RESUMO
Aflatoxin is a highly toxic substance, of which aflatoxin B1 is the most toxic and carcinogenic among aflatoxins. In this paper, the team used homemade CdSe/Zns quantum dots to construct a fluorescent immunoprobe and all-antigen coupling with aflatoxin B1. It used a self-developed fluorescence intensity detector to detect aflatoxin B1 in five traditional Chinese medicines, namely, ginseng, Panax ginseng, Chuanxiong rhizome, rhubarb, and yam. The recoveries were 80.0-102.0%; the relative standard deviations (RSD)were from 2.4 to 9.2.
Assuntos
Compostos de Cádmio , Pontos Quânticos , Compostos de Selênio , Aflatoxina B1/análise , FluorescênciaRESUMO
Norcantharidin (NCTD) is currently used for anticancer therapy but the exact mechanism of action remains unknown. Pre-replicative complexes (pre-RCs) are essential for cell DNA replication and highly related to malignant proliferation. Here, we examined the inhibitory effect of NCTD on pre-RC components in HepG2 cells. We showed that NCTD induced degradation of Cdc6 and Mcm2 in a dose-dependent manner. Under 100 µM NCTD concentration, about 70% of Cdc6 and 50% of Mcm2 were degraded. In addition, the nuclear translocation of Mcm6 was inhibited by NCTD. Further studies aiming at G1 synchronous cells showed that, NCTD reduced the chromatin-bound Cdc6, Mcm2 and Mcm6. Moreover, the cells were blocked from entering the S phase and accumulated at the G1 phase when released synchronously into the cell cycle. Consistently, the DNA replication was inhibited by NCTD. Finally, the combination NCTD with Cdc6 depletion lead to more severe cytotoxicity (88%) than NCTD (52%) and Cdc6 depletion (39%) alone. A synergic cytotoxicity was observed between Cdc6 depletion and NCTD. In conclusion, our results demonstrate that NCTD inhibits pre-RC assembly; subsequently blocks the G1 to S transition; and inhibits DNA replication in HepG2 cells. Pre-RCs are an intriguing target for cancer therapy, which merits further investigations for anticancer development.