Oleanolic Acid, a pentacyclic triterpene attenuates the mustard oil-induced colonic nociception in mice

The Nexus of Inflammation-Induced Epithelial-Mesenchymal Transition and Lung Cancer Progression: A Roadmap to Pentacyclic Triterpenoid-Based Therapies

Lung cancer is the leading cause of cancer-related death worldwide. Its high mortality is partly due to chronic inflammation that accompanies the disease and stimulates cancer progression. In this review, we analyzed recent studies and highlighted the role of the epithelial-mesenchymal transition (EMT) as a link between inflammation and lung cancer. In the inflammatory tumor microenvironment (iTME), fibroblasts, macrophages, granulocytes, and lymphocytes produce inflammatory mediators, some of which can induce EMT. This leads to increased invasiveness of tumor cells and self-renewal of cancer stem cells (CSCs), which are associated with metastasis and tumor recurrence, respectively. Based on published data, we propose that inflammation-induced EMT may be a potential therapeutic target for the treatment of lung cancer. This prospect is partially realized in the development of EMT inhibitors based on pentacyclic triterpenoids (PTs), described in the second part of our study. PTs reduce the metastatic potential and stemness of tumor cells, making PTs promising candidates for lung cancer therapy. We emphasize that the high diversity of molecular mechanisms underlying inflammation-induced EMT far exceeds those that have been implicated in drug development. Therefore, analysis of information on the relationship between the iTME and EMT is of great interest and may provide ideas for novel treatment approaches for lung cancer.

From Plant to Chemistry: Sources of Active Opioid Antinociceptive Principles for Medicinal Chemistry and Drug Design

Pain continues to be an enormous global health challenge, with millions of new untreated or inadequately treated patients reported annually. With respect to current clinical applications, opioids remain the mainstay for the treatment of pain, although they are often associated with serious side effects. To optimize their tolerability profiles, medicinal chemistry continues to study novel ligands and innovative approaches. Among them, natural products are known to be a rich source of lead compounds for drug discovery, and they hold potential for pain management. Traditional medicine has had a long history in clinical practice due to the fact that nature provides a rich source of active principles. For instance, opium had been used for pain management until the 19th century when its individual components, such as morphine, were purified and identified. In this review article, we conducted a literature survey aimed at identifying natural products interacting either directly with opioid receptors or indirectly through other mechanisms controlling opioid receptor signaling, whose structures could be interesting from a drug design perspective.

Tapentadol: A Review of Experimental Pharmacology Studies, Clinical Trials, and Recent Findings

Tapentadol is an analgesic compound that acts centrally to attenuate pain. Previous studies have shown that tapentadol has dual mechanisms of action as a mu-opioid receptor agonist and noradrenaline re-uptake inhibition. Therefore, tapentadol provides a great advantage over classic opioids in pain management from nociceptive to neuropathic. Cumulative evidence from in vitro data suggests that tapentadol effect of norepinephrine re-uptake could be a new target that overcomes other classic opioids in chronic neuropathic pain. Compared to tramadol and other opioids, tapentadol is associated with fewer adverse effects than tramadol. Tapentadol is a new alternative to treat acute, chronic, and neuropathic pain. Thus, this review article was focused on understanding the studies that led to the development of tapentadol as a novel analgesic drug and its advantages over conventional opioids. Thus, tapentadol is a good alternative with fewer adverse effects and is available for human use.

Peripheral Anti-nociceptive and Anti-inflammatory Effect of Oleanolic Acid in a Rat Model of Osteoarthritis

BACKGROUND

Oleanolic acid (OA) is a naturally occurring pentacyclic triterpenoid with multifarious actions. Chief among them is the anti-inflammatory effect it exerts when taken orally; however, the underpinning mechanisms of such effects have not yet been fully explored.

METHODS

In the present study, we evaluated the anti-inflammatory and anti-nociceptive effect of OA by injecting it directly into the knee joint using an animal model of osteoarthritis. Behavioral and electrophysiological studies were conducted to determine whether OA exerts a direct modulatory effect on primary sensory afferents that could lead to a decrease in pain-related behaviors and inflammatory responses. Rats were divided into two main groups: a pre- and a post-treatment group. Knee joint inflammation was induced by injecting a mixture of 3% kaolin and carrageenan (K/C). In the pre-treatment groups, two different doses of OA [5 mg/ml (n=5) and 30 mg/ml (n=4); 0.1 ml per injection] were administered into the synovial cavity of the knee joint before induction of inflammation. In the post-treatment group, rats received only one dose [5 mg/ml (n=5)] of OA after induction of inflammation.

RESULTS

Results indicate that intra-articular injection of OA improves motor coordination and attenuates nociceptive behav-ior and inflammatory reactions. More importantly, we observed a direct depolarizing action of OA on articular sensory fi-bers, a crucial mechanism that activates descending inhibitory pathways and controls incoming nociceptive signals to the spinal cord.

CONCLUSION

Overall, our findings suggest that OA can be used as preventive and therapeutic approach for the management of osteoarthritis.

Antinociceptive effects of Salvia divinorum and bioactive salvinorins in experimental pain models in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Salvia divinorum Epling & Játiva is a Mexican plant used not only in rituals but also in traditional medicine for pain relief. One of the most known bioactive compounds is salvinorin A, which acts centrally in kappa-type opioid receptors.

AIM OF THE STUDY

Despite its traditional use as a medicinal plant, there is not enough scientific investigation to reinforce its potential as analgesic. In this study, Salvia divinorum antinociceptive activity was evaluated in experimental models of nociceptive pain; the writhing test and formalin-induced licking behavior in mice.

MATERIAL AND METHODS

Different Salvia divinorum extracts were prepared by maceration at room temperature in increased polarity (hexane, ethyl acetate and methanol). The ethyl acetate extract (EAEx) was chosen in order to be fractioned and to obtain a mixture of salvinorins. The antinociceptive effect of EAEx (3, 10, 30, and 100 mg/kg, i.p.) was compared with that of tramadol (a partial opioid agonist analgesic drug, 30 mg/kg, i.p.) and the mixture of salvinorins (30 mg/kg, i.p.). In addition, a participation of opioids (naloxone, NX 1 and/or 3 mg/kg, i.p.) and serotonin 5-HT_1A receptors (WAY100635, 0.32 mg/kg, i.p.) was investigated as possible inhibitory neurotransmission involved.

