Antinociceptive Effect of the Polygala sabulosa Hydroalcoholic Extract in Mice: Evidence for the Involvement of Glutamatergic Receptors and Cytokine Pathways

The Analgesic Potential of Litsea Species: A Systematic Review

Various plant species from the Litsea genus have been claimed to be beneficial for pain relief. The PRISMA approach was adopted to identify studies that reported analgesic properties of plants from the Litsea genus. Out of 450 records returned, 19 primary studies revealed the analgesic potential of nine Litsea species including (1) Litsea cubeba, (2) Litsea elliptibacea, (3) Litsea japonica, (4) Litsea glutinosa, (5) Litsea glaucescens, (6) Litsea guatemalensis, (7) Litsea lancifolia, (8) Litsea liyuyingi and (9) Litsea monopetala. Six of the species, 1, 3, 4, 7, 8 and 9, demonstrated peripheral antinociceptive properties as they inhibited acetic-acid-induced writhing in animal models. Species 1, 3, 4, 8 and 9 further showed effects via the central analgesic route at the spinal level by increasing the latencies of heat stimulated-nocifensive responses in the tail flick assay. The hot plate assay also revealed the efficacies of 4 and 9 at the supraspinal level. Species 6 was reported to ameliorate hyperalgesia induced via partial sciatic nerve ligation (PSNL). The antinociceptive effects of 1 and 3 were attributed to the regulatory effects of their bioactive compounds on inflammatory mediators. As for 2 and 5, their analgesic effect may be a result of their activity with the 5-hydroxytryptamine 1A receptor (5-HT1AR) which disrupted the pain-stimulating actions of 5-HT. Antinociceptive activities were documented for various major compounds of the Litsea plants. Overall, the findings suggested Litsea species as good sources of antinociceptive compounds that can be further developed to complement or substitute prescription drugs for pain management.

Scopoletin: a review of its pharmacology, pharmacokinetics, and toxicity

Scopoletin is a coumarin synthesized by diverse medicinal and edible plants, which plays a vital role as a therapeutic and chemopreventive agent in the treatment of a variety of diseases. In this review, an overview of the pharmacology, pharmacokinetics, and toxicity of scopoletin is provided. In addition, the prospects and outlook for future studies are appraised. Scopoletin is indicated to have antimicrobial, anticancer, anti-inflammation, anti-angiogenesis, anti-oxidation, antidiabetic, antihypertensive, hepatoprotective, and neuroprotective properties and immunomodulatory effects in both in vitro and in vivo experimental trials. In addition, it is an inhibitor of various enzymes, including choline acetyltransferase, acetylcholinesterase, and monoamine oxidase. Pharmacokinetic studies have demonstrated the low bioavailability, rapid absorption, and extensive metabolism of scopoletin. These properties may be associated with its poor solubility in aqueous media. In addition, toxicity research indicates the non-toxicity of scopoletin to most cell types tested to date, suggesting that scopoletin will neither induce treatment-associated mortality nor abnormal performance with the test dose. Considering its favorable pharmacological activities, scopoletin has the potential to act as a drug candidate in the treatment of cancer, liver disease, diabetes, neurodegenerative disease, and mental disorders. In view of its merits and limitations, scopoletin is a suitable lead compound for the development of new, efficient, and low-toxicity derivatives. Additional studies are needed to explore its molecular mechanisms and targets, verify its toxicity, and promote its oral bioavailability.

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

Pain is associated with many health problems and a reduced quality of life and has been a common reason for seeking medical attention. Several therapeutics are available on the market, although side effects, physical dependence, and abuse limit their use. As the process of pain transmission and modulation is regulated by different peripheral and central mechanisms and neurotransmitters, 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 due to their chemical structural variety and different analgesic mechanisms. Numerous studies suggested that some chemicals from medicinal plants could be alternative options for pain relief and management. Previously, we conducted a literature search aimed at identifying natural products interacting either directly or indirectly with opioid receptors. In this review, instead, we have made an excursus including active ingredients derived from plants whose mechanism of action appears from the literature to be other than the modulation of the opioid system. These substances could, either by themselves or through synthetic and/or semi-synthetic derivatives, be investigated in order to improve their pharmacokinetic characteristics and could represent a valid alternative to the opioid approach to pain therapy. They could also be the basis for the study of new mechanisms of action in the approach to this complex and disabling pathology.

