Analgesic and antimalarial activities of crude leaf extract and fractions of Acalypha wilkensiana

Aim of the study

Antiplasmodial and analgesic activities of leaf extract and fractions of Acalypha wilkensiana were evaluated to ascertain the folkloric claim of its antimalarial and analgesic activities.

Materials and methods

The crude leaf extract (220–659 mg/kg) and fractions (chloroform and aqueous; 440 mg/kg) of Acalypha wilkensiana were investigated for antiplasmodial activity against chloroquine sensitive Plasmodium berghei infections in mice and for analgesic activity against chemical and heat-induced pains. The antiplasmodial activity during early and established infections as well as prophylactic activity were investigated. Chloroquine (5 mg/kg) and pyrimethamine (1.2 mg/kg) were used as positive controls. Thin films made from tail blood of each mouse were used to assess the level of parasitaemia of the mice. Analgesic activity of the crude extract was also evaluated against acetic acid, formalin and heat-induced pains.

Results

The extract and its fractions dose-dependently reduced parasitaemia induced by chloroquine sensitive Plasmodium berghei infection in prophylactic, suppressive and curative models in mice. These reductions were statistically significant (p < 0.001). They also improved the mean survival time (MST) from 16 to 22 days relative to control (p < 0.01–0.001). The activities of extract/fractions were incomparable to that of the standard drugs used (chloroquine and pyrimethamine). On chemically and thermally induced pains, the extract inhibited acetic acid and formalin-induced inflammation as well as hot plate-induced pain in mice. These inhibitions were statistically significant (p < 0.001) and in a dose-dependent fashion.

Conclusion

The antiparasitaemic and analgesic effects may in part be mediated through the chemical constituents of the plant.     

Effects of leaf extracts from Croton zambesicus Müell. Arg. on hemostasis

Ethnopharmacological relevance

The leaf decoction of Croton zambesicus Müell. Arg. (Euphorbiaceae; syn. Croton amabilis Müell. Arg., Croton gratissimus Burch) is traditionally used in Benin to treat hypertension.

Aim of the study

As hypertension and thromboembolism are often associated in several cardiovascular diseases, we studied the potential effects of leaf extracts from Croton zambesicus on hemostasis.

Materials and methods

We prepared the dichloromethane and aqueous extracts from the air-dried leaves of Croton zambesicus and separated the aqueous extract in its aqueous and dichloromethane fractions. The potential effects of these four extracts/fractions were investigated on red blood cells integrity using spectrophotometric lysis assays, on primary hemostasis using platelet aggregation studies and on secondary hemostasis using calibrated automated thrombin generation assays and coagulation factors inhibition tests.

Results

In the in vitro testing, we found that none of the tested extracts/fractions exhibit hemolytic or antiplatelet activity. However, they display a moderate but significant anticoagulant activity which would be mediated through the direct inhibition of thrombin, FXa and TF/FVIIa. The active anticoagulant compound(s) seem to be mainly in the aqueous extract and especially in its aqueous fraction.

Conclusions

This experimental work reported for the first time the anticoagulant effect of leaf extracts from Croton zambesicus. These findings are of particular interest as the leaves from Croton zambesicus are commonly used in infusion by local population and may provide a new natural source for the development of original anticoagulant agents. Furthermore, this activity, associated with the vasorelaxant properties of some of its diterpenes may prove to be interesting for the prevention of cardiovascular diseases in traditional medicine.     

Trapa natans L. root extract suppresses hyperglycemic and hepatotoxic effects in STZ-induced diabetic rat model

Ethnopharmacological relevance

Trapa natans L. has a folkloric reputation as nutrient, appetizer and astringent. Its utility as antidiabetic, anticancer, diuretic, aphrodisiac, antidiarrhoeal and in many other maladies is well reported in the literature. Therefore, the present study has been carried out to study the antihyperglycemic effect of root extract of Trapa natans L. and its various fractions. Furthermore, hepatotoxic effects and lipid peroxidation risks have also been evaluated.

Methods

The ethanol extract and its successive fractions obtained from roots of Trapa natans have been administered in sucrose loaded and STZ- induced diabetic Wistar rats at doses of 50, 100 and 200 mg/kg b.w. Glibenclamide was used as positive control. The evaluation of protective effects of extract as well as fractions against hepatotoxicity and lipid peroxidation at 600 mg/kg b.w. has also been carried out.