RESULTS

As a result, the EAEx produced significant and dose-dependent antinociceptive effect concerning salvinorins constituents. This effect was blocked in the presence of NX and WAY100635 in the abdominal test, but only by NX in the formalin-induced licking behavior. Whereas, the effect of salvinorins mixture involved opioids and serotonin 5-HT_1A receptors.

CONCLUSION

Data provide evidence of the potential of this species, where salvinorin A is in part responsible bioactive constituent involving participation of the opioids and/or 5-HT_1A serotonin receptors depending on the kind of pain model explored.

Oleanolic acid administration alleviates neuropathic pain after a peripheral nerve injury by regulating microglia polarization-mediated neuroinflammation

Neuropathic pain caused by a peripheral nerve injury constitutes a great challenge in clinical treatments due to the unsatisfactory efficacy of the current strategy. Microglial activation-mediated neuroinflammation is a major characteristic of neuropathic pain. Oleanolic acid is a natural triterpenoid in food and medical plants, and fulfills pleiotropic functions in inflammatory diseases. Nevertheless, its role in neuropathic pain remains poorly elucidated. In the current study, oleanolic acid dose-dependently suppressed LPS-evoked IBA-1 expression (a microglial marker) without cytotoxicity to microglia, suggesting the inhibitory efficacy of oleanolic acid in microglial activation. Moreover, oleanolic acid incubation offset LPS-induced increases in the iNOS transcript and NO releases from microglia, concomitant with the decreases in pro-inflammatory cytokine transcripts and production including IL-6, IL-1β, and TNF-α. Simultaneously, oleanolic acid shifted the microglial polarization from the M1 phenotype to the M2 phenotype upon LPS conditions by suppressing LPS-induced M1 marker CD16, CD86 transcripts, and enhancing the M2 marker Arg-1 mRNA and anti-inflammatory IL-10 levels. In addition, the LPS-induced activation of TLR4-NF-κB signaling was suppressed in the microglia after the oleanolic acid treatment. Restoring this signaling by the TLR4 plasmid transfection overturned the suppressive effects of oleanolic acid on microglial polarization-evoked inflammation. In vivo, oleanolic acid injection alleviated allodynia and hyperalgesia in SNL-induced neuropathic pain mice. Concomitantly, oleanolic acid facilitated microglial polarization to M2, accompanied by inhibition in inflammatory cytokine levels and activation of TLR4-NF-κB signaling. Collectively, these findings confirm that oleanolic acid may ameliorate neuropathic pain by promoting microglial polarization from pro-inflammatory M1 to anti-inflammatory M2 phenotype via the TLR4-NF-κB pathway, thereby indicating its usefulness as therapeutic intervention in neuropathic pain.

Neuropathic pain caused by a peripheral nerve injury constitutes a great challenge in clinical treatments due to the unsatisfactory efficacy of the current strategy.

Hydrogen sulfide modulates IL-6/STAT3 pathway and inhibits oxidative stress, inflammation, and apoptosis in rat model of methotrexate hepatotoxicity

Methotrexate (MTX) is a commonly used anticancer and immunosuppressive agent. However, MTX can induce hepatotoxicity due to oxidative stress, inflammation, and apoptosis. Hydrogen sulfide (H₂S), the endogenous gaseous molecule, has antioxidant, anti-inflammatory, and anti-apoptotic effects. The present work explored the probable protective effect of H₂S against MTX hepatotoxicity in rats and also the possible mechanisms underlying this effect. MTX was given at a single intraperitoneal (i.p.) dose of 20 mg/kg. Sodium H₂S (56 µmol /kg/day, i.p.), as H₂S donor, was given for 10 days, starting 6 days before MTX administration. H₂S significantly reduced serum alanine aminotransferase, hepatic malondialdehyde, interleukin 6, nuclear factor κB p65, cytosolic cytochrome c, phosphorylated signal transducer and activator of transcription 3, and Bax/Bcl-2 ratio and significantly increased hepatic total antioxidant capacity and endothelial nitric oxide synthase (eNOS) in rats received MTX. In addition, H₂S minimized the histopathological injury and significantly decreased the expression of STAT3 in liver tissue of MTX-challenged rats. The effects of H₂S were significantly antagonized by administration of glibenclamide as K_ATP channel blocker, Nω-nitro-l-arginine, as eNOS inhibitor, or ruthenium red, as transient receptor potential vanilloid 1 (TRPV1) antagonist. It was concluded that H₂S provided significant hepatoprotection in MTX-challenged rats through its antioxidant, anti-inflammatory, anti-apoptotic effects. These effects are most probably mediated by the ability of H₂S to act as IL-6/STAT3 pathway modulator, K_ATP channel opener, eNOS activator, and TRPV1 agonist.

Screening of analgesic activity of Tunisian Urtica dioica and analysis of its major bioactive compounds by GCMS

The present study was aimed to evaluate the analgesic properties of Urtica dioica (UD) and to profile phytochemicals by gas chromatography-mass spectrometry (GC-MS). The ethanolic extracts were prepared by maceration method and extraction using rotary evaporator. The analgesic activity was analysed by hot plate method, formalin test, acetic acid-induced writhing test and the tail-flick test with different doses of the ethanolic extract. In all tests, the leaf's ethanolic extract exhibited significant analgesic activity (p < .001) at a dose of 400 mg/kg. Even with a low dose, we noticed an analgesic activity with many tests. The GC-MS analysis of the ethanol extract of leaf revealed many compounds; 2-methyltetradecane dodecane, 2,6,11-trimethyl-; 2,6,11-trimethyldodecane, and trimethylhexane which are pharmaceutically the most important. These findings justify that UD can be a valuable natural analgesic source which seemed to provide potential phototherapeutics against various ailments. The analysis of ethanolic extract of UD by GCMS revealed the presence of several compounds including polyphenols, flavonoids, triterpenes which can explain the analgesic effect of UD and its mechanism of action. Hence, UD could be another therapeutic alternative for relieving pain and for minimising the use of drugs that have long-term secondary effects.