The Antinociceptive Effect of a Hydroalcoholic Extract of Polygala altomontana and Its Chemical Profile Using UPLC-ESI-QTOF-HR-MS

The hydroalcoholic extract of Polygala altomontana (30, 100, and 300 mg/kg, i.g.) showed a dose-dependent antinociceptive action during the inflammatory phase of the formalin test. In addition, the preparation (30 and 300 mg/kg, i.g.) showed anti-hyperalgesic action when tested on a mechanical nociception model. UPLC-ESI-QTOF-MS data indicated the active extract contained phenylpropanoid sucrose esters, glycosylated quercetin derivatives, styrylpyrones, and coumarins. Some identified compounds, including styrylpyrones and coumarins, have previously demonstrated antinociceptive action. The results also show that P. altomontana shows potential for developing pain-relieving herbal remedies and drugs.

Date Palm as Source of Nutraceuticals for Health Promotion: a Review

PURPOSE OF REVIEW

Chronic diseases are problematic to health professional specially when using drugs throughout the course of life with un-tolerated side effects. Returning to nature through using nutraceuticals might have both protective and therapeutic effects. Date palm was claimed to be a good source of such nutraceuticals or functional food ingredients. The purpose of the present review was to spot light on the different phytochemicals, phytonutrients, and remedial effects of date palm (Phoenix dactylifera L.) in a goal to be utilized in form of nutraceuticals. The possible mechanisms of action of the remedial effects were among the aim of the study.

RECENT FINDINGS

A protein hydrolyzate prepared from date seed could prevent DNA mutation and susceptibility to cancer. In addition to cancer prevention, date palm fruit improved the treatment outcome of cancer pediatric patients and possesses anti-angiogenic activity as one of the important anticancer mechanisms of action. On the other hand, date seed extracts was recently reported to protect from ulcerative colitis. It seems that all the aforementioned remedial effect might be ascribed to immunoregulatory effect of date palm. These findings proposed that date palm is beneficial for health. Date palm fruit is a rich source of vitamins, minerals, dietary fibers, energy, and easily digestible and absorbable sugars that instantaneously replenish and revitalize the body specially after fasting condition. Mineral contents in date fruits include potassium, phosphorus, magnesium, and calcium. Diverse health claims were reported to belong to various parts of the tree including the edible part of fruits, the seeds, the leaves, spathe (an envelope-like structure that encloses male and female date palm flowers), and pollen grains due to the presence of different bioactive constituents. The main phytochemicals and phytonutrients reported in date palms are phenolic compounds, carotenoids, sterols, anthocyanins, and others. In folk medicine, date palm fruits are used for enhancing immunity and treating gastrointestinal tract disorders, edema, bronchitis, wound, cancer, as well as infectious diseases. However, the exact health benefits and remedial effects of date palm were not fully and deeply investigated. The present review focused on the bioactive constituents and the reported health benefits of date palm and proposed mechanism of action.

Polygala sabulosa A.W. Bennett extract mitigates motor and cognitive deficits in a mouse model of acute ischemia

Stroke is considered one of the leading causes of death worldwide. The treatment is limited; however, the Brazilian flora has a great source of natural products with therapeutic potentials. Studies with the medicinal plant Polygala sabulosa W. Bennett provided evidence for its use as an anti-inflammatory and neuroprotective drug. In the case of ischemic stroke due to lack of oxygen, both acute and chronic inflammatory processes are activated. Thus, we hypothesized that P. sabulosa (HEPs) has the potential to treat the motor and cognitive deficits generated by ischemic stroke. Male mice were subjected to global ischemia for 60 min, followed by reperfusion and orally treated with HEPs (100 mg/kg in saline + 3% tween 20) twice a day (12 h apart) for 48 h starting 3 h after surgery. Motor skills were assessed using grip force and open field tasks. Hippocampi were then collected for mRNA quantification of the cytokines IL-1-β and TNF-α levels. After 48 h of acute treatment, spatial reference memory was evaluated in a Morris water maze test for another group of animals. We show that HEPs treatment significantly prevented motor weakness induced by ischemia. Brain infarct area was reduced by 22.25% with downregulation of the levels of IL-1β and TNF-α mRNA. Learning performance and memory ability on Morris water maze task were similar to the sham group. Our data demonstrates the neuroprotective properties of HEPs through its anti-inflammatory activities, which prevent motor and cognitive impairments, suggesting that HEPs may be an effective therapy for ischemic stroke.

