1. You may select the initial dose for pharmacological evaluation of a plant extract based on ethnomedicinal use of the plant. for instance if two cups of water extract is used ethnomedicinally, extract the plant using traditional method, concentrate or dry the two cups and calculate the amount of the residue, extrapolate based on average human weight 70 KG to find the dose per KG. You can use this dose or its multiples as initial dose

2. Calculate the ED50 or ED90 (if its achievable) based on the initial 5 doses you tried for screening. You can use any of these dose preferably ED 90 for evaluation of mechanism of action. Its noteworthy that concentration required for establishing mechanism of action maybe some times in multiple or fraction of effective doses. But its always good to use more one concentration for determining mechanism of action

see our work on antidiabetic activity of the root juice of musa paradisiaca.

Dear Makanjoula ogunsina

Thanks a lot Sir,

Surely I will read article you have mentioned.

Follow OECD guidelines for acute oral toxicity- OECD 423. There lies the answer to your query.

Regards

Asalam.alaikum Hira,

I would like to suggest IC50 to select a single dose for evaluation of a pharmacological effect of plant extract. Initial dose is vary from plant to plant. Or you have to search relevant literature may be someone did IC50 of your plant you have.

Regards

You may calculate IC50 value to select a single dose.

U may use with reference of activity & toxicity established/reported in literature survey  (if any) or U may use selection of DOSE by DHAWAN from CDRI (India).

My area of research was/is also to investigate a plant extract/natural products for its pharmacological effect e.g antihypertensive / hypotensive effect !

For MoA most of Pharmacologist likely to be use sub-maximal effect/response (about 75-80%)