Potential Curative Effects of Aqueous Extracts of Cissus quadrangularis (Vitaceae) and Jatropha gossypiifolia (Euphorbiaceae) on Acetaminophen-Induced Liver Injury in Mice

Background

Acetaminophen-induced liver injury remains a significant public health problem because available treatments are limited due to their adverse effects. Medicinal plants, which are an important source of bioactive molecules, could be an alternative treatment for liver disease.

Objective

This study was designed to investigate the curative effect of aqueous extracts of Cissus quadrangularis (Vitaceae) and Jatropha gossypiifolia (Euphorbiaceae) on acetaminophen-induced liver injury in mice.

Methods

Mice were divided into groups and treated with distilled water, silymarin (50 mg/kg), a reference hepatoprotective agent, and aqueous extracts of C quadrangularis and J gossypiifolia (50 and 100 mg/kg, PO, respectively). These substances were given as a single daily dose 4 hours after acetaminophen administration (300 mg/kg, PO) for 2 days. Mice were humanely put to death 24 hours after the last dose and serum alanine aminotransferase and aspartate aminotransferase activities, total bilirubin and protein levels, reduced glutathione, superoxide dismutase, malondialdehyde, catalase, and nitrite tissue levels were assessed. Histology of the livers of the mice was performed by hematoxylin and eosin staining.

Results

Acetaminophen administration induced a significant (P < 0.05) mean (SEM) body weight loss (-14.45% [5.92%]), a significant elevation of alanine aminotransferase activity (15.08%), total protein and bilirubin levels (25.80%), and a significant (P < 0.05) increase in liver superoxide dismutase (67.71%), catalase (63.00%), glutathione (40.29%), malondialdehyde (30.67%), and nitrite levels compared with the control group. In curative treatment, C quadrangularis and J gossypiifolia (50 and 100 mg/kg) significantly (P < 0.05) reduced mean (SEM) body weight loss (16.67% [7.16%] and 1.25% [0.51%], respectively), serum alanine aminotransferase activity (17.62% and 11.14%, respectively), bilirubin level (29.62% and 49.14%, respectively) compared with acetaminophen group, and J gossypiifolia normalized serum total protein level. Both extracts significantly (P < 0.05) reduced the levels of glutathione and malondialdehyde and normalized that of nitrite, superoxide dismutase, and catalase compared with the acetaminophen group. Hepatocyte necrosis and inflammatory cell infiltration were remarkably reduced by the plant extracts.

Conclusions

The results obtained are evidence in favor of the development of a formulation based on the extracts of these plants against liver diseases.

Curative anti-typhoid effect of Detarium microcarpum Guill. & Perr. (Leguminosae) hydroethanolic extract root bark based-on in vivo and molecular docking analyses

ETHNOPHARMACOLOGICAL RELEVANCE

Detarium microcarpum is used to treat typhoid fever, a major public health problem, by indigenous population in Africa. Though its preventive activities have been documented, the curative effect is still to be confirmed.

AIM OF THE STUDY

This study aimed at evaluating the curative effects of the hydroethanolic extract of Detarium microcarpum root bark on Salmonella typhimurium-induced typhoid in rat and exploring the in-silico inhibition of some bacterial key enzymes.

STUDY DESIGN

In vitro antioxydant, in vivo antisalmonella of the extract and in silico molecular docking assay on the isolated compounds were carried out to explore the anti-salmonella effects of Detarium microcarpum.

MATERIAL AND METHODS

The in vitro antioxidant properties of the extract were evaluated using DPPH, ABTS and FRAP tests. The anti-salmonella activity of the extract was assessed through feacal sample from Salmonella typhimurium-infected rat cultured in Salmonella-Shigella agar (SS agar) medium. The affinity of isolated compounds (Rhinocerotinoic acid and Microcarposide) from the extract were performed on four key enzymes (Adenylosuccinate lyase, Acetyl coenzyme A synthetase, Thymidine phosphorylase and LuxS-Quorum sensor) using molecular docking simulation to elucidate the molecular level inhibition mechanism.

