MTT assay - (Mar/01/2006 )

i m evaluating cytotoxicity of a plant which was shown to be active in previous screening done around 1 year ago using the MTT assay. However, when the assay was repeated to confirm the plant's cytotoxicity property before separation of the active fraction, the test result were negative. what may have gone wrong that led to such inconsistent result?

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you may have encounter a difficulty to deliver MTT to mitochondrias?
bad product too?

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thanks for suggesting. err... i personally think that it's not the problem of the product. My other friend used the same MTT working solution to test on activity of another plant extract and the results were positive. If the problem was in delivering MTT into mitochondria, how can the previous assay done by another person showed positive cytotoxic activity?

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what wezre the conditions?
How old is the product? You've mentionned that the assays were done 1year ago. How was the product stored?

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Have you done yourself the previous screening?
If no, Can you contact the guy who did it? You have to check all little details, how was resuspended the drug? is there some vector effect? Were all controls done?

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thanks for the replies

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is there a possibility that degradation of compounds had occured to the plant sample i tested?
thanks

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anybody have suggestions?

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It's a possibility. I don't know. It depends how it was stored, how sensitive it is to temperature, light, humidity...

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why don't u re-ferment the sample from fresh plants and test them again, and how have ur standard cytotoxic drug worked in the assay system. If the extracts were not stored well (or immaterial of the storage conditions) 'cause of unstability issues they extract may have gone bad.
pls check in other cytotoxic assays too.
vilas

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