Antinociceptive activity of Amaranthus spinosus in experimental animals

Phytochemical and pharmacological aspects of genus Amaranthus

The variety of bioactive compounds found in different species of Amaranthus, an herb that is a staple food in many parts of India. The plethora of herb Amaranthus has been a rich source of bioactive compounds like essential oils, sesquiterpenes, diterpenes, triterpenes, phenolic acids, flavonoids, etc. The traditional uses of Amaranthus, spp. have been established scientifically and were shown due to the presence of different phytochemicals. Although the pharmacological activities of Amaranthus genus have been well-documented, further studies are needed to fully understand their mechanisms of action and clinical applications. In conclusion, the phytochemistry and pharmacological activity of genus Amaranthus make it a promising source of natural products for drug discovery and development. The present is review mainly concise to the ethnopharmacological relevance and pharmacological studies of Amaranthus species. This conclusive review work may on Amaranthus species provided the interconnection of bioactive molecules with its ethno pharmacological utility of plant species.

Toxicological evaluation of the dried hydroethanolic extract of Amaranthus spinosus L. roots in Artemia salina larvae and Sprague Dawley rats

Background

Amaranthus spinosus is a medicinal plant used in traditional medicine to treat several diseases including diabetes and its complications. The aim of this study was to prove the safety of the plant in animal health.

Methods

The dry extract was obtained following the hydroethanolic extraction of A. spinosus roots. The cytotoxicity was evaluated in vitro by incubating Artemia salina larvae with the extract for 24 h. In vivo toxicity was assessed in Sprague Dawley rats. A single dose of 5000 mg/kg bw of extract was administered orally to female rats in acute toxicity and observed for 14 days for mortality and signs of toxicity. In subchronic toxicity, extract doses of 500 and 1000 mg/kg bw were administered orally to male and female rats for 28 consecutive days and observed for previous signs. Body weight was recorded daily and blood glucose levels every week. On day 29, blood was collected for biochemical and hematological studies. Organs were then exised for gross autopsy and histopathological examination.

Results

The in vitro study showed that the extract had a LC50 = 1.178 mg/mL in larvae and was considered to be non-cytotoxic. Oral administration of extract at a single dose of 5000 mg/kg bw did not cause any mortality or sign of toxicity in gross necropsy. In subchronic oral toxicity, repeated doses of 500 and 1000 mg/kg bw of extract, did not also cause any mortality or significant change in body weight, relative weight of vital organs. Furthermore, hematological and biochemical parameters and histopathological examination did not show any significant change. The observed decrease in blood glucose levels did not correlate with organ damage and supports the safety of the plant. However, the reduction of LDL-cholesterol has shown that the extract can prevent cardiovascular disease.

Conclusions

This finding demonstrated that A. spinosus root is non-toxic with a LD50 > 5000 mg/kg bw. Thus, the extract can be used for cutaneous and subchronic oral administration at doses ≤ 1000 mg/kg bw. However, further studies such as embryo/fetotoxicity, genotoxicity and neurotoxicity will be needed to prove the safety of chronic administration of the extract in patients and fetuses.

Anti-inflammatory and analgesic effects of methanol extract of red cultivar Allium cepa bulbs in rats and mice

OBJECTIVES

Several cultivars of Allium cepa L. have been studied for anti-inflammatory and analgesic activities but there is inadequate information on such biological activities of the concentrated extracts of the Nigerian grown red cultivar A. cepa bulb.

METHODS

The anti-inflammatory models used in this study were Carrageenan-induced paw oedema and formalin-induced paw lick in rats, while acetic acid-induced abdominal writhing, hot plate reaction, hot water tail flick tests in mice were the analgesic models.

RESULTS

At 30 min post-induction (pi), the inhibition of paw oedema (62.50%) by 200 mg/kg of methanol extract of red cultivar A. cepa bulb (MERCACB) was significantly (p<0.001) higher than that of indomethacin (15.63%) at 10 mg/kg. The paw oedema inhibition at 60 min pi by MERCACB (76.92%) was significantly higher than that of indomethacin (41.03%). At the early phase of formalin paw-lick test, the pain reaction time (PRT) of rat treated with MERCACB (400 mg/kg) was significantly lower than that of indomethacin and the control groups. The hotplate test revealed that PRT of mice treated with 800 mg/kg of MERCACB were significantly (p<0.01) longer in comparism to indomethacin and control groups. The PRT of mice subjected to thermal pain due to hot water and treated with 800 mg/kg of MERCACB was significantly (p<0.05) longer than that of the control group.

