The selectivity index is a measure of the safety of an extract or compound. It is calculated by dividing the concentration that will harm animal cells by the concentration that would kill a microorganism. Most people consider that a minimum inhibitory activity of less than 0.1 mg/ml represents good activity.
Does anybody know what LD50 (concentration that kills 50% of cells) of an extract or compound would be considered as safe. Any reference would be welcomed.
the correlation is not possible because of pharmacokinetics and metabolism and type of lab animals involved. One should start getting these values by simple testing.
Hi Eloff,
Safe for what? That question has been around for many years! If you only want to state "low toxicity" towards the actual cell line you're testing it on, that's OK, but extrapolating to humans(?) from cell data is not possible or valid. Even different cell lines will respond differently to the same plant extract, let alone a whole organism. It is best to run a positive control, a known toxic agent, in the same assay and then compare the IC50 (or LD50) of the 2 as a measure of toxicity.
Go step by step. I would suggest staring with rats, make LD50, and at safe dose check for a pharmacological activity. Go in vitro for biomolecular mechanisms. Active in vitro does not mean active in vivo and likewise, so we have missed hundreds of leads..
Pienso que la respuesta de Lynda Baldury es correcta, hay que considerar que un extracto tiene muchos componentes y que el componente activo puede no ser toxico pero otros no citotoxico si. En cuanto a las lineas celulares es logico que la respuesta sea diferente para cada linea por su genetica. Debe considerarse la citotoxicidad sobre celulas no cancerosas, esto es mas recomendable. La toxicidad sobre celulas cacerosas , con mecanismos de reproduccion alterados es un problema de consideracion. La toxicidad en organos es distinta a la toxicidad en celulas, por los mecanismos de desintoxicacion de cada organismos. Gracias por considerar la opinion.
creo que el traductor automatico hizo desastres con mi opinion
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