Background and Objectives: Iron is an essential element that plays a vital role in a wide variety of cellular processes. But when present in excess concentration in organs, it may increase the risk for liver disease, heart failure, and diabetes. Recently, siderophores, which are iron-chelating agents produced by microorganisms, have attracted tremendous attention because of their strong binding and high selectivity to the ferric form of iron. Thus, the use of siderophore in sequestering excess iron in the body as a form of therapy is very attractive. This study determined the effects of commercially available siderophore in sequestering excess iron in organs such as liver, heart, and pancreas under excess iron conditions. Methodology: First, iron-overload was induced by injecting iron dextran (20 mg) into male ICR mice for three consecutive days. The effects of iron to the liver, heart, and pancreas and the possible sequestration by siderophore were determined by scoring histological sections. The liver iron concentration was also assessed by atomic absorption spectroscopy (AAS). Results and Conclusion The study showed that iron-overloaded mice exhibited skin hyperpigmentation and hemosiderosis in liver, heart, and pancreas. Significant changes in the liver include hepatomegaly and development of tumor. Iron-overloaded mice had 2,935% increase in liver iron content compared to the salinetreated mice. However, when iron-overloaded mice were treated with either 100 µg or 200 µg siderophore, there was a 77% and 84% decrease in liver iron content, respectively. Moreover, the treatment of ironoverloaded mice with siderophore prevented the development of hemosiderosis, tumor, and structural changes in the tissues studied. The results showed that siderophore can effectively reduce excess iron and organ damage in iron-overloaded mice and can be potentially employed in chelation therapy of iron-overload diseases. Further studies on the possible mechanisms of siderophore aside from decreasing iron excess and lowering organ dysfunction are recommended.
Siderophores ; Iron Overload ; Iron Chelating Agents ; Hemosiderosis ; Hepatomegaly

OBJECTIVES: Chitosan has been widely investigated and used. However, the literature does not refer to the shelf life of this solution. This study evaluated, through the colorimetric titration technique and an analysis of dentin micro-hardness, the shelf life of 0.2% chitosan solution. MATERIALS AND METHODS: Thirty human canines were sectioned, and specimens were obtained from the second and third slices, from cemento-enamel junction to the apex. A 0.2% chitosan solution was prepared and distributed in 3 identical glass bottles (v1, v2, and v3) and 3 plastic bottles (p1, p2, and p3). At 0, 7, 15, 30, 45, 60, 90, 120, 150, and 180 days, the specimens were immersed in each solution for 5 minutes (n = 3 each). The chelating effect of the solution was assessed by micro-hardness and colorimetric analysis of the dentin specimens. 17% EDTA and distilled water were used as controls. Data were analyzed statistically by two-way and Tukey-Kramer multiple comparison (α = 0.05). RESULTS: There was no statistically significant difference among the solutions with respect to the study time (p = 0.113) and micro-hardness/time interaction (p = 0.329). Chitosan solutions and EDTA reduced the micro-hardness in a similar manner and differed significantly from the control group (p < 0.001). Chitosan solutions chelated calcium ions throughout the entire experiment. CONCLUSIONS: Regardless of the storage form, chitosan demonstrates a chelating property for a minimum period of 6 months.
Calcium ; Chelating Agents ; Chitosan* ; Colorimetry* ; Dentin* ; Edetic Acid ; Glass ; Humans ; Ions ; Plastics ; Product Packaging* ; Water

No abstract available.
Chelating Agents* ; Lead Poisoning*

Deferasirox is a new oral iron chelator. It is the first oral iron chelator approved in USA by FDA for transfusion-dependent patients above 2 years suffering from severe chronic iron overload. It is also recommended as the initial therapy for patients over the age of 6 years who are suffering from beta-thalassaemia. The clinical study is developing in China. This review focuses the related studies and the latest progression about deferasirox. The phase II and III clinical trials and pharmacokinetics indicated that deferasirox is a safety and effective oral iron chelator, can significantly decrease the myocardial and hepatic iron load, also is easy to accept for patients. The common adverse reactions are gastrointestinal symptom and rash. But it was recently reported that deferasirox has some rare adverse events to which we must attach importance, especially for the special people. Besides the patients with chronic iron overload resulting from blood transfusions (transfusional hemosiderosis), the drug is also used for the patients who has accepted auto-SCT or suffered from reversible renal inadequacy caused by Fanconi syndrome. The standard dosage is not useful to every patient. The clinician should adjust dosage based on the patient's condition and related indexes. The serum ferritin is not one and reliable index to monitoring the effect and adjust the dosage. Otherwise, this review recommends some new characters of deferasirox, e.g. anti-fungus, anti-cell proliferation and so on.
Benzoates ; administration & dosage ; Clinical Trials as Topic ; Humans ; Iron Chelating Agents ; administration & dosage ; Triazoles ; administration & dosage

BACKGROUNDAlthough there are several drugs and drug combinations for the treatment of Pneumocystis carinii (P. carinii) pneumonia, all drugs have the toxicity as well as low efficacy. Iron chelators have been proposed as a source of new drugs for combating these infections. We hypothesized that iron chelators would suppress the growth of P. carinii by deprivation of the nutritional iron required for growth. In this study, a short-term axenic culture system of P. carinii was established. Daphnetin (7,8-dihydroxycoumarin), a known iron chelator, was demonstrated to exhibit in vitro activity against P. carinii in this system.