Artemisia scoparia and Metabolic Health: Untapped Potential of an Ancient Remedy for Modern Use

Botanicals have a long history of medicinal use for a multitude of ailments, and many modern pharmaceuticals were originally isolated from plants or derived from phytochemicals. Among these, artemisinin, first isolated from Artemisia annua, is the foundation for standard anti-malarial therapies. Plants of the genus Artemisia are among the most common herbal remedies across Asia and Central Europe. The species Artemisia scoparia (SCOPA) is widely used in traditional folk medicine for various liver diseases and inflammatory conditions, as well as for infections, fever, pain, cancer, and diabetes. Modern in vivo and in vitro studies have now investigated SCOPA's effects on these pathologies and its ability to mitigate hepatotoxicity, oxidative stress, obesity, diabetes, and other disease states. This review focuses on the effects of SCOPA that are particularly relevant to metabolic health. Indeed, in recent years, an ethanolic extract of SCOPA has been shown to enhance differentiation of cultured adipocytes and to share some properties of thiazolidinediones (TZDs), a class of insulin-sensitizing agonists of the adipogenic transcription factor PPARγ. In a mouse model of diet-induced obesity, SCOPA diet supplementation lowered fasting insulin and glucose levels, while inducing metabolically favorable changes in adipose tissue and liver. These observations are consistent with many lines of evidence from various tissues and cell types known to contribute to metabolic homeostasis, including immune cells, hepatocytes, and pancreatic beta-cells. Compounds belonging to several classes of phytochemicals have been implicated in these effects, and we provide an overview of these bioactives. The ongoing global epidemics of obesity and metabolic disease clearly require novel therapeutic approaches. While the mechanisms involved in SCOPA's effects on metabolic, anti-inflammatory, and oxidative stress pathways are not fully characterized, current data support further investigation of this plant and its bioactives as potential therapeutic agents in obesity-related metabolic dysfunction and many other conditions.

α-Terpineol, a natural monoterpene: A review of its biological properties

Terpineols are monocyclic monoterpene tertiary alcohols which are naturally present in plant species. There are five common isomers of terpineols, alpha-, beta-, gamma-, delta- and terpinen-4-ol, of which α-terpineol and its isomer terpinen-4-ol are the most common terpineols found in nature. α-Terpineol plays an important role in the industrial field. It has a pleasant odor similar to lilacs and it is a common ingredient in perfumes, cosmetics, and aromatic scents.

In addition, α-terpineol attracts a great interest as it has a wide range of biological applications as an antioxidant, anticancer, anticonvulsant, antiulcer, antihypertensive, anti-nociceptive compound. It is also used to enhance skin penetration, and also has insecticidal properties. This study reviews the relevance of α-terpineol based on scientific findings on Google Scholar, Pubmed, Web of Science, Scopus and Chemical Abstracts.

Collectively, the use of α-terpineol in medicine and in the pharmaceutical industry plays an important role in therapeutic applications. This review will, therefore, support future research in the utilization of α-terpineol.

Antinociceptive effect of methanol extract of Celosia cristata Linn. in mice

BACKGROUND

Celosia cristata Linn. (Amaranthaceae) is used in traditional medicine for the treatment of headache, sores, ulcers, eye inflammations, skin eruption, painful menstruation and carpal tunnel syndrome. This study was performed to evaluate the antinociceptive activity of methanol extract of the whole plant of C. cristata (MECC).

METHODS

The evaluation of the antinociceptive effect of MECC was performed using thermal (hot plate, tail immersion test) and chemical (acetic acid, formalin, and glutamate-induced nociception test) pain models in mice at four different doses (50, 100, 200, 400 mg/kg; p.o.). Involvement of opioid receptors mediated central antinociceptive mechanism of MECC was evaluated using naloxone. Furthermore, the association of ATP-sensitive K+ channel and cGMP pathway were evaluated using glibenclamide and methylene blue respectively.

RESULTS

Oral treatment of MECC produced significant, strong and dose-dependent central and peripheral antinociceptive effect in experimental pain models. MECC significantly increased the latency time of thermal threshold in both hot plate and tail immersion test. The inhibition of writhing syndrome by the extract in the acetic acid-induced writhing test was remarkable. MECC significantly reduced the formalin-induced neurogenic and inflammatory pain. In addition, the inhibition of glutamate-induced paw licking and edema by MECC was significant. The antinociceptive effect was significantly reversed by naloxone and glibenclamide, suggesting the association of opioid and ATP-sensitive K+ channel system respectively. In addition, MECC also demonstrated the involvement of cGMP pathway in the antinociceptive action.

