Background: The bark of Guaiacum officinale (Lignum vitae) is used in folklore practice to relieve pain and swelling associated with arthritis and gout and on this basis an aqueous extract was tested on histamine-induced oedema and pain in rats in the present study.
Subjects and method: Intraperitoneal injections of aqueous lignum vitae extract (16 mg/kg and 32 mg/kg) were tested on oedema induced by sub plantar injection (0.2 mL) of 1 mg of /kg histamine in rat paws (n = 6). Control animals received distilled water (0.2 mL) and ibuprofen (10 mg/kg) was used as positive control. The analgesic efficacy of the extract was also evaluated using an analgesiometer for recording latency period.
Results: Lignum vitae extract (32 mg/kg) and ibuprofen treated groups displayed increased latency period and which confirmed analgesic efficacy (p < 0.05) when compared to control animals and animals treated with 16 mg/kg extract (p > 0.05). Significant anti-inflammatory effects were also observed with administration of 32 mg/kg lignum vitae extract. In the acute toxicity test, no signs of toxicity were observed when extract was given in doses of 300 mg/kg and 128 mg/kg.
Conclusion: The aqueous extract from lignum vitae bark showed significant anti-inflammatory and analgesic activity with no observable toxic effects at a dose ten times that of the other extract producing these pharmacological effects. These results are consistent with anecdotal claims of swelling and pain relief with the tea from lignum vitae bark and can provide guide-lines for quantification and safety in folkloric use of this extract.