Are you trying to remove stains ?
Or, do you just want to brighten your leathers up ?
I use Renapur on my leathers, this waterproofs and nourishes, restores there original softness and colour, preserves its looks and extends its life. (It says on the tin ).
For my boots I use Nikwax, This does a similar job and allows the leather to breathe. Availabe from horsey type shops/sadlers.