Among 27 filamentous fungi, a strain Aspergillus niger An76 gave the highest siderophore yield even when cultured on natural medium or minimal medium containing 1 mmol L^-1 Fe^3＋. Whereas for most other strains, the ...Among 27 filamentous fungi, a strain Aspergillus niger An76 gave the highest siderophore yield even when cultured on natural medium or minimal medium containing 1 mmol L^-1 Fe^3＋. Whereas for most other strains, the capacities of siderophore production was repressed as the concentrations of Fe^3＋ was higher than 20 ~tmol L^-1. Lower ferric iron concentrations were more conducive to siderophore synthesis for those strains. The An76 siderophore was partially purified through a series of chromatography steps using Sephadex LH20 and CM-Sepharose Fast Flow columns. Its structural characteristics differed from typical siderophores, such as catecholates or hydroxamates, and no amino acids or peptide bonds were detected. It may therefore represent a new type of siderophore structure. TBA assay and ESR trapping studies showed that An76 siderophore had remarkable scavenging activity of hydroxyl free radicals in vitro. The antibiotic activities of siderophores produced by An76 were tested against 29 bacterial strains, including plant, animal, and human pathogens. The growth of 14 bacterial strains could be completely inhibited at a siderophore concentration of 8 mg ml^-1 with an incubation time of 30 min. Evidence suggests that the An76 siderophore has potential value as an antioxidant and a biocontrol agent against pathogenic microorganisms.展开更多
OBJECTIVE: To assess the antioxidant capacity of aqueous extracts of buds and flowers of Lonicera japonica Thunb.(BLJ and FLJ) using in vitro assays.METHODS: We assessed the in vitro antioxidant activities of aqueous ...OBJECTIVE: To assess the antioxidant capacity of aqueous extracts of buds and flowers of Lonicera japonica Thunb.(BLJ and FLJ) using in vitro assays.METHODS: We assessed the in vitro antioxidant activities of aqueous extracts of BLJ and FLJ and compared with that of classical antioxidants vitamin C and butylated hydroxytoluene, using several well-established methods including the 1,1-diphenyl-2-picryl-hydrazyl assay, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) assay, reducing power assay, fluorescence recovery after photobleaching assay, β-carotene bleaching assay, ferric thiocyanate assay, and thiobarbituric acid method.RESULTS: The aqueous extracts of both BLJ and FLJ had similarly potent antioxidant capacity. There were no significance differences between BLJ and FLJ in all the assays.CONCLUSION: The aqueous extracts of both BLJ and FLJ have antioxidant activity with comparable efficacy. These findings suggest that both BLJ and FLJ may have the potential as natural antioxidants.展开更多
基金This work was supported by the National Natural Science Foundation of China （No. 30470051）, the Major State Basic Research Development Program of China （973, No. 2004CB7197）, and the Natural Science Foundation of Shandong Province （No. Y2004D07）.
文摘Among 27 filamentous fungi, a strain Aspergillus niger An76 gave the highest siderophore yield even when cultured on natural medium or minimal medium containing 1 mmol L^-1 Fe^3＋. Whereas for most other strains, the capacities of siderophore production was repressed as the concentrations of Fe^3＋ was higher than 20 ~tmol L^-1. Lower ferric iron concentrations were more conducive to siderophore synthesis for those strains. The An76 siderophore was partially purified through a series of chromatography steps using Sephadex LH20 and CM-Sepharose Fast Flow columns. Its structural characteristics differed from typical siderophores, such as catecholates or hydroxamates, and no amino acids or peptide bonds were detected. It may therefore represent a new type of siderophore structure. TBA assay and ESR trapping studies showed that An76 siderophore had remarkable scavenging activity of hydroxyl free radicals in vitro. The antibiotic activities of siderophores produced by An76 were tested against 29 bacterial strains, including plant, animal, and human pathogens. The growth of 14 bacterial strains could be completely inhibited at a siderophore concentration of 8 mg ml^-1 with an incubation time of 30 min. Evidence suggests that the An76 siderophore has potential value as an antioxidant and a biocontrol agent against pathogenic microorganisms.
基金Supported by National Science and Technology Major New Drugs Project of China:Study on the allergic markers and early warning system of Shuanghuanglian Injection,(No.2014ZX09201022-006)
文摘OBJECTIVE: To assess the antioxidant capacity of aqueous extracts of buds and flowers of Lonicera japonica Thunb.(BLJ and FLJ) using in vitro assays.METHODS: We assessed the in vitro antioxidant activities of aqueous extracts of BLJ and FLJ and compared with that of classical antioxidants vitamin C and butylated hydroxytoluene, using several well-established methods including the 1,1-diphenyl-2-picryl-hydrazyl assay, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) assay, reducing power assay, fluorescence recovery after photobleaching assay, β-carotene bleaching assay, ferric thiocyanate assay, and thiobarbituric acid method.RESULTS: The aqueous extracts of both BLJ and FLJ had similarly potent antioxidant capacity. There were no significance differences between BLJ and FLJ in all the assays.CONCLUSION: The aqueous extracts of both BLJ and FLJ have antioxidant activity with comparable efficacy. These findings suggest that both BLJ and FLJ may have the potential as natural antioxidants.