Antimalarial, antiplasmodial and analgesic activities of root extract of Alchornea laxiflora

CONTEXT

Alchornea laxiflora (Benth.) Pax. & Hoffman (Euphorbiaceae) root decoctions are traditionally used in the treatment of malaria and pain in Nigeria.

OBJECTIVE

To assess the antimalarial, antiplasmodial and analgesic potentials of root extract and fractions against malarial infections and chemically-induced pains.

MATERIAL AND METHODS

The root extract and fractions of Alchornea laxiflora were investigated for antimalarial activity against Plasmodium berghei infection in mice, antiplasmodial activity against chloroquine sensitive (Pf 3D7) and resistant (Pf INDO) strains of Plasmodium falciparum using SYBR green assay method and analgesic activity against experimentally-induced pain models. Acute toxicity study of the extract, cytotoxic activity against HeLa cells and GCMS analysis of the active fraction were carried out.

RESULTS

The root extract (75-225 mg/kg, p.o.) with LD50 of 748.33 mg/kg exerted significant (p < 0.05-0.001) antimalarial activity against P. berghei infection in suppressive, prophylactive and curative tests. The root extract and fractions also exerted moderate activity against chloroquine sensitive (Pf 3D7) and resistant (Pf INDO) strains of P. falciparum with the ethyl acetate fraction exerting the highest activity with IC50 value of 38.44 ± 0.89 μg/mL (Pf 3D7) and 40.17 ± 0.78 μg/mL (Pf INDO). The crude extract was not cytotoxic to HeLa cells with LC50 value >100 μg/mL. The crude extract and ethyl acetate fraction exerted significant (p < 0.05-0.001) analgesic activity in all pain models used.

DISCUSSION AND CONCLUSIONS

These results suggest that the root extract/fractions of A. laxiflora possess antimalarial, antiplasmodial and analgesic potentials and these justify its use in ethnomedicine to treat malaria and pain.

Strong and Long-Lasting Antinociceptive and Anti-inflammatory Conjugate of Naturally Occurring Oleanolic Acid and Aspirin

The conjugate 8 was obtained as a result of condensation of 3-hydroxyiminooleanolic acid morfolide (7) and aspirin in dioxane. Analgesic effect of OAO-ASA (8) for the range of doses 0.3–300.0 mg/kg (p.o.) was performed in mice using a hot-plate test. Anti-inflammatory activity was assessed on carrageenan-induced paw edema in rats for the same range of doses. The conjugate OAO-ASA (8) did not significantly change locomotor activity of mice, therefore sedative properties of the compound should be excluded. The compound 8 proved a simple, proportional, dose-dependent analgesic action and expressed strong anti-inflammatory activity showing a reversed U-shaped, dose-dependent relation with its maximum at 30.0 mg/kg. After its combined administration with morphine (MF, 5.0 mg/kg, s.c.) the lowering of antinociceptive activity was found; however, the interaction with naloxone (NL, 3.0 mg/kg, s.c.) did not affect the antinociceptive effect of OAO-ASA (8), therefore its opioid mechanism of action should be rather excluded. After combined administration with acetylsalicylic acid (ASA, 300.0 mg/kg, p.o.) in hot-plate test, the examined compound 8 enhanced the antinociceptive activity in significant way. It also shows that rather the whole molecule is responsible for the antinociceptive and anti-inflammatory effect of the tested compound 8, however, it cannot be excluded that the summarizing effect is produced by ASA released from the compound 8 and the rest of triterpene derivative. The occurrence of tolerance for triterpenic derivative 8 was not observed, since the analgesic and anti-inflammatory effects after chronic administration of the conjugate OAO-ASA (8) was on the same level as after its single treatment. It seemed that the anti-inflammatory mechanism of action of OAO-ASA (8) is not simple, even its chronic administration lowered both blood concentration of IL-6 and mRNA IL-6 expression. However, the effects of the conjugate OAO-ASA (8) on TNF-α level and mRNA expression were opposite. Moreover, compound 8 did not change unequivocally mRNA TLR1, and TLR3 expression. Concluding, the obtained results regarding the antinociceptive and anti-inflammatory activity of new conjugate of oleanolic acid oxime and acetylsalicylic acid (OAO-ASA 8) are very interesting, but for explanation of its mechanism of action, more detailed studies are necessary.

Preclinical Assessment of Inflammatory Pain

While acute inflammation is a natural physiological response to tissue injury or infection, chronic inflammation is maladaptive and engenders a considerable amount of adverse pain. The chemical mediators responsible for tissue inflammation act on nociceptive nerve endings to lower neuronal excitation threshold and sensitize afferent firing rate leading to the development of allodynia and hyperalgesia, respectively. Animal models have aided in our understanding of the pathophysiological mechanisms responsible for the generation of chronic inflammatory pain and allowed us to identify and validate numerous analgesic drug candidates. Here we review some of the commonly used models of skin, joint, and gut inflammatory pain along with their relative benefits and limitations. In addition, we describe and discuss several behavioral and electrophysiological approaches used to assess the inflammatory pain in these preclinical models. Despite significant advances having been made in this area, a gap still exists between fundamental research and the implementation of these findings into a clinical setting. As such we need to characterize inherent pathophysiological pathways and develop new endpoints in these animal models to improve their predictive value of human inflammatory diseases in order to design safer and more effective analgesics.

Simultaneous determination of 3-O-acetyloleanolic acid and oleanolic acid in rat plasma using liquid chromatography coupled to tandem mass spectrometry

3-O-Acetyloleanolic acid (OAA) is a triterpenoid compound, and exerts an apoptosis in cancer cell lines, an inhibition of both atopic and allergic contact dermatitis in murine model, and a suppression of inflammatory bone loss in mice. OAA can be converted into oleanolic acid (OA) by hydrolysis in vivo, and OA exhibits several pharmacological effects as well. A liquid chromatographic method using tandem mass spectrometry (MS/MS) was developed for the simultaneous determination of OAA and OA in rat plasma. After liquid-liquid extraction with ethylacetate, both substances were chromatographed on a reversed phase column with a mobile phase of 0.1% formic acid aqueous solution and acetonitrile (1:9, v/v). The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This analytical method was successfully applied to monitor plasma concentrations of both substances over time following an intravenous administration of OAA in rats.