RESULTS

Crude extract of D. microcarpum root bark showed variable activities on DPPH (RSa50: 6.09 ± 1.04 μg/mL), ABTS (RSa50: 24.46 ± 0.27), and FRAP (RSa50: 23.30 ± 0.23). The extract at all the doses exhibited significant healing effect of infected rats, with the complete clearance. The extract restored hematological, biochemical and histological parameters closed to the normal control. The molecular docking results indicates that rhinocerotinoic acid and microcarposide present more affinity to the LuxS-Quorum sensor and Acetyl coenzyme A synthetase protein as compared to the others.

CONCLUSION

These results demonstrate potent anti-typhoid activities of the hydroethanolic of Detarium microcarpum root bark extract through antioxidant properties and high inhibitory affinity of its compounds on some bacterial key enzymes that justify its use as traditional medicine to typhoid fever.

In Vitro Assessment of the Cercaricidal Activity of Sida acuta Burm. F. and Sida rhombifolia Linn. (Malvaceae) Hydroethanolic Extracts, Cytotoxicity, and Phytochemical Studies

Despite the global efforts, schistosomiasis remains a public health problem in several tropical and subtropical countries. One of the major challenges in the fight against schistosomiasis is the interruption of the parasite life cycle. Here, we evaluated the anticercarial, cytotoxicity, and phytochemical profiles of Sida acuta (HESa) and Sida rhombifolia (HESr) hydroethanolic extracts (Malvaceae). Schistosoma mansoni cercaria was collected from fifteen Biomphalaria pfeifferi-infected snails. Twenty-five cercariae were incubated in duplicate with different concentrations (31.25-1,000 μg/mL) of HESa or HESr. The cercaria viability was monitored at 30 min time intervals for 150 min, and the concentration-response curve of each plant extract was used to determine their respective lethal concentration 50 (LC50). Additionally, the cytotoxicity profile of each plant extract was evaluated on the Hepa 1-6 cell line at a concentration range of 15.625-1,000 µg/mL using the WST-8 assay method and its inhibitory concentration 50 (IC50) was calculated. Moreover, phytochemical characterization of each plant extract was carried out by HPLC-MS. Both extracts exhibited cercaricidal activity in a time- and concentration-dependent manner. At 30 min time point, HESa (LC50 = 28.41 ± 3.5 µg/mL) was more effective than HESr (LC50 = 172.42 ± 26.16 µg/mL) in killing S. mansoni cercariae. Regarding the cytotoxicity effect of both extracts, the IC50 of HESa (IC50 = 109.67 µg/mL) was lower than that of HESr (IC50 = 888.79 µg/mL). The selectivity index was 3.86 and 5.15 for HESa and HESr, respectively. Fifteen compounds were identified from HESa and HESr after HPLC-MS analysis. N-Feruloyltyramine, a polyphenol, and thamnosmonin, a coumarin, were identified in both extracts. HESa and HESr displayed cercaricidal activity and were not toxic on Hepa 1-6 cell line. Based on the selectivity index of these extracts, S. rhombifolia extract could be more effective on S. mansoni cercariae than S. acuta extract. This study could provide baseline information for further investigations aiming to develop plant-based alternative drugs against S. mansoni.

Antibacterial and antishigellosis activity of Xylopia staudtii (engl. & diels), Annonaceae

ETHNOPHARMACOLOGICAL RELEVANCE

Xylopia staudtii is a medicinal plant which fruits are traditionally used in western Cameroon as a spice in the preparation of soups known for their abdominal cramp relieving properties. Often identified as Xylopia africana, its bark is used in the treatment of dysentery in Mont Cameroun localities. This plant could therefore contain active ingredients against intestinal pathogens, including Shigella spp, which are responsible of the deathly dysenteric diarrhoea.

