Have the samples been disrupted (ground or cut) in any way?  If you grind plant leaves in this solution then centrifuge in a table top microcentrifuge the solution will contain most of the DNA, RNA and proteins with pellet of mostly cell walls and non-broken cells.  What are you hoping to extract?

First of all Amy I would like to appreciate you for a response to my post.

I used liquid nitrogen to crush the leaves to powder and then added PBS buffer to it. After centrifugation,the supernatant collected was pale yellow colored and the pellet was dark green ( due to presence of chlorophyll). So I was wondering what are the constituents of collected supernatant? And for extracting DNA and RNA dont we need isopropanol, CTAB etc?

Hi Smruti,

The supernatant will contain both the DNA and RNA, they won't be very pure (there will still be proteins, salt from the PBS, general cytoplasmic contents).  Do you need any protocols for RNA or DNA extraction?  We do CTAB-based methods for both (no kit required).  You will need isopropanol or ethanol for the precipitation step as well as chloroform for the initial cleanup. 

Amy