Principles of the bark of Amphipterygium adstringens (Julianaceae) with anti-inflammatory activity.

Despite the fact that Amphipterygium adstringens (usually known as "cuachalalate") is used intensively in traditional medicine throughout México, there are, to our knowledge, no previous studies concerning the actual therapeutic, anti-inflammatory properties of this species. This lack of data prompted us to evaluate the aqueous (AE) and hexane (HE) extracts from A. adstringens in two models of acute inflammation: 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear edema and carrageenan-induced paw edema. The results showed that HE possesses dose-dependent activity, while AE showed no anti-inflammatory effect on TPA-induced edema. Reverse effects were found in the carrageenan test, wherein AE showed a 73.5% of inhibition of edema, while HE showed only a 14.4% activity at 100 mg/kg body weight. These results could indicate that AE and HE possess different anti-inflammatory mechanisms of action. On the other hand, it is known that masticadienonic (1) and 3alpha-hydroxymasticadienonic (2) acids are the main constituents of the organic extract of A. adstringens bark. Because of this knowledge, we tested 1 and 2 in the same experimental models. The results showed that 2 possesses a dose-dependent effect, while 1 does not show a dose-dependent response in TPA-induced edema. In carrageenan-induced edema tests, both 1 and 2 showed almost the same activity (approximately 44% inhibition at 100 mg/kg body weight). In order to determine whether the anti-inflammatory activities of AE, HE, 1 and 2 are involved in the alteration of inducible nitric oxide synthase (iNOS) activity, we evaluated these substances by examining nitric oxide generation in lipopolysaccharide (LPS)-activated peritoneal macrophages. The results showed that 1 presented the highest activity (93.3%), followed by 2 (86.5%), while AE (57%) and HE (33.6%) showed the lowest. In the cytotoxic MTT assay, however only 1 and 2 showed any activity whatsoever.