Hi Sanjana, I have had similar problems when I run rather polar compounds (especially carboxylic acids). My best solutions have been to dry load and decrease the amount of crude sample I am putting onto the column (if you are trying to purify 500 mg, maybe try 100 mg). Also, if you are running a flash column, let gravity do the work for a while before you apply pressure. 

It seems like the compounds are tailing. Consider the use of a modifier to keep the compounds in a single ionized state. As I didn't see what sort of compounds you are running, I can't make good suggestions for modifiers. If dry loading, try reducing the proportion of compound to silica. Perhaps instead of adsorbing on silica, the compound is coating the silica due to a high loading.

Thank you, Mr. Rittichier and Mr. Silver. The sample was dry loaded, but the extract to silica ratio was very high. That is most probably the reason. 

I aim at isolating polyphenolic compounds from the plant extract. Can you suggest some modifiers that can be used for the silica gel.

When you run a chromatographic column is common not to have pure fraction, most  of the times you have to purify the fractions through another small column. It depends how you see the spots in a TLC.  

I would start with a special cocktail my colleague has affectionately named Polar Express (shout-out Brennan). Like EtOAc/hexane, you have a polar and nonpolar portion for the mobile phase. But for Polar Express, your polar portion is a three solvent mix (EtOAc:EtOH:AcOH {3:1:2%}) and your nonpolar portion is hexane or heptane. I have found this to be very effective at purifying acidic compounds. Evan better than DCM:MeOH:AcOH. Please see figure two of Green Chem., 2014, 16, 4060–4075 (DOI: 10.1039/c4gc00615a). 

Mostly chlorophlly and carotenoids will interfering the collected fraction. So, the fraction should purified again and again by repeating column . you should conform the fraction by TLC whether the same compounds are exist or not. If same compound repeated use the another solvent combination for further process.

Thank you all for the suggestions.