CONCLUSIONS

These findings indicate that MERCACB possesses potent anti-inflammatory and analgesic properties which confirm the traditional use of the plant for the treatment of inflammatory diseases and may be useful as a future therapeutic agent.

Improvement of Pain Relief of Fentanyl Citrate Drug Encapsulated in Nanostructured Lipid Carrier: Drug Formulation, Parameter Optimization, in vitro and in vivo Studies

Introduction

In this study, the encapsulation of fentanyl citrate as an opioid drug with hydrophobic nature in the nanostructured lipid carrier (NLC) is performed.

Methods

For encapsulation of fentanyl citrate drug, hot homogenization method is used. The pharmacokinetics of encapsulated fentanyl citrate for pain relief of rats are investigated. The influence of important variables such as the ratio of liquid lipid to the total amount of lipids, surfactant type and concentration on the particle size is investigated using response surface method.

Results

Results show that the optimal NLC size is about 90 nm with PDI value around 0.2 and zeta potential of -25±4.01 mV. Characterization analysis of optimal nanostructure shows successful encapsulation of the drug in nanostructure with a spherical morphology of the NLC structure. Results of drug release from commercial fentanyl citrate ampoule and NLC form indicate a control drug release from the NLC within 72 hours in comparison to the commercial ampoule. In vivo studies show that fentanyl citrate-loaded NLC not only has the potential to relieve pain in doses equal to commercial drug but also it can reduce the dose of the drug about 50%.

Conclusion

In conclusion, NLC form of fentanyl citrate can increase the efficacy of the drug by appropriate drug distribution in the body and can reduce the risks of overdose.

HPLC-DAD identification of polyphenols from ethyl acetate extract of Amaranthus spinosus leaves and determination of their antioxidant and antinociceptive effects

Amaranthus spinosus has been consumed traditionally to prevent various diseases including abdominal pain. In this study, the phytochemical composition, antioxidant and analgesic activities of an ethyl acetate extract of A. spinosus leaves (ASEA) were evaluated. The ASEA had the highest concentrations of total phenols (462.2 mg GAE/g DW), condensed tannin (5.01 mg CE/g DW) and total flavonoid contents (30.07 mg CE/g DW) compared to the chloroform, n-hexane, n-butanol and water extracts. Similarly, ASEA showed the most effective total antioxidant activity (45.45 µg/mL), DPPH scavenging activity (27.32 µg/mL) and hydrogen peroxide scavenging activity (30.60 µg/mL). ASEA with the doses of 200-600 mg/kg (p.o.) clearly demonstrated antinociceptive effects by reducing acetic acid-induced abdominal contortions with a maximal inhibition of 79.57% at 600 mg/kg and increasing latencies of the hot-plate paw-licking response. The tested doses also significantly (p < 0.001) decreased the reaction time in the formalin test at the neurogenic and inflammatory phases. ASEA contained ten polyphenols with caffeic acid being the predominant polyphenol. Overall, this study gave evidence that A. spinosus is a new antioxidant and analgesic agent, and justified its traditional use for the treatment of pain.

Chronic Monosodium Glutamate Administration Induced Hyperalgesia in Mice

Monosodium glutamate (MSG) is a widely used food additive. Although it is generally considered safe, some questions regarding the impact of its use on general health have arisen. Several reports correlate MSG consumption with a series of unwanted reactions, including headaches and mechanical sensitivity in pericranial muscles. Endogenous glutamate plays a significant role in nociceptive processing, this neurotransmitter being associated with hyperalgesia and central sensitization. One of the mechanisms underlying these phenomena is the stimulation of Ca2+/calmodulin sensitive nitric oxide synthase, and a subsequent increase in nitric oxide production. This molecule is a key player in nociceptive processing, with implications in acute and chronic pain states. Our purpose was to investigate the effect of this food additive on the nociceptive threshold when given orally to mice. Hot-plate and formalin tests were used to assess nociceptive behaviour. We also tried to determine if a correlation between chronic administration of MSG and variations in central nitric oxide (NO) concentration could be established. We found that a dose of 300 mg/kg MSG given for 21 days reduces the pain threshold and is associated with a significant increase in brain NO level. The implications of these findings on food additive-drug interaction, and on pain perception in healthy humans, as well as in those suffering from affections involving chronic pain, are still to be investigated.

A survey of herbal weeds for treating skin disorders from Southern Thailand: Songkhla and Krabi Province

ETHNOPHARMACOLOGICAL RELEVANCE

Skin diseases are common health problems which affecting to all ages. In Thailand, the number of patients diagnosed with skin diseases is increasing every year. Nowadays, The Ministry of Public Health is supporting and promoting herbs for treating various disorders, including disorders of the skin to reduce the problem of antibiotic resistance and adverse drug reactions. This study aimed to: (1) enumerate the herbal weeds for treating skin disorders; (2) study local knowledge of weed utilization for treating skin disorders according to the folk healers in Songkhla and Krabi province; and (3) study quantitative data by Informant consensus factor (ICF), Use value (UV) and Fidelity level (FL) value.