Results

The methanol fraction emerged as the most potent antihyperglycemic fraction. It has also been found that the ethanolic extract as well as its fractions did not cause any lipid peroxidation and hepatotoxicity risks.

Conclusion

It can be concluded that the intense investigations of the methanol fraction obtained from Trapa natans root extract can be done to provide an alternative natural therapy for hyperglycemia.     

Anticonvulsant,anxiolytic and sedative activities of the aqueous root extract of Securidaca longepedunculata Fresen.

Aim of the study

The objective of this study is to investigate the anticonvulsant, anxiolytic and sedative activities of the aqueous root extract of Securidaca longepedunculata.

Materials and methods

The anticonvulsant effect of the aqueous root extract (100, 200 and 400 mg/kg) was evaluated in mice using the strychnine- and picrotoxin-induced seizure models. Its anxiolytic activity was evaluated using the elevated plus maze (EPM) and the Y maze (YM) methods (14 and 32) while the hexobarbitone induced sleep and the hole board models were used to evaluate the sedative and exploratory activities in mice respectively. The acute toxicity studies and phytochemical analysis of the extract were also carried out.

Results

The extract (100–400 mg/kg) produced a significant (P < 0.01) dose dependent increase in onset of convulsion compared to the control for strychnine- and picrotoxin-induced seizures. It also produced a significant (P < 0.01) dose dependent prolongation of the cumulative time spent in the open arms of the elevated plus maze and Y maze compared with the control. The extract (100–400 mg/kg) produced significant (P < 0.01) reduction in the time of onset of sleep induced by hexobarbitone. The prolongation of hexobarbitone sleeping time by the extract (200 mg/kg) was comparable to that produced by diazepam (3 mg/kg). At doses of 100–400 mg/kg, the extract produced a dose dependent decrease in exploratory activity of the mice. The reduction in exploratory activity produced by the extract (400 mg/kg) was greater than that of chlorpromazine (1 mg/kg). The results obtained from the experiments indicate that the extract has central nervous system depressant and anxiolytic activities. The LD₅₀ obtained for the acute toxicity studies using both oral and intraperitoneal routes of administration were 1.74 g/kg and 19.95 mg/kg respectively.

Conclusion

These findings justify the use of Securidaca longepedunculata in traditional medicine for the management of convulsion and psychosis.     

In vivo antimalarial activities of Enantia polycarpa stem bark against Plasmodium berghei berghei in mice

Ethnopharmacological relevance

Enantia polycarpa (PC) Engl. Et Diels (Annonaceae) is used in traditional medicine as an antimalarial remedy in Southern Nigeria.

Aim of the study

The antimalarial activities of ethanolic stem bark extracts of Enantia polycarpa was studied in vivo, in mice infected with Plasmodium berghei berghei.

Materials and methods

The ethanolic stem bark extract of Enantia polycarpa was administered at doses ranging from 200 to 600 mg/kg/day to Plasmodium berghei infected mice in both early and established models of antiplasmodial studies.

Results

The extract of Enantia polycarpa exhibited promising antimalarial activity against both early and established infections. At a dose of 600 mg/kg the extract achieved a 75.8% and 72% chemosuppression of parasitaemia in the study of acute and established infections, respectively. The extract also prolonged mean survival time of Plasmodium berghei infected mice during the study of established infection. The mean survival time of mice administered Enantia polycarpa extract at 600 mg/kg/day (27 days) was significantly longer than infected/untreated control (12 days). For the acute toxicity study the extract had an intraperitoneal LD₅₀ of 186 mg/kg but caused no mortality when administered orally at doses as high as 2,000 and 4,000 mg/kg.

Conclusions

Collectively, the results indicate that Enantia polycarpa is safe when administered orally and possesses promising antimalarial activity, thus supporting its use in traditional medicine for the treatment of malaria.     

Mast cell stabilizing effects of Sphaeranthus indicus

Aim of the study

We investigated the effects of Sphaeranthus indicus on mast cell stabilizing activity to provide scientific basis for the clinical use of S. indicus.

