Evaluation of genotoxic potential of tert-butylquinone and its derivatives in prokaryotic and eukaryotic test models.

Tert-butylquinone (TBQ) and its alkylamino and aralkylamino derivatives are of high interest as a potential antitumor agent. Therefore, it was necessary to investigate if the compounds exert undesirable activities such as interaction with DNA molecule which could result in negative side effects in the case of their use in the diseases treatment. The major aim of this study was to investigate genotoxic potential of TBQ and selected derivatives in an acellular model by using plasmid DNA, in the prokaryotic model by the SOS/umuC assay in Salmonella typhimurium TA1535/pSK1002 and in eukaryotic models by using comet assay in human fetal lung cell line (MRC-5) and human liver cancer cell line (HepG2). Results indicated that in the acellular model TBQ and its derivatives do not interact with plasmid pUC19. In the prokaryotic model, only TBQ exerted weak genotoxic potential and only at highly cytotoxic concentrations. In eukaryotic models, genotoxic potential was detected mainly at the highest concentrations of the tested substances but the effect was lower in both cell lines in comparison with benzo[a]pyrene and etoposide which were used as positive controls. Weak genotoxic potential of tested compounds recommends them as good candidates for further testing in development of new antitumor agents.

Potential of Natural-Based Anticancer Compounds for P-Glycoprotein Inhibition.

Medicinal value of natural products comes from symbiotic and competitive evolution in Earth's complex biosphere. Billions of years of co-evolutionary interactions among millions of species have produced a large repertoire of defense molecules effective in fighting bacteria, viral, and fungal pathogens. Each species contains millions of different and useful molecules and new research technologies enabled the screening of molecules and complex mixtures from diverse biological sources. Traditional use of plants and other species led to the discovery of many bioactive compounds with various properties. In the last four decades, a large number of them were evaluated for their potential to treat cancer. Penetration of drugs into the cancer cell is necessary for their lethal pharmacological effect through interaction with intracellular target molecules. Increased activity of membrane efflux pumps reduces the intracellular drug accumulation, thereby preventing drug-target interactions. The discovery of the efflux transporter P-glycoprotein (P-gp) in multidrug resistant (MDR) cancer cells prompted the efforts in overcoming drug resistance by P-gp inhibition. The search for nontoxic anticancer agents from natural sources able to overcome MDR has been imperative in the field of drug design and discovery. Herein, we review various natural compounds from diverse sources emphasizing their potential to inhibit P-gp activity and/or expression.

Simple avarone mimetics as selective agents against multidrug resistant cancer cells.

In this work, synthesis of alkylamino and aralkylamino derivatives of sesquiterpene quinone avarone and its model compound tert-butylquinone was described. For all obtained derivatives biological activity was studied. Cytotoxic activity of the synthesized derivatives towards multidrug resistant MDR human non-small cell lung carcinoma NCI-H460/R cells, their sensitive counterpart NCI-H460 and human normal keratinocytes (HaCaT) as well as detection of cell death superoxide anion generation were investigated. Antimicrobial activity towards Gram positive and Gram negative bacteria and fungal cultures was determined. The results showed that strong cytotoxic activity toward cancer cells was improved with simple avarone mimetics. Some derivatives were selective towards MDR cancer cells. The most active derivatives induced apoptosis in both cancer cell lines, but not in normal cells. Superoxide production was induced by 2,6-disubstituted compounds in MDR cancer cells and not by less active 2,5-disubstituted compounds and was accompanied by the collapse of the mitochondrial transmembrane potential. Two tert-butylquinone derivatives were particularly selective towards MDR cancer cells. Some tert-butylquinone derivatives exhibited a strong antimicrobial activity.