银杏外种皮对钉螺的杀灭机理

To study the toxicity of extracts of Ginkgo biloba sarcotesta to Oncomelania hupensis,snails were exposed to 40% and 80% of 24 h LC 50 of the extract of Ginkgo bilba for 24 h,choline esterase(ChE),alanine aminotransferase(ALT),alkaline phosphatase(ALP),lactate dehydrogenase(LDH),succino dehydrogenase(SDH),malic dehydrogenase(MDH)activities in cephalopodium and liver were determined by enzyme kinetic assay.Arecoline and niclosamide were used as reference molluscicides.The results showed that sarcotesta of Ginkgo biloba could inhibit ChE,ALT,ALP and MDH activities both in cephalopodium and liver;arecoline could inhibit ChE,ALP,SDH and MDH activities in cephalopodium and ChE,ALT,ALP,SDH and MDH activities in liver.Niclosamide had inhibitory effects upon ChE,ALT,ALP,SDH and MDH activities in cephalopodium,and ChE,ALT,ALP and SDH activities in liver.All three molluscicides did not inhibite LDH activity in cephalopodium and liver.These results indicate that lethal effects of extracts of sarcotesta of Ginkgo biloba are mediated via inhibition of MDH activitiy,and interference with the NADH respiratory chains.Inhibition of vital enzymic mechanisms causes snails to death.

Actions of four organic acids in radix isatidis on endotoxin-neutralization investigated by kinetic turbidimetric assay

OBJECTIVE:To investigate anti-endotoxin action of four OAs reacted with endotoxin by the LAL assay with KTA.METHODS:Using a incubating kinetic tube reader and kinetic turbidimetric assay(KTA),the concentration-response time curve of endotoxin reacted with limulus amebocyte lysate(LAL) at 37℃ were obtained and the action of four organic acids(OAs) on it were investigated.The four OAs were benzoic acid,salicylic acid,syringic acid and 2-amino-benzoic acid from Radix isatidis.Meanwhile,the temperature variation caused by endotoxin with the four OAs was studied by the rabbit pyrogen test(RPT).RESULTS:It was showed that a low concentration(1 mg/mL) of the four OAs had a little effect of anti-endotoxin,and when the concentrations of the four OAs were 30 mg/mL,the endotoxin was neutralized completely.The relationships between the concentrations of endotoxin and the OAs were all linear with correlation coefficients of greater than 0.9995,indicating that the four OAs all had strong anti-endotoxin action,while syringic acid had the strongest action among the four OAs with IC50 of 12.84 mg/mL.CONCLUSION:The investigations of KTA agreed well with the results obtained by means of RPT.