Riparin is a nonspecific smooth muscle relaxant. Riparin inhibits CaCl2-induced contractions in a reversible and non-competitive manner and can be used in spasmolytic studies.
References:
[1]. Thomas G, et al. Studies on the mechanism of spasmolytic activity of (O-metl-)-N-(2,6-didroxybenzoyl)tyramine, a constituent of Aniba riparia (Nees) Mez. (Lauraceae), in rat uterus, rabbit aorta and guinea-pig alveolar leucocytes. J Pharm Pharmacol. 1994 Feb;46(2):103-7.