AIM OF THE STUDY

This study aims to assess the efficacy of the hydroethanolic extract from Xylopia staudtii bark in immunodepressed mice infected with Shigella flexneri.

MATERIALS AND METHODS

Qualitative detection of compounds in the crude extract was done using UPLC-DAD-(HR) ESI-MS analysis in an attempt to link the activity to the chemical composition. The MIC and the MBC of the extract was determined using broth dilution method. Shigellosis was induced by intraperitoneal administration of Shigella flexneri to immunodepressed mice pretreated with streptomycin. These infected mice were then treated with the extract (100, 200 and 400 mg/kg), and reference substances (ciprofloxacin and saline). During the 9 days of treatment, animal morphology, fecal pathology and deaths were recorded. At the end of the treatment period, blood and organs were collected from any surviving animals for hematological, biochemical and histopathological analyses.

RESULTS

The extract was found to be significantly active, with a bactericidal effect against Shigella and a bacteriostatic effect against Escherichia coli. It was able to reduce and stop the faecal pathology caused by the infection in mice, as well as the rate of deaths which was brought to zero (0) in animal treated at 400 mg/kg. The bacteria load in faeces was reduced by 100% in animal treated at 400 mg/kg. Xylopia staudtii extract elicited anti-inflammatory properties by reducing MPO activity and Lcn2 intestinal level. It also prevents damages in the intestinal tissue and the shortening of colon which characterise Shigella infection. The serum level of ASAT, ALAT, bilirubin, urea and creatinine in animals treated with the extract was similar to those of normal animal used in the study. These activities of the plant may be due at least in part to the presence of ent-kauran type diterpens such as kaurenoic acid identified in the extract.

CONCLUSION

These findings support the usage of Xylopia staudtii as an antimicrobial against bacillary dysentery, making this plant a potential candidate for the formulation of an improved standardized traditional medicine.

Hypolipidemic and anti-atherosclerogenic effects of aqueous extract of Ipomoea batatas leaves in diet-induced hypercholesterolemic rats

OBJECTIVE

Ipomoea batatas (L.) Lam. is a food plant used in African traditional medicine to treat cardiovascular diseases and related conditions. We assessed the hypolipidemic and anti-atherosclerogenic properties of the aqueous extract of I. batatas leaves in a rat model of diet-induced hypercholesterolemia.

METHODS

Hypercholesterolemia was induced in male Wistar rats by exclusive feeding with a cholesterol-enriched (1%) standard diet for four weeks. Then, rats were treated once daily (per os) with I. batatas extract at doses of 400, 500 and 600 mg/kg or with atorvastatin (2 mg/kg), for four weeks. Following treatment, animals were observed for another four weeks and then sacrificed. Aortas were excised and processed for histopathological studies, and blood glucose level and lipid profile were measured.

RESULTS

Hypercholesterolemic animals experienced a 21.5% faster increase in body weight, significant increases in blood glucose and blood lipids (148.94% triglycerides, 196.97% high-density lipoprotein cholesterol, 773.04% low-density lipoprotein cholesterol, 148.93% very low-density lipoprotein cholesterol and 210.42% total cholesterol), and increases in aorta thickness and atherosclerotic plaque sizes compared to rats fed standard diet. Treatment of hypercholesterolemic rats with the extract mitigated these alterations and restored blood glucose and blood lipid levels to normocholesterolemic values.

CONCLUSION

Our findings suggest that I. batatas leaves have hypolipidemic and anti-atherosclerogenic properties and justify their use in traditional medicine.

Curative effects of the aqueous extract of Tithonia diversifolia (Hemsl.) A. gray (Asteraceae) against ethanol induced-hepatotoxicity in rats

OBJECTIVES

Tithonia diversifolia (Asteraceae) is used in Cameroonian traditional medicine for the treatment of several diseases amongst which are hepatic disorders. Anti-inflammatory, analgesic and anti-diabetic properties have been reported but, there is no scientific information on its hepato-protective effects. The aim of this study was to evaluate the curative effects of the Tithonia diversifolia (T. diversifolia) leaves aqueous extract on ethanol induced-hepatotoxicity in rats.

