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PubMedDate not supplied

Cytotoxic activity of deferiprone, maltol and related hydroxyketones against human tumor cell lines.

Hydroxyketone chelators, deferiprone (HK1), maltol (HK3) and their related compounds (HK2, 4-8), were characterized for their cytotoxic profiles against oral human normal and tumor cells. Most hydroxyketones except HK6 showed relatively higher tumor-specific cytotoxicity. Deferiprone (HK1), which showed the highest tumor specificity, had 10 times higher cytotoxicity than maltol (HK3) in both human promyelocytic leukemia HL-60 and human oral squamous cell carcinoma HSC-2 cell lines. The cytotoxic activity of HK1 against HL-60 and HSC-2 cells was reduced in the presence of FeCl3, while that of HK3 was significantly increased by FeCl3. Agarose gel electrophoresis showed that HK1 induced internucleosomal DNA fragmentation in HL-60 cells, but the addition of FeCl3 inhibited the DNA fragmentation. HK3 did not induce DNA fragmentation in HL-60 cells, regardless of the presence or absence of FeCl3. In HSC-2 cells, HK1 and 3 did not induce DNA fragmentation in the presence or absence of FeCl3. Colorimetric protease assay showed that HK1 activated the caspase 3, 8 and 9 in HL-60 cells. On the other hand, HK3 did not activate the caspase 3, 8 and 9 in HL-60 cells, but activated the caspase 3 only slightly in the presence of FeCl3. HK1 and 3 also activated the caspase 3, 8 and 9 in HSC-2 cells, but to a lesser extent. The present study suggested that the antitumor activity of hydroxyketones may be modified by Fe3+ concentration.

Antineoplastic Agents↗
PubMed2006

Production of sepedonin by Sepedonium chrysospermum NT-1 in submerged culture.

Strains of Sepedonium chrysospermum and the anamorph strain of Hypomyces chrysospermus (congruent with Apiocrea chrysosperma) were isolated and purified from parasitic filamentous fungi on the fruiting bodies of Boletaceae, such as the Gyroponus and Suillus genera in Japan, and identified from formations of conidia and chlamydospores. It is known that these strains produce sepedonin. S. chrysospermum NT-1 strain was selected from these strains and isolated. As the optimum medium (CY-1 medium), 0.1% yeast extract was added to the fruiting-body-forming medium (C medium) of Schizophyllum commune. After 8 days of growth on CY-1 medium, the yield of sepedonin was about 34 mg per 2 g of glucose added. This sepedonin seemed to inhibit the growth of various gram-positive and gram-negative bacteria, yeasts and molds.

Anti-Infective Agents↗
PubMed1991

Investigation of the mechanism of the interaction of tubulin with derivatives of 2-styrylquinazolin-4(3H)-one.

A new class of antimitotic agents, derivatives of 2-styrylquinazolin-4(3H)-one (SQZ), was recently described [J. Med. Chem. 33:1721-1728 (1990)]. Because they appeared to interact at a new ligand binding site on tubulin, we attempted to determine their mechanism of action as inhibitors of tubulin polymerization. Although in initial studies inhibition of colchicine binding was negligible, substantial and competitive inhibition of this reaction could be demonstrated with very short incubation times (less than 5 min), provided that a relatively low colchicine to tubulin ratio was used. The initial apparent failure to inhibit colchicine binding resulted from extremely rapid binding to tubulin and dissociation from tubulin by the SQZ derivatives, in comparison with the slow, temperature-dependent, poorly reversible binding of colchicine. The most inhibitory of the SQZ derivatives in the colchicine binding assay was 6-methyl-2-styrylquinazolin-4(3H)-one (NSC 379310), and its interaction with tubulin, particularly as an inhibitor of colchicine binding, was compared with that of 2-methoxy-5-(2',3',4'-trimethoxyphenyl)tropone (MTPT), because the binding parameters of MTPT with tubulin have been well described. The data indicate that NSC 379310 binds to tubulin and dissociates from the protein about 3 times as rapidly as MTPT. The other SQZ derivatives with equal or greater potency as inhibitors of tubulin polymerization but apparently less potency as inhibitors of colchicine binding presumably bind to and/or dissociate from tubulin even more rapidly than does NSC 379310.