CONCLUSION

The study suggests that C. cristata possess significant antinociceptive effect which is associated with both central and peripheral mechanisms and provides a rationale for its extensive use at different painful conditions in traditional medicine.

Antinociceptive effect of hydroalcoholic extract and isoflavone isolated from Polygala molluginifolia in mice: evidence for the involvement of opioid receptors and TRPV1 and TRPA1 channels

PURPOSE

The plants of the genus Polygala (Polygalaceae) have been used for a long time in folk medicine to treat pain and inflammation. The species Polygala molluginifolia is native to southern Brazil and is popularly known as "cânfora". The presented study analyzes the antinociceptive effect of hydroalcoholic extract from Polygala molluginifolia (HEPm) and an isoflavone (ISO) isolated from the extract, in behavioral models of pain in mice, as well as the mechanism underlying this effect.

MATERIALS AND METHODS

The phytochemical analysis of HEPm was performed through a capillary electrophoresis analysis and colorimetric test. The antinociceptive effects of HEPm and ISO (10-1000 mg/kg, i.g.) were evaluated by applying the formalin test; mechanical and thermal hyperalgesia to postoperative pain in mice. The possible involvement of opioid receptors, TRPV1 and TRPA1 channels in the antinociceptive effect of HEPm and ISO were also evaluated. Finally, the nonspecific effects of HEPm and ISO were evaluated by measuring locomotor activity (Open-field Test) and corporal temperature.

RESULTS

The 5,3',4'-trihydroxy-6″,6″-dimethylpyrano[2″,3″:7,6] isoflavone (ISO) was identified in HEPm by capillary electrophoresis analysis and selected for the experimental tests. The oral administration of HEPm or of ISO significantly inhibited the neurogenic and inflammatory phases of formalin-induced pain, edema formation and local hyperemia, without causing any change to locomotor activity. Acute and repeated treatment of animals with HEPm reduced mechanical and thermal (heat and cold) hyperalgesia in the postoperative pain. In addition, administering HEPm or ISO markedly reduced nociceptive behavior induced by the peripheral and central injection of TRPV1 and TRPA1 channels activators. Finally, the antinociception provided by the administration of HEPm or ISO was reversed by the preadministration of naloxone.

CONCLUSIONS

Taken together, these results provide the first experimental evidence of the significant antinociceptive effect of HEPm and ISO in animal models of acute pain without causing sedation or locomotor dysfunction. This effect appears to be mediated, at least in part, by the activation of opioid receptors and/or by the inhibition of TRPV1 and TRPA1 channels. Moreover, this study adds new scientific evidence and highlights the therapeutic potential of the medicinal plant Polygala molluginifolia in the development of phytomedicines with analgesic properties.

Antinociceptive effect of palm date spathe hydroalcoholic extract on acute and chronic pain in mice as compared with analgesic effect of morphine and diclofenac

BACKGROUNDS

In Persian traditional medicine, palm date spathe (PDS) is introduced as an analgesic. Therefore, this study was designed to investigate the analgesic effect of hydroalcoholic extract of PDS on acute and chronic pain in mice in comparison with diclofenac and morphine.

MATERIALS AND METHODS

In this study, which was conducted in summer 2014, 220 male mice (20-30 g) were randomly divided into two categories, each consists of 11 groups as follows: A normal control group, a solvent (Tween 80) control group, 3 morphine positive control groups (2, 4 and 8 mg/kg), 3 diclofenac positive control groups (10, 20 and 30 mg/kg), and 3 main experimental PDS groups (2, 20, and 200 mg/kg). Hot plate was applied on animals in one category and writing test on the other category to assess acute and chronic pain, respectively.

RESULTS

In the writing test, the average writing time and number of animals receiving a maximum dosage of morphine, diclofenac, and PDS were significantly less than the control group. In the hot plate test, only groups receiving different doses of morphine at different time points and those received 30 mg/kg diclofenac at 15 min after the intervention showed significant difference with the control group.

CONCLUSION

200 mg/kg extract of PDS, revealed a significant analgesic effect on chronic pain, but it did not show any analgesic effect on acute pain.