Short-term effect of acute and repeated urinary bladder inflammation on thigmotactic behaviour in the laboratory rat

Understanding the non-sensory components of the pain experience is crucial to developing effective treatments for pain conditions. Chronic pain is associated with increased incidence of anxio-depressive disorders, and patients often report feelings of vulnerability which can decrease quality of life. In animal models of pain, observation of behaviours such as thigmotaxis can be used to detect such affective disturbances by exploiting the influence of nociceptive stimuli on the innate behavioural conflict between exploration of a novel space and predator avoidance behaviour. This study investigates whether acute and repeated bladder inflammation in adult female Wistar rats increases thigmotactic behaviour in the open field paradigm, and aims to determine whether this correlates with activation in the central amygdala, as measured by c-Fos immunoreactivity. Additionally, up-regulation of inflammatory mediators in the urinary bladder was measured using RT-qPCR array featuring 92 transcripts to examine how local mediators change under experimental conditions. We found acute but not repeated turpentine inflammation of the bladder increased thigmotactic behaviour (decreased frequency of entry to the inner zone) in the open field paradigm, a result that was also observed in the catheter-only instrumentation group. Decreases in locomotor activity were also observed in both models in turpentine and instrumentation groups. No differences were observed in c-Fos activation, although a general increased in activation along the rostro-caudal axis was seen. Inflammatory mediator up-regulation was greatest following acute inflammation, with CCL12, CCL7, and IL-1β significantly up-regulated in both conditions when compared to naïve tissue. These results suggest that acute catheterisation, with or without turpentine inflammation, induces affective alterations detectable in the open field paradigm accompanied by up-regulation of multiple inflammatory mediators.

Formulation and in vitro characterization of a novel solid lipid-based drug delivery system

The liquid self-emulsifying drug delivery system (L-SEDDS), commonly used to deliver effective but poorly water-soluble oleanolic acid (OA), has many limitations such as high manufacturing costs, few choices of dosage forms, risk of leakage from hard gelatin capsules, low stability, limited portability, incompatibility with capsule materials, and relatively restricted storage conditions. Thus the main purpose of our study was to develop a promising solid lipid-based drug delivery system (S-SEDDS) for OA. The S-SEDDS, prepared from wet granulation with an optimized L-SEDDS formulation and mannitol, was characterized by particle size analysis, scanning electron microscopy, differential scanning calorimetry, and X-ray powder diffraction. Finally, the solubility of the OA-loaded S-SEDDS was compared with that of OA powder in the dissolution assay. Our new S-SEDDS for OA was developed from the optimum L-SEDDS with ethyl oleate (oil phase), Labrasol (surfactant), and Transcutol P (cosurfactant) at a volume ratio of 15:71:14 with 1.5% w/v OA and mannitol. The dissolution of OA was improved by 60% compared with that of the pure OA powder. All the problems associated with the L-SEDDS were resolved. The methodologies we developed for OA delivery could also be utilized for the delivery of other drugs with the S-SEDDS.

Anti-inflammatory and antinociceptive activities of Homalium letestui

CONTEXT

Homalium letestui Pellegr (Flacourtiaceae) is used in various decoctions traditionally by the Ibibios of the Niger Delta of Nigeria to treat stomach ulcer, malaria and other inflammatory diseases, as well as an aphrodisiac.

OBJECTIVE

To investigate the anti-inflammatory and antinociceptive activities of the stem extract of the plant.

MATERIALS AND METHODS

The ethanol stem extract (500, 750, 1000 mg/kg, i.p.) of H. letestui was investigated for anti-inflammatory activity using carrageenan, egg albumin-induced and xylene-induced ear edema models and analgesic activity using acetic acid-induced writhing, formalin-induced paw licking and thermal-induced pain models. The ethanol extract was administered to the animals orally, 30 min to 1 h depending on the model, before induction of inflammation/pain. The LD50 was also determined. GC-MS analysis of dichloromethane fraction was carried out.

RESULTS

The extract caused a significant (p < 0.05-0.001) reduction of inflammation induced by carrageenan (8.3-70.0%), egg albumin (10.0-71.42%) and xylene (39.39-84.84%). The extract also reduced significantly (p < 0.05-0.001) pain induced by acetic acid (44.22-73.65%), formalin (55.89-79.21%) and hot plate (93.0-214.5%). The LD50 was determined to be 4.38 ± 35.72 g/kg.

DISCUSSION AND CONCLUSION

The results of this study suggest that the ethanol stem extract of H. letestui possesses anti-inflammatory and analgesic properties which may in part be mediated through the chemical constituents of the plant as revealed by the GC-MS.

An evaluation of the anti-tumor efficacy of oleanolic acid-loaded PEGylated liposomes

The effective delivery of oleanolic acid (OA) to the target site has several benefits in therapy for different pathologies. However, the delivery of OA is challenging due to its poor aqueous solubility. The study aims to evaluate the tumor inhibition effect of the PEGylated OA nanoliposome on the U14 cervical carcinoma cell line. In our previous study, OA was successfully encapsulated into PEGylated liposome with the modified ethanol injection method. Oral administration of PEGylated OA liposome was demonstrated to be more efficient in inhibiting xenograft tumors. The results of organ index indicated that PEG liposome exhibited higher anti-tumor activity and lower cytotoxicity. It was also found that OA and OA liposomes induced tumor cell apoptosis detected by flow cytometry. Furthermore, effects of OA on the morphology of tumor and other tissues were observed by hematoxylin and eosin staining. The histopathology sections did not show pathological changes in kidney or liver in tested mice. In contrast, there was a significant difference in tumor tissues between treatment groups and the negative control group. These observations imply that PEGylated liposomes seem to have advantages for cancer therapy in terms of effective delivery of OA.

