A partial agonist of PPARγ prevents paclitaxel-induced peripheral neuropathy in mice, by inhibiting neuroinflammation

BACKGROUND AND PURPOSE

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of paclitaxel, affecting 30-50% of patients. Increased survival and concern with patients' quality of life have encouraged the search for new tools to prevent paclitaxel-induced neuropathy. This study presents the glitazone 4-[(Z)-(2,4-dioxo-1,3-thiazolidin-5-ylidene)methyl]-N-phenylbenzene-sulfonamide (TZD-A1) as a partial agonist of peroxisome proliferator-activated receptor γ (PPARγ), its toxicological profile and effects on paclitaxel-induced CIPN in mice.

EXPERIMENTAL APPROACH

Interactions of TZD-A1 with PPARγ were analysed using in silico docking and in vitro reporter gene assays. Pharmacokinetics and toxicity were evaluated using in silico, in vitro and in vivo (C57Bl/6 mice) analyses. Effects of TZD-A1 on CIPN were investigated in paclitaxel-injected mice. Axonal and dorsal root ganglion damage, mitochondrial complex activity and cytokine levels, brain-derived neurotrophic factor (BDNF), nuclear factor erythroid 2-related factor 2 (Nrf2) and PPARγ, were also measured.

KEY RESULTS

Docking analysis predicted TZD-A1 interactions with PPARγ compatible with partial agonism, which were corroborated by in vitro reporter gene assays. Good oral bioavailability and safety profile of TZD-A1 were shown in silico, in vitro and in vivo. Paclitaxel-injected mice, concomitantly treated with TZD-A1 by i.p. or oral administration, exhibited decreased mechanical and thermal hypersensitivity, effects apparently mediated by inhibition of neuroinflammation and mitochondrial damage, through increasing Nrf2 and PPARγ levels, and up-regulating BDNF.

CONCLUSION AND IMPLICATIONS

TZD-A1, a partial agonist of PPARγ, provided neuroprotection and reduced hypersensitivity induced by paclitaxel. Allied to its safety profile and good bioavailability, TZD-A1 is a promising drug candidate to prevent and treat CIPN in cancer patients.

Chemical Composition and Antinociceptive Potential of Plinia edulis Fruits Peels

The present study deals with the chemical composition and antinociceptive effects of Plinia edulis fruit peels, analyzed by writhing, formalin, glutamate and capsaicin tests and comparison with two reference analgesic drugs, acetylsalicylic acid and acetaminophen. Phytochemical analyses of the nonpolar fraction (dichloromethane) obtained from the peels of P. edulis fruits revealed the presence of two triterpenes, maslinic acid and ursolic acid. The methanol extract of P. edulis peels showed a pronounced antinociceptive activity in the writhing test, with inhibition of 91.3% at 10 mg/kg, and its dichloromethane and ethyl acetate fractions presented inhibition of 68.3% and 51.5%, respectively. Maslinic acid showed a dose-dependent effect with inhibition of 60.8% at a dose of 10 mg/kg and ID50 value of 3.31 (2.75 to 4.0) mg/kg. The dichloromethane fraction, evaluated in the formalin-induced pain model at a dose of 10 mg/kg, showed a significant effect on both phases of pain. Maslinic acid was evaluated at different doses (1, 3 and 6 mg/kg) and presented a dose-dependent profile in both phases of pain, being more effective than the reference drug (acetaminophen), which was evaluated at 10 mg/kg. The dichloromethane fraction also inhibited the pain induced by glutamate and capsaicin by around 54% and 44%, respectively, whereas maslinic acid was more effective against glutamate, with 62.5% inhibition at 6 mg/kg, and 32% inhibition against capsaicin-induced pain. The results demonstrated that the pronounced antinociceptive effect presented by P. edulis fruits peels is related, at least in part, to the presence of the triterpenes evidenced in this study.

Chemical Composition and Antinociceptive Potential of Campomanesia reitziana Fruits

The methanolic extract from Campomanesia reitziana fruits and the main active principle, identified as 4',6'-dihydroxy-3',5'-dimethyl-2'-methoxy chalcone or dimethyl cardamonin (1), exhibited pronounced antinociceptive effects against two models of pain in mice. Compound 1 caused dose-dependent inhibition of abdominal constrictions, with a calculated ID50 value of 8.1 (6.5-10.1) μmol/kg (i.p.), being about 16-fold more potent than two reference analgesic drugs. Methanolic extract and 1 were also effective against the formalin model, inhibiting both phases of pain, causing reductions of 39.9% and 26.8% (extract, 10 mg/kg) and 52.9% and 57.6% (compound 1, 5 mg/kg) for the first and second phases, respectively.

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

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.

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

A magnetic nanogel based on O-carboxymethylchitosan for antitumor drug delivery: synthesis, characterization and in vitro drug release

This paper studied the synthesis, characterization and use of the magnetic chitosan nanogel for carrying meleimidic compounds. The hydrogel polymer was prepared using O-carboxymethylchitosan, which was crosslinked with epichlorohydrin for subsequent incorporation of iron oxide magnetic nanoparticles. The characterization revealed that the magnetic material comprises about 10% of the hydrogel. This material is comprised of magnetite and maghemite and exhibits ferro-ferrimagnetic behavior. The average particle size is 4.2 nm. There was high incorporation efficiency of maleimides in the magnetic nanogel. The release was of sustained character and there was a greater release when an external magnetic field was applied. The mathematical model that best explained the process of drug release by the magnetic hydrogel was that of Peppas-Sahlin. The magnetic nanogel proved to be an excellent candidate for use in drug-delivery systems.

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.

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.