METHODS

Ethanol 40° (4 g/kg) was administered daily by intragastric gavage for 21 days, and then the extract was administered concomitantly with ethanol for two more weeks. Some biochemical serum and tissue parameters were evaluated. Histopathologic analysis of the liver was carried out.

RESULTS

The ingestion of ethanol induced a significant reduction of body weight and a significant increase in some markers of hepatic function (Alanine Amino-transferase, Aspartate Amino-transferase, alkaline phosphatase, gamma glutamyl-transferase, total bilirubin and albumin). These alterations were accompanied by a significant increase in the levels of serum triglycerides (p<0.001). Intoxicated animals were also characterized by a significant decrease of reduced glutathione and nitrites concentrations, catalase and superoxide dismutase activities as well as an increase of malondialdehyde levels. The histopathological examination showed vascular congestion, disorganized parenchyma, liver inflammation and dilation of sinusoid. The extract at the doses of 60 and 120 mg/kg reversed ethanol-induced adverse effects.

CONCLUSION

Our study found that, the aqueous extract of T. diversifolia leaves has hepato-protective activity against ethanol-induced liver damages due partly to its antioxidant effect. This result justifies its empirical use for the treatment of liver problems.

In vitro and in vivo anti-salmonella properties of hydroethanolic extract of Detarium microcarpum Guill. & Perr. (Leguminosae) root bark and LC-MS-based phytochemical analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Typhoid fever treatment remains a challenge in endemic countries. Detarium microcarpum is traditionally used to manage typhoid.

AIM OF THE STUDY

The study aims to explore the efficacy of hydroethanolic extract of Detarium microcarpum root bark in rats infected with salmonella.

MATERIAL AND METHODS

The phytochemical profile of the extract was obtained by UHPLC-MS analysis in an attempt of standardization. The in vitro antimicrobial activity was determined using broth dilution method. Salmonella infection was induced by oral administration of S. thyphimurium to immunosuppressed rats. Infected rats were then treated 2 h later with the extract (75, 150 and 300 mg/kg), distilled water (normal and salmonella control) and ciprofloxacin (8 mg/kg) for control. Body weight was monitored and stools were cultured to determine the number of colony-forming units. At the end of treatment, animals were sacrificed, blood and organs were collected for hematological, biochemical and histopathological analyses.

RESULTS

Detarium microcarpum extract as well as the isolated compound (rhinocerotinoic acid) exhibited good antimicrobial activity in vitro with bacteriostatic effects. The plant extract significantly (p < 0.05) inhibited the bacterial development in infected animals with an effective dose (ED₅₀) of 75 mg/kg. In addition, the extract prevented body weight loss, hematological, biochemical and histopathological damages in treated rats.

CONCLUSION

Detarium microcarpum extract possesses antisalmonella properties justifying its traditional use for the typhoid fever management.

Antidiabetic and Wound Healing Effects of Smeathxanthone A

The purpose of this study was to investigate whether smeathxanthone A isolated from Garcinia smeathmaniiimproves incisional wound healing in diabetic mice. Male albino alloxan-induced diabetic mice (n= 20) were divided into five groups: normal control, diabetic control, 2.5 mg/kg glibenclamide given orally, 0.05 and 0.1 mg/kg smeathxanthone A given subcutaneously. Animals were euthanized on postoperative day 10 after wounding; body weight, blood glucose, breaking strength, and histologic examination were reviewed. Smeathxanthone A significantly increased skin tensile strength (24% higher than diabetic control group when given at 0.1 mg/kg), stimulated hair growth, and reduced signs of inflammation in the scar sections. Smeathxanthone A also reduced blood glucose levels in diabetic mice (45% higher than diabetic control group when given at 0.1 mg/kg). The present study demonstrates that administration of smeathxanthone A after laparotomy expedites wound healing in mice. We suggest that it could confer benefits to tissue healing by significantly enhancing tissue collagen deposition and controlling blood glucose levels.