Antinociceptive and neuropharmacological activities of methanol extract of Phoenix sylvestris fruit pulp

Fruits of Phoenix sylvestris Roxb. (Arecaceae) are used to treat back pain, toothache, headache, arthritis, nervous debility and as sedative. The aim of this study was to evaluate the antinociceptive and neuropharmacological activities of methanol extract of P. sylvestris fruit pulp (MEPS). The antinociceptive activity of MEPS was evaluated by heat-induced (hot plate, tail immersion test) and chemical-induced pain models (acetic acid-induced writhing, formalin-induced nociception, glutamate-induced nociception and paw edema test). The effect of MEPS on central nervous system (CNS) was studied using hole cross test, open field test, sodium thiopental-induced sleeping time and elevated plus maze test. MEPS showed strong, significant and dose-dependent antinociceptive activity in all heat-induced and chemical-induced pain models at all experimental doses. Involvement of opioid receptor mediated analgesia was evident from the reversal of analgesic effect by naloxone. MEPS also showed reduced locomotor activity in both hole cross and open field tests. The increase in sleeping time in sodium thiopental-induced sleeping test and anxiolytic activity in elevated plus maze test were also significant. So, it is evident that MEPS possesses strong central and peripheral antinociceptive activity as well as CNS depressant, sedative and anxiolytic activity. The results justify the ethnomedicinal use of P. sylvestris fruit in different painful conditions and CNS disorders.

Anti-inflammatory action of hydroalcoholic extract, dichloromethane fraction and steroid α-spinasterol from Polygala sabulosa in LPS-induced peritonitis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Polygala sabulosa A. W. Bennett is a small herb popularly known as "timutu-pinheirinho" that is widely distributed in southern Brazil and that is used to treat disorders of the bowel and kidney and as a topical anesthetic and expectorant in folk medicine. This study was designed to investigate the anti-inflammatory properties of the hydroalcoholic extract (HEPs), CH2Cl2 fraction and the steroid α-spinasterol obtained from the aerial parts of Polygala sabulosa in a model of acute inflammation induced by intraperitoneal injection of bacterial lipopolysaccharide in mice.

MATERIALS AND METHODS

The anti-inflammatory effect of HEPs (3-300 mg/kg, i.g.), CH2Cl2 fraction (0.003-30 mg/kg, i.g.) and steroid α-spinasterol (0.001-1mg/kg, i.p. or 1-10mg/kg, i.g.), were evaluated in mice subjected to the acute inflammation caused by intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 0.02 µg/kg). The anti-inflammatory activity of the HEPs, CH2Cl2 fraction and steroid were assessed by determining the total numbers of leukocytes and differential cell counts (neutrophils and mononuclear cells) and levels of pro-inflammatory (IL-1β, TNF-α, IL-6) or anti-inflammatory (IL-10) cytokines in peritoneal fluid.

RESULTS

The administration of HEPs (3-300 mg/kg, i.g.) completely inhibited inflammatory cell infiltration (300 mg/kg, i.g.) and it reduced TNF-α (100-300 mg/kg) and IL-1β (100mg/kg) levels in LPS-injected mice. Furthermore, the administration of CH2Cl2 fraction (0.003-30 mg/kg, i.g.) or α-spinasterol (0.001-10mg/kg, by i.p. or i.g.) significantly reduces inflammatory cell infiltration in LPS-injected mice. Moreover, dexamethasone (0.5mg/kg, i.p., used as a positive control) inhibited inflammatory cell infiltration and reduced the levels of TNF-α, IL-1β and IL-6 in LPS-injected mice.

CONCLUSIONS

Taken together, these results provide the first experimental evidence demonstrating that HEPs have significant anti-inflammatory effects on LPS-induced inflammation. These effects appear to be, at least in part, due to the presence of α-spinasterol. These findings support the widespread use of Polygala sabulosa in popular medicine and demonstrate that this plant has therapeutic potential for the development of phytomedicines with anti-inflammatory properties.

Citronellal, a monoterpene present in Java citronella oil, attenuates mechanical nociception response in mice

CONTEXT

Citronellal is a monoterpene present in the oil of many species, including Cymbopogon winterianus Jowitt (Poaceae).

OBJECTIVE

The present study investigated the effect of citronellal on inflammatory nociception induced by different stimuli and examined the involvement of the NO-cGMP-ATP-sensitive K⁺ channel pathway.

