Stabilität des Ferricinium-Kations und seine cytostatische Wirkung / Stability of Ferricinium and its Cytostatic Effect

The relative stabilities of different ferricinium cations were studied in buffer or serum-containing solution and in vivo and compared with their cytostatic effects in cultures of Yoshida ascites tumor cells.

Although the ferricinium cation itself was the most unstable cation compared with the dimethyl-ferricinium cation and the deuterated ferricinium derivatives it showed the highest cytostatic effect.

Synthesis, characterization, and antiplasmodial activity of polymer-incorporated aminoquinolines

In this research, aminoquinoline compounds were synthesized, characterized, and incorporated into water-soluble polymers to form conjugates. The conjugates were characterized by X-ray diffraction, thermal gravimetric analysis, scanning electron microscope, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy to confirm the successful incorporation of the aminoquinoline compound on to the polymer. The synthesized conjugates were screened for in vitro antiplasmodial activity in triplet test against chloroquine-sensitive strain of Plasmodium falciparum and chloroquine drug was used as a reference drug in all the experiments. A full dose-response was performed to determine the concentration inhibiting 50% of parasite growth (IC50 value). Polymeric conjugates containing 3-diethylamino-1-propylamine solubilizing units were found to be most active against the chloroquine-sensitive strain of P. falciparum.

Evaluation of cisplatin and a novel platinum polymer conjugate for drug toxicity and drug distribution in mice

The toxicity and distribution of cisplatin and two novel platinum (Pt) polymer conjugates (Pt-6 and Pt-7) were determined in serum and tissue of BALB/c mice at specific time points after i.p. administration of a drug bolus containing identical Pt concentrations. Pt concentrations were determined in serum, liver and kidney at 5 and 15 min, respectively, after drug administration by inductively coupled plasma mass spectrometry. It was found that the Pt polymer Pt-7 gave rise to a considerably lower Pt concentration in serum and considerably higher concentration in liver and kidney than cisplatin. LD25 measurements indicated that the Pt-7 polymer is considerably less toxic than cisplatin. In vitro experiments and determination of IC50 values in a variety of human tumor cell lines, normal lymphocytes and fibroblasts confirmed that Pt-6 and Pt-7 polymers are 40-500 times more toxic for tumor cells than for normal cells, perhaps reflecting preferential uptake. The toxicity of cisplatin was found to be only 1.6-40 times more effective in tumor cells. These inter-relationships are supported by the observation that the tumor enrichment factor (TEF) for cisplatin is only in the region of 6, and much lower than for Pt-6 and Pt-7, where TEFs are in the region of 40 and 150, respectively. These results demonstrate that the Pt polymer conjugates exhibit greater tumor specificity than cisplatin, killing tumor cells more effectively while being considerably less toxic for normal cells. It is concluded that the Pt polymer conjugates may be superior for cancer therapy and warrant further testing to assess their full clinical potential.

Polyaspartamides as water-soluble drug carriers. Part 1: Antineoplastic activity of ferrocene-containing polyaspartamide conjugates

BACKGROUND

Numerous detrimental side effects and/or lack of water-solubility of anticancer drugs often prove dose-limiting in chemotherapy. Water-soluble polymeric drug carriers may overcome/minimise many of these limitations.

MATERIALS AND METHODS

Aspartic acid polymers to which ferrocene-containing antineoplastic agents are covalently bound, were tested for cytotoxicity against murine EMT-6 cancer cells. Cell survival was measured by means of the colorometric 3-(4,5-dimethylthiazol-2-yl)-diphenyltertrazolium bromide assay.

RESULTS

The 90% lethal dosage of pure 3-ferrocenylbutanoic acid is 452 microg/mL LD90 for the polymeric derivative, expressed in terms of 3-ferrocenylbutanoic acid content, is only 65 microg/ml. A polymer structural effect in drug activity was evident: longer side chains linking drugs to polymer backbones enhanced drug activity. Drug activity is also enhanced if drug modifications (to enable drug anchoring) resulted in a lower ferrocenyl reduction potential.

CONCLUSIONS

The effectivity of antineoplastic drugs may be enhanced by covalently anchoring them on suitable biodegradable water-soluble polymeric drug carriers.

[Stability of ferricinium cations and their cytostatic effect]

The relative stabilities of different ferricinium cations were studied in buffer or serum-containing solution and in vivo and compared with their cytostatic effects in cultures of Yoshida ascites tumor cells. Although the ferricinium cation itself was the most unstable cation compared with the dimethyl-ferricinium cation and the deuterated ferricinium derivatives it showed the highest cytostatic effect.

Ferricenium complexes: a new type of water-soluble antitumor agent

The antitumor activity of a series of iron complexes, i.e., of ferrocene [Cp2Fe], of tetrachloroferrates(III) [R4N]+[FeCl4]-, and of ferricenium complexes [Cp2Fe]+X- (X- = [FeCl4]-, 1/2 [Cl3FeOFeCl3]2-, [H5Mo7O24]- X 2H2O, [2,4,6-(NO2)3C6H2O]-, or [CCl3COO]- X 2 CCl3COOH) was investigated against EAT in CF1 mice. Whereas ferrocene and the ammonium tetrachloroferrates(III) did not show recognizable tumor-inhibiting activity, such activity was exhibited by the water-soluble, salt-like ferricenium complexes; the best antineoplastic properties, with optimum cure rates of 100%, were found for ferricenium picrate and ferricenium trichloroacetate. The ferricenium compounds are the first iron complexes for which antineoplastic activity has now been shown. They represent a new type of antitumor agent insofar as they differ fundamentally from known inorganic and organometallic antitumor agents (a) by their ionic, salt-like character, which is responsible for their high water solubility, and (b) by the absence of a cis-dihalometal moiety; this moiety has been recognized as important for the intracellular action of other known inorganic cytostatics.