Acute and sub-acute toxicity of a lyophilised aqueous extract of the aerial part of Spilanthes africana Delile in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Spilanthes africana is a plant used in several countries for the treatment of toothache, malaria, fracture, pneumonia, and dysentery. In order to establish the safety of aerial part of the plant extract, the acute and sub-acute toxicity of the aqueous extract of this plant has been evaluated in male and female young rats.

MATERIAL AND METHODS

In acute toxicity, the effects of a single oral dose (2,000 mg/kg and 5,000 mg/kg) of the lyophilised aqueous extract have been determined. General behaviour, adverse effects and mortality were determined for up to 14 days. In sub-acute treatment, the effects of the extract in daily single oral administration at the doses of 250, 500 and 1,000 mg/kg during 28 days were evaluated. One group treated at the dose of 1,000 mg/kg for 28 days was let without treatment during 14 days to assess the possible reversibility of the harmful effects of the extract. Body weight, food and water intakes, biochemical and haematological parameters were recorded. Histopathological examination of liver, kidney and lungs were assessed.

RESULTS

In acute study, a single administration of the aqueous extract at the doses of 2,000 mg/kg or 5,000 mg/kg did not induce mortality. Thus, the LD50 of the aqueous extract of S. africana has been estimated higher than 5,000 mg/kg. Four hours after administration of the extract, a reduction of the mobility, sensitivity to the noise and to touch has been observed. In sub-acute study, the administration of the extract during 28 days at all doses did not significantly modify the body weight. On the haematological analysis, a decrease of the rate of monocytes and a rise of lymphocytes counts were observed among the male group. In both sexes, it appeared a decrease of the rate of granulocytes two weeks after stopping the treatment. It has also been observed in different groups among the females, an increase of the mean corpuscular content and the mean concentration in haemoglobin as well as an increase of platelets. A significant decrease of transaminases, alkaline phosphatase, triglycerides, and a significant increase of total bilirubin compared to the normal group has been observed. There was a significant decrease in renal catalase in both sexes compared with different control groups. Besides, a significant increase of the kidney rates of glutathione and malondialdehyde have also been observed in the female treated at the doses of 1,000 mg/kg. Histopathological analysis has shown vascular congestion and leucocyte infiltrations in the liver of animals treated at the dose of 1,000 mg/kg. This congestion has been marked in satellite group. In the kidney female satellite group, tubular clarifications have been observed and disappear when stopping the treatment.

CONCLUSION

These results show that the aqueous extract of S. africana given by the oral route is slightly toxic. However in sub-acute treatment, higher doses could provoke functional and structural changes in the organism which could in part reversible. Thus the extract should be used with caution.

The proliferative and chronotropic effects of Brillantaisia nitens Lindau (Acanthaceae) extracts on pluripotent stem cells and their cardiomyocytes derivatives

ETHNOPHARMACOLOGICAL RELEVANCE

Brillantaisia nitens Lindau (Acanthaceae) leaves are commonly used in traditional medicine in Africa for the treatment of many disorders including heart diseases and malaria. In this study, we therefore evaluated the effect of the methylene chloride/methanol leaf extract of Brillantaisia nitens on the proliferation of mouse pluripotent stem cells and their cardiomyocyte derivatives.

MATERIALS AND METHODS

In this study, we combined two emerging technologies, pluripotent stem cell-derived cardiomyocytes and modern electrophysiology systems (impedance-based real-time) to assess the cytotoxicity of Brillantaisia nitens extract (BNE). Undifferentiated pluripotent cells and cardiomyocytes were exposed to different concentrations of BNE. Cell viability and contraction were monitored by impedance using the xCELLigence system for short- and long-term treatment whereas the excitability of single cardiomyocytes was captured by patch clamp technique after BNE acute exposure.

