Novel Pyrimidine Derivatives as Antioxidant and Anticancer Agents: Design, Synthesis and Molecular Modeling Studies

The heterocyclic ring system of pyrido [2,3-d]pyrimidines is a privileged scaffold in medicinal chemistry, possessing several biological activities. The synthesis of the pyrimidine derivatives was performed via the condensation of a suitable α,β-unsaturated ketone with 4-amino-6-hydroxy-2-mercaptopyrimidine monohydrate in glacial acetic acid. Chalcones were synthesized, as starting materials, via the Claisen-Schmidt condensation of an appropriately substituted ketone and an appropriately substituted aldehyde in the presence of aqueous KOH 40% w/v in ethanol. All the synthesized compounds were characterized using IR, ¹H-NMR, ¹³C-NMR, LC-MS and elemental analysis. The synthesized compounds were evaluated for their antioxidant (DPPH assay), anti-lipid peroxidation (AAPH), anti-LOX activities and ability to interact with glutathione. The compounds do not interact significantly with DPPH but strongly inhibit lipid peroxidation. Pyrimidine derivatives 2a (IC₅₀ = 42 μΜ), 2f (IC₅₀ = 47.5 μΜ) and chalcone 1g (IC₅₀ = 17 μM) were the most potent lipoxygenase inhibitors. All the tested compounds were found to interact with glutathione, apart from 1h. Cell viability and cytotoxicity assays were performed with the HaCaT and A549 cell lines, respectively. In the MTT assay towards the HaCaT cell line, none of the compounds presented viability at 100 μM. On the contrary, in the MTT assay towards the A549 cell line, the tested compounds showed strong cytotoxicity at 100 μM, with derivative 2d presenting the strongest cytotoxic effects at the concentration of 50 μΜ.

Flower beverages of native medicinal plants from Argentina (Acacia caven, Geoffroea decorticans and Larrea divaricata) as antioxidant and anti-inflammatory

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal beverages have been used as a natural part of the medicinal and food culture in northwestern Argentina. The flower beverages (infusion or decoction) of Acacia caven, Geoffroea decorticans and Larrea divaricata, three native species from arid and semiarid regions of Argentina are widely used as anti-inflammatory and anti-rheumatic by several local communities.

AIM OF THE STUDY

The aim of this study was to analyze the phytochemical composition of some Argentine flower beverage and to validate its traditional use as an antioxidant and anti-inflammatory agent.

MATERIALS AND METHODS

Phenolic profiles from all flower infusions and decoctions were analyzed by both spectrophotometric analysis and HPLC-DAD. ABTS^•+; the scavenging activity of both hydrogen peroxide and hydroxyl radical was determined and finally, their ability to inhibit pro-inflammatory enzymes, such as xanthine oxidase (XOD), and lipoxygenase (LOX) was also assessed.

RESULTS

The flower beverages of all assayed species showed a high level of phenolic compounds with similar chromatographic patterns in both infusions and decoctions of each plant species, the major components of which have been identified. The flower beverages, especially G. decorticans infusion and decoctions, displayed an important antioxidant activity (SC₅₀ values between 18.14 and 47 μg/mL) through different mechanisms; all of them were able to inhibit the XOD enzyme activity and, consequently, the formation of uric acid and reactive oxygen species, the primary cause of arthritis-related diseases. The most active beverages as XOD inhibitor were G. decorticans flower infusion and decoctions (IC₅₀ values of 20 and 35 μg/mL, respectively). Pro-inflammatory enzymes, such as LOX, were also inhibited by infusions and decoctions of G. decorticans, L. cuneifolia and A caven flowers, lessening inflammation mediators in all beverages.

CONCLUSIONS

The present work validates the traditional medicinal use of flower beverages from Argentina as an anti-rheumatic and anti-inflammatory agent as it has been used for hundreds of years in several pathologies associated with oxidative stress.

Novel quinolinone-pyrazoline hybrids: synthesis and evaluation of antioxidant and lipoxygenase inhibitory activity

The present project deals with the investigation of structure-activity relationship of several quinolinone-chalcone and quinolinone-pyrazoline hybrids, in an effort to discover promising antioxidant and anti-inflammatory agents. In order to accomplish this goal, four bioactive hybrid quinolinone-chalcone compounds (8a-8d) were synthesized via an aldol condensation reaction, which were then chemically modified, forming fifteen new pyrazoline analogues (9a-9o). All the synthesized analogues were in vitro evaluated in terms of their antioxidant and soybean lipoxygenase (LOX) inhibitory activity. Among all the pyrazoline derivatives, compounds 9b and 9m were found to possess the best combined activity, whereas 9b analogue exhibited the most potent LOX inhibitory activity, with IC50 value 10 μM. The in silico docking results revealed that the synthetic pyrazoline analogue 9b showed high AutoDock Vina score (- 10.3 kcal/mol), while all the tested derivatives presented allosteric interactions with the enzyme.

In Vivo Expansion of Cancer Stemness Affords Novel Cancer Stem Cell Targets: Malignant Rhabdoid Tumor as an Example

Cancer stem cell (CSC) identification relies on transplantation assays of cell subpopulations sorted from fresh tumor samples. Here, we attempt to bypass limitations of abundant tumor source and predetermined immune selection by in vivo propagating patient-derived xenografts (PDX) from human malignant rhabdoid tumor (MRT), a rare and lethal pediatric neoplasm, to an advanced state in which most cells behave as CSCs. Stemness is then probed by comparative transcriptomics of serial PDXs generating a gene signature of epithelial to mesenchymal transition, invasion/motility, metastasis, and self-renewal, pinpointing putative MRT CSC markers. The relevance of these putative CSC molecules is analyzed by sorting tumorigenic fractions from early-passaged PDX according to one such molecule, deciphering expression in archived primary tumors, and testing the effects of CSC molecule inhibition on MRT growth. Using this platform, we identify ALDH1 and lysyl oxidase (LOX) as relevant targets and provide a larger framework for target and drug discovery in rare pediatric cancers.

•

Human malignant rhabdoid tumor (MRT) can be propagated in vivo as tumor xenografts

•

Long-term propagated PDX enrich for CSC frequency with no need for immune selection

•

Distinct gene signature in stem-like MRT xenografts reveals putative CSC biomarkers

•

Screening of putative CSC biomarkers allows identification of therapeutic targets