Materials and methods

The protective effect of different extracts of whole plant of S. indicus against compound 48/80 and sheep serum induced mast cell degranulation was evaluated.

Results

Ethanol extract of S. indicus at the doses of 150 mg/kg and 300 mg/kg and ethyl acetate extract at the dose of 100 mg/kg, 150 mg/kg and 300 mg/kg showed slightly better protection of mast cell degranulation (77–86%) than the standard drug ketotifen (75%) in the sheep serum model. These extracts also showed better mast cell stabilizing activity (77–88%) than the standard drug (69%) when peritoneal mast cells are treated with compound 48/80.

Conclusion

These results suggest that S. indicus has potent mast cell stabilizing effects thereby inhibiting mediator release from mast cells.     

Renoprotective effects of the crude extract and solvent fractions of the leaves of Euclea divinorum Hierns against gentamicin-induced nephrotoxicity in rats

Ethnopharmacological relevance

Euclea divinorum Hierns (Ebenaceae) is used in Ethiopian folklore medicine to treat scabies, inflammation of the skin, eczema, abdominal pain, gonorrhea, and kidney problems. However, the claim has not been scientifically validated.

Aim of the study

To assess the renoprotective effects of the crude extract and solvent fractions of E. divinorum leaves against gentamicin-induced nephrotoxicity in rats.

Materials and method

Rats of either sex were divided into seven experimental groups, each comprising six animals. Group I served as control and given vehicle (Tween 80, 2%, v/v in water) and Group II were treated with gentamicin intraperitoneally (100 mg/kg/day) for eight days. Group III–V received crude extract at three different doses 100 mg/kg, 150 mg/kg and 200 mg/kg, respectively. Group VI received 100 mg/kg of the methanolic fraction and Group VII 100 mg/kg of the aqueous fraction. The extract was administered orally two days before and eight days concomitantly with gentamicin. Following treatment, blood and renal tissue were used to assess creatinine, blood urea nitrogen (BUN), malondialdehyde (MDA), antioxidant enzymes and tubular necrosis using recommended procedures. In addition, free radical scavenging activity was determined using in vitro methods.

Results

Gentamicin significantly increased serum creatinine and BUN, MDA and tubular necrosis in rats. It also decreased activity of catalase and superoxide dismutase as well as levels of gluthatione. Pre- and co-treatment with the crude extract and solvent fractions of Euclea divinorum leaves reversed gentamicin-induced alterations as evidenced by a decrease in tubular necrosis, serum and oxidant markers as well as by an increase in antioxidant molecules. Effect was found to decrease with dose when the crude extract was used and maximum protection was conferred by 100 mg/kg of the methanolic fraction in both in vivo and in vitro studies.

Conclusions

Euclea divinorum reversed gentamicin-induced nephrotoxicity, probably via its antioxidant activity. The fact that the methanol fraction conferred maximum protection suggests that semi-polar antioxidant principles might be responsible for the observed effect.     

Antiulcerogenic effect of Croton urucurana Baillon bark

Ethnopharmacological relevance

Croton urucurana (Euphorbiaceae) bark is used to treat gastric ulcers. However, to our knowledge, no study has been conducted to confirm this therapeutic property.

Aim of the study

To evaluate the antiulcerogenic effect and any possible toxic effects of Croton urucurana bark in an induced gastric ulcer model in rats.

Materials and methods

The preventive and healing properties of Croton urucurana bark methanol extract (CUE) were evaluated in experimental models of acute (ethanol and indomethacin) and chronic (acetic acid) gastric ulcers. The gastric juice and mucous were evaluated using the pylorus ligation model, while the gastroprotective action of sulphydryl compounds and nitric oxide were analysed using the ethanol model. The toxicity was evaluated with acute and subacute toxicity tests.

