Camphor is a terpene ketone with aromatic and volatile properties in nature derived from the bark of Cinnamomum camphora or synthesized from turpentine. Camphor exhibits various biological properties such as anti-microbial, anti-viral, anti-coccidial, and anti-cancer. It is also used as a form of topical medication for skin irritation, joint pain, and as a relief for itching from insect bites. However, even though the high dose of camphor has been documented to be toxic/lethal in humans in different studies, camphor’s developmental toxicity has not yet been explored, and its extensive mechanism of action is still unclear. In the present study, we aimed to assess the toxic effects of camphor in zebrafish embryos in the initial developmental stages. The obtained results demonstrated that a sub-lethal dose of camphor caused a decrease in hatching rate, body length, and substantial elevation in malformation rate on zebrafish embryos. On further observation, in the following time frame, curved body and pericardial edema of zebrafish were also observed. Furthermore, exposure to a sub-lethal dose of camphor was also able to trigger cardiotoxicity in zebrafish larvae. Later, on subsequent biochemical analysis, it was found that the antioxidant capacity inhibition and oxidative stress elevation that occurred after camphor exposure might be associated with the inhibition of total superoxide dismutase (SOD) activity and an increase in reactive oxygen species (ROS) and malondialdehyde (MDA) concentration. In addition, compared to the control group, several apoptotic cells in treated zebrafish were also found to be elevated. Finally, after further investigation on marker gene expressions, we conclude that the developmental toxicity of camphor exposure might be associated with apoptosis elevation and oxidative stress. Taken together, the current study provides a better understanding of the developmental toxicity of camphor on zebrafish, a promising alternative animal model to assess the developmental toxicity of chemical compounds.

樟脑是一种萜烯酮，在自然界中具有芳香和挥发性，来源于樟树的树皮或由松节油合成。樟脑具有多种生物学特性，例如抗微生物、抗病毒、抗球虫和抗癌。它还用作一种局部用药，用于治疗皮肤刺激、关节疼痛，以及缓解昆虫叮咬引起的瘙痒。然而，尽管在不同的研究中已经证明高剂量的樟脑对人体有毒/致命，但尚未探索樟脑的发育毒性，其广泛的作用机制仍不清楚。在本研究中，我们旨在评估樟脑在斑马鱼胚胎初始发育阶段的毒性作用。获得的结果表明，亚致死剂量的樟脑导致斑马鱼胚胎的孵化率、体长和畸形率显着降低。进一步观察，在随后的时间范围内，还观察到斑马鱼的弯曲身体和心包水肿。此外，暴露于亚致死剂量的樟脑也能够引发斑马鱼幼虫的心脏毒性。后来，在随后的生化分析中，发现樟脑暴露后发生的抗氧化能力抑制和氧化应激升高可能与总超氧化物歧化酶（SOD）活性的抑制和活性氧（ROS）和丙二醛的增加有关(MDA) 浓度。此外，与对照组相比，处理过的斑马鱼中的几个凋亡细胞也被发现升高。最后，在进一步研究标记基因表达后，我们得出结论，樟脑暴露的发育毒性可能与细胞凋亡升高和氧化应激有关。总之，目前的研究提供了对樟脑对斑马鱼发育毒性的更好理解，斑马鱼是一种有前途的替代动物模型，用于评估化合物的发育毒性。