Acmella uliginosa (Sw.) Cass. is a medicinal herbaceous plant that is commonly used by the Malay community in Malaysia to relieve pain often associated with mouth ulcers, toothache, sore throat, and stomach ache.
Imatinib, a selective tyrosine kinase inhibitor, is the first line treatment against chronic myelogenous leukaemia (CML) and gastrointestinal stromal tumors (GIST). Several fatal cases have been associated with imatinib hepatotoxicity. Acetaminophen, an over-the-counter analgesic, anti-pyretic drug, which can cause hepatotoxicity, is commonly used in cancer pain management. We assessed renal and hepatic toxicity after imatinib and acetaminophen co-administration in a preclinical model. Four groups of male ICR mice (30-35 g) were fasted overnight and administered either saline solution orally (baseline control), imatinib 100 mg/kg orally (control), acetaminophen 700 mg/kg intraperitoneally (positive control) or co-administered imatinib 100 mg/kg orally and acetaminophen 700 mg/kg intraperitoneally (study group), and sacrificed at 15 min, 30 min, 1 h, 2 h, 4 h and 6 h post-administration (n = 4 per time point). The liver and kidneys were harvested for histopathology assessment. The liver showed reversible cell damage like feathery degeneration, microvesicular fatty change, sinusoidal congestion and pyknosis, when imatinib or acetaminophen were administered separately. The damage increased gradually with time, peaked at 2 h but resolved by 4 h. When both drugs were administered concurrently, the liver showed irreversible damage (cytolysis, karyolysis and karyorrhexis) which did not resolve by 6 h. Very minor renal changes were observed. Acetaminophen and imatinib co-administration increased hepatoxicity which become irreversible, probably due to shared P450 biotransformation pathways and transporters in the liver.
Ethanolic extract of Curcuma xanthorrhiza was used to evaluate the analgesic and toxicity effects in vivo. The extract was standardized using GC-MS, which showed that 1 mg of Curcuma xanthorrhiza ethanolic extract contains 0.1238 mg of xanthorrhizol. The analgesic activity was studied in rats using three different models, namely the hot plate test, tail flick test and formalin-induced pain test. The acute oral toxicity was examined by the oral administration of standardized Curcuma xanthorrhiza ethanolic extract in mice at doses ranging from 300-5,000 mg/kg and observation for 14 days. Standardized Curcuma xanthorrhiza ethanolic extract did not show significant analgesic effect in the hot plate and tail flick tests. However, in the formalin-induced pain test, Curcuma xanthorrhiza ethanolic extract significantly (P < 0.05) suppressed the paw licking time of rats in both early and late phases at doses 200 and 400 mg/kg of the extract, respectively. In the acute oral toxicity study, Curcuma xanthorrhiza ethanolic extract did not show any toxic effects in mice at 5 g/kg. These experimental results suggest that the standardized Curcuma xanthorrhiza ethanolic extract showed peripheral and central antinociceptive activity associated with neurogenic pain as well as a relative absence of toxic effects which could compromise the medicinal use of this plant in folk medicine.
This study investigated the potential antinociceptive efficacy of a novel synthetic curcuminoid analogue, 2,6-bis-(4-hydroxy-3-methoxybenzylidene)cyclohexanone (BHMC), using chemical- and thermal-induced nociception test models in mice. BHMC (0.03, 0.1, 0.3 and 1.0 mg/kg) administered via intraperitoneal route (i.p.) produced significant dose-related inhibition in the acetic acid-induced abdominal constriction test in mice with an ID(50) of 0.15 (0.13-0.18) mg/kg. It was also demonstrated that BHMC produced significant inhibition in both neurogenic (first phase) and inflammatory phases (second phase) of the formalin-induced paw licking test with an ID(50) of 0.35 (0.27-0.46) mg/kg and 0.07 (0.06-0.08) mg/kg, respectively. Similarly, BHMC also exerted significant increase in the response latency period in the hot-plate test. Moreover, the antinociceptive effect of the BHMC in the formalin-induced paw licking test and the hot-plate test was antagonized by pre-treatment with the non-selective opioid receptor antagonist, naloxone. Together, these results indicate that the compound acts both centrally and peripherally. In addition, administration of BHMC exhibited significant inhibition of the neurogenic nociception induced by intraplantar injections of glutamate and capsaicin with ID(50) of 0.66 (0.41-1.07) mg/kg and 0.42 (0.38-0.51) mg/kg, respectively. Finally, it was also shown that BHMC-induced antinociception was devoid of toxic effects and its antinociceptive effect was associated with neither muscle relaxant nor sedative action. In conclusion, BHMC at all doses investigated did not cause any toxic and sedative effects and produced pronounced central and peripheral antinociceptive activities. The central antinociceptive activity of BHMC was possibly mediated through activation of the opioid system as well as inhibition of the glutamatergic system and TRPV1 receptors, while the peripheral antinociceptive activity was perhaps mediated through inhibition of various inflammatory mediators.