as i said in another thread i think you should stop straigtening your hair, as if you do it chemically it will damage your scalp, and if you do it manually the heat will damage your scalp and hair so you lose either way.
however if you are hell bent on straightening your hair, then eucapil is a dht inhibitor which contains no water, simply fluridil and grapeseed oil. as to what it will do to straightened hair i don't know, but it has no water in it.