Results

No signs of toxicity were observed in the parameters analysed. All of the CUE doses tested (50, 100 and 250 mg/kg) significantly reduced the gastric lesions by 70.25, 95.40 and 98.71%, respectively. Treatment with 30 mg/kg lansoprazole (positive control) inhibited 82.58% of the gastric lesions. In the indomethacin model, the 50, 100 and 250 mg/kg doses of CUE significantly reduced gastric damage by 67.85, 82.50 and 71.01%, respectively, and the positive control, cimetidine (200 mg/kg), reduced gastric damage by 91.02%. The CUE (100 mg/kg) and cimetidine (200 mg/kg) treatments significantly reduced the ulcerative pathology induced by acetic acid, promoting 81.55 and 72.62% healing, respectively. Nitric oxide did not change the cytoprotection generated by CUE. However, the antiulcerogenic activity of CUE appears to involve sulphydryl compounds because CUE activity was inhibited in animals receiving a sulphydryl compound blocker. In addition, CUE exhibited systemic effects, increasing mucous production and decreasing gastric acidity.

Conclusions

The present study shows that Croton urucurana bark exerts gastroprotective activity in rats without causing toxicity. This effect appears to involve sulphydryl compounds, increasing mucus production and reducing gastric acidity.     

Protective effects of Croton campestris A. St-Hill in different ulcer models in rodents: Evidence for the involvement of nitric oxide and prostaglandins

Ethnopharmacological relevance

Croton campestris A. St.-Hill., popularly known as “velame do campo”, is a species native from savannah area of Northeast Brazil, which is used by traditional communities in folk medicine for a variety of health problems, especially detoxification, inflammation and gastritis. The present study investigates the possible gastric antiulcer activity of Croton campestris root extract (CCRE) and mechanisms of action underlying this effect.

Materials and methods

Gastric lesions were induced in mice by ethanol, acidified ethanol and indomethacin. CCRE was previously administered orally in doses ranging from 50 to 750 mg/kg. Stomach lesions were measured. The involvement of Nitric Oxide (NO), prostaglandins (PGEs), ATP-dependent K+ channel and adrenergic receptor was investigated through specific inhibitors.

Results

CCRE produced significant antiulcer activity against absolute ethanol, acidified ethanol and indomethacin induced gastric lesions. The pretreatment with L-NAME (10 mg/kg, p.o.), an inhibitor of nitric oxide synthesis and indomethacin (10 mg/kg, s.c.), an inhibitor of prostaglandin production, reversed the antiulcer action of CCRE.

Conclusion

Taking together, these results suggest that the antiulcer activity of CCRE is dependent of NO and prostaglandin pathways possibly due to its ability to stimulate the synthesis of NO, and activation of endogenous prostaglandin production. Therefore, the use of CCRE in traditional Brazilian medicine against gastric disorders has a scientific basis.     

Evaluation of mechanisms involved in the antinociception of the ethanol extract from the inner bark of Caesalpinia pyramidalis in mice

Ethnopharmacological relevance

Caesalpinia pyramidalis Tul. (Fabaceae) is an endemic tree of the Northeast region of Brazil, mainly in the Caatinga region. More commonly, inner bark or flowers are traditionally used to treat many painful and inflammatory processes. A common use of this plant is made by macerating a handful of its stem bark in a liter of wine or sugarcane brandy. It is drunk against stomachache, dysenteries, and diarrheas.

Materials and methods

The ethanol extract of Caesalpinia pyramidalis inner bark was used in mice via oral route, at the doses of 10, 30, and 100 mg/kg, in behavioral models of nociception and investigates some of the mechanisms underlying this effect.

Results

The ethanol extract (30 and 100 mg/kg, P<0.001), given orally, produced dose dependent inhibition of acetic acid-induced visceral pain. The ethanol extract also caused significant and dose-dependent inhibition of capsaicin-(100 mg/kg, P<0.001) and glutamate-(10, 30, and 100 mg/kg, P<0.01) induced pain. The antinociception caused by the ethanol extract (30 mg/kg) in the abdominal constriction test was significantly attenuated (P<0.001) by intraperitoneal treatment of mice with l-arginine (600 mg/kg).

Conclusions

Collectively, the present results suggest that the ethanol extract of Caesalpinia pyramidalis produced dose-related antinociception in several models of pain through mechanisms that involved both glutamatergic system and/or the l-arginine–nitric oxide pathway, supporting the folkloric usage of the plant to treat various painful processes.     

Characterization of the antinociceptive and anti-inflammatory activities from Cocos nucifera L. (Palmae)

Aim of the study

Cocos nucifera cultivated in Brazil is known as “coco-da-Bahia” or “coqueiro-da-Índia”. The tea from the husk fiber is widely used to several inflammatory disorders. Crude extract and fractions obtained from Cocos nucifera “common variety” were evaluated to test the anti-inflammatory and antinociceptive activities.

