Synthesis, Characterization and Cytotoxic Evaluation of New Pyrrolo[1,2-b]pyridazines Obtained via Mesoionic Oxazolo-Pyridazinones

Abstract

New pyrrolo[1,2-b]pyridazines were synthesized by 3 + 2 cycloaddition reaction between mesoionic oxazolo-pyridazinones and methyl/ethyl propiolate. The mesoionic compounds were generated in situ by action of acetic anhydride on 3(2H)pyridazinone acids obtained from corresponding esters by alkaline hydrolysis followed by acidification. The structures of the compounds were confirmed by elemental analyses and IR, 1H-NMR, 13C-NMR, and X-ray diffraction data. The regioselectivity of cycloaddition was evidenced by NMR spectroscopy and confirmed by X-ray analysis. The compounds were evaluated for their cytotoxicity on plant cells (Triticum aestivum L.) and crustacean animal cells (Artemia franciscana Kellogg and Daphnia magna Straus). The results indicated that the tested compounds exhibited low toxicity on the plant cell (IC50 values higher than 200 µM), while on Artemia nauplii no lethality was observed. Daphnia magna assay showed that pyrrolo[1,2-b]pyridazines 5a and 5c could exhibit toxic effects, whereas, for the other compounds, toxicity was low to moderate. Also, the cytotoxic effects of the compounds were tested on three human adenocarcinoma-derived adherent cell lines (colon LoVo, ovary SK-OV-3, breast MCF-7). The in vitro compound-mediated cytotoxicity assays, performed by the MTS technique, demonstrated dose- and time-dependent cytotoxic activity for several compounds, the highest anti-tumor activity being observed for 5a, 2c, and 5f, especially against colon cancer cells.

Antioxidant and Cytotoxic Properties of <em>Berberis vulgaris</em> (L.) Stem Bark Dry Extract

“…For the cytotoxicity assays, cells were detached from culture flasks and then cultivated in 96-well flat bottom plates for 24 hours until they reached around 70% confluence. Then, cells were treated for various periods (24h and 48h) with different concentrations of BVE, BS, or oncolytic drugs (5-FU, CisPt, DOX) -used as positive controls [39]. BVE and BS stock solutions were prepared by dissolving them in a minimal amount of DMSO and preserved at 4⁰ C; all working solutions were prepared from the stocks by serial dilutions with culture medium before each treatment assay [17].…”

Antioxidant and Cytotoxic Properties of Berberis vulgaris (L.) Stem Bark Dry Extract

“…For the cytotoxicity assays, the cells were detached from the culture flasks and then cultivated in 96-well flat-bottom plates for 24 h until they reached around 70% confluence. Then, the cells were treated for various periods (24 h and 48 h) with different concentrations of BVE, BS, or oncolytic drugs (5-FU, CisPt, DOX) used as positive controls [43]. The BVE and BS stock solutions were prepared by dissolving them in a minimal amount of DMSO and preserved at 4 • C; all the working solutions were prepared from the stocks by serial dilutions with culture medium before each treatment assay [17].…”