ETHNOPHARMACOLOGICAL RELEVANCE: Doyerea emetocathartica is a Cucurbitaceae known as ''cabeça de negro'' and used by North-eastern Brazil and South-eastern Mexico communities to treat rheumatism, inflammation and pain. Despite ethnopharmacological reports, there is currently a lack of evidence about its chemical composition, toxicity and pharmacological effects. AIM OF THE STUDY: This study aimed to investigate the chemical composition of the aqueous extract of D. emetocathartica stems (DEAQ), evaluate its acute oral toxicity, mutagenicity and its anti-inflammatory profile in mice. MATERIAL AND METHODS: The DEAQ chemical composition was evaluated through HPLC-MS/MS. Acute oral toxicity was assessed for 14 days after the oral administration of DEAQ in a single dose of 2000 mg kg RESULTS: Using HPLC-MS/MS the cayaponoside D CONCLUSIONS: The in vivo tests results indicated that DEAQ showed strong anti-inflammatory activity, with possible cayaponoside D