Materials and methods

Crude extract (CE, 50, 100, and 150 mg/kg), fraction 1 (F1, molecular weight lesser than 1 kDa, 1, 10, and 50 mg/kg), fraction 2 (F2, molecular weight higher than 1 kDa, 1, 10, and 50 mg/kg), and the references drugs morphine (5 mg/kg), acetilsalicilic acid (200 mg/kg), prometazine (30 mg/kg), and metisergide (5 mg/kg) were evaluated on models of analgesia and inflammation.

Results

CE, F1, and F2 significantly develop peripheral and central antinociceptive activity but with less effect on supra-spinal regions of the brain. Administration of the opioid antagonist, naloxone (5 mg/kg) inhibited the antinociceptive effect indicating that Cocos nucifera crude extract and fractions may be acting in opioid receptors. CE and F1 also inhibited rat paw edema induced by histamine, and serotonin.

Conclusions

results demonstrated that Cocos nucifera and its fractions have antinociceptive and anti-inflammatory activities which confirm the popular use of this plant in several inflammatory disorders.     

Toxicity and potential anti-trypanosomal activity of ethanolic extract of Azadirachta indica (Maliacea) stem bark: An in vivo and in vitro approach using Trypanosoma brucei

Aim of the study

To determine the toxicity and anti-trypanosomal activity of the ethanolic extract of Azadirachta indica (Maliacea) stem bark, through in vivo and in vitro approach using Trypanosoma brucei brucei.

Materials and methods

Graded concentrations (100, 200, 400, 800, 1600 and 3200 mg/kg) of the crude stem bark ethanolic extract of Azadirachta indica, Hochst ex. A. Dc. (Maliacea) was tested for acute toxicity in 35 out bred Swiss (Wister) adult albino rats of both sexes. Secondly, the in vitro activity in test tubes and in vivo activity of the extract in 30 out bred Swiss (Wister) adult albino rats against Trypanosoma brucei brucei strain NITR/14 (Federe) was evaluated in a graded dose manner.

Results

The calculated intra-peritoneal LD₅₀ of the extract was 870 mg/kg and produced toxicity at high doses (>800 mg/kg). Graded concentrations of the ethanolic extract produced remarkable in vitro activity against Trypanosoma brucei brucei within seconds of inoculation. It also suppressed the establishment of parasitaemia at 100 mg/kg when administered simultaneously with infection in vivo. Similarly, at 200 and 400 mg/kg, the extract administered at the onset of parasitaemia for 4 consecutive days reduced parasitaemia, modulated declined packed volume (PCV) changes by day 48 post-infection in vivo.

Conclusion

The results confirm that the folkloric medicinal application of the extract of Azadirachta indica (Maliacea) has a pharmacological basis. Further investigation is however, needed to optimize the effectiveness of the extract.     

The antinociceptive activity of Polygonatumverticillatum rhizomes in pain models

Aim of the study

The current study was designed to establish the pharmacological rationale for the traditional use of the rhizomes of Polygonatum verticillatum in the treatment of painful conditions and as a plant diuretic.

Materials and methods

The crude methanolic extract of the rhizomes of Polygonatumverticillatum (PR) was tested in various established pain models in rodents at 50, 100 and 200 mg/kg i.p. while the diuretic activity was assessed at 300 and 600 mg/kg p.o. in rats.

Results

PR demonstrated significant reduction (14–72%) in the number of writhes induced by acetic acid in a dose-dependent manner. When nociceptive threshold was measured in the formalin test, PR strongly attenuated the formalin-induced flinching behaviour in both phases (6–30% in first phase while 12–72% in second phase). Central involvement in the analgesic profile of PR was confirmed by the hot plate test, in which PR elicited a significant (P < 0.01) analgesic activity by increasing latency time. However, an opioid receptor antagonist, naloxone (2 mg/kg s.c.) strongly antagonized the antinociceptive activity of PR. As a plant diuretic, PR showed mild but statistically insignificant diuretic activity at 300 mg/kg. The crude extract and solvent fractions of the plant contained reasonable quantity of total saponin and alkaloid contents.