MATERIALS AND METHODS

We used male Swiss mice (n = 6 per group) that were treated intraperitoneally with citronellal (25, 50 or 100 mg/kg) 0.5 h after the subplantar injection of 20 μl of carrageenan (CG; 300 µg/paw), tumor necrosis factor-α (TNF-α; 100 pg/paw), prostaglandin E₂ (PGE₂; 100 ng/paw) or dopamine (DA; 30 μg/paw). The mechanical nociception was evaluated at 0.5, 1, 2 and 3 h after the injection of the agents, using a digital analgesimeter (von Frey). The effects of citronellal were also evaluated in the presence of L-NAME (30 mg/kg) or glibenclamide (5 mg/kg).

RESULTS

At all times, citronellal in all doses inhibited the development of mechanical nociception induced by CG (p < 0.001 and p < 0.01) and TNF-α (p < 0.001, p < 0.01, and p < 0.05). The citronellal was able to increase the pain threshold in the DA test (p < 0.001, p < 0.01, and p < 0.05) and in the PGE₂ test at all times (p < 0.001 and p < 0.05). L-NAME and glibenclamide reversed the antinociceptive effects of the citronellal at higher doses in the PGE₂ test.

DISCUSSION AND CONCLUSION

These data suggest that citronellal attenuated mechanical nociception, mediated in part by the NO-cGMP-ATP-sensitive K⁺ channel pathway.

Ethnopharmacological Survey of Plants Used in the Traditional Treatment of Gastrointestinal Pain, Inflammation and Diarrhea in Africa: Future Perspectives for Integration into Modern Medicine

There is a growing need to find the most appropriate and effective treatment options for a variety of painful syndromes, including conditions affecting the gastrointestinal tract, for treating both veterinary and human patients. The most successful regimen may come through integrated therapies including combining current and novel western drugs with acupuncture and botanical therapies or their derivatives. There is an extensive history and use of plants in African traditional medicine. In this review, we have highlighted botanical remedies used for treatment of pain, diarrheas and inflammation in traditional veterinary and human health care in Africa. These preparations are promising sources of new compounds comprised of flavonoids, bioflavanones, xanthones, terpenoids, sterols and glycosides as well as compound formulas and supplements for future use in multimodal treatment approaches to chronic pain, gastrointestinal disorders and inflammation. The advancement of plant therapies and their derivative compounds will require the identification and validation of compounds having specific anti-nociceptive neuromodulatory and/or anti-inflammatory effects. In particular, there is need for the identification of the presence of compounds that affect purinergic, GABA, glutamate, TRP, opioid and cannabinoid receptors, serotonergic and chloride channel systems through bioactivity-guided, high-throughput screening and biotesting. This will create new frontiers for obtaining novel compounds and herbal supplements to relieve pain and gastrointestinal disorders, and suppress inflammation.

Evidence for the analgesic activity of resveratrol in acute models of nociception in mice

The effects of trans-resveratrol (1) were evaluated in acute nociception models induced by capsaicin or glutamate in mice, in an attempt to further characterize its mechanism of action. The oral administration of 1 (50 and 100 mg/kg) reduced significantly the licking behavior elicited by capsaicin (1.6 μg/paw) or glutamate (10 μmol/paw). The co-administration of 1 into the mouse paw (200 μg/site) markedly prevented glutamate-induced licking, without affecting capsaicin responses. In addition, the intrathecal (it) injection of 1 (150 to 600 μg/site) greatly reduced the licking behavior caused by capsaicin, but not glutamate. Similarly, the intracerebroventricular injection of 1 (300 μg/site) caused a potent inhibition of capsaicin-induced nociception, while the glutamate responses remained unaffected. However, the co-administration of 1 (300 μg/site) reduced the biting behavior induced by spinal injection of glutamate (30 μg/site, it), leaving capsaicin (6.4 μg/site)-induced biting unaltered. Notably, the oral administration of 1 (100 mg/kg) inhibited significantly the capsaicin-induced increase of c-Fos and COX-2 labeling in the spinal cord and COX-2 expression in the cortex, but failed to affect c-Fos and COX-2 expression in the glutamate model. This study has explored the effects of 1 in both the capsaicin and glutamate models, extending current knowledge on the analgesic effects of trans-resveratrol.