Antiallodynic and analgesic effects of maslinic acid, a pentacyclic triterpenoid from Olea europaea

The effects of maslinic acid (1), a pentacyclic triterpenoid obtained from Olea europaea, were studied in several tests for nociception in mice. Systemic administration of 1 reduced acetic acid-induced writhing, the inflammatory phase of formalin-induced pain, and capsaicin-induced mechanical allodynia. However, it did not induce motor incoordination in the rotarod test. The topical administration of 1 also reduced the inflammatory phase of the formalin test, indicating that at least some of its effects are mediated peripherally. The present results demonstrate for the first time that maslinic acid induces antinociceptive and antiallodynic effects.

Antinociceptive effect of Lecythis pisonis Camb. (Lecythidaceae) in models of acute pain in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Lecythis pisonis Camb., also known in Brazil as sapucaia, is used in folk medicine against pruritus, muscle pain and gastric ulcer.

AIM OF THE STUDY

To investigate the antinociceptive effect of ethanol extract from Lecythis pisonis leaves (LPEE), fractions (hexane-LPHF, ether-LPEF and ethyl acetate-LPEAF) and mixture of triterpenes [ursolic and oleanolic acids (MT)] in mice.

MATERIALS AND METHODS

LPEE and LPEF were evaluated on the acetic acid induced writhings and formalin, capsaicin and glutamate tests. In addition, MT was investigated on the writhings induced by acetic acid, capsaicin and glutamate tests. In the study of some possible mechanisms involved on the antinociceptive effect of LPEF, it was investigated the participation of opioid system, K+ATP channels and L-arginine-nitric oxide pathway.

RESULTS

LPEE (12.5 and 25 mg/kg, p.o.), LPEF and MT (6.25, 12.5 and 25 mg/kg, p.o.) reduced the writhings in comparison to saline. LPEE (100 mg/kg, p.o.) and LPEF (50 mg/kg, p.o.) were effective in inhibiting both phases of formalin test. In capsaicin test, LPEE (100 and 200 mg/kg, p.o.), LPEF (12.5-50 mg/kg, p.o) and MT (6.25-25 mg/kg, p.o.) showed a significant antinociceptive effect compared to the control. LPEE (25 and 50 mg/kg, p.o.), LPEF (50 and 100 mg/kg, p.o.) and MT (12.5 and 25 mg/kg, p.o.) reduced the glutamate-evoked nociceptive response. Treatment with naloxone, L-arginine and glibenclamide reversed the effect of LPEF in glutamate test.

CONCLUSIONS

These results indicate the antinociceptive effect of Lecythis pisonis leaves and suggest that this effect may be related to opioid pathway, K+ATP channels, and L-arginine-nitric oxide modulation. Furthermore, these data support the ethnomedical use of this plant.

Antidepressive-Like Property of Dichloromethane Fraction of Pimenta pseudocaryophyllus and Relevance of Monoamine Metabolic Enzymes

Pimenta pseudocaryophyllus popularly referred to as craveiro is considered as a calming agent in different local preparations. The present study attempted to examine antidepressant-like effect of dichloromethane fraction (DF) and role of monoamine oxidase (MAO), tryptophan, and tyrosine hydroxylase. Based on the research focus, tail suspension (TS), forced swimming (FS), and open field (OF) tests were conducted after oral administration of DF (125, 250, or 500 mg/Kg). Ex vivo assay of MAO was also conducted to evaluate inhibitory effect of DF (250 mg/Kg). Administration of DF elicits antidepressant-like response in the TS and FS. However, DF 500 mg/Kg did not alter mice performance in these models. The data obtained in the OF showed a reduction in total crossing and rearing activity; these effects suggest motor interference in TS and FS performance. Mice pretreatment with p-chlorophenylalanine methyl ester (PCPA) (100 mg/kg, i.p.—serotonin biosynthesis inhibitor) for 4 consecutive days or acute administration of α-methyl-p-tyrosine (AMPT) (100 mg/kg, i.p.—catecholamine synthesis inhibitor) blocked anti-immobility effect of DF in the FS. In ex vivo assay of MAO, DF did not inhibit catabolic activity of MAO. Our findings support antidepressant-like activity of DF and suggest an effect that depends on monoamine biosynthesis.

Bioactive oleanane, lupane and ursane triterpene acid derivatives

Betulinic, ursolic and oleanolic acids isolated from the aerial parts of Eriope blanchetii (Lamiaceae) were subjected to different esterification reactions, yielding 12 C-3 position ester derivatives. All compounds were identified using spectroscopic techniques, such as IR, 1H-NMR and MS. The derivatives were further investigated for their antioxidant level, Artemia salina lethality and antimicrobial activity.

Anti-nociceptive and anti-inflammatory activities of the Agastache mexicana extracts by using several experimental models in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Agastache mexicana is a plant that has long been used in large demand in Mexican folk medicine to treat pain, among others affections. Nevertheless, no scientific data confirming its use have been reported. The aim of this investigation was to examine the spectrum of antinociceptive activity of A. mexicana by using different experimental models of nociception in rodents.

MATERIAL AND METHODS

Nociceptive activity was induced 30 min post treatment of different doses of hexane, ethyl acetate and methanol extracts from A. mexicana aerial parts. The writhing test in mice, and the formalin and plantar tests as well as the pain-induced functional impairment assay in rats (PIFIR model) were the experimental nociceptive models used. Antinociceptive response of the organic extracts was compared to that observed with the analgesic drug tramadol.

RESULTS

A. mexicana organic extracts produced a dose-dependent and significant inhibition of the abdominal constrictions caused by 1% acetic acid injection (i.p.) in mice. A maximal antinociceptive effectiveness obtained with tramadol was also observed with the administration of hexane and ethyl acetate extracts in comparison to less effectiveness obtained with the methanol extract. At the same range of doses, A. mexicana organic extracts inhibited the behavioral responses in both phases of the formalin pain test, in which a more intense effect was observed in the inflammatory phase than in the neurogenic stage. With regard to the plantar test and PIFIR model, a significant but not dose-dependent antinociceptive response was observed at specific doses that depended on the organic extract evaluated.

CONCLUSION

The antinociceptive activity of A. mexicana aerial parts depends on the intensity of the painful stimulus induced and involves different kinds of constituents. Our present results reinforce the use of this species in traditional medicine and its utility for pain treatment mainly associated with inflammation.