METHODSP. carinii organisms were obtained from the lungs of immunosuppressed rats. The culture system consisted of Iscove Dulbecco Eagle's Minimum Essential Medium (IMDM), supplemented with S-adenosyl-L-methionine, N-acetylglucosamine, putrescine, L-cysteine, L-glutamine, 2-mercaptoethanol, and fetal bovine serum, and was maintained at 37 degrees C, in 5% CO(2), 95% O(2), at the optimal pH of 8.0. The culture system was used to assess the effect of daphnetin on the proliferation of P. carinii organisms. The ultrastructures of the treated organisms were observed by transmission electron microscopy.

RESULTSThe number of cysts and trophozoites increased 8- to 9-fold and 11- to 12-fold, respectively, after 10 days of culture. Daphnetin was found to suppress the growth of P. carinii in a dose-dependent manner at concentrations between 1 micromol/L and 20 micromol/L. The inhibitory activity was suppressed by the chelation of daphnetin with ferrous sulfate in a 2:1 molar ratio, but it was not suppressed by mixing the culture medium with magnesium sulfate. Reduction of P. carinii numbers after treatment with daphnetin correlated with morphological changes in the organisms, as determined by transmission electron microscopy.

CONCLUSIONSDaphnetin can suppress the growth of P. carinii in vitro. The efficacy of daphnetin in suppressing the the growth of P. carinii in vitro is related to its ability to chelate iron.

Iron ; physiology ; Iron Chelating Agents ; pharmacology ; Microscopy, Electron ; Pneumocystis carinii ; drug effects ; growth & development ; ultrastructure ; Umbelliferones ; pharmacology

BACKGROUND: The iron chelating agents (ICA) have various biological effects besides iron chelation. We investigated the immunomodulatory effects of Deferasirox (DFS) compared to Deferoxamine (DFO). METHODS: Spleen cells (SP) were obtained from 5 week-old C57/BL6 (H-2(b)). The cytotoxicity of ICAs was examined using the CCK8 method. For the cell proliferation assay, SP were cultured with irradiated in addition to 10, 50, 100micrometer of DFS or DFO and 200ng/mL of cyclosporin A (CSA). Cytokines and nitrite levels were evaluated from supernatants by ELISA. RESULTS: The viability of ICA was reported to be over 100%. Both DFS and DFO inhibited cell proliferation in a manner comparable to CSA. Cell proliferation without iron was reduced at the concentration of 100micrometer of DFO. With iron treatment, the reduction of the stimulation index was dependent on DFO concentrations. DFS decreased the proliferation without reference to the concentrations. After stimulation of phytohemagglutinin, the nitrite concentrations increased with iron. With lipopolysaccharides, the nitrite levels were higher in DFO with iron than control, but similar in DFS regardless of iron treatment. The levels of interleukin-2 were not different. Interleukin-10 was more abundantly produced in 50micrometer of DFO compared to DFS. Transforming growth factor-beta was higher in DFS than DFO at the low concentration, but opposite at the high concentration. CONCLUSION: These data suggested that both iron chelating agents possessed immune suppressive effects comparable to CSA. The immunosuppressive effect of DFS may be distinct from DFO. More experiments are required to determine the exact mechanism of the immunosuppressive effect of DFS.
Benzoates ; Cell Proliferation ; Cyclosporine ; Cytokines ; Deferoxamine ; Interleukin-10 ; Interleukin-2 ; Iron ; Iron Chelating Agents ; Lipopolysaccharides ; Spleen ; Triazoles

Infection with V. vulnificus resulting in septicemia accompanied with skin gangrene and high mortality of 50% or more freqently occurs in people with liver disenses. And it has also been demonstrated that serum iron, essential to the growth of microorganisms, has been elevated in liver damaged animals. In spite of many efforts to reveal the pathogenesis of this fatal disease, there is no clear conclusion so far. Significant increase or decrease in LD of V. vulnificus (CDC C7184) was observed when mice were treated with ferric arnmonium citrate (FAC) and a specific iron chelator, desferal(Df), originated from Streptomyces pilosus and a broad spectrurn cation chelator, calciurn disodium ethylenediaminetetraacetate (CaEDTA) widly used in heavy metal poisoning treated alone or in combination. The results were obtained as follows. FAC and Df lowered LD to approximately 1.96x 10(3) colony forming unit (CFU) and 9.77x10(2) CFU respectively from 4.46 x 10(5) CFU, LDso of the control group. However, CaEDTA elevated the I D to 4.97 X 10(7) CFU. The LD of the group administered FAC and Df simultaneously was about 9.28x10(1) CFU. Whereas, the LD of the group administered FAC and CaEDTA simultaneously was approximately 7.88 x 10(5), similar to that of the control group. This study demonstrates that there is a close association of the iron with V. vulnificus septicemia and Df lowers LD of the rnice. CaED7A, however, elevated the LD. The author hereby proposes carefully iron chelators such as CaEDTA as an agent for a new adjuvant therapy of the V. vulnificus septicernia.
Animals ; Chelating Agents* ; Citric Acid ; Gangrene ; Iron* ; Liver ; Mice* ; Mortality ; Poisoning ; Sepsis* ; Skin ; Stem Cells ; Streptomyces ; Vibrio vulnificus* ; Vibrio*