MATERIALS AND METHODS

Field surveys and Semi-structured interviews about the local names, parts of plants used, preparation and use method, as well as local properties were done. The data were further analyzed by descriptive statistics, interpretation and quantitative indexes (ICF, UV as well as FL).

RESULTS

The results discovered 44 herbal species of weeds belonging to 41 genera in 25 families. The most used plant families were Amaranthaceae (6 species). Most plants were used to treat abscess (18 species; 40.91%). The highest UV was recorded for Commelina benghalensis (0.65). The highest ICF values were found in vitiligo, ringworm, tinea versicolor and burns (1.00 each). The highest FL values were recorded for Cleome gynandra, Cleome viscosa, Sphenoclea zeylanica, Acmella oleracea, Leersia hexandra, Cyperus involucratus, Phyllanthus urinaria and Iresine herbstii (100.00 each). A review of the literatures revealed that 34 plant species had already been tested for their pharmacological activities. The biological activities associated with treatment of skin diseases can be divided into four categories: antimicrobial, anti-inflammatory, wound healing and antioxidant activity.

CONCLUSION

The information indicates that herbal weedy utilization is still importance to the treatment of traditional healers through accumulated experience for a long time. Therefore, this study is a guide to the conservation of folk medicinal knowledge. It might be implied as the basis for drug development and application of herbal weeds to treat skin disorders along with promoting sustainable use of natural resource.

Antinociceptive activity of Euadenia trifoliolata (Schum. & Thonn.) Oliv. leaves and roots in mice

The leaves and roots of Euadenia trifoliolata are used in Nigeria traditional medicine for the treatment of ear ache, head ache and inflammation. The aim of the study was to evaluate the antinociceptive activity of ethanolic extract of the leaves (EL) and roots (ER) of E. trifoliolata in mice. Oral toxicity testing was performed using OECD guidelines. Antinociceptive effect was studied in mice using acetic acid-induced writhing, formalin, tail immersion and hot plate tests. Total polyphenolic contents were determined using standard methods. No mortality was recorded 24 h after oral administration of both EL and ER up to 5000 mg/kg. At the dose of 50, 100 and 200 mg/kg, administration of EL and ER resulted in significant reduction in the number of writhes compared to control. The percentage inhibition of writhings was calculated as 35.67%, 46.71% and 67.94% (EL) and 55.41%, 57.32% and 72.61% (ER), respectively. In hot plate test, EL and ER showed statistically significant antinociceptive effect, although low percentage inhibition (<50%) was recorded for ER at all the doses tested. Only EL (100 and 200 mg/kg) significantly (p < 0.001) increased the reaction time in tail immersion test. Both extracts significantly (p < 0.001) reduced the licking time in both phases of formalin test compared to control. The content of total phenolic, flavonoid and proanthocyanidin varies between the two extracts and may be the basis of the observed antinociceptive effect. The results indicate antinociceptive activity for the leaves and roots of E. trifoliolata, with the extract of the leaves showing better activity.

Nitroxyl inhibits overt pain-like behavior in mice: role of cGMP/PKG/ATP-sensitive potassium channel signaling pathway

BACKGROUND

Several lines of evidence have indicated that nitric oxide (NO) plays complex and diverse roles in modulation of pain/analgesia. However, the roles of charged and uncharged congeners of NO are less well understood. In the present study, the antinociceptive effect of the nitroxyl (HNO) donor, Angeli's salt (Na2N2O3; AS) was investigated in models of overt pain-like behavior. Moreover, whether the antinociceptive effect of nitroxyl was dependent on the activation of cGMP (cyclic guanosine monophosphate)/PKG (protein kinase G)/ATP-sensitive potassium channels was addressed.

METHODS

The antinociceptive effect of AS was evaluated on phenyl-p-benzoquinone (PBQ)- and acetic acid-induced writhings and via the formalin test. In addition, pharmacological treatments targeting guanylate cyclase (ODQ), PKG (KT5923) and ATP-sensitive potassium channel (glybenclamide) were used.

RESULTS

PBQ and acetic acid induced significant writhing responses over 20min. The nociceptive response in these models were significantly reduced in a dose-dependent manner by subcutaneous pre-treatment with AS. Furthermore, AS also inhibited both phases of the formalin test. Subsequently, the inhibitory effect of AS in writhing and flinching responses were prevented by ODQ, KT5823 and glybenclamide, although these inhibitors alone did not alter the writhing score. Furthermore, pretreatment with L-cysteine, an HNO scavenger, confirmed that the antinociceptive effect of AS depends on HNO.

