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Antinociceptive properties of caffeic acid derivatives in mice

Ten ester derivatives from caffeic acid were synthesized, and their antinociceptive properties are evaluated in mice. The most active compound, dodecyl ester derivative, exhibited potent and dose-related activity against the writhing test, with a calculated ID(50) value of 15.1 (11.9-19.1)micromol/kg and MI of 78.8% being several times more active than reference drugs. It was also effective in other experimental models, such as formalin, capsaicin and glutamate-induced pain tests, but was inactive in the hot-plate test. Although the mechanism of action has still not been elucidated, these results appear to support its therapeutic potential against painful diseases.

Synthesis of new 1-phenyl-3-{4-[(2E)-3-phenylprop-2-enoyl]phenyl}-thiourea and urea derivatives with anti-nociceptive activity

Chalcones or 1,3-diaryl-2-propen-1-ones are known to be useful for treating pain, inflammation, and certain diseases although their uses have not been scientifically verified. Due to the limitations of opioid and NSAID therapy, there is a continuing search for new analgesics. A series of novel new 1-phenyl-3-{4-[(2E)-3-phenylprop-2-enoyl]phenyl}-thiourea and urea derivatives were synthesized and evaluated against writhing test in mice, following the aromatic substitution pattern proposed by Topliss. The results of the preliminary bioassays indicate that compound 3 presents promising anti-nociceptive activity in acetic acid-, formalin-, and glutamate-induced pain in mice, compared with some well-known non-steroidal anti-inflammatory and analgesic drugs.

Anti-hyperalgesic activity of corilagin, a tannin isolated from Phyllanthus niruri L. (Euphorbiaceae)

ETHNOPHARMACOLOGICAL RELEVANCE Corilagin (β-1-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-D-glucose) is a tannin isolated from Phyllanthus niruri (Euphorbiaceae). This plant is well known for their therapeutic purposes to treat several diseases associated with dolorous process and are used in several ethno-medicines in tropical and subtropical countries. AIM OF THE STUDY This study was designed to evaluate the anti-hyperalgesic activity of corilagin using chemically and thermally based nociception models in mice. MATERIALS AND METHODS Corilagin was isolated from Phyllanthus niruri (Euphorbiaceae) by extraction and chromatographic procedures and the anti-hyperalgesic activity was evaluated by using writhing, formalin, capsaicin, glutamate and hot plate tests in mice. RESULTS Corilagin presented activity in acetic acid model with the ID50 calculated value of 6.46 (3.09-13.51) being about 20.6 fold more potent than acetylsalicylic acid. It also exhibited activity against the first phase of formalin test with ID50 value of 18.38 (15.15-22.59) μmol/kg. In the capsaicin and glutamate models, corilagin demonstrated significant activity at the 3 mg/kg. CONCLUSION The experimental data demonstrated that corilagin exhibits anti-hyperalgesic activity that may be due to interaction with the glutamatergic system.

Biological Evaluation of Some Selected Cyclic Imides: Mitochondrial Effects and in vitro Cytotoxicity

Abstract Cyclic imides such as succinimides, maleimides, glutarimides, phthalimides and their derivatives contain an imide ring and a general structure -CO-N(R)-CO- that confers hydrophobicity and neutral characteristic. A diversity of biological activities and pharmaceutical uses have been attributed to them, such as antibacterial, antifungal, antinociceptive, anticonvulsant, antitumor. In spite of these activities, much of their action mechanisms at molecular and cellular levels remain to be elucidated. We now show the effects of several related cyclic imides: maleimides (S2, S2.1, S2.2, S3), glutarimides (S4, S5, S6), 4-aminoantipyrine derivatives (L1, F1, AL1, F1.14, F1.2) and sulfonated succinimides (RO1, FA, FE, FD, MC, DMC) on isolated rat liver mitochondria, B16-F10 melanoma cell line, peritoneal macrophages and different bacterial streams. The effects on mitochondrial respiratory parameters, cell viability and antibacterial activity were also evaluated. The results indicated that S3, S5 and S6 caused an increased oxygen consumption in the presence of ADP (state III) or its absence (state IV), while all other compounds decreased those parameters at different degrees of inhibition. All the compounds decreased the respiratory control coefficient (RCC). Loss of cell viability of peritoneal macrophages and the B16- F10 cell line was observed, L1 and S2.1 being more effective. S1, S2, S3, L1 and F1 compounds showed antibacterial activity at experimental concentrations.

New antinociceptive agents related to dihydrosphingosine

The main objective of this study was to evaluate the antinociceptive activity of three ethylenediamine derivatives and three β-aminoethanol lipidic derivatives structurally related to dihydrosphingosine. These derivatives were selected on the basis of previous results from in vitro and in vivo anti-inflammatory studies. For all of the assayed compounds, an intraperitoneal dose of 3 mg/kg caused pronounced pain inhibition as measured by the acetic acid-induced writhing model in mice. Compounds 3 and 6 demonstrated strong antinociceptive activity at doses as low as 1 mg/kg and proved to be considerably more potent than the common nonsteroidal anti-inflammatory drugs (NSAIDs), acetylsalicylic acid (ASA) and acetaminophen (ACE). We further analyzed these compounds using the capsaicin- and glutamate-induced pain tests. Compounds 3 and 6 also exhibited considerable antinociceptive effects under these conditions, but their inhibitory effects in the formalin test were less pronounced. The exact mechanism of action for these compounds has yet to be established. However, based the results from a hot-plate test, it can be stated that these new drugs do not interact with the opioid system.

