Antipyretic and antinociceptive effects of five herbal root extracts of bencha-loga-wichian remedy

Abstract

Bencha-loga-wichian remedy is a famous antipyretic drug of Thai traditional medicine which includes roots of Ching-chee, Khon-thaa, Yaa-nang, Mai-tao-yai-mom and Ma-dueo-chumporn. We initially determined the antipyretic property of each herbal root extract (CM, HP, TT, CP and FR) and the extract of Bencha-loga-wichian remedy (BEN) using LPS-induced fever model in rats. The animals were induced with i.m. injection of LPS (50 g/kg) 1 hr after oral administration of 2%Tween 80, acetylsalicylic acid (ASA; 300 mg/kg) or various doses of CM, HP, TT, CP, FR and BEN (25, 50, 100, 200 and 400 mg/kg). Rectal temperature was measured before the treatment and at 1 hr interval for 7 hr after LPS injection. All doses of CM, HP, TT, CP, FR and BEN significantly (p<0.05) reduced the increased rectal temperature at 1 or 2 hr after LPS injection. BEN 400 mg/kg seemed to have the highest antipyretic efficacy. Studies then determined the antinociceptive property of a range of five herbal root extracts and BEN doses in the mouse hot-plate test. Hot-plate latencies were determined in male ICR mice prior to the administration of 0.9% normal saline solution (NSS; 10 ml/kg, i.p.), morphine (MO; 10 mg/kg, i.p.), 2% Tween 80 (10 ml/kg, p.o) or various doses of CM, HP, TT, CP, FR and BEN (25-400 mg/kg, p.o.). Hot-plate latencies were subsequently determined at 15, 30, 45, 60, 90, 120 and 240 min. The percent maximum possible effect (%MPE) was calculated and used in the determination of the area of analgesia (%MPE-min). Most doses of CM, HP, TT, CP, FR tested produced a significant (p<0.05) analgesic response, while CP and BEN only at the dose of 400 mg/kg had significant analgesic response. CM 200 mg/kg and HP, TT, CP, FR (400 mg/kg) produced analgesic response that was naloxone-sensitive suggesting opioid-mediated mechanism. In the mouse tail-flick test, tail-flick latencies were determined prior to the administration of NSS (10 ml/kg, i.p), MO (10 mg/kg, i.p.), 2% Tween 80 (10 ml/kg, p.o.) or various doses of CM, HP, TT, CP, FR and BEN (25-400 mg/kg, p.o.) and were subsequently determined at 7 intervals over a 4 hr period. Most doses of HP TT, CP, FR and BEN produced significant analgesic response. All doses of CM failed to produce analgesic response in this method. In the acetic acid-induced writhing in mice, the animals were induced with i.p. injection of 0.6% acetic acid (10 ml/kg) 30 min after the administration of 2% Tween 80, indomethacin (IND; 10 mg/kg, p.o.), or various doses of CM, HP, TT, CP, FR and BEN (25-400 mg/kg, p.o.) and the mean writhing response was determined for 30 min. Most doses of CM, HP, TT, CP, FR and BEN significantly (p<0.05) decreased the mean writhing response compared to vehicle controls. Taken together these results demonstrated that all five root extracts and BEN remedy have antipyretic activity and the antipyretic mechanism may involve the inhibition of TNF- synthesis and release. In addition, all five root extracts and BEN remedy also possess both central and peripheral analgesic activities and mechanism of action seems to be partly related to opioid receptors. These results provide another scientific evidence to support its use in Thai traditional medicine.