High-performance liquid chromatography assay of bleomycin in human plasma and rat hepatocytes in culture

An effective validation of analytical method for determination of a polar complexing agent: the illustrative case of cytotoxic bleomycin

The effectiveness of highly polar agents in cancer treatment is well recognized, but their physicochemical properties make their analytical determination a demanding task. Their analysis requires peculiar sample preparation and chromatographic separation, which heavily impacts the precision of such an analytical method. As a case study, we chose a polar cytotoxic bleomycin, which is a mixture of complexing congeners with relatively high molecular mass, a fact that creates an added challenge in regard to its detection via electrospray mass spectrometry. These issues combined lead to a deprived method performance, so the aim of this study is manifold, i.e., to optimize, validate, and establish quality performance measures for determination of bleomycin in pharmaceutical and biological specimens. Quantification of bleomycin is done at diametrically different concentration levels: at the concentrations relevant for analysis of pharmaceutical dosage forms it is based on a direct reversed-phase HPLC-UV detection, involving minimum sample pretreatment. On the contrary, analysis of bleomycin in biological specimens requires phospholipid removal and protein precipitation followed by HILIC chromatography with MS/MS detection of bleomycin A2 and B2 copper complexes being the predominant species. This study further attempts to solve the traceability issue in the absence of certified reference standards, determines measurement uncertainty, investigates BLM stability and method performance characteristics, and, last but not least, provides an explanatory example of how a method quality assurance procedure should be established in case of an exceedingly complex analytical method.

Target-initiated synthesis of fluorescent copper nanoparticles for the sensitive and label-free detection of bleomycin

Fluorescent copper nanoparticles (CuNPs) have received great attention due to their distinct characteristics of facile synthesis, tunable fluorescence emission, high photostability, and biological compatibility, and they have been widely used for chemical and biological analyses. Bleomycins (BLMs) are widely used antitumor agents for the clinical treatment of various cancers. Here, we develop a sensitive and label-free fluorescence method for the quantitative detection of BLM on the basis of BLM-initiated enzymatic polymerization-mediated synthesis of fluorescent CuNPs. We design two hairpin DNAs: one (Hp1) for the recognition of BLM and the other (Hp2) for signal amplification. In the presence of BLM, it may recognize and cleave the 5'-GC-3' site of the Hp1 stem, releasing the 8-17 DNAzyme fragment. The resultant 8-17 DNAzyme fragments may bind with the loop of Hp2 to form a partial double-stranded DNA (dsDNA) duplex, initiating the cyclic cleavage of Hp2 in the presence of Zn2+-dependent DNAzymes and generating numerous new DNA fragments with the free 3'-OH terminal, which can induce the formation of a poly(thymine) (poly-T) sequence with the assistance of terminal deoxynucleotidyl transferase (TdTase). Subsequently, the ploy-T sequence may function as the template for the synthesis of CuNPs with strong fluorescence emission. This method shows good selectivity and high sensitivity with a detection limit as low as 8.1 × 10-16 M, and it exhibits good performance in serum samples. Moreover, this method has distinct advantages of simplicity and low cost, holding great potential in clinical diagnosis and biomedical research.

Mass spectrometry in the pharmacokinetic studies of anticancer natural products

In the history of medicine, nature has represented the main source of medical products. Indeed, the therapeutic use of plants certainly goes back to the Sumerian and Hippocrates and nowadays nature still represents the major source for new drugs discovery. Moreover, in the cancer treatment, drugs are either natural compounds or have been developed from naturally occurring parent compounds firstly isolated from plants and microbes from terrestrial and marine environment. A critical element of an anticancer drug is represented by its severe toxicities and, after administration, the drug concentrations have to remain in an appropriate range to be effective. Anyway, the drug dosage defined during the clinical studies could be inappropriate for an individual patient due to differences in drug absorption, metabolism and excretion. For this reason, personalized medicine, based on therapeutic drug monitoring (TDM), represents one of most important challenges in cancer therapy. Mass spectrometry sensitivity, specificity and fastness lead to elect this technique as the Golden Standard for pharmacokinetics and drug metabolism studies therefore for TDM. This review focuses on the mass spectrometry-based methods developed for pharmacokinetic quantification in human plasma of anticancer drugs derived from natural sources and already used in clinical practice. Particular emphasis was placed both on the pre-analytical and analytical steps, such as: sample preparation procedures, sample size required by the analysis and the limit of quantification of drugs and metabolites to give some insights on the clinical practice applicability. © 2015 Wiley Periodicals, Inc. Mass Spec Rev. 36:213-251, 2017.