RESULTS

Brillantaisia nitens extract inhibited the proliferation and increased cytotoxicity of embryonic stem cells in a concentration-dependent manner. With the increase in concentration of BNE, beating rate and the contractile amplitude of cardiomyocytes changed significantly. Spontaneous rhythmic activity of cardiomyocytes was completely suppressed after 48 and 24h exposures to relatively low (4.16 mg/ml) and high (8.32 mg/ml) concentrations of BNE, respectively. Moreover, acute application of 4.16 mg/ml of BNE led to a significant alteration of action potential (AP) parameters such as beating frequency, amplitude and AP duration at 90% of repolarization.

CONCLUSION

Brillantaisia nitens extract inhibits the proliferative capacity of pluripotent stem cells and reduces electrical activity of cardiomyocytes, confirming its depressant action on the heart.

Antihypertensive activities of the aqueous extract of Kalanchoe pinnata (Crassulaceae) in high salt-loaded rats

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Kalanchoe pinnata (Crassulaceae) are used in Cameroon folk medicine to manage many diseases such as cardiovascular dysfunctions. In this work, we aimed to evaluate the activities of aqueous leaf extract of Kalanchoe pinnata on the blood pressure of normotensive rat (NTR) and salt hypertensive rats (SHR), as well as its antioxidant properties.

MATERIALS AND METHODS

Hypertension was induced in rats by oral administration of 18% NaCl for 4 weeks. For the preventive study, three groups of rats received 18% NaCl solution and the plant extract at 25 mg/kg/day, 50 mg/kg/day or 100 mg/kg/day by gavage. Two positive control groups received 18% NaCl solution and either spironolactone (0.71 mg/kg/day) or eupressyl (0.86 mg/kg/day) by gavage for 4 weeks. At the end of this experimental period, systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and heart rate (HR) were measured by the invasive method. Some oxidative stress biomarkers (reduced glutathione (GSH), superoxide dismutase (SOD), nitric monoxide (NO) were evaluated in heart, aorta, liver and kidney. NO level was indirectly evaluated by measuring nitrite concentration.

RESULTS

Kalanchoe pinnata extract prevented significantly the increase of systolic and diastolic arterial pressures in high salt-loaded rats (SHR). In SHR, concomitant administration of Kalanchoe pinnata at 25, 50 and 100 mg/kg/day significantly prevented the increase in blood pressure by 32%, 24% and 47% (for SAP); 35%, 33% and 56% (for DAP), respectively. No significant change was recorded in heart rate of those rats. The plant extract improved antioxidant status in various organs, but more potently in aorta. Thus, antioxidant and modulatory effects of Kalanchoe pinnata at the vasculature might be of preponderant contribution to its overall antihypertensive activity.

CONCLUSION

The work demonstrated that the concomitant administration of high-salt and the aqueous extract of Kalanchoe pinnata elicits prevention of salt-induced hypertension in rat. This antihypertensive activity is associated with an improvement of antioxidant status. Overall, results justify and support the use of Kalanchoe pinnata as antihypertensive medicine.

Ethanol extract of Peperomia pellucida (Piperaceae) promotes fracture healing by an anabolic effect on osteoblasts

ETHNOPHARMACOLOGICAL RELEVANCE

The whole plant or some part of Peperomia pellucida (L.) HBK is used in some parts of Cameroon as a treatment for fracture healing.

AIM OF THE STUDY

To evaluate the effect of ethanolic extracts of Peperomia pellucida (L.), a Cameroonian medicinal plant on bone regeneration following bone and marrow injury, and determine the mode of action.

