Identification Of Ciguatoxin And The Study Of Its Cytotoxicity And Degradation

Ciguatoxins is a kind of neurotoxic marine algal toxins. Ciguatoxins are mainly initiated by cambierdiscus toxicus, which are first accumulated by herbivorous fish and transmitted to larger carnivorous fish through the food chain until reaching humans to cause intoxication. Ciguatera is caused by the consumption of tropical and sub-tropical fishes containing ciguatoxin, The disease is characterized by gastrointestinal, neurological and cardiovascular disturbances, in some cases of severe toxicity, paralysis, coma and death may occur. It was estimated that each year more than 50000 persons suffer from ciguatera worldwide. In recent years, ciguatoxin poisoning cases frequently occurred in Guangdong and Hong Kong, which have a serious threat to the human safety of consumption of marine fish. To provide references for detection and prevention of ciguatera fish poisoning, in this paper, we studied the extraction and identification of ciguatoxin, including the cytotoxicity and degradation of ciguatoxin.The methods:The content levels of ciguatoxin in fish is minimal, mainly in the gut of the fish. Here we estalish a rapid extraction method that extraction and purification with Florisil,Solid Extraction Method and Sephadex LH-20 chromatography from Epinephelussp liver, and preparation of high purity ciguatoxin extracts. Ciguatoxin extracts were detected compared with pacific ciguatoxin-1 by high-performance liquid chromatography(HPLC); High-performance liquid chromatography/mass spectrometry(HPLC/MS) was used for the detection of ciguatoxin extracts; We studied the ciguatoxin extracts cytotoxicity on the human neuroblastoma (SK-N-SH) with Methyl Thiazolyl Tetrazolium (MTT) in the presence of ouabain and veratridine as activators. Photocatalytic degradation of ciguatoxin in aqueous solution by nanocomposition was studied. The characteristics of the degradation by TiO2-ZnO nanocomposition were investigated by changes of some factors such as the initial concentration of ciguatoxin, reaction time and light source.The results:(1) In this paper, we estalish a ciguatoxin rapid extraction and purification method from fish. (2) The same retention time at 8.705 min between the extracts and P-CTX-1 were identified by HPLC monitored at 215nm.(3) It was also identified as P-CTX-1 because the purified sample of Ciguatoxin is fully consistent with the report about [M+H]+ m/z=1111.3 and [M+Na]+ m/z=1133 by HPLC/MS. (4) It was verified that ciguatoxin extract not only has an impact on cell morphology, but also on the cell viability. We analysed the ciguatoxin cytotoxicity on SK-N-SH with MTT, there was linear relationship between dose and inhibition, with the detection limit of 0.1 ng/mL, IC50=200 ng/mL. The cytotoxicity assay not only can determine the toxicity of ciguatoxin extracts on SK-N-SH, but also can detection of ciguatoxin quantitatively. (5) It showed that the effects photocatalytic degradation of ciguatoxin was the best under the ray of the ultraviolet (UV), with concention of 2mg/L, and it was completely degraded within 40 minutes.The conclusions:This topic had extracted and purified high purity ciguatoxin from Epinephelussp liver successfully, and it was identified as P-CTX-1 by HPLC/MS and cytotoxicity assay, we also studied the photocatalytic degradation of ciguatoxin by TiO2-ZnO nanocomposition. This topic laid the foundation for the research work related to ciguatoxin in china.