Re: why phenol turns reddish brown?

I am assuming based on the color that you used phenol red.  It is a reddish brown cystalline 
powder that is commonly used as a pH indicator in tissue culture but can also be used to indicate 
the presence of DNA.  The only problem with this is that it is not reddish in color in pure 
solution.  But, If this is the case, this sort of phenol is water soluble and therefore not good to 
extract the proteins away from the DNA.

If this is not phenol red then it is hard to say without anymore specifics. A couple questions is, 
did you get DNA? If so then I'm sure it is fine. Phenol itself would not harm DNA nor degrade it. 
You could always do an ethanol precipitation and resuspend in a solution of Tris-EDTA or even 
water and check the purity UV absorption.

Feel free to email me the exacts of the chemical you added. I cannot find anything else phenol 
related that you would be used.  But there are many chemical reactions with phenolics that can 
produce reddish brown color.