CONCLUSION

The present study demonstrates the efficacy of a nitroxyl donor and its analgesic mechanisms in overt pain-like behavior by activating the cGMP/PKG/ATP-sensitive potassium channel (K(+)) signaling pathway.

Anti-inflammatory and antinociceptive activity of epiisopiloturine, an imidazole alkaloid isolated from Pilocarpus microphyllus

The aim of this study was to investigate the antinociceptive and anti-inflammatory activities of epiisopiloturine (1), an imidazole alkaloid found in the leaves of Pilocarpus microphyllus. The anti-inflammatory activity of 1 was evaluated using several agents that induce paw edema and peritonitis in Swiss mice. Paw tissue and peritoneal fluid samples were obtained to determine myeloperoxidase (MPO) activity or tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels. The antinociceptive activity was evaluated by acetic acid-induced writhing, the hot plate test, and pain induction using formalin. Compared to vehicle treatment, pretreatment with 1 (0.1, 0.3, and 1 mg/kg, ip) of mice significantly reduced carrageenan-induced paw edema (p < 0.05). Furthermore, compound 1 at a dose of 1 mg/kg effectively inhibited edema induced by dextran sulfate, serotonin, and bradykinin, but had no effect on histamine-induced edema. The administration of 1 (1 mg/kg) following carrageenan-induced peritonitis reduced total and differential peritoneal leukocyte counts and also carrageenan-induced paw MPO activity and TNF-α and IL-1β levels in the peritoneal cavity. Pretreatment with 1 also reduced acetic acid-induced writhing and inhibited the first and second phases of the formalin test, but did not alter response latency in the hot plate test. Pretreatment with naloxone reversed the antinociceptive effect of 1.

Evaluation of gut modulatory and bronchodilator activities of Amaranthus spinosus Linn

BACKGROUND

The aqueous-methanolic extract of Amaranthus spinosus (A. spinosus Linn.,) whole plant, was studied for its laxative, spasmolytic and bronchodilator activities to validate some of its medicinal uses.

METHODS

The crude extract of A. spinosus was studied in-vivo for bronchodilator and laxative activities and in-vitro using isolated tissue preparations which were mounted in tissue baths assembly containing physiological salt solutions, maintained at 37°C and aerated with carbogen, to assess the spasmolytic effect and to find out the possible underlying mechanisms.

RESULTS

In the in-vivo experiments in mice, the administration of A. spinosus increased fecal output at doses of 100 and 300 mg/kg showing laxative activity. It also inhibited carbachol-induced bronchospasm in anesthetized rats at 1, 3, 10 and 30 mg/kg indicative of bronchodilator activity. When tested on isolated gut preparations, the plant extract showed a concentration-dependent (0.01-10.0 mg/ml) spasmogenic effect in spontaneously contracting rabbit jejunum and guinea-pig ileum. The spasmogenic effect was partially blocked in tissues pretreated with atropine (0.1 μM). When tested on K+ (80 mM)-induced sustained contractions in isolated rabbit jejunum, the plant extract caused complete relaxation and also produced a shift in the Ca++ concentration-response curves (CRCs) towards right, similar to diltiazem. In rabbit trachea, the plant extract completely inhibited K+ (80 mM) and carbachol (CCh, 1 μM)-induced contractions at 1 mg/ml but pretreatment of tissue with propranolol (1 μM), caused around 10 fold shift in the inhibitory CRCs of the plant extract constructed against CCh-induced contraction. The plant extract (up to 0.3 mg/ml) also increased both force and rate of spontaneous contractions of isolated guinea-pig atria, followed by relaxation at higher concentration (1.0-5.0 mg/ml). The cardio-stimulant effect was abolished in the presence of propranolol, similar to that of isoprenaline. Activity-directed fractionation revealed that the spasmolytic component(s) was separated in the organic fraction, whereas the spasmogenic component was concentrated in the aqueous fraction.

CONCLUSION

These results indicate that A. spinosus possesses laxative activity partially mediated through cholinergic action. The spasmolytic effect was mediated through calcium channel blocking (CCB), while bronchodilator activity through a combination of β-adrenergic and CCB pathways, which may explain the traditional uses of A. spinosus in gut and airways disorders.

