Drug repositioning is a revolution breakthrough of drug discovery that presents outstanding privilege with already safer agents by scanning the existing candidates as therapeutic switching or repurposing for marketed drugs. Sitagliptin, vildagliptin, saxagliptin & linagliptin showed antioxidant and neurorestorative effects in previous studies linked to DPP-4 inhibition. Literature showed that gliptins did not cross the blood brain barrier (BBB) while omarigliptin was the first gliptin that crossed it successfully in the present work. LC-MS/MS determination of once-weekly anti-diabetic DPP-4 inhibitors; omarigliptin & trelagliptin in plasma and brain tissue was employed after 2 h of oral administration to rats. The brain/plasma concentration ratio was used to deduce the penetration power through the BBB. Results showed that only omarigliptin crossed the BBB due to its low molecular weight & lipophilic properties suggesting its repositioning as antiparkinsonian agent. The results of BBB crossing will be of interest for researchers interested in Parkinson’s disease. A novel intranasal formulation was developed using sodium lauryl sulphate surfactant to solubilize the lipophilic omarigliptin with penetration enhancing & antimicrobial properties. Intranasal administration showed enhanced brain/plasma ratio by 3.3 folds compared to the oral group accompanied with 2.6 folds increase in brain glucagon-like peptide-1 concentration compared to the control group.

Chlorambucil (N,N-bis(2-chloroethyl)-p-aminophenylbutyric acid) is a bifunctional alkylating drug belonging to the nitrogen mustard group and is widely used as an anticancer agent. As the antitumor activity of the nitrogen mustards is based on the formation of adducts with genomic DNA, calf thymus DNA-Chlorambucil adducts were the major target in this study. Calf thymus DNA was incubated with Chlorambucil to induce the formation of a wide variety of adducts. Subsequently, enzymatic digestion of the DNA was performed using Benzonase and Nuclease S1 aiming at the production of oligonucleotides. Separation and structure elucidation of the individual DNA-Chlorambucil adducts was achieved using HPLC interfaced to electrospray ionization ion trap mass spectrometry. Both trinucleotide and tetranucleotide Chlorambucil adducts were detected. The majority of the detected trinucleotide adducts involved monofunctional alkylation with guanine being the hotspot for alkylation. Only a few bifunctional trinucleotide adducts both intra- and interstrand cross-links were found. On the contrary, cross-linked adducts were the major detected tetranucleotides in which the intrastrand cross-links predominated over the interstrand cross-links. To a lesser extent, monofunctional guanine alkylated tetranucleotides were detected as well. With MS(n) experiments, the detailed structures of Chlorambucil adducts of the tri- and tetranucleotides were determined.

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Oxaliplatin is a third-generation platinum complex, and has a broad spectrum of antitumor activity. Such platinum complexes with the DACH carrier ligand have recently received increasing attention since they show efficacy against cisplatin-resistant cell lines. As the foremost indication of antitumor activity of platinum drugs is the formation of adducts with genomic DNA, calf thymus DNA-oxaliplatin adducts were the major target in this study. Calf thymus DNA was incubated with oxaliplatin, resulting in the formation of a large number of platinum-DNA adducts. Treated DNA was digested into the dinucleotides with a combination of enzymes, namely, benzonase, alkaline phosphatase, and nuclease S1. Using a high-performance liquid chromatography, we carried out the separation of individual platinum-DNA adducts which were concurrently identified using electrospray ionization ion trap mass spectrometry (MS). Both 1,2-intrastrand and 1,2-interstrand cross-linked adducts were found; however, those of the intrastrand nature have a considerably higher abundance than those of the interstrand cross-links. Among them, d(GpG)-oxaliplatin was the most abundant bifuctional adduct. To a lesser extent, a few monofunctional adducts were detected as well. MS(n) experiments served to ascertain the detailed structures of oxaliplatin adducts of dinucleoside monophosphates and of dinucleotides.

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Oxaliplatin, [(1R,2R)-cyclohexane-1,2-diamine](ethanedioato-O,O')platinum(II) shows a great efficiency against colorectal cancer. Although the mode of action of oxaliplatin is not yet understood, it is commonly accepted that binding of oxaliplatin to DNA prevents DNA synthesis and alters protein to DNA binding. In order to elucidate the modified DNA-protein interaction and thus to understand the mechanisms leading to cellular misinterpretation of DNA information and apoptosis, we have identified the preferential binding sites and the dynamics of the oxaliplatin-DNA intrastrand and interstrand adducts at the oligomer level using high-performance liquid chromatography/electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS) and HPLC/inductively coupled plasma-MS for quantitative studies. We used a combination of benzonase, alkaline phosphatase and Nuclease S1 for digestion. This digestion procedure allows the study of platinated oligomeric nucleotides and more complex interstrand adducts. The digestion products were mostly chromatographically separated and characterized using HPLC/ESI-ion trap MS/MS experiments. We could show that the adducts to guanine and adenine are quite dynamic; that is, the ratios are changing for several days. In addition, the resulting adducts provide evidence for the action of the digesting enzymes and indicate that the adduct spectrum at the oligomeric level is different to that at the commonly studies dinucleotide level.

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