Antineoplastic Agents↗
PubMed1990

Sodium dodecyl sulfate activation of a plant polyphenoloxidase. Effect of sodium dodecyl sulfate on enzymatic and physical characteristics of purified broad bean polyphenoloxidase.

Latent broad bean polyphenoloxidase was purified and shown to be activated by sodium dodecyl sulfate (SDS). Further characterization of the enzyme was carried out in the presence and absence of SDS. Activation of the enzyme increased in a sigmoidal manner with increasing SDS concentrations up to a maximum of 1.75 mM. The presence of SDS eliminated a low pH optimum induced by acid shocking. Increased thermolability of the enzyme was observed in the presence of SDS as well as an increased binding of [14C]dihydroxy-phenylalanine. Size exclusion chromatography on high performance liquid chromatography showed that the size and apparent molecular mass of the enzyme were slightly altered in the presence (48 kDa) versus absence (47 kDa) of SDS. Although the estimations were larger than those obtained by size exclusion techniques, no large differences in molecular weight were observed after sedimentation equilibrium of the enzyme in the presence (53.9 kDa) and absence (52.3 kDa) of SDS. Relative electrophoretic mobility and intrinsic fluorescence of tyrosine and tryptophan residues increased in a complex fashion as the SDS concentration was increased. Plateau regions in these latter experiments corresponded to concentrations of SDS needed for activation. The ability of SDS to activate the enzyme alters both its enzymatic and physical characteristics and suggests that a limited conformational change, due to binding of small amounts of SDS, may induce or initiate the activation of latent enzyme.

Catechol Oxidase↗
PubMed1990

[Platelet production, clearance and distribution in patients with idiopathic thrombocytopenic purpura].

We have studied 8 normal subjects, and 12 patients with idiopathic thrombocytopenic purpura whose platelet counts ranged from 9 x 10(9)/L to 40 x 10(9)/L. Autologous platelets labeled with 111Intropolone were used for evaluation of mean platelet survival, platelet turnover, platelet sequestration sites, and platelet production (turnover) to clearance (sum of platelet uptake in the liver and the spleen) ratio. Platelet survival correlated directly with platelet counts. There was no significant correlation between the platelet sequestration pattern and platelet count, survival, or turnover. Sum of platelet uptake in the liver and the spleen showed a significant inverse correlation with platelet survival. No significant correlation was found between platelet turnover and platelet count. There was a significant correlation between the platelet production to clearance index when all subjects were analyzed. The distribution of platelet turnover showed considerable individual variation; eight of twelve patients showed platelet turnover less than mean minus 2SD of the control value, but others showed normal range. We conclude that although platelet destruction mechanism in RES shows a primary role of thrombocytopenia, impaired rate of effective thrombopoiesis may also contribute to disease severity in ITP.

Adult↗
PubMed1990

The kinetics and quantitation of platelet deposition on control (CPC) and heparin-bonded polyurethane angio-catheter (HBPC) with indium-111 labeled platelets in a dog model.

The dynamics of platelet deposition on CPC and HBPC was evaluated with In-111 labeled platelets (In-PLT) with a computerized gamma camera (CGC). Ten non-heparinized dogs (18-25 kg) were catheterized in both femoral arteries with 10 cm of CPC and HBPC (5 Fr., Cordis, Inc.) 24 hours post-injection of 300-420 microcuries of In-PLT, and imaged for 3 hours with gamma camera. The regional platelet deposition on three segments of catheters and puncture site was determined. The catheters were harvested and radioactivity on the catheter segments (proximal: PROX, middle: MID, distal: DIST and puncture site: PS) of both was determined. From the platelet count in blood, radioactivity in blood and segments of catheters, adjacent artery and area of artery and catheter, the platelet-density [X10(3)] (mean +/- S.D.) on catheter and artery were calculated and tabulated: (table; see text) The large standard deviation of retained platelets is due to embolization. The platelet-density and regional counts on catheter segments were lower in the HBPC than CPC. The rate of platelet-deposition was lower in the HBPC than CPC. Most of the thrombi were lost during pullout of the catheter. Both in vivo (dynamic) and in vitro studies were necessary for evaluation of CPC thrombogenicity.

Animals↗