The analgesic and anti-inflammatory effect of new oleanolic acid acyloxyimino derivative

The new derivative of well-known triterpene, oleanolic acid: methyl 3-octanoyloxyiminoolean-12-en-28-oate 5, was synthesized by the action of caprylic acid on methyl oleanolate 3-oxime in the presence of dicyclohexylcarbodiimide in dioxane. The molecular structure of the obtained product 5 was confirmed by spectral methods. The acute toxicity, locomotor activity, and the dose-dependent analgesic activity were studied. In addition, the effect of compound 5 on morphine-induced analgesic activity, the dose-dependent anti-inflammatory activity and the effect of the compound on diclofenac anti-inflammatory activity study were performed. The results proved a low toxicity (LD₅₀ > 2 g/kg) of the tested product 5, which affected neither vertical nor horizontal locomotor activity in the given range of doses. The triterpene 5 also produced centrally mediated (morphine-like) analgesic action; however, only in the highest dose. The synergistic analgesic activity of 5 and morphine in the doses of 30.0 and 300.0mg/kg was found. Compound 5 expressed the anti-inflammatory action which did not affect the anti-inflammatory activity of diclofenac after their combined administration.

Antinociceptive effectiveness of triterpenes from rosemary in visceral nociception

ETHNOPHARMACOLOGICAL RELEVANCE

Rosemary is a species used worldwide as a common spice, but also in folk medicine for their therapeutic properties against abdominal pain. The rationale of this study was to examine the involvement of triterpenes and to compare their effectiveness in the antinociceptive effect of an ethanol extract of Rosmarinus officinalis L. (Lamiaceae).

MATERIAL AND METHODS

Fractionation and HPLC analyses allowed the identification of a mixture of micromeric (121 mg/g), oleanolic (64 mg/g) and ursolic (83 mg/g) acids as partial antinociceptive responsible in an ethyl acetate fraction of R. officinalis by using the acetic acid-induced abdominal constrictions model in mice.

RESULTS

These triterpenes individually evaluated produced a significant and dose-dependent antinociceptive response with similar potency as follows: ED₅₀=1.1 mg/kg (0.9-1.3 mg/kg), 2.1 mg/kg (1.6-2.6 mg/kg) and 1.6 mg/kg (1.1-2.1 mg/kg), respectively, by using the intraperitoneal (i.p.) route of administration in mice. Their maximal antinociceptive efficacy resembled that produced by ketorolac (10 mg/kg, i.p.), a common clinic analgesic.

CONCLUSION

Our results provide evidence that these triterpenes participate in the antinociceptive activity of R. officinalis. In addition, each individual triterpene showed a similar potency to that observed with ketorolac, a non-steroidal anti-inflammatory drug, in this experimental model.

Black cohosh: coming full circle?

ETHNOPHARMACOLOGICAL RELEVANCE

Black cohosh (Actaea racemosa L.), Ranunculaceae, thrives in temperate climates east of the Mississippi River in the USA. It is economically important to the Appalachian region where it is wild harvested, but it has resisted most efforts at deliberate cultivation. Black cohosh has been used for many centuries both in Europe and in the US (by indigenous people and subsequent Caucasian medical practitioners), most notably for indications of premenstrual syndrome (PMS), menstrual pain and cramping.

AIM OF THE STUDY

To highlight black cohosh as an example in which disregard for the ethnobotanical and ethnopharmacologic usages of a plant has perhaps hindered modern scientific attempts to understand the mechanism of action of its bioactive phytochemicals, and ascribe cause to effect.

RESULTS

Research on its mode of action has historically focused on its presumed hormonal (phytoestrogenic) activity, but very recent work suggests that it may in fact be acting as an antinociceptive agent. Re-examination of some of the writings of 19th and 20th century physicians and folk literature suggests that this mode of action may have been overlooked in modern experimentalists' in vitro and animal studies and in the very few well conducted human trials to date.

CONCLUSIONS

The common folk perception of this plant as a "remedy for female problems" may thus require revision, as it may possess more general analgesic properties. In the broader context, ethnopharmacologic indications for other herbal remedies must be revisited in light of the explosion in understanding of mechanisms of action of small molecule effectors of which actein and cimicifugoside (from black cohosh) are only two examples.

Antinociceptive and anti-inflammatory potential of extract and isolated compounds from the leaves of Salvia officinalis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Salvia officinalis L. has been used as a traditional herbal medicine for gastric disturbances and inflammatory processes. This study investigated the toxicological, antinociceptive and anti-inflammatory effects of the hydroalcoholic extract (HE) from leaves of Salvia officinalis and its isolated compounds in mice.

MATERIALS AND METHODS

Mice were treated with HE before the induction of nociceptive response by chemical agents (acetic-acid, formalin, glutamate, capsaicin and cinnamaldehyde). Total leukocytes and plasma extravasation induced by acetic acid and paw oedema induced by glutamate, capsaicin and cinnamaldehyde were also measured. The antinociceptive effect of carnosol and ursolic acid/oleanolic acid were evaluated on formalin and cinnamaldehyde models.

RESULTS

In the acute toxicity test the value of estimated LD50 for HE was 44.7579 g/kg. Oral administration of HE (10, 30 and 100 mg/kg) inhibited the number of writhings, total leukocytes and plasma extravasation induced by acetic acid. In the formalin test, HE reduced both neurogenic and inflammatory phases, effect that was affected by naloxone. The glutamate-, capsaicin- and cinnamaldehyde-induced nociception and paw oedema were reduced by HE at doses that did not affect the locomotor activity of mice in the open field test. Carnosol (10mg/kg) and ursolic acid/oleanolic acid (30 mg/kg) inhibited the inflammatory phase of formalin and the nociception and mechanical allodynia induced by cinnamaldehyde.

CONCLUSIONS

These results demonstrate that HE presents significant anti-inflammatory and also antinociceptive effects on chemical behavioral models of nociception that involves an opioid mechanism. In addition, carnosol and ursolic acid/oleanolic acid contained in this plant appears to contribute for the antinociceptive property of the extract, possibly through a modulatory influence on TRPA1-receptors. However, further studies regarding the precise site and the mechanism of action of HE and carnosol and ursolic acid/oleanolic acid merited exploring further.

