In the present study, the rhizome essential oil from Zingiber zerumbet (Zingiberaceae) was evaluated for antinociceptive activity using chemical and thermal models of nociception, namely, the acetic acid-induced abdominal writhing test, the hot-plate test and the formalin-induced paw licking test. It was demonstrated that intraperitoneal administration of the essential oil of Z. zerumbet (EOZZ) at the doses of 30, 100 and 300 mg/kg produced significant dose-dependent inhibition of acetic acid-induced abdominal writhing, comparable to that of obtained with acetylsalicylic acid (100 mg/kg). At the same doses, the EOZZ produced significant dose-dependent increases in the latency time in the hot-plate test with respect to controls, and in the formalin-induced paw licking test, the EOZZ also significantly reduced the painful stimulus in both neurogenic and inflammatory phase of the test. In addition, the antinociceptive effect of the EOZZ in the formalin-induced paw licking test as well as hot-plate test was reversed by the nonselective opioid receptor antagonist, naloxone suggesting that the opioid system was involved in its analgesic mechanism of action. On the basis of these data, we concluded that the EOZZ possessed both central and peripheral antinociceptive activities which justifying its popular folkloric use to relieve some pain conditions.
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.
The present study examined the potential antinociceptive activity of flavokawin B (6'-hydroxy-2',4'-dimethoxychalcone), a synthetic chalcone using chemical- and thermal-induced nociception models in mice. It was demonstrated that flavokawin B (FKB; 0.3, 1, 3 and 10 mg/kg) administered via both oral (p.o.) and intraperitoneal (i.p.) routes produced significant and dose-dependent inhibition in the abdominal constrictions induced by acetic acid, with the i.p. route producing antinociception of approximately 7-fold more potent than the p.o. route. It was also demonstrated that FKB produced significant inhibition in the two phases of the formalin-induced paw licking test. In addition, the same treatment of flavokawin B (FKB) exhibited significant inhibition of the neurogenic nociceptive induced by intraplantar injections of glutamate and capsaicin. Likewise, this compound also induced a significant increase in the response latency period to thermal stimuli in the hot plate test and its antinociceptive effect was not related to muscle relaxant or sedative action. Moreover, the antinociception effect of the FKB in the formalin-induced paw licking test and the hot plate test was not affected by pretreatment of non-selective opioid receptor antagonist, naloxone. The present results indicate that FKB produced pronounced antinociception effect against both chemical and thermal models of pain in mice that exhibited both peripheral and central analgesic activity.
Pain is one of the most common cause for hospital visits. It plays an important role in inflammation and serves as a warning sign to avoid further injury. Analgesics are used to manage pain and provide comfort to patients. However, prolonged usage of pain treatments like opioids and NSAIDs are accompanied with undesirable side effects. Therefore, research to identify novel compounds that produce analgesia with lesser side effects are necessary. The present study investigated the antinociceptive potentials of a natural compound, cardamonin, isolated from Boesenbergia rotunda (L) Mansf. using chemical and thermal models of nociception. Our findings showed that intraperitoneal and oral administration of cardamonin (0.3, 1, 3, and 10 mg/kg) produced significant and dose-dependent inhibition of pain in abdominal writhing responses induced by acetic acid. The present study also demonstrated that cardamonin produced significant analgesia in formalin-, capsaicin-, and glutamate-induced paw licking tests. In the thermal-induced nociception model, cardamonin exhibited significant increase in response latency time of animals subjected to hot-plate thermal stimuli. The rota-rod assessment confirmed that the antinociceptive activities elicited by cardamonin was not related to muscle relaxant or sedative effects of the compound. In conclusion, the present findings showed that cardamonin exerted significant peripheral and central antinociception through chemical- and thermal-induced nociception in mice through the involvement of TRPV₁, glutamate, and opioid receptors.
The antinociceptive effects produced by intraperitoneal administration of a novel synthetic chalcone, 3-(2,3-dimethoxyphenyl)-1-(5-methylfuran-2-yl)prop-2-en-1-one (DMFP), were investigated in several mouse models of induced nociception. The administration of DMFP (0.1, 0.5, 1.0 and 5.0 mg/kg) produced significant attenuation on the acetic acid-induced abdominal-writhing test. It also produced a significant increase in response latency time in the hot-plate test and a marked reduction in time spent licking the injected paw in both phases of the formalin-induced paw-licking test. In addition, it was also demonstrated that DMFP exhibited significant inhibition of the neurogenic nociceptive response induced by intraplantar injections of capsaicin and glutamate. Moreover, the antinociceptive effect of DMFP in the acetic acid-induced abdominal-writhing test and the hot-plate test was not antagonized by pretreatment with a non-selective opioid receptor antagonist, naloxone. Finally, DMFP did not show any toxic effects and/or mortality in a study of acute toxicity and did not interfere with motor coordination during the Rota-rod test. Our present results show that DMFP exhibits both peripheral and central antinociceptive effects. It was suggested that its peripheral antinociceptive activity is associated with attenuated production and/or release of NO and various pro-inflammatory mediators, while central antinociceptive activity seems to be unrelated to the opioidergic system, but could involve, at least in part, an interaction with the inhibition of capsaicin-sensitive fibers and the glutamatergic system.
