Screening model in <i>Caenorhabditis elegans</i> for radioprotective natural products

Ionizing radiation (IR) could induce damage such as DNA damage and oxidative stress. Natural products, like tea, have been demonstrated potential in mitigating these damages. However, the lack of efficient and rapid screening methods for natural products hinders their widespread application. To address this challenge, this study utilized <i>Caenorhabditis elegans</i> (<i>C. elegans</i>) as an <i>in vivo</i> model to investigate radioprotective natural products. L1 stage <i>C. elegans</i> were exposed to X-rays or ⁶⁰Co γ-rays at varying dosages (20, 50, and 100 Gy), then the growth, reproduction, and lifespan of the nematodes were observed. Different culture and sample-administered modes were tested. Known radioprotective agents, including Amifostine (WR2721), <i>Lycium barbarum</i> extract (LBE), and <i>Trillium tschonoskii</i> fraction (TTF), served as positive controls to validate the reliability of the model. The radioprotective activity of teas with different fermentation degrees was compared based on this screening model. A screening model in <i>C. elegans</i> was established by X-rays at 20 Gy. An appropriate sample-administrated approach was investigated, which involves adding the sample to the nematode growth medium (NGM) agar covered with inactivated <i>Escherichia coli</i> 2 h before irradiation. The known radioprotective agents (WR2721, LBE, and TTF) validated that the model is stable. Our results of the model application revealed that teas with lower fermentation levels, such as green tea and oolong tea, particularly the <i>n</i>-butanol and ethyl acetate fractions from oolong tea, exhibited significant radioprotective activity. This study presents an effective <i>in vivo</i> approach for the initial screening of radioprotective natural products.