Sensitive fluorescence “turn-on” detection of bleomycin based on a superquenched perylene–DNA complex

We introduced a superquenched perylene–DNA complex based method for sensitive fluorescence “turn-on” detection of bleomycin.

Bleomycin, neocarzinostatin and ionising radiation-induced bystander effects in normal diploid human lung fibroblasts, bone marrow mesenchymal stem cells, lung adenocarcinoma cells and peripheral blood lymphocytes

PURPOSE

To determine whether the bystander effects induced by chemotherapeutic agents are similar to those induced by ionising radiation and to analyse the cell dependency, if any, in different human cell types such as normal lung fibroblasts (WI-38), human bone marrow mesenchymal stem cells (hBMSC), lung adenocarcinoma (A-549, NCI-H23) and peripheral blood lymphocytes (PBL).

MATERIALS AND METHODS

The cells mentioned above were exposed to two different concentrations of bleomycin (BLM) and neocarzinostatin (NCS) and to X-irradiation. Co-culture methodology was adopted to study the in vitro bystander effects. DNA damage was measured using a micronucleus (MN) assay as an endpoint to study the bystander response. High performance liquid chromatography (HPLC) was performed to rule out any residual activity of BLM and NCS. To further investigate if this bystander response is mediated through reactive oxygen species (ROS), the bystander cells were pretreated with dimethyl sulphoxide (DMSO), an ROS scavenger, and co-cultured with cells exposed to BLM.

RESULTS

Bystander response was observed in all five types of human cells (WI-38, hBMSC, NCI-H23, A-549 and PBL) co-cultured with exposed cells. While all cell types showed a bystander response, undifferentiated hBMSC and PBL showed a higher magnitude of bystander response. A reduction in the MN frequency was observed in co-cultured hBMSC and PBL pretreated with DMSO.

CONCLUSION

These results suggest that the chemotherapeutic agents, BLM and NCS, induce bystander response which is similar to that induced by radiation. Furthermore, it is observed that the bystander effect is independent of the cell type studied. Our results further support the involvement of ROS in mediating the bystander response induced by BLM.

A highly sensitive resonance Rayleigh scattering method for the determination of bleomycinA5 and bleomycinA2 with some halofluorescein dyes

In a weak acidic medium, bleomycinA(5) (BLMA(5)) and bleomycinA(2) (BLMA(2)) can react with halofluorescein dyes such as erythrosine (Ery), eosin Y (EY), eosin B (EB) and Rose Bengal (RB) by virtue of electrostatic attraction and hydrophobic force to form ion-association complexes, which can result in the large-scale enhancement of resonance Rayleigh scattering (RRS) and the appearance of new RRS spectra. The increments of scattering intensity (Delta I) were directly proportional to the concentrations of bleomycin (BLM) in certain ranges. The detection limits for BLMA(5) and BLMA(2) ranged from 0.017 to 0.062 microg ml(-1). The Ery system had the highest sensitivity and its detection limit (3sigma) was 0.017 microg ml(-1) for BLMA(5) and 0.018 microg ml(-1) for BLMA(2), respectively. Using Ery as a RRS probe, a new highly sensitive method for the determination of BLM anticancer drugs has been developed. It was applied in the determination of BLMA(5) and BLMA(2) in serum and urine samples. The recovery was from 99.0% to 103.0%. In this work, the RRS spectral characteristics of the binding products and the optimum conditions of the reaction were investigated. The mechanism of ion-association reaction and the reasons of enhancement of resonance light scattering were discussed.