Pharmaceutical compositions for the treatment of hypertension comprising an effective anti-hypertensive amount of at least one compound in association with a pharmaceutically acceptable, substantially non-toxic carrier or excipient, the compound having one of the formulae (I), (II), (III) or (IV), and methods for the treatment of hypertension or effecting anti-hypertensive action which comprises administering to a patient requiring anti-hypertensive therapy or effect at least one of the above-described compounds.