Umm, MATLAB is built around the idea that all of your basic functionality is provided and you can use this to finetune it into any task you want to focus onto. Quite simply there is no text mining toolbox in MATLAB because all of the functionality that you need for doing these things are in base MATLAB itself.
You can try to look up regexp, strfind, strrep, and other functions that deal with handling strings in MATLAB. These will provide you the means to easily program as many and as specific functions that you want to accomplish all of these text mining tasks and more.
In short, MATLAB is the tool that you can use to design the tools for text mining. You might also try out the File Exchange to see if someone has done that for you already.
