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PubMed1990

Interaction of platinum complexes of thiazin and xanthene dyes with hyperthermia.

In an attempt to develop platinum-containing drugs for use with hyperthermia that would be relatively nontoxic at 37 degrees C but would become very cytotoxic at 42 degrees or 43 degrees C, several nuclear dyes were complexed to the tetrachloroplatinum(II) dianion (PtCl4) at a ratio of 2:1. The cytotoxicity of PtCl4 complexes of three thiazin dyes (thionin, azure B, and methylene blue), the xanthene dye pyronin Y, and the thiazole dye thioflavin was examined in exponentially growing euoxic and hypoxic EMT6 cells in vitro at 37 degrees, 42 degrees, and 43 degrees C and at pH 7.40 and 6.45. Of the thiazin dye complexes, the cytotoxicity of Pt(methylene blue)2 was most enhanced at hyperthermic temperatures. Both Pt(pyronin Y)2 and Pt(thioflavin)2 also became markedly more cytotoxic at 42 degrees and 43 degrees C at pH 6.45 vs pH 7.40. In vivo tumor excision assays in the FSaIIC fibrosarcoma showed that with each of the thiazin dye-platinum complexes, hyperthermia enhanced cell kill [most effectively on Pt(methylene blue)2] but was not dose-modifying. For both Pt(pyronin Y)2 and Pt(thioflavin)2, however, administration of 43 degrees C, 30-min hyperthermia to the tumor immediately after i.p. drug injection was dose-modifying. Tumor growth delay studies in the FSaIIC tumor system demonstrated that, as with the in vitro studies, Pt(pyronin Y)2 and Pt(methylene blue)2 were most enhanced by hyperthermia [tumor growth delay increased by 4.8- and 3.0-fold, respectively, vs only 1.3-fold for cisplatin (CDDP)]. Examination of intracellular platinum levels after exposure of EMT6 cells to 25 microM of drug for 1 h at 37 degrees and 42 degrees C and at pH 7.40 and 6.45 showed that each platinum-dye complex achieved platinum levels that were 100-600 times higher at 37 degrees C and pH 7.40 than those obtained using CDDP. The platinum levels for each drug dropped markedly when exposure took place at pH 6.45. Exposure at 42 degrees C only moderately increased platinum levels in cells exposed to these drugs. Thus, for several of these drugs the level of cytotoxicity observed was in great part independent of the intracellular platinum levels achieved. Pt(pyronin Y)2 is an effective drug for use with hyperthermia, and further studies using this combination with and without radiation are under way.

Animals↗
PubMed1990

Cytotoxicity, radiosensitization, and DNA interaction of platinum complexes of thiazin and xanthene dyes.

Complexes of the platinum(II) tetrachlorodianion with positively charged nuclear dyes have been prepared in an effort to produce neutral molecules which could gain ready access to the nuclear DNA where the platinum(II) tetrachlorodianion could function as a radiosensitizing and a bifunctional alkylating agent. The thiazin dyes Thionin, Azure B, and Methylene Blue, the aminoxanthene dye Pyronin Y, and the thiazole dye Thioflavin have each been complexed to the platinum(II) tetrachlorodianion(PtCl4) in a ratio of 2:1(dye:PtCl4). Studies of the interaction of these complexes and of the dyes with the pBR322 plasmid superhelical DNA demonstrated that while each complex and dye readily associated with the DNA in a dose-dependent manner, only Pt(Thioflavin)2 and Thioflavin produced irreversible DNA changes (single-strand breaks). In exponentially growing EMT6 cells the cytotoxicity of these drugs was assessed in normally oxygenated and hypoxic cells at both pH 7.4 and 6.45. At concentrations ranging from 1 to 500 microM, Pt(Methylene Blue)2 was significantly more cytotoxic than the other thiazin dye complexes Pt(Thionin)2 and Pt(Azure B)2. The cytotoxicity of Pt(Thionin)2 and Pt(Methylene Blue)2 was increased in normally oxygenated and hypoxic cells at low pH. Both Pt(Pyronin Y)2 and Pt(Thioflavin)2 were more toxic than the thiazin complexes. Pt(Pyronin Y)2 was most cytotoxic to normally oxygenated cells at normal pH and hypoxic cells at low pH, while Pt(Thioflavin)2 was most cytotoxic to cells at low pH under both oxygenation conditions. In vitro studies of the radiosensitizing properties of these agents in EMT6 cells demonstrated that exposure to 100 microM for 1 h before and during irradiation (except for Pt[Thioflavin]2, which was assayed at 25 microM) resulted in enhancement rations of 2.5, 1.9, 1.5, and 1.5 for Pt(Azure B)2, Pt(Thionin)2, Pt(Pyronin Y)2, and Pt(Thioflavin)2, respectively, in hypoxic cells. In contrast, Pt(Methylene Blue)2 (and Methylene Blue) proved to be a radioprotector of normally oxygenated cells and did not sensitize hypoxic cells to the cytotoxic effects of radiation. In the FSaIIC fibrosarcoma in vivo administration of each drug at 100 mg/kg intraperitoneally (ip) 15 min prior to irradiation (except for Pt[Thioflavin]2, which was given at 1 mg/kg ip) showed that, with single radiation fractions of 10 and 20 Gy, dose-modifying factors of 2.1, 1.8, 1.5, and 1.2 were produced by Pt(Azure B)2, Pt(Thionin)2, Pt(Pyronin Y), and Pt(Methylene Blue)2, respectively, after correcting for growth delays induced by the drug alone. In comparison, misonidazole at 1 g/kg ip produced a dose-modifying factor of 1.4.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[The fluorometric method for analysis of some acid drugs].