Growth under conditions of iron-restriction and the production of siderophore was examined in Vibrio mimicus ATCC 33653. This strain grew and multiplied in the presence of the high-affinity iron chelators ethylenediamine-di (o-hydroxyphenylacetic acid). Chrorne azurol S (CAS) agar and solution were used to detect the production of siderophore under these condition. Siderophore could be detected in the iron-rcstricted culture supernatants. The siderophore was extracted from iron-restricted culture supernatants by phenol-chloroform-ether method and purified by Dowex ion-exchange and Sephadex G-25 gel filtracton chromatography. The purified siderophore was confirmed by paper chromatography and HPLC. The Purified siderophore enhanced the growth of V. mimicus when the bacterium was grown in iron limited medium. Injection of both the siderohore and the bacteria to mice resulted in more rapid death than that of the only bacteria. However, the siderophore did not show lethality to mice and any toxicity to cell line like HeLa and U937.
Agar ; Animals ; Bacteria ; Cell Line ; Chelating Agents ; Chromatography ; Chromatography, High Pressure Liquid ; Chromatography, Paper ; Iron ; Mice ; Vibrio mimicus* ; Vibrio*

OBJECTIVETo study the molecular mechanism of apoptosis of leukemic cells (K562 cells) induced by iron chelating agent deferoxamine (DFO).

METHODSThe exponentially growing K562 cells were used (1×10(6)/mL) in this study. The K562 cells were treated with different concentrations of DFO (10, 50 and 100 mmol/L), DFO+FeCl3 (10 μmol/L each) or normal saline (blank control). The cellular labile iron pool was measured with a fluorimetric assay using the metalsensitive probe calcein-AM. The viable count and cell viability were determined by typanblue assay. Cell apoptosis was determined by morphological study and flow cytometry assay. Caspase-3 activity in K562 cells was detected by colorimetry.

RESULTSAfter DFO treatment, the cellular labile iron pool and the viability of K562 cells were reduced and the cell apoptosis increased in a time- and dose-dependent manner compared with the blank control group. The apoptosis rate of K562 cells in the DFO+FeCl3 treatment group was not significantly different from that in the blank control group. The caspase-3 activity in K562 cells increased significantly 24 hrs after 50 and 100 μmmol DFO treatment when compared with the blank control group (P<0.01). There was a negative correlation between cellular labile iron pool and caspase-3 activity of K562 cells (r=-0.894, P<0.05).

CONCLUSIONSDFO induces apoptosis of leukemic cells possibly through decreasing cellular labile iron pool and increasing caspase-3 activity of the cells.

Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Deferoxamine ; pharmacology ; Flow Cytometry ; Humans ; Iron Chelating Agents ; pharmacology ; K562 Cells

The present study investigated the stimulatory effects of iron (or ascorbate) on cyclosporine-induced kidney mitochondrial damage. Damaging effect of 50 muM cyclosporine plus 20 muM Fe2+ on mitochondrial lipids and proteins of rat kidney and hyaluronic acid was greater than the summation of oxidizing action of each compound alone, except sulfhydryl oxidation. Cyclosporine and 100 muM ascorbate showed an enhanced damaging effect on lipids but not on proteins. The peroxidative action of cyclosporine on lipids was enhanced with increasing concentrations of Fe2+. Ferric ion (20 muM) also interacted with cyclosporine to stimulate lipid peroxidation. Damaging action of cyclosporine on mitochondrial lipids was enhanced by ascorbate (100 muM and 1 mM). Iron chelators, DTPA and EDTA, attenuated carbonyl formation induced by cyclosporine plus ascorbate. Cyclosporine (100 muM) and 50 muM Fe2+ (or 100 muM ascorbate) synergistically stimulated degradation of 2- alpha deoxyribose. Cyclosporine (1 to 100 muM) reduced ferric ion in a dose dependent manner, which is much less than ascorbate action. Addition of Fe2+ caused a change in absorbance spectrum of cyclosporine in 230~350 nm of wavelengths. The results show that cyclosporine plus iron (or ascorbate) exerts an enhanced damaging effect on kidney mitochondria. Iron and ascorbate appear to promote the nephrotoxicity induced by cyclosporine.
Animals ; Chelating Agents ; Cyclosporine ; Deoxyribose ; Edetic Acid ; Hyaluronic Acid ; Iron* ; Kidney* ; Lipid Peroxidation ; Mitochondria* ; Pentetic Acid ; Rats