| Study on the Reproductive Toxicity in Rats of Heteropoly TungstosilicateSubstituted by NiobiumPolyoxometalate (HC), is not only an early transition metal oxyanion clustercompound but also a polynuclear complex. It characterize in its high-charge, HMW(high molecular weight), oxidation-reduction ability and its variety of structurecomposition. HC has a wide range of uses. Apart from its traditional uses such ascatalysis, functional materials, phase transfer, etc., HC is gradually extending its scopeby absorbing more fields such as analytical chemistry, clinical chemistry, medicinalchemistry, etc.In the study of medicinal chemistry, HC showed an eurytopic antivirus tendencyagainst various RNA viruses and certain DNA viruses, especially the HIV virus,influenza virus and SARS virus. We have previously designed and created a new kindof HC (codename: NCW-6); its single-crystal structure was successfully interpretedand understood. In the meantime, its general pharmacodynamics and toxic effect wereexamined. The result showed that NCW-6has an outstanding anti-HBV effect, that ismuch stronger than the positive control medicine; its general toxic effect (acutetoxicity,90d administration) results showed that its toxic effect is lower. Based on theprevious study results, this study aims to provide more evidence for its safetyassessment, using teratogenic sensitive period tests and embryo midbrain micelle teststo further explore the reproductive toxicity of NCW-6on ratsand provide a solid basisfor our native original intellectual property of non-nucleoside reverse transcriptaseinhibitor.It is the first time that the NCW-6was tested against the HBV virus, and thepharmacology experiments demonstrated its anti-HBV activity. The safety of NCW-6was discussed according to the pre-clinical toxicology evaluation method for newdrugs,. Based on the acute toxicity test, genetic toxicity test, and90d-feeding test, the teratogenic sensitive period test and rat embryo midbrain micelle test were applied tofurther explore the reproductive toxicity of NCW-6to rats in order to improve itstoxicologieal safety as well as to provide more detailed toxicological information forits further development as a new anti-HBV virus drug.This study assesses the reproductive toxicity of NCW-6basically from2approaches: in vivo and in vitro reproductive and developmental tests. Thereproductive developmental toxicity in vitro---micelle of midbrain cell test, whichhad short experimental period and was low-cost, reproducible, and easy to use forcomparison in different labs, was introduced to examine the cytotoxicity in vitro. Onthe basis of the theory that, on the thirteenth day of pregnancy in rats, the embryonicmidbrain cells which are before the neural differentiation are very sensitive tochemical poison effect which means the cell poison could restrain the cells in thisperiod from differentiating and surviving, in order to decrease the number of cellcolonies and cells, the teratogenicity from exogenous chemicals was discussed whichprovided clues to reveal the mechanisms of teratogens through integrated study of thetested drug in vivo and vitro experiments.1Teratogenic sensitive period experimentOne of the most important in vivo reproductive and developmental tests, theteratogenic sensitive period experiment was performed to generally and systematicallyassess the effect of NCW-6on rat embryosby observing the general status of pregnantrats, the development of the embryos, embryogenesis, and appearance; viscus andskeleton deformity of embryo rats was thoroughly analyzed. After2weeks of feeding,all the rats were randomly divided into5groups which were tagged separately asnegative control, positive control, NCW-6-HD(high-dose),NCW-6-MD(medium-dose),and NCW-6-LD(low-dose).5mL/kg distilled water,130mg/kg tretinoin,1467.5mg/kg NCW-6,366.8mg/kg NCW-6,and91.7mg/kgNCW-6were given respectively. The negative control group and three medicatedgroups would be continuously given their appointed doses by intragastricadministration at a certain time each day, starting6-15days after the female rats got pregnant; the positive control group got intragastric administration starting the10thday after gestation. The doses changed according to changes in the rats’ weights,which were measured every3days. The general condition during the experimentalperiod was carefully observed and the weight changes and number of deaths wererecorded. The results indicated that the medicated groups had no obvious difference inweight compared with the control group which gained weight (P>0.05); there is alsono important difference found in the numbers of general CL(corpora lutea),implantations, live births,stillbirths and fetal resorptions compared to the negativecontrol group(P>0.05); the three medicated groups showed an even result in weight,height, tail length,general weight of fetus, and litter weight compared to the negativegroup (P>0.05); the medicated groups showed a similar appearance, rate of internalanomalies, and rate of skeleton deformity compared to the negative group(P>0.05).According to drug toxicology assessment methods, these results showed no significantadverse effect of NCW-6on parental conditions, embryos, fatal rats’ morphology,organ abnormalities, or skeleton deformity rates, so the conclusion can be drawn thatNCW-6had no toxic effects on pregnant rats, neither toxic nor teratogenic effects onfatal rats.2. Midbrain micelle experimentIn this experiment, the brain cells that were drawn from embryo rats after13daysof pregnancy were suspended in at the density of5x106cells per milliliter in orderto perform cell proliferation and cell differentiation experiments. The result indicatedthat the compound got the reproductive toxicity assessment since the tested drug IV50is1074.17μg·mL-1and the ID50is394.36μg·mL-1with R=2.72.In conclusion, the tested drug showed a low reproductive and developmentaltoxicity in both in vivo and in vitro toxicity experiments. Such results improved itstoxicological safety and provided evidence for its further study in toxicology. |
