Molluscicidal activity of the secondary metabolites from Streptomyces nigrogriseolus XD 2-7 against Oncomelania hupensis and its preliminary mechanisms of molluscicidal actions / 中国血吸虫病防治杂志

OBJECTIVE@#To evaluate the storage stability of metabolites from actinomycetes Streptomyces nigrogriseolus XD 2-7 and the mollcuscicidal activity against Oncomelania hupensis in the laboratory, and to preliminarily explore the mechanisms of the molluscicidal activity.@*METHODS@#The fermentation supernatant of S. nigrogriseolus XD 2-7 was prepared and stored at -20, 4 °C and 28 °C without light for 10 d; then, the molluscicidal effect was tested against O. hupensis following immersion for 72 h. The fermentation supernatant was boiled in a 100 °C water bath for 30 min and recovered to room temperature, and then the molluscicidal effect was tested against O. hupensis following immersion for 72 h. The pH values of the fermentation supernatant were adjusted to 4.0, 6.0 and 9.0 with concentrated hydrochloric acid and sodium hydroxide, and the fermentation supernatant was stilled at room temperature for 12 h, with its pH adjusted to 7.0; then, the molluscicidal effect was tested against O. hupensis following immersion for 72 h. The fermentation product of S. nigrogriseolus XD 2-7was isolated and purified four times with macroporous resin, silica gel and octadecylsilane bonded silica gel. The final products were prepared into solutions at concentrations of 10.00, 5.00, 2.50, 1.25 mg/L and 0.63 mg/L, and the molluscicidal effect of the final productswas tested against O. hupensis following immersion for 72 h, while dechlorination water served as blank controls, and 0.10 mg/L niclosamide served as positive control. The adenosine triphosphate (ATP) and adenosine diphosphate (ADP) levels were measured in in O. hupensis soft tissues using high performance liquid chromatography (HPLC) following exposure to the final purified fermentation products of S. nigrogriseolus XD 2-7.@*RESULTS@#After the fermentation supernatant of S. nigrogriseolus XD 2-7 was placed at -20, 4 °C and 28 °C without light for 10 d, immersion in the stock solution and solutions at 10- and 50-fold dilutions for 72 h resulted in a 100% (30/30) O. hupensis mortality. Following boiling at 100 °C for 30 min, immersion in the stock solution and solutions at 10- and 50-fold dilutions for 72 h resulted in a 100.00% (30/30) O. hupensis mortality. Following storage at pH values of 4.0 and 6.0 for 12 h, immersion in the fermentation supernatant of S. nigrogriseolus XD 2-7 for 72 h resulted in a 100.00% (30/30) O. hupensis mortality, and following storage at a pH value of 9.0 for 12 h, immersion in the fermentation supernatant of S. nigrogriseolus XD 2-7 for 72 h resulted in a 33.33% (10/30) O. hupensis mortality (χ2 = 30.000, P < 0.05). The minimum concentration of the final purified fermentation products of S. nigrogriseolus XD 2-7 was 1.25 mg/L for achieving a 100% (30/30) O. hupensis mortality. The ATP level was significantly lower in O. hupensis soft tissues exposed to 0.10 mg/L and 1.00 mg/L of the final purified fermentation products of S. nigrogriseolus XD 2-7 than in controls (F = 7.274, P < 0.05), while no significant difference was detected in the ADP level between the treatment group and controls (F = 2.485, P > 0.05).@*CONCLUSIONS@#The active mollcuscicidal ingredients of the S. nigrogriseolus XD 2-7 metabolites are maintained stably at -20, 4 °C and 28 °C for 10 d, and are heat and acid resistant but not alkali resistant. The metabolites from S. nigrogriseolus XD 2-7 may cause energy metabolism disorders in O. hupensis, leading to O. hupensis death.

Development of a novel method for UPLC-QTOF-MS analysis of anti-schis-tosomiasis heterocyclic compounds / 中国血吸虫病防治杂志

Objective To develop an ultra-performance liquid chromatography/quadrupole-time of flight mass spectrometry(UPLC-QTOF-MS)method for the determination of an oxadiazole-2-oxide heterocyclic compound F-2015-14.Methods Mouse plasma and liver homogenate specimens were extracted with ethyl acetate and chromatographed on a Waters CORTECS column(C18,1.6μm,2.1 mm×150 mm)by using a mobile phase of 10％acetonitrile-0.1％formic acid with by a volume fractionation by gradient elution.Then,UPLC-QTOF-MS was performed to determine F-2015-14 in mouse plasma and liver homogenate speci-mens.Results The linearity of F-2015-14 in plasma ranged from 12.5 to 250 μg/mL with a correlation coefficient of 0.990 and a detection limit of 8.8 μg/mL.F-2015-14 in liver homogenates ranged from 12.5 to 250 μg/mL.The linearity was good with a cor-relation coefficient of 0.992 and a limit of detection of 5.6 μg/mL.If the concentration of plasma and liver homogenate specimens was 12.5 μg/mL,the accuracy and the matrix effect were 80％to 120％,and the inter-day and intra-day precision was within 20％.If the concentrations of plasma and liver homogenate specimens were 100 μg/mL and 200 μg/mL,the accuracy and the ma-trix effect were 85％to 115％,and the inter-day and intra-day precision was within 15％.Conclusion The UPLC-QTOF-MS es-tablished in this study has a high sensitivity and good reproducibility for the determination of F-2015-14,which provides bases for the development of novel anti-schistosomiasis drugs.