MATERIALS AND METHODS

Ethanol extract of Peperomia pellucida was administered at 100 and 200mg/kg doses orally to adult female Sprague-Dawley rats having a drill hole injury (0.8mm) in the femur diaphysis. Vehicle (gum-acacia in distilled water) was given to the control group. After 12 days of treatment, animals were euthanized and femur bones collected. Confocal microscopy of calcein labeling at the drill hole site was performed to evaluate bone regeneration. 3-D microarchitecture of drill hole site was analyzed by micorocomputed tomography. Osteogenic effects of the extract were evaluated by assessing mineralized nodule formation of bone marrow stromal cells and expression of osteogenic genes (mRNA level of type-1 collagen, bone morphogenetic protein-2 and osteocalcin genes) in the femur.

RESULTS

Ethanol extract from Peperomia Pellucida (L.) dose-dependently induced bone regeneration at the fracture site. At 200mg/kg dose, the extract significantly increased mineral deposition compared to controls. The extract also improved microarchitecture of the regenerating bone evident from increased bone volume fraction, trabecular thickness, trabecular number, and decreased trabecular separation and structure model index. In addition, the extract increased the formation of mineralized nodules from the bone marrow stromal cells. Furthermore, the extract induced the expression of osteogenic genes in the femur including type 1 collagen, osteocalcin and BMP-2, compared to control.

CONCLUSION

Ethanolic extract of P. pellucid (L.) accelerates fracture repair in rats via stimulatory effects on osteoblast differentiation and mineralization, thereby justifying its traditional use.

Compounds from Sorindeia juglandifolia (Anacardiaceae) exhibit potent anti-plasmodial activities in vitro and in vivo

Background

Discovering new lead compounds against malaria parasites is a crucial step to ensuring a sustainable global pipeline for effective anti-malarial drugs. As far as we know, no previous phytochemical or pharmacological investigations have been carried out on Sorindeia juglandifolia. This paper describes the results of an anti-malarial activity-driven investigation of the fruits of this Cameroonian plant.

Methods

Air-dried fruits were extracted by maceration using methanol. The extract was fractionated by flash chromatography followed by column chromatography over silica gel, eluting with gradients of hexane-ethyl acetate mixtures. Resulting fractions and compounds were tested in vitro against the Plasmodium falciparum chloroquine-resistant strain W2, against field isolates of P. falciparum, and against the P. falciparum recombinant cysteine protease falcipain-2. Promising fractions were assessed for acute toxicity after oral administration in mice. One of the promising isolated compounds was assessed in vivo against the rodent malaria parasite Plasmodium berghei.

Results

The main end-products of the activity-guided fractionation were 2,3,6-trihydroxy benzoic acid (1) and 2,3,6-trihydroxy methyl benzoate (2). Overall, nine fractions tested against P. falciparum W2 and falcipain-2 were active, with IC₅₀ values of 2.3-11.6 μg/ml for W2, and 1.1-21.9 μg/ml for falcipain-2. Purified compounds (1) and (2) also showed inhibitory effects against P. falciparum W2 (IC50s 16.5 μM and 13.0 μM) and falcipain-2 (IC50s 35.4 and 6.1 μM). In studies of P. falciparum isolates from Cameroon, the plant fractions demonstrated IC₅₀ values of 0.14-19.4 μg/ml and compounds (1) and (2) values of 6.3 and 36.1 μM. In vivo assessment of compound (1) showed activity against P. berghei strain B, with mean parasitaemia suppressive dose and curative dose of 44.9 mg/kg and 42.2 mg/kg, respectively. Active fractions were found to be safe in mice after oral administration of 7 g/kg body weight.

Conclusions

Fractions of Sorindeia juglandifolia and two compounds isolated from these fractions were active against cultured malaria parasites, the P. falciparum protease falcipain-2, and in a rodent malaria model. These results suggest that further investigation of the anti-malarial activities of natural products from S. juglandifolia will be appropriate.

