No, You must extract the antioxidant and you may even discover that the solvent plays an important role in DPPH activity.

right sir, but in old times people use to take them directly by making their powder, so what happened in that case?

secondly, in order to check that in which solvent we can get maximum amount of antioxidants, we will have to use all solvents, will it not be time consuming and when we extract them and dry them to use them in medicines, what will be the best procedure.

Not possible. You have to use the extracts for DPPH activity.

Since this is a research problem, you must try as many solvents possible. No Short-cuts.

You can determine antioxidant activity of plant materials without any extractions. There is a direct method so called QUENCHER procedure (DOI: 10.1021/jf071291z). It has been successfully applied to several food materials including cereals, nuts, meat... It is easy to apply and time-saving. I would recommend some of the publications here regarding this method.

Serpen, A., Gökmen, V., Pellegrini, N., Fogliano, V. Journal of Cereal Science (2008) 48: 816-820. doi:10.1016/j.jcs.2008.06.002

Açar, Ö.Ç., Gökmen, V., Pellegrini, N. et al. Eur Food Res Technol (2009) 229: 961-969. doi:10.1007/s00217-009-1131-z

Serpen, A., Gökmen, V., Fogliano, V. Trends in Food Science & Technology (2009) 20: 278-288. http://dx.doi.org/10.1016/j.tifs.2009.03.010

Serpen, A., Gökmen, V., Fogliano, V. Meat Science (2012) 90: 60-65. doi:10.1016/j.meatsci.2011.05.027 

Thank you all.