Kavain analogues as potential analgesic agents

BACKGROUND Kavalactones are pharmacologically active compounds present in preparations of the root trunk of Piper methysticum Forst, known as kava. This work describes the analgesic activity of some synthesized analogues of synthetic kavain, which is the main component of kava. METHODS The essays were initially performed against the writhing test in mice, and the most promising compound was analyzed using other classical models of nociception, including formalin-, capsaicin-, glutamate-induced nociception, the hot plate test, and measurement of motor performance. RESULTS The results indicated that compound 6-(4-fluorophenyl)-4-methoxy-5,6-dihydropyran-2-one (2d) exerts potent and dose-dependent analgesic activity, inhibiting abdominal constrictions caused by acetic acid in mice, and being more active than some reference drugs. It also presented activity in the other models of pain, with the exception of the hot plate test and the measurement of motor performance. CONCLUSIONS Although compound 2d exerts antinociceptive activity, the mechanism of action remains uncertain, but it does not involve the opioid system and does not appear to be associated with non-specific effects such as changes in locomotor activity or motor coordination.

Antinociceptive Activity and Preliminary Structure-Activity Relationship of Chalcone-Like Compounds

Abstract Chalcones belong to a class of α,β unsaturated aromatic ketones which occur abundantly in nature, especially in plants. They are promising and interesting compounds due to their vast applications in pharmaceuticals, agriculture and industry. Several studies have shown that these compounds exert important biological activities in different experimental models. The present work deals with the antinociceptive activity, evaluated against the writhing test, of three series of chalcone-like compounds obtained by the Claisen-Schmidt condensation, using different aldehydes and substituted acetophenones. The results reveal that the compounds synthesized show a significant antinociceptive effect compared with nonsteroidal drugs such as aspirin, paracetamol and diclofenac. They also show that the electronic demand of the substituents is the dominant factor of the biological activity.

Benzofuranones as potential antinociceptive agents: structure-activity relationships.

This work evaluates the antinociceptive properties of benzofuranones using chemically induced models of pain and the hot plate test. All the compounds exhibited significant antinociceptive activity, with 3-[2-(4-chlorophenyl)-2-oxoetil]-2-benzofuran-1(3H)-one (3d) being the most active. According to the application of the Topliss method, the 2π-π(2) parameter was the preponderant one, indicating that the hydrophobicity (π) seems to be more involved in the antinociceptive activity. Based on the table of other possible substituents proposed by Topliss, three derived from compound 3d were tested. 3-[2-(3-methoxyphenyl)-2-oxoetil]-2-benzofuran-1(3H)-one (3g) showed greater antinociceptive activity with better pharmacokinetic properties predicted. These results show the efficiency of the Topliss Method as a research tool for the discovery of potential candidate molecules for a new antinociceptive drug.

Phytochemical and Antinociceptive Properties of Matayba elaeagnoides Radlk. Barks

A mixture of triterpenes named lupeol (1), α-amyrin (2), β-amyrin (3), and β-sitosterol (4) has been isolated from the hexane fraction of Matayba elaeagnoides. In addition, scopoletin (5), umbelliferone (6), 3β-O-d-glycopyranosyl-sitosterol (7) and betulin (8) were isolated from the chloroform fraction. All the structures were identified by spectroscopic techniques in accordance with literature data. The extracts (hydroalcoholic and methanolic) and some fractions (hexane, chloroform, ethyl acetate and butanol) exerted promising antinociceptive effects in mice. In addition, we have tested the pure compound betulin (8). When analyzed against induced pain using the writhing test (3-10 mg kg-1, i.p.), betulin showed a dosedependent effect with a calculated ID50 value of 7.74 (6.53-9.17) mg kg-1 [17.5 (14.7-20.7) μmol kg-1] and a maximal inhibition (MI) of 58.3% in relation to the control group. When evaluated in the formalin test (3-10 mg kg-1, i.p.), this compound inhibited both phases of pain (neurogenic and inflammatory pain), with calculated ID50 values of 18.3 (17.7-18.9) and 8.3 (7.7-8.9) mg kg-1 [41.5 (38.4-42.7) and 18.8 (17.6-19.9) μmol kg-1] and maximal inhibition of 40.8 and 64.39% for the first and second phases, respectively. Using the same models, this compound was several times more active than two clinically used drugs, namely aspirin and paracetamol, suggesting that its main active principle is related to the antinociceptive effect found for the chloroform fraction of M. elaeagnoids barks