Conclusions

The mechanisms underlying the analgesic action of PR shows that the opioid dependant central mediation has synergistic effect by enforcing the peripheral analgesic effects. Interestingly, our findings not only substantiated the folk use of the plant as an analgesic but also reported for the first time in the whole genus.     

In vivo antimalarial activity of Keetia leucantha twigs extracts and in vitro antiplasmodial effect of their constituents

Ethnopharmacological relevance

The West African tree Keetia leucantha (Rubiaceae) is used in traditional medicine in Benin to treat malaria. The twigs dichloromethane extract was previously shown to inhibit in vitro Plasmodium falciparum growth with no cytotoxicity (>100 µg/ml on human normal fibroblasts).

Materials and methods

The dichloromethane and aqueous extracts of twigs of K. leucantha were evaluated in vivo against Plasmodium berghei NK 173 by the 4-day suppressive test and in vitro against a chloroquine-sensitive strain of Plasmodium falciparum (3D7) using the measurement of the plasmodial lactate dehydrogenase activity. Bioguided fractionations were realized and compounds were structurally elucidated using extensive spectroscopic analysis.

Results

The in vivo antimalarial activity of K. leucantha dichloromethane and aqueous twigs extracts were assessed in mice at the dose of 200 mg/kg/day. Both extracts exhibited significant effect in inhibiting parasite growth by 56.8% and 53.0% (p<0.0001) on day 7-postinfection. An LC–MS analysis and bioguided fractionations on the twigs dichloromethane extract led to the isolation and structural determination of scopoletin (1), stigmasterol (2), three phenolic compounds: vanillin (3), hydroxybenzaldehyde (4) and ferulaldehyde (5), eight triterpenic esters (6–13), oleanolic acid and ursolic acid. The antiplasmodial activity of the mixture of the eight triterpenic esters showed an antiplasmodial activity of 1.66±0.54 µg/ml on the 3D7 strain, and the same range of activity was observed for isolated isomers mixtures.

Conclusions

This is the first report on the in vivo activity of K. leucantha extracts, the isolation of thirteen compounds and analysis of their antiplasmodial activity. The results obtained may partially justify the traditional use of K. leucantha to treat malaria in Benin.     

Anti-inflammatory and analgesic properties of Heracleum persicum essential oil and hydroalcoholic extract in animal models

Ethnopharmacological relevance

Fruits of Heracleum persicum (Apiaceae) are used as pain killer in Iranian folkloric medicine.

Aims of study

To evaluate the anti-inflammatory and analgesic effects of the hydroalcoholic extract and essential oil of the plant fruits and analyzing the essential oil.

Materials and methods

Essential oil and hydroalcoholic extracts of the fruits were prepared according to standard methods and the components of essential oil were identified using GC–MS method. The acetic acid-induced writhing response and formalin test were used in male mice to assess analgesic activity. For evaluation of anti-inflammatory effect, carrageenan-induced rat paw edema was used.

Results

Hexyl butyrate (56.5%), octyl acetate (16.5%), hexyl 2-methylbutanoate (5.2%) and hexyl isobutyrate (3.4%) were identified as the major constituents of the oil. Oral or intraperitoneal administration of Heracleum persicum essential oil (HPEO) at doses of 50–200 mg/kg and Heracleum persicum hydroalcoholic extract (HPHE) at doses of 250 and 500 mg/kg significantly reduced acetic acid-induced abdominal constrictions. HPEO and HPHE also significantly attenuated the pain response of the second phase of formalin test.In carrageenan test HPEO at doses of 100 and 200 mg/kg and HPHE at a dose of 400 mg/kg induced a significant reduction of paw edema.

Conclusions

These results clearly show the analgesic and anti-inflammatory effects of the plant essential oil and hydroalcoholic extract. Further studies are needed to clarify the mechanism of action and the components responsible for these pharmacological effects.     

Anxiolytic and sedative activities of Passiflora edulis f. flavicarpa

Aim of the study

Many plants in the genus Passiflora have long been used in traditional folk medicines as a remedy for many neurogenic diseases in many countries. A number of species of the genus was studied about their neuropharmacological activities, but the results were inconsistent. No literature reported neuropharmacological studies on Passiflora edulis f. flavicarpa as yet. The present study was aimed at evaluating the anxiolytic and sedative activities of Passiflora edulis f. flavicarpa.