Analgesic and anti-inflammatory effects of Cassia siamea Lam. stem bark extracts

AIM OF THE STUDY

The present study was carried out to investigate analgesic and anti-inflammatory activities of Cassia siamea Lam stem bark extracts. We have also determined the cytotoxicity of each extract.

MATERIALS AND METHODS

C. siamea, a widespread medicinal plant traditionally used in sub-Saharan Africa, was collected in Congo Brazzaville. Stem bark was extracted with petroleum ether (CSE1), chloroform (CSE2), ethanol (CSE3) and water (CSE4). Analgesic, anti-inflammatory and antipyretic activities of these extracts were assessed in rats with hot plate test, paw pressure and carrageenan induced paw oedema. Cytotoxicity was assessed against KB and Vero cells.

RESULTS

At the doses used (100, 200, and 400mg/kg) ethanol and water extracts showed significant and dose-dependent analgesic and anti-inflammatory effects. None of the extracts had cytotoxic activity on KB and Vero cell lines and the most active extracts (CSE3 and CSE4) had no acute toxicity.

CONCLUSIONS

The study highlighted the analgesic and anti-inflammatory of C. siamea stem bark. Four major families of compounds present in the plant may explain these activities: triterpenes (lupeol, oleanolic acid, ursolic acid, friedelin, betulin), flavonoids (apigenin, kaempferol, luteolin), anthraquinones (emodin), phytosterols (stigmasterol, beta-sitosterol).

Utilizing nature as a source of new probes for opioid pharmacology

Background: Traditional and current opioid pharmacology is fundamentally based on interactions between opioid receptors and compounds isolated from natural sources. Adverse effects associated with opioids have led to the search for compounds with diminished side effects. Discussion: Recent discoveries of non-nitrogenous and structurally diverse alkaloids as novel opioid ligands have led to renewed interest in the development of novel chemotypes for opioid receptors. Conclusion: The strong history of natural products as opioid receptor ligands suggests that nature is one of the most promising for the identification of novel opioids. This review highlights the vast potential of investigating natural products as novel probes of opioid receptors.

Interspecies scaling of oleanolic acid in mice, rats, rabbits and dogs and prediction of human pharmacokinetics

This study was conducted to predict the pharmacokinetics of oleanolic acid in humans based on animal data by allometry and several species-invariant time methods. Oleanolic acid was injected intravenously to mice, rats, rabbit and dogs (dose 1 mg/kg). The serum concentration-time profiles of oleanolic acid were best described by bi-exponential equation in all animal species. The average Cl, V ( ss ) and t ( 1/2 ) were 0.065 L/h, 0.019 L and 28.7 min in mice, 0.47 +/- 0.06 L/h, 0.117 +/- 0.029 L and 29.7 +/- 12.2 min in rats, 2.77 +/- 0.88 L/h, 1.83 +/- 0.60 L and 84.4 +/- 16.9 min in rabbits and 14.0 +/- 0.7 L/h, 9.2 +/- 10.1 L and 54.5 +/- 57.2 min in dogs, respectively. Based on animal data, human pharmacokinetic parameters of Cl, V ( ss ) and t (1/2) were predicted by simple allometry. In addition, actual concentration-time profiles obtained from animals were transformed to human profiles by species-invariant times of kallynochron, apolysichron and dienetichron. The predicted human pharmacokinetic parameters of Cl, V ( ss ) and t (1/2) by using simple allometry and species-invariant time transformation method ranged from 48.3-97.2 L/h, 49.1-92.9 L and 45.6-187.2 min, respectively. Those predicted parameters of oleanolic acid may be useful in designing dosing schedules of oleanolic acid in future clinical studies.

Oleanolic acid and related derivatives as medicinally important compounds

Oleanolic acid has been isolated from chloroform extract of Olea ferruginea Royle after removal of organic bases and free acids. The literature survey revealed it to be biologically very important. In this review the biological significance of oleanolic acid and its derivatives has been discussed. The aim of this review is to update current knowledge on oleanolic acid and its natural and semisynthetic analogs, focussing on its cytotoxic, antitumer, antioxidant, anti-inflamatory, anti-HIV, acetyl cholinesterase, alpha-glucosidase, antimicrobial, hepatoprotective, anti-inflammatory, antipruritic, spasmolytic activity, anti-angiogenic, antiallergic, antiviral and immunomodulatory activities. We present in this review, for the first time, a compilation of the most relevant scientific papers and technical reports of the chemical, pre-clinical and clinical research on the properties of oleanolic acid and its derivatives.

Endogenous opiates and behavior: 2006

This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Analgesic activity of Ugni molinae (murtilla) in mice models of acute pain

Leaf extracts of Ugni molinae Turcz. (Myrtaceae) are used in Chilean folk medicine as analgesic and anti-inflammatory. The antinociceptive effect of dichloromethane (DCM), ethyl acetate (EA) and methanol (ME) leaf extracts was assessed by intraperitoneal, oral and topical administration in writhing, tail flick, and tail formalin tests in mice. The extracts showed a dose-dependent antinociceptive activity in all the assays under different administration routes. The ED(50) values for the different tests for the DCM, EA, ME extract and reference drug (ibuprofen) were as follows. Writhing test in acetic acid (i.p. administration): 0.21, 0.37, 1.37 and 0.85mg/kg, respectively; tail flick test (oral administration): 199, 189, 120 and 45.9mg/kg. The EC(50) values for tail flick test were (topical administration): 2.0, 0.35, 1.4 and 8.2% (w/v), respectively; and the topical analgesic effects were (formalin assay) 75.5, 77.5, 31.6 and 76.5%, respectively. Ugni molinae extracts produce antinociception in chemical and thermal pain models through a mechanism partially linked to either lipooxygenase and/or cyclooxygenase via the arachidonic acid cascade and/or opioid receptors. Flavonoid glycosides and triterpenoids have been isolated from the plant and can be associated with the observed effect. Our results corroborate the analgesic effects of Ugni molinae, and justify its traditional use for treating pain.