The fresh leaves of Murraya koenigii are often added to various dishes in Asian countries due to the delicious taste and flavour that they impart. In the present study, the effect of the total alkaloidal extract from Murraya koenigii leaves (MKA) with respect to anti-inflammatory, analgesic and anti-ulcerogenic effects were evaluated using different experimental animal models. Oral supplementation of MKA at 10, 20 and 40 mg kg(-1) body weight successfully and dose-dependently reduced the formation of oedema induced by carrageenan, histamine and serotonin as well as formaldehyde-induced arthritis. In addition, the extract (10, 20 and 40 mg kg(-1), p.o.) attenuated the writhing responses induced by an intraperitoneal injection of acetic acid and late phase of pain response induced by a subplantar injection of formalin in mice. MKA at higher doses (20 and 40 mg kg(-1), p.o) reduced the early phase response induced by formalin as well as reaction time on hot plate models. Interestingly, there was no ulcer score with the ulcerogenic effect of MKA. Moreover, all the doses of MKA (10, 20 and 40 mg kg(-1), p.o) showed promising anti-ulcerogenic activity with protection against acute gastric ulcers induced by ethanol plus hydrochloric acid and aspirin models in a dose dependent manner.
Elephantopus tomentosus is widely used in Asia, especially in Malaysia, for the treatment of pain and inflammation. In the present study, the analgesic and anti-inflammatory effects of a 95% ethanol extract of E. tomentosus were investigated in different experimental models. In the anti-inflammation study, 1000 mg/kg of extract significantly reduced carrageenan-induced hind paw edema (p < 0.05) and inhibited abdominal permeability compared with control (p < 0.01). The analgesic activity was assayed in several experimental models in mice: (1) hot plate, (2) tail flick, (3) writhing test; and rats: carrageenan-induced hyperalgesia pain threshold test. However, at the doses tested, no significant activity was found in the hot plate test and the tail flick test. E. tomentosus ethanol extract at 1000 mg/kg significantly (p < 0.05) increased hyperalgesia pain threshold and inhibited writhing activity. The results suggest that E. tomentosus ethanol extract at 1000 mg/kg dose is effective in anti-inflammatory and non-steroidal anti-inflammatory drug type anti-nociception activities.
The present study investigated the anti-inflammatory and analgesic activities of novel aspirin oil-in-water (O/W) nanoemulsion and water-in-oil-in-water (W/O/W) nano multiple emulsion formulations generated using ultrasound cavitation techniques. The anti-inflammatory activities of nanoemulsion and nano multiple emulsion were determined using the λ-carrageenan-induced paw edema model. The analgesic activities of both nanoformulations were determined using acetic acid-induced writhing response and hot plate assay. For comparison, the effect of pretreatment with blank nanoemulsion and reference aspirin suspension were also studied for their anti-inflammatory and antinociceptive activities. The results showed that oral administration of nanoemulsion and nano multiple emulsion containing aspirin (60 mg/kg) significantly reduced paw edema induced by λ-carrageenan injection. Both nanoformulations decreased the number of abdominal constriction in acetic acid-induced writhing model. Pretreatment with nanoformulations led to a significant increase in reaction time in hot plate assay. Nanoemulsion demonstrated an enhanced anti-inflammatory and analgesic effects compared to reference suspension while nano multiple emulsion exhibited a mild inhibitory effects in the three experimental animal model tests. The results obtained for nano multiple emulsion were relatively lower than reference. However, administration of blank nanoemulsion did not alter the nociceptive response significantly though it showed slight anti-inflammatory effect. These experimental studies suggest that nanoemulsion and nano multiple emulsion produced a pronounced anti-inflammatory and analgesic effects in rats and may be candidates as new nanocarriers for pharmacological NSAIDs in the treatment of inflammatory disorders and alleviating pains.
The pattern of analgesic use, abuse and incidence of analgesic-associated nephropathy in 79 patients with chronic headache was studied. Sixty-eight of these patients had migraine. Most patients had consumed a combination of analgesics (81%) while 19% had taken single analgesics for their headache. Nonsteroidal anti-inflammatory drugs were the most commonly used analgesics (96.2%) followed by paracetamol (70.9%) and aspirin, phenacetin and caffeine compounds (5.1%). Mefenamic acid was the commonest nonsteroidal anti-inflammatory drug consumed (97.4%). Analgesic abuse which was defined as a minimum total of 1 kg of analgesics such as paracetamol or aspirin, phenacetin and caffeine compounds or 400 capsules/tablets of nonsteroidal anti-inflammatory drugs was noted in 65 patients. Nonsteroidal anti-inflammatory drugs were the most commonly abused analgesics (89.2%) followed by paracetamol (38.5%). Forty-five of the 65 analgesic abusers had an intravenous urogram or ultrasound performed and renal papillary necrosis was documented in one patient. Three (4.6%) of the analgesic abusers had mildly raised serum creatinine levels. Mild proteinuria of less than 1 gm/litre was present in 27.7% of abusers. In conclusion, although analgesic use and abuse is common in patients with chronic headache, the short term incidence of analgesic-associated nephropathy (2.2%) and renal impairment (4.6%) was low. Prolonged observations will be necessary to ascertain the safety of these drugs for long term use.
Anti-inflammatory and analgesic activities of a standardized Orthosiphon stamineus methanol:water (50:50 vol/vol) leaf extract (SEOS) were evaluated in animal models. Oral administration of SEOS at doses of 500 and 1,000 mg/kg significantly reduced the hind paw edema in rats at 3 and 5 hours after carrageenan administration (P < .01 and P < .01; P < .01 and P < .05, respectively). SEOS (1,000 mg/kg, p.o.) also produced significant (P < .05) analgesic activity in both the acetic acid-induced writhing test and the formalin-induced licking test (late phase) in mice and rats, respectively. However, SEOS showed no effect on the tail flick and hot plate tests in mice. The results of the present study support the proposal that O. stamineus has anti-inflammatory and non-narcotic analgesic activities. These findings justify the traditional use of the plant for treating pain and inflammation.