Materials and methods

Swiss albino mice were used as experimental animals in elevated plus-maze (EPM) test and spontaneous activity (SA) test to assay the behavioral effects of ethanolic extract (EE) of the aerial part of Passiflora edulis f. flavicarpa and its fractions, viz. petrol ether extract (PEE), ethyl acetate extract (EAE), n-BuOH extract (BE) and aqueous extract (AE), together with subfractions of BE, viz. BEF-I, BEF-II, BEF-III, BEF-IV and isoorientin, a flavonoid component isolated from BEF-III.

Results

In the EPM test, single-dose oral administration of EE (300 mg/kg and 400 mg/kg), BE (125 mg/kg and 200 mg/kg), AE (200 mg/kg and 300 mg/kg), BEF-I (200 mg/kg), BEF-II (200 mg/kg), BEF-III (100 mg/kg), or isoorientin (20 mg/kg) resulted in anxiolytic-like effects, but a sedative-like activity was produced at higher doses, such as 300 mg/kg of BE, 200 mg/kg of BEF-III, or 40 mg/kg and 80 mg/kg of isoorientin. The results of the SA test manifested that treatment with 400 mg/kg of EE, 300 mg/kg of BE, or 40 mg/kg and 80 mg/kg of isoorientin compromised motor activity in mice, which are in line with the results of the EPM test.

Conclusions

The aerial part of Passiflora edulis f. flavicarpa was anxiolytic at low dose but sedative at high dose. Flavonoids are important active constituents. Since AE contained little flavonoids, it was conjectured that there were other components responsible for the anxiolytic effect of Passiflora edulis f. flavicarpa besides flavonoids.     

In vivo antimalarial evaluation of Gomphostenins

Aim of the study

The present study aims to evaluate the in vivo antimalarial potential of the leaf extract of Gomphostemma niveum and two new compounds; named as Gomphostenin (GN–6) and acetyl Gomphostenin (GN–10) isolated and purified from this plant against Plasmodium berghei in mice.

Materials and methods

The blood schizontocidal activity was performed in early infection of Plasmodium berghei and also in established infection of Plasmodium berghei. The mice were orally administrated with various doses of water and chloroform extracts of leaves of Gomphostemma niveum (GN–W and GN–C, 300, 400 and 500 mg/kg/day), GN–6 and GN–10 (50, 100, 150 and 200 mg/kg/day). Chloroquine (8 mg/kg) used as a positive control, while an equal volume of saline plus 0.5% tween-80 was used as a negative control.

Results

GN–W, GN–C and pure compounds (GN–6 and GN–10) produced a dose dependent chemosuppression effect at various dose levels. GN–10 exhibited highest percent of chemosuppression i.e. 92.65% at a dose level of 200 mg/kg/day. In case of curative test, the survival period of the parasitized infected mice was significantly prolonged at 200 mg/kg dose of GN–10.

Conclusions

The studies have indicated that clerodane class of diterpenes GN–6 and GN–10 certainly holds great promise for malaria control and will be useful in antimalarial chemotherapy.     

Anticonvulsant activity of Benkara malabarica (Linn.) root extract: In vitro and in vivo investigation

Aim of the study

To systematically investigate the anticonvulsant activity of methanol extract of Benkara malabarica roots and to provide a biochemical basis elucidating its mode of action.

Methods

The median lethal dose (LD₅₀) of Benkara malabarica extract was determined. The anticonvulsant activity of the extract was assessed in strychnine-induced and isoniazide-induced convulsion models; phenytoin (20 mg/kg) and diazepam (1 mg/kg) were used as standards, respectively. Percentage protection provided by the drug was accounted as decrease in the number of convulsions within 8 h of observation. Mechanism of action was studied by performing GABA transaminase (GABA-T) assay, isolated from rat brain. Active constituent was isolated and characterized from the plant extract.

