermophila</i>. In this study, we used the protozoan <i>T. thermophila</i> as an experimental model to investigate the potential toxicity-induced mechanism of gelsemine in the unicellular eukaryote. Our results clearly showed gelsemine inhibited <i>T. thermophila</i> growth in a dose-dependent manner. This exposure also resulted in oxidative stress on <i>T. thermophila</i> cells and antioxidant enzyme levels were significantly altered at high gelsemine levels (<i>p</i> < 0.05). Gelsemine produced a slight apoptotic effect at the highest (0.8 mg/mL) gelsemine level used here (<i>p</i> < 0.05). Furthermore, the toxin-induced DNA damage in a dose-dependent manner. The ultrastructural analysis also revealed mitophagic vacuoles at 0.4 and 0.8 mg/mL levels of gelsemine exposure. Moreover, expressions of oxidative stress-related and MAP kinase genes were significantly changed after exposure to 0.8 mg/mL level of gelsemine (<i>p</i> < 0.05). Altogether, our results clearly show that gelsemine from <i>G. elegans</i> can inhibit the growth via inducing oxidative stress and DNA damage in <i>T. thermophila</i> cells.