| To evaluate the the prevention and cure effect of cruciferous vegetables on lead poisoning,the antagonistic effect of Chinese kale flower extracts(containing mainly glucosinolates,GS) against the lead toxicity was studied.The composition and content of GS in various cultivars of cruciferous vegetables were detected by high performance liquid chromatography.The content of glucoraphanin(RAA),one of the most potent natural antioxidant,and the indolyl GS,which may give rise to degradation products(e.g.,indole-3-carbinol) that can enhance tumorigenesis were two major screening index.The Chinese kale flower was chosen to be the extracting material,for it contained relatively high level of RAA and relatively low level of indolyl GS.GS were efficiently extracted from plants,as well as the degradation products of them,were obtained by hydrolysising with myrosinase.An experiment was conducted using Kunming mice to evaluate the effects of three antioxidants,the extract of cruciferious vegetable and its degradation product,selenium alone and along with the extract,on lead accumulation,status of lipid peroxidation of lead-treated rats.Screening of extract materialsMethod GS composition and contents were detected in three kinds of cruciferous vegetables,including broccoli sprouts,mature broccoli plants,Chinese kale flowers, by high performance liquid chromatography.One of them,which contained relatively high level of RAA and relatively low level of indolyl GS,would be chosen as extraction material.Result 1) Total GS content:Among these three brassicas,broccoli sprouts had the highest total GS content,followed by mature broccoli plants,the lowest was Chinese kale flowers.2) Indolyl GS content:All of these three brassicas,the ratio of indolyl GS content to total GS content was less than 15%,the lowest concentration was found in mature broccoli plants,which was nearly zero.3) RAA content:The broccoli sprouts contain highest levels of RAA,followed by Chinese kale flowers,the lowest concentration of RAA was found in mature broccoli plants,which is close to zero.Conclusion Among these three brassicas,broccoli sprouts contain the highest quantities of total GS and RAA,negligible quantities of indole GS;Mature broccoli plants contained negligible amount of RAA;Chinese kale flower contains relatively high level of total RAA.Finally,Chinese kale flower was chosen to be the extracting material.Preparation of extractsMethod After twice ultrasonic extracted in 70%methanol(v/v),the extract was collected and concentrated by a rotary evaporator until its volume was 10%(W/V), and extracts were obtained through lyophilization.The profiles and content of GS were quantitative detected by HPLC-UV,and were identified by ESI-MS/MS.Result Total amount of extracts were obtained 279g by extracting,in which the content of total GS was 77.44μg/g,RAA reached about 18%of the total GS.Animal experimentMethod One hundred and ten male mice weighing 18-21g were randomly divided into eleven groups.All groups received 300 ppm lead in the drinking water,except the blank control group.In the meantime,the mice were fed with sulpplyments as follows: blank and model control groups received deionized water;positive drug group received dimercaptosuccinic acid(DMSA) solution,GS groups(0.133μmol/g BW, 0.044μmol/g BW,0.022μmol/g BW),ITC groups(0.133μmol/g BW,0.044μmol/g BW, 0.022μmol/g BW),selenium yeast group(33.2μg selenium/kg BW),selenium yeast and GS mixture group(0.044μmol GS/g BW and 33.2μg selenium/kg BW)were administered respectively to each group by gavages.After 30 days,specimen such as blood and liver,brain,bone were collected.The lead concentration were analyzed by graphite furnace atomic absorption spectrophotometer,selenium concentration were analyzed by hydride generation atomic fluorescence spectrometry.The activity of SOD,GPx, and GST in blood,of GPx,GST,and MDA in liver was determined by reagent kits. Result 1) Antagonistic effect against the toxicity of lead:GS groups,lead concentration in L-GS was significantly lower than the model control group in each site,brain lead concentration in H-GS was the same as the model control group,liver and bone lead concentration in M-GS was the same as the model control group.ITC groups,blood lead concentration in H-ITC,M-ITC,and L-ITC were obviously lower than the model control group,brain lead concentration in L-ITC,liver lead concentration in M-ITC,bone lead concentration in H-ITC was the same as the model control group.2) Antioxidant effect:In blood,the activity of GST in each group were the same as the model control group except H-ITC group;the activity of GPx in each group were obviously higher than the model control group except M-ITC,H-GS group;the activity of SOD in each group were obviously higher than the model control group except H-ITC,H-GS group.In liver,the activity of GPx in each group was the same as the model control group except Se.The activity of GST in each group was the same as the model control group except M-ITC.The activity of MDA in each group was the same as the model control group.3) The correlations between the antioxidant level and the lead concentration:The activity of GPx,GST and SOD in blood was negatively correlated to lead concentration(P<0.05).The activity of GPx, GST in liver was negatively correlation with lead concentration,the activity of MDA in liver was positively correlated to lead concentration(P<0.05).Conclusion 1) The extracts of Chinese kale flower did protect partially against lead poisoning rats,but no obvious dose-response relationship was found.2) The extracts of Chinese kale flower can effectively enhance the antioxidant level in vivo,and there was significant negatively correlation of antioxidant level to lead concentration.3) No obvious synergy effect was found between GS and selenium.4) The similar effect of the antagonistic effect against lead toxicity and antioxidation were found between the extracts of Chinese kale flower and its degradation products,indicating that the GS and its degradation products have similar biological activity. |
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