Evaluation of the analgesic potential and safety of Cinnamomum camphora chvar. Borneol essential oil

Cinnamomum camphora chvar. Borneol essential oil (BEO, 18.2% v/v borneol) is a by-product of steam distillation to produce natural crystalline borneol (NCB, 98.4% v/v borneol). Given the known medicinal properties of borneol, the analgesic function and safety were studied. Horn’s method and the Draize test revealed a gender difference in mice regarding acute oral LD50, i.e., low-toxicity to female mice (2749 mg/kg), but practically nontoxic to male mice (5081 mg/kg). There was no acute and skin or eye irritation when BEO was applied directly, if the BEO concentration was less than 50%. The analgesic effect of BEO was evaluated by the glacial acetic acid-induced writhing pain model. Continuous topical application of BEO to the abdomen of mice for 6 d, significantly reduced observed writhing in mice (p 2 (PGE2) and transient receptor potential melastatin-8 (TRPM8) were significantly reduced (p