Anti-inflammatory effect of triterpene 3β, 6β, 16β-trihydroxylup-20(29)-ene obtained from Combretum leprosum Mart & Eich in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The 3β, 6β, 16β-trihydroxylup-20(29)-ene (TTHL) is a pentacyclic triterpene obtained from a medicinal plant named Combretum leprosum. In folk medicine, this plant is used to treat several diseases associated with inflammation and pain. We previously demonstrated that TTHL presents a significant antinociceptive effect, suggesting the involvement of the glutamatergic system.

AIM OF THE STUDY

This study was designed to investigate the effect of TTHL on nociception and vascular permeability induced by acetic acid. We also evaluated the effect of TTHL on carrageenan-induced peritonitis and the levels of cytokines (interleukin 1-β [IL-1β], tumor necrosis factor α [TNF-α] and interleukin 10 [IL-10]) on peritoneal fluid.

MATERIALS AND METHODS

TTHL was administered orally by intra-gastric gavage (i.g.) 60 min prior to experimentation. Abdominal contractions and vascular permeability were induced by an intraperitoneal (i.p.) injection of acetic acid (0.6%). We also investigated whether TTHL decreases carrageenan-induced peritonitis (750 μg/cavity) by measuring leukocyte migration and vascular permeability. In addition, we evaluated the effects of TTHL on TNF-α, IL-1β and IL-10 release induced by carrageenan on peritoneal fluid. The levels of these cytokines were measured by ELISA.

RESULTS

TTHL (0.01-10 mg/kg) administered by intra-gastric (i.g.) gavage inhibited (69±3%) acetic acid-induced abdominal constrictions, with an ID₅₀ of 0.15 (0.03-0.8) mg/kg. TTHL (10mg/kg) also reduced the leukocyte infiltration induced by acetic acid, with an inhibition of 59±9 but had no effect on abdominal vascular permeability. In addition, indomethacin (10 mg/kg, i.p.) reduced the nociceptive behavior (92±1%), total leukocyte migration (29±3%) and capillary permeability (71±3%) induced by acetic acid. While the glucocorticoid dexamethasone (2 mg/kg, s.c.) reduced partially but significantly the nociception (31±1%), besides to promote a marked reduction on total leukocyte migration (60±2%) to the peritoneal cavity caused by acetic acid. In a model of peritonitis induced by carrageenan, TTHL also reduced total leukocyte migration, mainly neutrophils (inhibition of 84±3% and 85±2% at 30 mg/kg and 100 mg/kg, respectively). Likewise, dexamethasone (0.5 mg/kg, i.p.) resulted in an inhibition of 93±3%. Nevertheless, carrageenan-induced abdominal vascular permeability was reduced by dexamethasone but was not altered by TTHL. Furthermore, dexamethasone and TTHL significantly reduced the TNF-α and IL-1β levels in peritoneal fluid, whereas the IL-10 levels were unchanged.

CONCLUSIONS

Altogether, our data confirm the antinociceptive effect of TTHL and demonstrate its effect in inflammatory animal models, providing novel data about this compound, which could be useful as an anti-inflammatory drug.

The antinociceptive and anti-inflammatory activities of caulerpin, a bisindole alkaloid isolated from seaweeds of the genus Caulerpa

The antinociceptive and anti-inflammatory activity of caulerpin was investigated. This bisindole alkaloid was isolated from the lipoid extract of Caulerpa racemosa and its structure was identified by spectroscopic methods, including IR and NMR techniques. The pharmacological assays used were the writhing and the hot plate tests, the formalin-induced pain, the capsaicin-induced ear edema and the carrageenan-induced peritonitis. Caulerpin was given orally at a concentration of 100 micromol/kg. In the abdominal constriction test caulerpin showed reduction in the acetic acid-induced nociception at 0.0945 micromol (0.0103-1.0984) and for dypirone it was 0.0426 micromol (0.0092-0.1972). In the hot plate test in vivo the inhibition of nociception by caulerpin (100 micromol/kg, p.o.) was also favorable. This result suggests that this compound exhibits a central activity, without changing the motor activity (seen in the rotarod test). Caulerpin (100 micromol/kg, p.o.) reduced the formalin effects in both phases by 35.4% and 45.6%, respectively. The possible anti-inflammatory activity observed in the second phase in the formalin test of caulerpin (100 micromol/kg, p.o.) was confirmed on the capsaicin-induced ear edema model, where an inhibition of 55.8% was presented. Indeed, it was also observed in the carrageenan-induced peritonitis that caulerpin (100 micromol/kg, p.o.) exhibited anti-inflammatory activity, reducing significantly the number of recruit cells by 48.3%. Pharmacological studies are continuing in order to characterize the mechanism(s) responsible for the antinociceptive and anti-inflammatory actions and also to identify other active principles present in Caulerpa racemosa.