Artemisinins as potential anticancer agents: uptake detection in erythrocytes using Fourier transform infrared spectroscopy and cytotoxicity against bladder cancer cells.

AIMS: Semisynthetic derivatives of the antimalarial drug artemisinin may also possess anticancer properties. The ability to detect artemisinin uptake and distribution in cells would facilitate live cell imaging without labelling. This study describes mid-range infrared absorption spectra for three artemisinin variants and attempts to detect their presence in a simple cell model (erythrocytes). Cytotoxicity assays assess potential anticancer properties against bladder cancer cells. METHODS: Mid-range Fourier transform infrared spectra were obtained from dry preparations of dihydroartemisinin (DHA), artesunate (ART) and artemether (ARTE). Erythrocytes were prepared from normal blood and incubated for 30 min at 37°C with the three artemisinin derivatives. Cytospin preparations were prepared on aluminium foil for spectroscopy. Potential for growth inhibition in the RT112 bladder carcinoma cell line was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide residual viable biomass method. RESULTS: Spectra were obtained from the three native compounds. Repeat scans after 8 weeks showed ART and ARTE to be stable, stored under manufacturer's recommendations. DHA exhibited marked changes over the same period. It was possible by subtraction to detect DHA in cytospins, but not ART or ARTE. The fit between the subtraction spectrum and that of the native compound was >80%. DHA and ART showed strong cytotoxic potential against RT112 cells. CONCLUSIONS: The artemisinin derivatives tested exhibit unique mid-range infrared absorption spectra which can be used to monitor degradation and, for DHA, can be detected by subtraction in loaded erythrocytes rendering future imaging studies feasible. Its cytotoxic efficacy against RT112 cells suggests bladder cancer as a possible target disease.