Acute Toxicity, Analgesic, and Anti-inflammatory Activities of Folk Thai Herbal Medicine: Yafon Formula

Yafon (YF), a formula composed of 14 herbal constituents, has been used in folk Thai herbal medicine to treat various indications, including pain relief, antipyretics, and anti-inflammatory properties. Nevertheless, this formula lacks adequate toxicological and efficacy data. Hence, this study aims to assess the safety and efficacy of YF in animal models. The study on acute oral toxicity was conducted by the Organization for Economic Co-operation and Development (OECD) number 420 guidelines. The results demonstrated that the administration of YF at a high dose of 2000 mg/kg did not result in fatality or exhibit any toxicity. The analgesic effect of YF in mice was investigated using the acetic acid-induced writhing test and the formalin test. The anti-inflammatory activity of YF was assessed in rats using the carrageenan-induced paw edema test. This investigation employed YF doses of 200, 400, and 800 mg/kg/day. The study found that all YF doses reduced writhing in the acetic acid, and YF doses of 400 and 800 mg/kg/day reduced the licking time in the late phase of the formalin test. In addition, all YF doses effectively suppressed paw edema in the carrageenan-induced paw edema test. This study demonstrated that the YF formula showed no acute toxicity and possessed acute anti-inflammatory and analgesic effects by blocking pain signals originating from the peripheral nervous system. These findings provided empirical evidence supporting the use of YF formula as an analgesic and anti-inflammatory agent.