Comparison of selected gene expression profiles in sensitive and resistant cancer cells treated with doxorubicin and Selol.

AIM OF THE STUDY: Cellular resistance is strongly correlated with the risk of failure in doxorubicin (DOX) treatment, and the knowledge of the mechanisms of resistance and its possible modulation is still very limited. MATERIAL AND METHODS: In this study, we assessed the effect of 5% Selol and DOX on the expression of genes that affect cell proliferation in the resistant KB-V1 and sensitive HeLa cell lines, using RT2 ProfilerTM PCR Array matrix "Human Cancer Drug Resistance and Metabolism" (SABiosciences). RESULTS: We showed that HeLa and KB-V1 cell lines, characterised by varying susceptibility to DOX, have different genetic profiles as regards the studied genes. KB-V1 cells show overexpression of MYC and BCL2 genes, which encode proteins with anti apoptotic properties. Selol, when used in KB-V1 cells, reduced the expression of MYC and BCL2 genes, suggested as a new therapeutic target in the treatment of cancers resistant to cytostatic drugs. CONCLUSIONS: The results suggest that Selol could be used as a modulator that enhances the cytotoxic effects of doxorubicin, particularly in cells resistant to this drug.

New potential renin inhibitors with dipeptide replacements in the molecule.

A series of eight non-peptidic potential renin inhibitors have been designed and synthesized. All of them contain dipeptide replacement: (3S,4S)-4-amino-5-cyclohexyl-3-hydroxypentanoic acid (ACHPA) in their molecules. Four among them comprise two additional analogs of dipeptide: (3S,4S)-4-amino-3-hydroxy-5-phenylpentanoic acid (AHPPA) and (3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid (statine, Sta). All of the synthesized compounds contain also hydrophobic portions to receive a moderate lipophilicity of the molecules. Inhibitory activity of the compounds was measured in vitro by I-IPLC determination of Leu-Val-Tyr-Ser released from the N-acetyltetradecapeptide substrate by renin in the presence of the inhibitor. Asp-alpha(OEt)-(S,S)-ACHPA-epsilonAhx-Iaa (23) shows inhibitory activity (7%) at the concentration of 1.0 x 10(-2) M. The other synthesized compounds show no inhibitory activity up to this concentration.

New renin inhibitors containing pseudodipeptidic units in P3-P2 and P1-P1' positions.

A series of four non-peptidic renin inhibitors have been designed and synthesized. All of them contain in their molecule (3S,4S)-4-amino-5-cyclohexyl-3-hydroxypentanoic acid (ACHPA), a hydrophobic portion at the C-terminus and a second dipeptide-like transition state analog or unnatural dipeptidic fragment at the N-terminus. Inhibitory activity of the compounds was measured in vitro by high performance liquid chromatography (HPLC). Their IC50 (M/l) values were: <10(-3) (12), 1.0 x 10(-6) (19), 4.0 x 10(-4) (23) and 1.0 x 10(-6) (29), respectively. All the compounds are stable against chymotrypsin.

Determination of in vitro activity renin inhibitors by HPLC method.

A high-performance liquid chromatographic assay has been developed to the separation of angiotensin I, tetradecapeptide and the tetrapeptide Leu-Val-Tyr-Ser. This purpose is achieved in a single step, using HPLC technique in the reversed phase system. The method is based on enzymatic hydrolysis of a substrate renin (TDP) with formation of angiotensin I (DP). After 1 h incubation at 37 degrees C the reaction mixture is introduced directly into the chromatographic system. A 200 microl reaction mixture is needed for analysis. Acetonitrile gradient in 0.01 M ammonium acetate buffer allows a satisfactory separation of hydrolysis products. The application of this technique for the determination of in vitro renin activity and evaluation the potency of human renin inhibitors, employing the artificial renin substrate tetradecapeptide, is demonstrated.

Application of the HPLC method for benzalkonium chloride determination in aerosol preparations.

Benzalkonium chloride (BAC) is a bacteriostatic agent used in the pharmaceutical industry as a preservative. BAC is a mixture of alkylbenzyldimethylammonium chlorides, the three most important of which being those with alkyl substituents C12, C14, C16 at the quaternary ammonium salt. The purpose of this study was to develop a method for determining benzalkonium chloride identity and content in aerosol preparations in which protein or steroid hormones are the active components. The high performance liquid chromatography (HPLC) method was used for this purpose. In the performed comparison of the influence of selected factors on the process of the separation of BAC homologues, a column with packing modified with cyan groups and mobile phase containing 0.075 M acetate buffer with acetonitrile (45:55), in an isocratic elution, was used for qualitative and quantitative determinations and for method validation. The developed method may be used for the assessment of the identity and content of BAC homologues in various pharmaceutical preparations. It is simple and it does not require particular sample preparation for the tests. It is characterized by good selectivity and high precision of the determinations.

Application of high-performance size exclusion chromatography to the determination of erythropoietin in pharmaceutical preparations.

High performance size exclusion chromatography with fluorimetric detection for the determination of erythropoietin in pharmaceutical preparations has been developed. The applied chromatographic system has been enabled a quick estimation of the identity and contents of the studied compound. The method was validated and showed good validation data in terms of linearity, precision and repeatability. The validated method was successfully applied to the determination of erythropoietin content in commercially available preparations.

Determination of the content of desmopressin in pharmaceutical preparations by HPLC and validation of the method.

The aim of this study was to apply high performance liquid chromatography to the determination of content of desmopressin in pharmaceutical preparations and validation of the method. The satisfactory results have been obtained using a column Luna C 8.5 microm, 100 x 4.6 mm and a mobile phase containing 0.067 M phosphate buffer of pH = 7 and acetonitrile in the proportion 83:17. It has been shown that the elaborated method shows good precision and accuracy and can be applied to the qualitative and quantitative analysis of pharmaceutical preparations containing desmopressin.