Effects of honokiol and magnolol on substance P-induced thermal hyperalgesia in mice. Honokiol (0.5 or 1.0 μg/paw), magnolol (0.5 or 1.0 μg/paw) and vehicle were administered 20 min prior to substance-P (0.5 μg) injection into hindpaw. The paw withdrawal latency in the 47°C water was measured during 5-120 min after intraplantar injection of substance P. Each point represents the mean ± S.E.M. (n = 7-9). * indicates significantly different from vehicle group, *p < 0.05.