Antihyperalgesic activity of the methanol extract and some constituents obtained from Polygala cyparissias (Polygalaceae)

Polygala cyparissias, used in folk medicine as an anaesthetic, has already demonstrated antinociceptive activity against acute pain. In this study, we investigated the antihyperalgesic activity of the P. cyparissias methanol extract (PCME) from which the following compounds were isolated: α-spinasterol (PC1), 1,3-dihydroxy-7-methoxyxanthone (PC2), 1,7-dihydroxy-2,3-methylenedioxyxanthone (PC3) and 1,3,6,8-tetrahydroxy-2,7-dimethoxyxanthone (PC4). The antihyperalgesic effect was evaluated using experimental models of persistent pain induced by carrageenan, lipopolysaccharide (LPS), Freund's Complete Adjuvant (CFA), PGE(2) or epinephrine. The partial ligation of the sciatic nerve (PLSN) model was also used. In inflammatory hyperalgesia induced by carrageenan, LPS, CFA or PGE(2), the inhibition values obtained with the PCME treatment were 68 ± 3%, 89 ± 5%, 43 ± 3% and 40 ± 4%, respectively. In epinephrine-induced hyperalgesia, the extract was effective, reducing 99 ± 11% of response frequency, while in PLSN, 54 ± 4% of inhibition was obtained. These results allow to suggest that the antihyperalgesic activity of PCME is, at least in part, related to its capability to inhibit the hypersensitization induced by pro-inflammatory mediators, such as LPS, carrageenan and CFA, without interfering with locomotor activity or motor performance. Furthermore, compounds PC1, PC3 and PC4 inhibited the carrageenan-induced hyperalgesia with inhibition of 42 ± 6%, 48 ± 5% and 64 ± 4%, respectively. In summary, our data demonstrate that PCME has relevant antihyperalgesic activity and that the isolated PC1, PC3 and PC4 seem to be responsible, at least in part, for this important effect.

Antifungal activity of five species of Polygala

Crude extracts and fractions of five species of Polygala - P. campestris, P. cyparissias, P. paniculata, P. pulchella and P. sabulosa - were investigated for their in vitro antifungal activity against opportunistic Candida species, Cryptococcus gattii and Sporothrix schenckii with bioautographic and microdilution assays. In the bioautographic assays, the major extracts were active against the fungi tested. In the minimal concentration inhibitory (MIC) assay, the hexane extract of P. paniculata and EtOAc fraction of P. sabulosa showed the best antifungal activity, with MIC values of 60 and 30 μg/mL, respectively, against C. tropicalis, C. gattii and S. schenckii. The compounds isolated from P. sabulosa prenyloxycoumarin and 1,2,3,4,5,6-hexanehexol displayed antifungal activity against S. schenckii (with MICs of 125 μg/mL and 250 μg/mL, respectively) and C. gattii (both with MICs of 250 μg/mL). Rutin and aurapten isolated from P. paniculata showed antifungal activity against C. gattii with MIC values of 60 and 250 μg/mL, respectively. In the antifungal screening, few of the isolated compounds showed good antifungal inhibition. The compound α-spinasterol showed broad activity against the species tested, while rutin had the best activity with the lowest MIC values for the microorganisms tested. These two compounds may be chemically modified by the introduction of a substitute group that would alter several physico-chemical properties of the molecule, such as hydrophobicity, electronic density and steric strain.

α-Terpineol reduces nociceptive behavior in mice

CONTEXT

α-Terpineol (TPN) is a monoterpenoid alcohol present in the essential oils of several species of the Eucalyptus genus (Myrtaceae).

OBJECTIVE

TPN was assessed for its antinociceptive activity in rodents.

MATERIALS AND METHODS

The antinociceptive effect of TPN was examined using the acetic acid writhing reflex, formalin, glutamate, and capsaicin-induced nociception tests.

RESULTS

TPN produced a significant (P < 0.01 or P < 0.001) analgesic effect by reduction at the early and late phases of paw licking and reduced the writhing reflex in mice (formalin and writhing tests, respectively). In the glutamate test, all doses of TPN produced significant (P < 0.01) nociceptive protection. When the capsaicin-induced nociception test was conducted, TPN produced dose-related inhibition of the nociceptive behavior. In addition, the results of a hot plate test showed central analgesic properties for TPN (P < 0.01 or P < 0.001). Such results were unlikely to be provoked by motor abnormality.

CONCLUSION

Our results suggest that TPN might represent an important tool for management and/or treatment of painful conditions.