Sesquiterpene lactones possess a variety of
biological activities, including anti-inflammatory activity. Two plants native to the southeastern United States, Magnolia grandiflora (L.) and Smallanthus uvedalius (L.) [syn Polymnia uvedalius (L.)], are novel sources of the
sesquiterpene lactones parthenolide and
enhydrin, respectively. In this study, the anti-inflammatory and anti-hyperalgesic effects of these isolated
lactones from these two plant sources were evaluated in the rat
carrageenan inflammation model. Rats received ip
injections of either vehicle (
propylene glycol),
indomethacin (5 mg/kg), 11,13-dihydroparthenolide (20 mg/kg),
parthenolide (5 or 20 mg/kg) or
enhydrin (5 or 20 mg/kg). A 100-microl injection of 2.0%
carrageenan was made into the plantar surface of the right hindpaw. Paw withdrawal latencies and paw volumes in both inflamed and non-inflamed paws were recorded at four test intervals: pre-
inflammation baseline (0 time point), and 1, 2 and 4 h post-
carrageenan injection. Vehicle-treated animals exhibited a significant time-dependent hyperalgesic and
edema response that was greatest at the 4-h test interval.
Indomethacin significantly blocked the hyperalgesic response and modestly attenuated the
edema response.
Parthenolide (20 mg/kg) and
enhydrin (20 mg/kg) significantly blocked the hyperalgesic response and significantly attenuated the
edema response; 11,13-dihydroparthenolide did not affect either
inflammation or
hyperalgesia. These findings suggest that
parthenolide and
enhydrin from these plant sources may be useful in the treatment of inflammatory
pain.