Improved high-performance liquid chromatographic analysis of teniposide in human plasma

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.

Natural compounds with P2X7 receptor-modulating properties

The adenosine 5'-triphosphate (ATP)-gated P2X7 receptor is a membrane-bound, non-selective cation channel, expressed in a variety of cell types. The P2X7 senses high extracellular ATP concentrations and seems to be implicated in a wide range of cellular functions as well as pathophysiological processes, including immune responses and inflammation, release of gliotransmitters and cytokines, cancer cell growth or development of neurodegenerative diseases. In the present study, we identified natural compounds and analogues that can block or sensitize the ATP (1 mM)-induced Ca(2+) response using a HEK293 cell line stably expressing human P2X7 and fluorometric imaging plate reader technology. For instance, teniposide potently blocked the human P2X7 at sub-miromolar concentrations, but not human P2X4 or rat P2X2. A marked block of ATP-induced Ca(2+) entry and Yo-Pro-1 uptake was also observed in human A375 melanoma cells and mouse microglial cells, both expressing P2X7. On the other hand, agelasine (AGL) and garcinolic acid (GA) facilitated the P2X7 response to ATP in all three cell populations. GA also enhanced the YO-PRO-1 uptake, whereas AGL did not affect the ATP-stimulated intracellular accumulation of this dye. According to the pathophysiological role of P2X7 in various diseases, selective modulators may have potential for further development, e.g. as neuroprotective or antineoplastic drugs.

A cremophor-free self-microemulsified delivery system for intravenous injection of teniposide: evaluation in vitro and in vivo

In order to tackle the problems on low water solubility of teniposide, involvement of toxic surfactant in its injection, and the poor stability during infusion, a Cremophor-free teniposide self-microemulsified drug delivery system (TEN-SMEDDS) was prepared for the first time, characterized, and evaluated in comparison with teniposide injection (VUMON) in vitro and in vivo. The optimized formulation contained N, N-dimethylacetamide, medium-chain triglyceride, lecithin, and dehydrated alcohol besides teniposide. The TEN-SMEDDS could form fine droplets with mean diameter of 282 ± 21 nm and zeta potential of -7.5 ± 1.7 mV after dilution with 5% glucose, which were stable within 4 h. The release of teniposide from TEN-SMEDDS and VUMON was similar. However, the pharmacokinetic behavior of TEN-SMEDDS in rats was different from that of VUMON, evidenced by the lower area under the concentration-time curve and larger volume of distribution in emulsion group. Finally, TEN-SMEDDS was found to distribute more teniposide in most tissues, especially in reticuloendothelial system, after intravenous administration to rats. Importantly, brain drug level in TEN-SMEDDS group was higher than or similar to that in control group, although the emulsion system had a lower plasma drug concentration. In conclusion, the novel SMEDDS prepared here, without toxic surfactant and as an oil solution before use, may be potential for clinical use due to its low toxicity and high store stability. It may be favorable for the treatment of some tumors like cerebroma, since it may achieve the relatively higher drug level in brain but lower blood concentration.

High-performance liquid chromatographic methods for the determination of topoisomerase II inhibitors

Various methods for separating eleven different types of topoisomerase II (TOPO-2) inhibitors, including epipodophyllotoxins, anthracyclines, anthracenediones, anthrapyrazoles, anthracenebishydrazones, indole derivatives, aminoacridines, benzisoquinolinediones, isoflavones, bisdioxopiperazines and thiobarbituric acids, are summarized. Proper sample preparation and storage is critical to the successful analysis of some TOPO-2 inhibitors due to difficulties associated with adsorption, instability and complex biological components. Solid-phase and liquid-liquid extractions are widely used to separate TOPO-2 inhibitors from biological samples, although simple deproteinization followed by direct analysis of the supernatant is preferable to extraction based on its speed and simplicity. High-performance liquid chromatography (HPLC) is the favored method for the bioanalysis of TOPO-2 inhibitors. UV or diode array detection is generally employed for early pharmacokinetic studies, while fluorescence or electrochemical detection is used more frequently for analytes with fluorescent or oxidative-reductive properties. For analyses requiring highly sensitive and/or specific detection, electrospray mass spectrometry (ESI-MS or ESI-MS-MS) provides a suitable alternative. A comprehensive compilation of the HPLC techniques currently used to separate TOPO-2 inhibitors will aid the future development of analytical methods for new TOPO-2 inhibitors.