Amides Id (verongiaquinol) and Ih belonging to a group of compounds with the general formula I, occurring in nature in sponges of the Verongidae (Aplysinidae) family, were reported to exhibit a high cytostatic activity in vitro with respect to some tumor cells [1, 2] and a strong inhibiting effect with resect to Na+, K+, and Ca2+ ATPases [3, 4].