8,12-sesquiterpene lactones(STLs)are an important class of natural products with unique pharmaceutical activities.For years the pathway leading to 8,12-STLs remains an enigma.Xanthium strumarium accumulates abundant 8...8,12-sesquiterpene lactones(STLs)are an important class of natural products with unique pharmaceutical activities.For years the pathway leading to 8,12-STLs remains an enigma.Xanthium strumarium accumulates abundant 8,12-STLs,and xanthatin is a characteristic 8,12-STL in it.Xanthatin has been previously postulated to be derived from germacrene A,but the steps from germacrene A to xanthatin are unknown.As part of an effort to understand the xanthatin biosynthetic pathway.This study reports the characterization of a unique germacrene A oxidase(XsGAO)from X.strumarium.Unlike a classical GAO enzyme,which is known to catalyze a three-step oxidation of germarene A to yield germacrene A acid(GAA),surprisingly,XsGAO catalyzed only one-step conversion of germacrene A to germacrene A alcohol.We discussed that GAO may be pressured to acquire a novel activity during the evolutionary path for the biosynthesis of 8,12-STLs.展开更多
Objective: To assess the impacts, mode of entry, trends, status, distribution and management practices of Xanthium strumarium (X. strumarium) in Borena Zone of Oromia Region. Methods: Four study districts and eight ke...Objective: To assess the impacts, mode of entry, trends, status, distribution and management practices of Xanthium strumarium (X. strumarium) in Borena Zone of Oromia Region. Methods: Four study districts and eight kebeles (peasant associations) were purposively selected based on distribution level and data from agricultural offices. Then, randomly, eight key informants were selected from each kebele. Data were collected using semi-structured interview and analyzed using SPSS version 21. Results: All respondents (100%) acknowledged that X. strumarium highly invaded the study area and its spread was increasing both in time and space. According to respondents, X. strumarium was introduced to the area mainly along with improved seed varieties, food aid, flood, animals and vehicles, and easily dispersed by clinging to animal hides and human clothing. In the past time, X. strumarium caused high level of damage on native biodiversity and thus respondents worried that this might continue in the future. Similarly, respondents (98.4%) stated that X. strumarium was out of control in the study area and they recommended further investigation by concerned body to control the spread. Conclusions: In conclusion, X. strumarium is spreading rapidly in the study area by threatening native biodiversity and adversely affecting agroeconomy of the farmers and the country. Therefore, it needs the effort of all concerned bodies to control the impacts.展开更多
Objective:To evaluate immature mosquitocidal properties of Xanthium strumarium plant extracts against Culex mosquitoes at Entomology Laboratory,Maraki Campus,University of Gondar.Methods:The immature mosquitocidal act...Objective:To evaluate immature mosquitocidal properties of Xanthium strumarium plant extracts against Culex mosquitoes at Entomology Laboratory,Maraki Campus,University of Gondar.Methods:The immature mosquitocidal activity of plant extracts was tested by following World Health Organization recommended protocol.Acetone,methanol and water extracts were prepared at 50,100,150,200 and 250 mg/L concentrations and tested against third and fourth instar larvae and pupae of Culex mosquitoes.The mortality rate of immature mosquitoes was recorded after 24,48 and 72 h exposure period continuously.Results:Third instar larvae after 24 h exposure period,maximum mortality of 77.80%was recorded at 250 mg/L concentration of acetone extract.After 48 h and 72 h exposure period,maximum mortality of 88.90%was recorded in acetone extract in all the tested concentration.The maximum mortality of fourth instar larvae was 88.90%in acetone extract at 200 and 250 mg/L concentrations.Pupal mortality was also greater in acetone extract.The percentage of mortality in all the stage of mosquitoes was higher in acetone extract followed by methanol and water extract.Conclusions:The percentage of mortality is associated with concentration of the extracts tested and exposure period.This laboratory study confirmed immature mosquitocidal activity of Xanthium strumarium leaf extracts against Culex mosquitoes.The aqueous leaf extract can be used by applying on small man-made breeding places to prevent adult emergence.展开更多
基金This work was supported by a grant from the National Natural Science Foundation of China(31370339).
文摘8,12-sesquiterpene lactones(STLs)are an important class of natural products with unique pharmaceutical activities.For years the pathway leading to 8,12-STLs remains an enigma.Xanthium strumarium accumulates abundant 8,12-STLs,and xanthatin is a characteristic 8,12-STL in it.Xanthatin has been previously postulated to be derived from germacrene A,but the steps from germacrene A to xanthatin are unknown.As part of an effort to understand the xanthatin biosynthetic pathway.This study reports the characterization of a unique germacrene A oxidase(XsGAO)from X.strumarium.Unlike a classical GAO enzyme,which is known to catalyze a three-step oxidation of germarene A to yield germacrene A acid(GAA),surprisingly,XsGAO catalyzed only one-step conversion of germacrene A to germacrene A alcohol.We discussed that GAO may be pressured to acquire a novel activity during the evolutionary path for the biosynthesis of 8,12-STLs.
文摘Objective: To assess the impacts, mode of entry, trends, status, distribution and management practices of Xanthium strumarium (X. strumarium) in Borena Zone of Oromia Region. Methods: Four study districts and eight kebeles (peasant associations) were purposively selected based on distribution level and data from agricultural offices. Then, randomly, eight key informants were selected from each kebele. Data were collected using semi-structured interview and analyzed using SPSS version 21. Results: All respondents (100%) acknowledged that X. strumarium highly invaded the study area and its spread was increasing both in time and space. According to respondents, X. strumarium was introduced to the area mainly along with improved seed varieties, food aid, flood, animals and vehicles, and easily dispersed by clinging to animal hides and human clothing. In the past time, X. strumarium caused high level of damage on native biodiversity and thus respondents worried that this might continue in the future. Similarly, respondents (98.4%) stated that X. strumarium was out of control in the study area and they recommended further investigation by concerned body to control the spread. Conclusions: In conclusion, X. strumarium is spreading rapidly in the study area by threatening native biodiversity and adversely affecting agroeconomy of the farmers and the country. Therefore, it needs the effort of all concerned bodies to control the impacts.
基金Supported by University of Gondar(UoG/Budget/no 6215/2015).
文摘Objective:To evaluate immature mosquitocidal properties of Xanthium strumarium plant extracts against Culex mosquitoes at Entomology Laboratory,Maraki Campus,University of Gondar.Methods:The immature mosquitocidal activity of plant extracts was tested by following World Health Organization recommended protocol.Acetone,methanol and water extracts were prepared at 50,100,150,200 and 250 mg/L concentrations and tested against third and fourth instar larvae and pupae of Culex mosquitoes.The mortality rate of immature mosquitoes was recorded after 24,48 and 72 h exposure period continuously.Results:Third instar larvae after 24 h exposure period,maximum mortality of 77.80%was recorded at 250 mg/L concentration of acetone extract.After 48 h and 72 h exposure period,maximum mortality of 88.90%was recorded in acetone extract in all the tested concentration.The maximum mortality of fourth instar larvae was 88.90%in acetone extract at 200 and 250 mg/L concentrations.Pupal mortality was also greater in acetone extract.The percentage of mortality in all the stage of mosquitoes was higher in acetone extract followed by methanol and water extract.Conclusions:The percentage of mortality is associated with concentration of the extracts tested and exposure period.This laboratory study confirmed immature mosquitocidal activity of Xanthium strumarium leaf extracts against Culex mosquitoes.The aqueous leaf extract can be used by applying on small man-made breeding places to prevent adult emergence.
