<i>Catasetum integerrimum</i> Hook. (Orchidaceae) Pseudobulbs Ethanol Extract Induces Antidiarrheal and Antinociceptive Actions

This work assessed the antioxidant, antimicrobial, genotoxic, acute toxicity, antidiarrheal, antinociceptive, and anti-inflammatory effects of an ethanolic extract from the Catasetum integerrimum pseudobulbs (CIE). The antidiarrheal activity of CIE (1-100 mg/kg p.o.) was assessed with castor oil-related tests. The anti-inflammatory activity was estimated using the 12-O-tetradecanoylphorbol-13-acetate ear-induced edema. CIE exerted antidiarrheal activity with an effective dose 50 (ED₅₀) of 2.0 mg/kg p.o. in the castor oil-induced diarrhea model and inhibited intestinal fluid accumulation. Three models demonstrated the antinociceptive effects of CIE, with the acetic acid-induced writhing test demonstrating the highest activity (ED₅₀ = 35 mg/kg p.o.). Naloxone reversed the antinociceptive effects of CIE in the hot plate test. The antidiarrheal mechanism of CIE relies on inhibiting secretory-induced diarrhea through the alpha-1 adrenergic system, decreasing pro-inflammatory mediators such as COX-2, and inhibiting fluid accumulation. The opioidergic system participates in the antinociceptive effects of CIE.