Hi Nithipong,

We use IC50 to determine the minimum inhibition concentration for inhibiting 50% of the pathogen and CC50 as the Cytotoxic concentration of the extracts to cause death to 50% of viable cells in the host. These are measured through dilution assays of your extracts added to virus infected host cells.

In the Ideal situation you want to have your IC50 concentration below your CC50 concentration and your CC50 and MNTD as high as possible. This would mean that you kill the pathogen before killing the host; as an example - if the IC50 is 0.1g/L and the CC50 is 100g/L then your host won't suffer any adverse effects if treated with the extracts.

These are important factors to consider when developing anti microbial compounds.

SI = CC50/IC50 

SI is a index value that gives you an idea about the selectivity. You need this to be a high value number which means that you achieve killing the virus before your host, i.e. the compound has selectivity towards your virus and not your host.

Hi Nithipong,

We use IC50 to determine the minimum inhibition concentration for inhibiting 50% of the pathogen and CC50 as the Cytotoxic concentration of the extracts to cause death to 50% of viable cells in the host. These are measured through dilution assays of your extracts added to virus infected host cells.

In the Ideal situation you want to have your IC50 concentration below your CC50 concentration and your CC50 and MNTD as high as possible. This would mean that you kill the pathogen before killing the host; as an example - if the IC50 is 0.1g/L and the CC50 is 100g/L then your host won't suffer any adverse effects if treated with the extracts.

These are important factors to consider when developing anti microbial compounds.

SI = CC50/IC50 

SI is a index value that gives you an idea about the selectivity. You need this to be a high value number which means that you achieve killing the virus before your host, i.e. the compound has selectivity towards your virus and not your host.

Well.. first ask yourself if you know what these three things are and whether they are the same. If they are not the same, do a bit of reading in a basic pharmacology text and find out and then, answer your own question!

Have fun.

G

Many thanks for your kind suggestion! Actually, I didn't want to know the definition of these three things but what I want to know is that how can I compare the antiviral activities of these six extracts, which has the difference MNTD. I don't think I can use just one MNTD value from each extracts in order to directly compare the antiviral activities without measuring the IC50 because the higher ability might come from the higher MNTD as I already told you. I'm a rookie in this field of study. It seems like I have to read more. Thank you so much!

www.fda.gov/OHRMS/DOCKETS/98fr/05d-0183-gdl0002-01.pdf

Because we have Rules and regulations as above :-)

Hi Nithipong,

you have compare your activity with activity  compound with known the virus infection inhibitory effect used in that field, and IC50 should be determined in the same conditions as for your extract. For CC50 you have compare action your extract may be on Vero cells. Read related literature.

Hi Jaco van Rooyen

Could you introduce a reference about SI?

Hi Alireza Badirzadeh

Here is the link that could bring you to the studies, which used selectivity index (SI) https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/selectivity-index

Thank you very much Nurhidanatasha .

Alireza

The best software in this topic is GraphPad Prism.

Thanks to all for guiding me.

hello guys, I would like to have a full reference on how to calculate CC50

Same here.