Dose-linear pharmacokinetics of oleanolic acid after intravenous and oral administration in rats

The pharmacokinetics of oleanolic acid was evaluated in vitro and in vivo. From Caco-2 cell permeation studies, oleanolic acid was a low permeability compound with no directional effects, suggesting a low in vivo absorption mediated by a passive diffusion. Oleanolic acid was metabolically unstable following incubation with rat liver microsomes in the presence of NADPH. After intravenous injection at doses of 0.5, 1 and 2 mg/kg doses, oleanolic acid showed dose-linear pharmacokinetics as evidenced by unaltered CL (28.6-33.0 ml/min/kg), Vss (437-583 ml/kg), dose-normalized AUC (16.0-17.9 microg min/ml based on 1 mg/kg) and t1/2 (41.9-52.7 min). Following oral administration of oleanolic acid at doses of 10, 25 and 50 mg/kg, Tmax, t1/2, dose-normalized Cmax (66-74 ng/ml based on 25 mg/kg) and dose-normalized AUC (5.4-5.9 microg min/ml based on 25 mg/kg) were comparable between 25 and 50 mg/kg dose, but the plasma concentrations at 10 mg/kg dose were not measurable as they were below the limit of quantitation (2 ng/ml). The absolute oral bioavailability was 0.7% for oral doses of 25 and 50 mg/kg. The extent of urinary excretion was minimal for both i.v. and oral doses. The very low oral bioavailability of oleanolic acid could be due to a poor absorption and extensive metabolic clearance.

The vanilloid receptor initiates and maintains colonic hypersensitivity induced by neonatal colon irritation in rats

BACKGROUND & AIMS

Robust chemical or mechanical irritation of the colon of neonatal rats leads to chronic visceral hypersensitivity. The clinical and physiologic relevance of such noxious stimulation in the context of human irritable bowel syndrome is questionable. The aims of this study were to determine whether mild chemical irritation of the colon of neonatal rats produced persistent changes in visceral sensitivity and to evaluate the role of transient receptor potential vanilloid 1 (TRPV1) in the initiation and maintenance of visceral hypersensitivity.

METHODS

Ten-day-old rat pups received an intracolonic infusion of 0.5% acetic acid in saline. TRPV1 inhibitors were administered 30 minutes before acetic acid sensitization. Sensitivity of the colon to balloon distention (CRD) in adults was measured by grading their abdominal withdrawal reflex and electromyographic responses. In adult rats, TRPV1 antagonist was injected intraperitoneally 30 minutes before CRD.

RESULTS

Neonatal acetic acid treatment resulted in higher sensitivity to CRD in adult rats compared with controls in the absence of histopathologic signs of inflammation. Treatment of colons of adult rats with acetic acid did not produce persistent sensitization. Antagonism of the TRPV1 before neonatal administration of acetic acid and after established visceral hypersensitivity attenuated sensitivity to CRD. TRPV1 expression was increased in dorsal root ganglia-containing colon afferent neurons.

CONCLUSIONS

We have described a new model for persistent colonic sensory dysfunction following a transient noxious stimulus in the neonatal period and a potentially important role for TRPV1 in initiation and maintenance of persistent visceral hypersensitivity.

Novel agonistic action of mustard oil on recombinant and endogenous porcine transient receptor potential V1 (pTRPV1) channels

Neurogenic components play a crucial role in inflammation and nociception. Mustard oil (MO) is a pungent plant extract from mustard seed, horseradish and wasabi, the main constituent of which is allylisothiocyanate. We have characterized the action of MO on transient receptor potential V1 (TRPV1), a key receptor of signal transduction pathways in the nociceptive system, using fura-2-based [Ca(2+)](i) imaging and the patch-clamp technique in a heterologous expression system and sensory neurons. In human embryonic kidney (HEK) 293 cells expressing porcine TRPV1 (pTRPV1), MO evoked increases of [Ca(2+)](i) in a concentration-dependent manner. A high concentration of MO elicited irreversible cell swelling. Capsazepine, ruthenium red and iodoresiniferatoxin dose-dependently suppressed the MO-induced [Ca(2+)](i) increase. MO elicited outward rectified currents in pTRPV1-expressing HEK 293 cells with a reversal potential similar to that of capsaicin. [Ca(2+)](i) responses to MO were completely abolished by the removal of external Ca(2+). MO simultaneously elicited an inward current and increase of [Ca(2+)](i) in the same cells, indicating that MO promoted Ca(2+) influx through TRPV1 channels. In cultured porcine dorsal root ganglion (DRG) neurons, MO elicited a [Ca(2+)](i) increase and inward current. Among DRG neurons responding to MO, 85% were also sensitive to capsaicin. The present data indicate that MO is a novel agonist of TRPV1 channels, and suggest that the action of MO in vivo may be partly mediated via TRPV1. These results provide an insight into the TRPV1-mediated effects of MO on inflammation and hyperalgesia.

Oleanolic acid, a pentacyclic triterpene attenuates capsaicin-induced nociception in mice: possible mechanisms

The anti-inflammatory pentacyclic triterpene, oleanolic acid (OA) was examined on acute nociception induced by intraplantar injection of capsaicin in mice. OA administered orally to mice at 10, 30 and 100 mgkg(-1), significantly attenuated the paw-licking response to capsaicin (1.6 microg/paw) by 53%, 68.5% and 36.6%, respectively. Ruthenium red (3 mgkg(-1), s.c.), a non-competitive vanilloid receptor (V1, TRPV1)-antagonist also suppressed the capsaicin nociception by 38.6%. The maximal antinociception produced by 30 mgkg(-1) OA was significantly blocked in animals pre-treated with naloxone (2 mgkg(-1), i.p.), the opioid antagonist; l-arginine (600 mgkg(-1), i.p.), the substrate for nitric oxide synthase; or glibenclamide (2 mgkg(-1), i.p.), the K(ATP)-channel blocker, but was unaffected by yohimbine (2 mgkg(-1), i.p.), an alpha(2)-adrenoceptor antagonist. In open-field and rota-rod tests that detect motor deficits, mice received 30 mgkg(-1) OA did not manifest any effect per se, indicating that the observed antinociception is not a consequence of motor abnormality. These data suggest that OA inhibits capsaicin-evoked acute nociception due to mechanisms possibly involving endogenous opioids, nitric oxide, and K(ATP)-channel opening.