I have some problems to use camptothecin. The first time I prepared a dilution in DMSO and it worked. The second time I used the dilution stored at -20°, but it didn't work. So I prepared again a new dilution from the powder, but it didn't work. Is it possible that the powder, just bought from Sigma, is completely inactive?
Does someone use CPT frequently and have similar problems or have any suggestion in the CPT preparation?
Thank you in advance,
Alessandra
Did you dissolve the powder in 100% DMSO to prepare the stock solution?
With other drugs (etoposide, bleomycin...) we keep the stock solution at 4°C and not at -20°C.
Hello Alessandra
I am also using Sigma camptothecin (5 mg/mL) solution prepared in DMSO. Upon using serial dilution of the stock, the MTT assay showed no concentration dependent cytotoxicity of camptothecin on established cell lines. I had used a dilution of 11 microgram to 90 nanogram for 10,000 cells and the % inhibition hovers around 30% throughout the dilution range after 24 hour exposure. Did you observe something like this in your first trial?
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