Analgesic and anti-inflammatory activities of Vitex trifolia extract and development of a topical herbal cream.

BACKGROUND: Vitex trifolia L. is a medicinal plant traditionally used in Thai medicine for treatment of muscle pain and skin disorders. OBJECTIVE: To evaluate the in vivo analgesic and anti-inflammatory activities of the ethanolic extract of Vitex trifolia (VTE) and to develop a stable topical herbal cream. MATERIALS AND METHODS: The analgesic activity of VTE was evaluated using acetic acid-induced writhing and hot plate tests. The anti-inflammatory activity was assessed using ethyl phenylpropiolate (EPP)-induced ear edema and carrageenan-induced paw edema models in rats. A topical cream was developed containing VTE at 0.4% w/w, and its physical characteristics (pH, viscosity, spreadability, and phase separation), short-term and accelerated stability (at 4 °C and 30 °C for 90 days), and phytochemical contents (phenolics, flavonoids, and proanthocyanidins) were analyzed. RESULTS: VTE (0.5-2.0 mg/ear) significantly reduced EPP-induced ear edema by up to 71.5% at 120 min (p < 0.001) and suppressed carrageenan-induced paw edema by 45.3% at 4 h with a 250 mg/kg body weight (p < 0.001), showing comparable efficacy to standard drugs. The number of abdominal writhes in mice treated with VTE remained statistically comparable to the control group (p > 0.05), and no significant increase in latency time was observed in the hot plate model. The HCF5 cream exhibited favorable physical characteristics (pH: 4.26-4.99; viscosity: 8683-40,065 cP), and remained stable over 90 days, especially at 30 °C. Phytochemical analysis showed stable retention of total phenolics, flavonoids, and proanthocyanidins with no significant degradation during storage. CONCLUSION: This study confirms the anti-inflammatory potential of VTE and its suitability for use in a stable topical herbal formulation.