Results

The median lethal dose (LD50) of Benkara malabarica was found to be more than 500 mg/kg. It demonstrated 30% and 35% protection against strychnine-induced convulsions and 60% and 80% protection against isoniazide-induced convulsions, at doses of 25 mg/kg and 50 mg/kg, respectively. Enzyme assay results revealed that Benkara malabarica extract possesses GABA-T inhibitory activity (IC50 = 0.721 mg/ml). Scopoletin which was identified as the major constituent of the extract was found to be an inhibitor of GABA-T (IC50 = 10.57 μM).

Conclusions

The anticonvulsant activity of the plant extract is predominantly GABA mediated and may be due to the action of scopoletin alone or is a result of synergy of different compounds in the extract in which scopoletin is the major constituent.     

Evaluation of the diuretic and analgesic activities of the rhizomes of Rumex abyssinicus Jacq in mice

Aim of the study

Rumex abyssinicus Jacq (Polygonaceae) has been used traditionally for treatment of hypertension, inflammatory and painful conditions in Ethiopia. The present study aimed to evaluate the diuretic and analgesic activities of extracts of Rumex abyssinicus at different doses in mice.

Materials and methods

The effect on urine volume and urinary electrolyte (Na⁺, K⁺ and Cl⁻) was assessed for a period of 5 h following oral administration of aqueous (500 mg/kg, 750 mg/kg or 1000 mg/kg) or 80% methanolic (250 mg/kg, 500 mg/kg or 750 mg/kg) extract or furosemide (10 mg/kg). Acetic acid-induced writhing and hot-plate tests were employed to study the analgesic effect of 80% methanolic extracts (250 mg/kg, 500 mg/kg or 1000 mg/kg, P.O.) and compared with that of aspirin (100 mg/kg, P.O.) or morphine (10 mg/kg, sc).

Results

The extracts displayed dose-dependent diuretic and analgesic effects. The highest doses of both extracts markedly and significantly increased (P < 0.001) urine volume and urinary electrolytes, qualitatively similar to that of furosemide. 1000 mg/kg of the extract reduced the number of writhing by 67.6% (P < 0.001) and conferred more than 70% protection against thermally induced pain stimuli after 45 min of treatment comparable to that of aspirin and morphine, respectively.

Conclusion

These findings collectively indicate that the extracts exhibited significant diuretic and analgesic activities, providing evidence, at least in part, for its folkloric use.     

Gastroprotective activity of the ethanol extract from the inner bark of Caesalpinia pyramidalis in rats

Ethnopharmacological relevance

Caesalpinia pyramidalis Tul. (Fabaceae), known as “catingueira”, has been used in folk medicine in the treatment of various disorders such as gastritis, heartburn, indigestion, and stomach ache. However, the gastroprotective properties of this species have not yet been studied.

Materials and methods

The ethanol extract of Caesalpinia pyramidalis inner bark was used in rats via oral route, at the doses of 30, 100, and 300 mg/kg. The antiulcer assays were performed using the ethanol- and nonsteroidal anti-inflammatory drug-induced ulcer models. Gastric secretion parameters (volume, pH, and total acidity) were also evaluated by the pylorus ligated model, and the mucus in the gastric content was determined. The anti-Helicobacter pylori activity of the ethanol extract of Caesalpinia pyramidalis was performed using the agar-well diffusion and broth microdilution methods.

Results

The ethanol extract (30, 100, and 300 mg/kg) produced dose dependent inhibition (P<0.01) on the ulcer lesion index, the total lesion area, and the percentage of lesion area in the ethanol-induced ulcer model. The ethanol extract (30, 100, and 300 mg/kg) also reduced (P<0.001) the ulcer index in the indomethacin-induced ulcer model. In the model ligature pylorus, the treatment with Caesalpinia pyramidalis ethanol extract failed to significantly change the gastric secretion parameters. However, after treatment with the ethanol extract of Caesalpinia pyramidalis (30, 100, and 300 mg/kg), there was a significant increase (P<0.05) in mucus production. The ethanol extract showed anti-Helicobacter pylori activity, with inhibition halos of 12.0±1.7 mm at 10,000 μg/mL. The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of the ethanol extract were of 625 and 10,000 μg/mL, respectively.

Conclusions

Collectively, the present results suggest that the ethanol extract of Caesalpinia pyramidalis displays gastroprotective actions, supporting the folkloric usage of the plant to treat various gastrointestinal disturbances.