Context: Currently, famous traditional Chinese medicine formulas have undergone re-evaluation and development in China. Wei-Chang-An-Wan (WCAW) as one of them has been used for treating various gastrointestinal diseases for several decades. The secondary development of WCAW is in progress so as to interpret the effective material basis or find new pharmacological activity.
Objective: To evaluate the antinociceptive effect of methanol extract of WCAW (ME) as well as four fractions (P.E., EtOAc, n-BuOH, H2O) and obtain information on the correlation between the contents of the fractions and antinociceptive effect.
Materials and methods: ME was divided into four parts extracted by petroleum ether, ethyl acetate and n-butanol. Antinociceptive activity was evaluated by three models of acetic acid-induced writhing, formalin and hot-plate test in mice after repetitive administration of ME at 200, 400 or 800 mg/kg, P.E. 132 mg/kg, EtOAc 106 mg/kg, n-BuOH 176 mg/kg and H2O 176 mg/kg for six days. The chemical compounds were analyzed by HPLC-ESI-MS.
Results: ME at 800 mg/kg inhibited acid-induced writhing by 84.69%, and reduced the licking time of second phase in formalin test by 53.23%. The inhibition rates in acid-induced writhing of P.E., EtOAc, n-BuOH and H2O were 27.79, 33.85, 38.97 and 37.69%, respectively, and in formalin test about 50%. They had no effect on the hot-plate test. HPLC-ESI-MS analysis showed that 68 chemical compounds were detected and 41 compounds were identified from ME.
Discussion and conclusion: The results obtained herein indicate that WCAW possesses the antinociceptive activity that provides a new aspect in clinical application.