Methods to isolate the alkaloids from the plant extract

i am performing TLC for seperation of alkaloids from the extract..But, alkaloid of my interest was run along with mobile phase and resolution is also poor , hence creating problem in its isolation.
What can i do to obtain better results?
I have used CHCl3:Ethyl acetate:methanol(4:5:0.5), it gives poor results...Currently , i m using Chloroform:Methanol (24:1).