By using salicylate as a working drug, pyronine was chosen from 31 dyes to form drug-dye complex. In Na2HPO4 solution, salicylate reacts with pyronine to form a complex which is soluble in chloroform. Pyronine fluoresces strongly at lambda ex 542 nm and lambda cm 566 nm and the intensity of pyronine in complex is proportional to the amount of salicylate in the complex with detection limit of 5 ng/ml. By using this method, suberogorgin, flufenamic acid, mechlofenamic acid, mefenamic acid, sodium tauroglycocholate and trichloroacetic acid may be determined with the sensitivity of 10 approximately 50 ng/ml. Salicylate in blood was determined by this method with the sensitivity of 10 ng/ml blood. Good recovery and precision were obtained.

Fluorometry↗
PubMed1983

A simple spectrophotometric method for the measurement of ribonuclease activity in biological fluids.

We have developed a rapid and sensitive method for detecting ribonuclease (RNAase). The method makes use of a RNA-Pyronine Y complex which has a different absorption spectrum from that of Pyronine Y alone. When the RNA is hydrolyzed by RNAase, the spectrum of the complex changes to that of unbound Pyronine Y. The resultant decrease in absorbance at 572 nm is linear for final RNAase concentrations ranging from 2 to 45 ng/ml. Optimal assay conditions were 11.5 micrograms/ml Pyronine Y, 0.56 mg/ml RNA, 80 mumol/ml Tris-HCl buffer, pH 7.8, and 2-45 ng/ml RNAase. The effect of complex concentration, pH, molarity and temperature upon the rate of the reaction were determined. The assay is applicable to crude cell-free extracts.

Animals↗
PubMed1995

Kinetic determination of carbimazole, methimazole and propylthiouracil in pharmaceuticals, animal feed and animal livers.

Kinetic methods are proposed for the determination of carbimazole(CBZ), methimazole(MMI) and propylthiouracil(PTU) based on their inhibitory effects on the palladium(II)-catalysed reaction between the pyronine G and hypophosphite ions. The reactions are monitored spectrophotometrically at 548 nm. The influence of reaction variables and the interfering effect of other substances were studied. Under the selected experimental conditions (CBZ: 3.6 x 10(-5) mol l-1 pyronine G; pH 3.0; 0.7 microgram ml-1 PdII and 0.2 mol l-1 H2PO2-; MMI: 6 x 10(-5) mol l-1 pyronine G, pH 3.0; 0.7 microgram ml-1 PdII, 0.4 mol l-1 H2PO2-; PTU: 3.6 x 10(-5) mol l-1 pyronine G; pH 3.0; 0.7 microgram ml-1 PdII and 0.3 mol l-1 H2PO2-), these three antithyroids were determined in the following ranges: CBZ, 0.04-0.70 microgram ml-1; MMI, 0.04-0.50 microgram ml-1; PTU 0.08-1.00 microgram ml-1. The methods were applied to the determination of CBZ, MMI and PTU, in pharmaceuticals, animal feed and animal livers.

Animal Feed↗
PubMed1978

A new rapid method for selective extraction of RNA from fixed mammalian tissues.

Treatment of formalin-fixed mammalian tissues with concentrated or 50% phosphoric acid at 5 degrees C for 20 and 50 min. respectively reveals complete extraction of RNA as judged by methyl green followed by staining with pyronin. This procedure also causes depolymerisation of DNA as indicated by the red staining of the nuclei. Sections treated with concentrated phosphoric acid at 5 degrees C for 30 min. causes disruption of the double helical structure of DNA what results in the depression of the pyronin staining. Similarly treated sections show Feulgen positive nuclei. Treatment of sections in 25 % phosphoric acid at 60 degrees C for 15 min. followed by staining with methyl green and pyronin show red nuclei, nucleoli and the cytoplasm. This indicates that extraction of RNA is only possible in cold and not at elevated temperature.

Animals↗
PubMed1989

The correlation between uptake of methyl green and Feulgen staining intensity of cell nuclei. An image analysis study.

Paraffin sections of rat tissue fixed in either formaldehyde solution (3.6% w/v) or in Carnoy's fluid were stained using standardized Methyl Green-Pyronin procedures with the dyes used either simultaneously or in sequence. The sections were evaluated for the uptake of the two dyes by cell nuclei, nucleoli and cytoplasm using colour TV-image analysis. The parameters measured were integrated optical density and the surface area of the object. The sections were then destained and a Feulgen reaction was performed. The coordinates of the cells measured after the simultaneous Methyl Green-Pyronin method were stored in the computer, making it possible to measure the same cells in the Feulgen-restained sections. Image analysis gave results which invalidate the sequential methods as opposed to the simultaneous method. Mean optical densities were significantly increased for both dyes with the simultaneous method after formaldehyde fixation as compared to Carnoy fixation. The quantitative correlation of Methyl Green and DNA in the simultaneous technique was found to parallel exactly that of the Feulgen stain. In conclusion, the simultaneous Methyl Green-Pyronin technique is recommended while the sequential methods seem to be of less value.

Animals↗