Kinetics of hydrolysis in vitro of nornitrogen mustard, a metabolite of phosphoramide mustard and cyclophosphamide

Substrate-Coated Illumination Droplet Spray Ionization: Real-Time Monitoring of Photocatalytic Reactions

Real-time monitoring of photocatalytic reactions facilitates the elucidation of the mechanisms of the reactions. However, suitable tools for real-time monitoring are lacking. Herein, a novel method based on droplet spray ionization named substrate-coated illumination droplet spray ionization (SCI-DSI) for direct analysis of photocatalytic reaction solution is reported. SCI-DSI addresses many of the analytical limitations of electrospray ionization (ESI) for analysis of photocatalytic-reaction intermediates, and has potential for both in situ analysis and real-time monitoring of photocatalytic reactions. In SCI-DSI-mass spectrometry (MS), a photocatalytic reaction occurs by loading sample solutions onto the substrate-coated cover slip and by applying UV light above the modified slip; one corner of this slip adjacent to the inlet of a mass spectrometer is the high-electric-field location for launching a charged-droplet spray. After both testing and optimizing the performance of SCI-DSI, the value of this method for in situ analysis and real-time monitoring of photocatalytic reactions was demonstrated by the removal of cyclophosphamide (CP) in TiO₂/UV. Reaction times ranged from seconds to minutes, and the proposed reaction intermediates were captured and identified by tandem mass spectrometry. Moreover, the free hydroxyl radical (·OH) was identified as the main radicals for CP removal. These results show that SCI-DSI is suitable for in situ analysis and real-time monitoring of CP removal under TiO₂-based photocatalytic reactions. SCI-DSI is also a potential tool for in situ analysis and real-time assessment of the roles of radicals during CP removal under TiO₂-based photocatalytic reactions.Graphical Abstract.

Photodegradation of the antineoplastic cyclophosphamide: a comparative study of the efficiencies of UV/H2O2, UV/Fe2+/H2O2 and UV/TiO2 processes

Anticancer drugs are harmful substances that can have carcinogenic, mutagenic, teratogenic, genotoxic, and cytotoxic effects even at low concentrations. More than 50 years after its introduction, the alkylating agent cyclophosphamide (CP) is still one of the most consumed anticancer drug worldwide. CP has been detected in water bodies in several studies and is known as being persistent in the aquatic environment. As the traditional water and wastewater treatment technologies are not able to remove CP from the water, different treatment options such as advanced oxidation processes (AOPs) are under discussion to eliminate these compounds. The present study investigated the degradation of CP by three different AOPs: UV/H2O2, UV/Fe(2+)/H2O2 and UV/TiO2. The light source was a Hg medium-pressure lamp. Prescreening tests were carried out and afterwards experiments based on the optimized conditions were performed. The primary elimination of the parent compounds and the detection of transformation products (TPs) were monitored with LC-UV-MS/MS analysis, whereas the degree of mineralization was monitored by measuring the dissolved organic carbon (DOC). Ecotoxicological assays were carried out with the luminescent bacteria Vibrio fischeri. CP was completely degraded in all treatments and UV/Fe(2+)/H2O2 was the fastest process, followed by UV/H2O2 and UV/TiO2. All the reactions obeyed pseudo-first order kinetics. Considering the mineralization UV/Fe(2+)/H2O2 and UV/TiO2 were the most efficient process with mineralization degrees higher than 85%, whereas UV/H2O2 achieved 72.5% of DOC removal. Five transformation products were formed during the reactions and identified. None of them showed significant toxicity against V. fischeri.

Silencing of the IGF1R gene enhances sensitivity to DNA-damaging agents in both PTEN wild-type and mutant human prostate cancer

The type 1 insulin-like growth factor receptor (IGF1R) is overexpressed in prostate cancer, and mediates proliferation, motility, and survival. Many prostate cancers harbor inactivating PTEN mutations, enhancing Akt phosphorylation. This activates the principal antiapoptotic pathway downstream of the IGF1R, calling into question the value of IGF1R targeting in this tumor. The aim of the current study was to assess the effect of IGF1R gene silencing in prostate cancer cells that lack functional PTEN protein. In human DU145, LNCaP and PC3 prostate cancer cells, transfection with IGF1R small interfering RNA induced significant enhancement of apoptosis and inhibition of survival, not only in PTEN wild-type DU145 but also in PTEN mutant LNCaP and PC3. This was attributed to attenuation of IGF signaling via Akt, ERKs and p38. In both DU145 and PC3, IGF1R knockdown led to enhancement of sensitivity to mitoxantrone, etoposide, nitrogen mustard and ionizing radiation. There was no sensitization to paclitaxel or 5-fluorouracil, which do not damage DNA, suggesting that chemosensitization results from impairment of the DNA damage response, in addition to removal of apoptosis protection. These results support the concept of IGF1R targeting in prostate cancer, and indicate that PTEN loss does not render tumor cells refractory to this strategy.

Degradation of NSC-281612 (4-[bis[2-[(Methylsulfonyl)Oxy]ethyl]amino]-2-methyl-benzaldehyde), an Experimental Antineoplastic Agent: Effects of PH, Solvent Composition, (SBE)7m-β-CD, and HP-β-CD on Stability

NSC-281612 (4-[bis[2-[(methylsulfonyl)oxy]ethyl]amino]-2-methyl-benzaldehyde, 1), is a chemically unstable, poorly water soluble, experimental antineoplastic agent. The saturated solubility in water at 25 degrees C was determined as approximately 30 microg/mL. In the pH range 2-11, 1 displayed pH-independent stability (t(50) was around 24 hr). However, an increase in the degradation rate was observed at pH 12. The hydrolysis of the methane sulfonate groups to the corresponding hydroxyl groups was the major degradation pathway in water in the absence of buffers and added halide ions. In phosphate buffer solutions without sodium chloride, phosphate degradants appear to be formed in addition to the mono- and dihydroxy degradants. Additional degradants, the mono- and dichloro degradation products, were formed when the ionic strength of the solution was adjusted with sodium chloride. When bromide and iodide ions were added, the corresponding mono- and dihalides were formed. The chloro compounds subsequently underwent further degradation to the hydroxy products. A deuterium kinetic solvent isotope effect study showed that water was minimally involved in the rate-determining step. The addition of either (SBE)(7m)-beta-cyclodextrin (CD) or HP-beta-CD resulted in a significant enhancement in drug solubility and stability. The apparent binding constants for HP-beta-CD and (SBE)(7m)-beta-CD were 1,486 and 2,740 M(-1), respectively. The stability of 1 in the presence of 0.1 M HP-beta-CD and (SBE)(7m)-beta-CD was enhanced 9- and 15-fold, respectively. Thus, (SBE)(7m)-beta-CD displayed better solubilization and stabilization efficacy than HP-beta-CD.

Cyclophosphamide and related anticancer drugs

This article presents an overview of the methods of bioanalysis of oxazaphosphorines, in particular, cyclophosphamide, ifosfamide, and trofosfamide as well as their metabolites. The metabolism of oxazaphosphorines is complex and leads to a large variety of metabolites and therefore the spectrum of methods used is relatively broad. The various methods used are shown in a table and the particularly important assays are described.