Anxiolytic activity evaluation of four medicinal plants from Cameroon

Afrormosia laxiflora (A. laxiflora), Chenopodium ambrosioides (C. ambrosioides), Microglossa pyrifolia (M. pyrifolia) and Mimosa pudica (M. pudica) are plants used in traditional medicine in Cameroon to treat insomnia, epilepsy, anxiety, and agitation. They were evaluated for their anxiolytic like activity in mice. Animal models (elevated plus maze and stress-induced hyperthermia tests) were used. The four plants showed anxiolytic activity. In stress-induced hyperthermia test, A. laxiflora, C. ambrosioides, M. pyrifolia and M. pudica significantly antagonised the increase of temperature. ΔT° decreased from 0.75°C in the control group to 0.36°C at the dose of 110 mg/kg for A. laxiflora; from 1°C in the control group to -1.1°C at the dose of 120 mg/kg for C. ambrosioides; from 1.7°C in the control group to 0.2°C at the dose of 128 mg/kg for M. pyrifolia and from 1.3°C in the control group to 0.5°C at the dose of 180 mg/kg for M. pudica. In the elevated plus maze test, the four plants increased the number of entries into, percentage of entries into, and percentage of time in open arms. A. laxiflora, C. ambrosioides and M. pudica also reduced the percentage of entries and time in closed arms. In addition, C. ambrosioides, M. pyrifolia and M. pudica showed antipyretic activity by reducing the body temperature. The results suggested that C. ambrosioides, M. pyrifolia and M. pudica posses anxiolytic-like and antipyretic activities while A. laxiflora possesses only anxiolytic-like properties. These plants could be helpful in the treatment of anxiety and fever in traditional medicine in Cameroon.

Acute and sub-chronic oral toxicity studies of an aqueous stem bark extract of Pterocarpus soyauxii Taub (Papilionaceae) in rodents

Pterocarpus soyauxii Taub (Papilionaceae) is used in Cameroonian traditional medicine and pharmacopoeia to treat hypertension, diabetes, gastrointestinal parasitizes and cutaneous diseases.

AIM OF THE STUDY

The present investigation was carried out to evaluate the safety of an aqueous stem bark extract of Pterocarpus soyauxii by determining toxicity after acute and sub-chronic oral administration in male and female rodents.

MATERIALS AND METHODS

The acute toxicity test was conducted in mice. An aqueous extract of barks was administrated by gavage in single doses of 2.5-12.5 g/kg. General behaviour and mortality were examined for up to 7 days. The sub-chronic toxicity test was performed in rats. The plant extract was administered by daily gavage of 150-600 mg/kg for 42 days. Body weight, food and water intakes were followed weekly. Haematological, biochemical and organ parameters were determined at the end of the 42-day administration.

RESULTS

In the acute study in mice, oral administration of the aqueous extract of Pterocarpus soyauxii caused dose-dependent general behaviour adverse effects and mortality. The no-observed adverse effect level (NOAEL) of the extract was 5.0 g/kg. The lowest-observed adverse effect level (LOAEL) was 7.5 mg/kg. Mortality increased with the dose, LD(50) was>10.75 g/kg for the mouse. In the sub-chronic study in rats, daily oral administration of the aqueous extract of Pterocarpus soyauxii did not result in death or significant changes in haematological or biochemical parameters, excepted increased hepatic catalase activity (P<0.05) at the dose of 600 mg/kg. No alteration was observed in body weight, food and water intake. Liver, kidney, lung and pancreas histopathology did not reveal morphological alteration.

CONCLUSIONS

The results showed that the aqueous stem bark extract of Pterocarpus soyauxii Taub had very low toxicity in oral acute high dose administration and no toxicity in oral sub-chronic low dose administration and indicate that the plant could be considered safe for oral medication.

In vitro inhibition of lipopolysaccharide and mycobacterium bovis bacillus Calmette Guérin-induced inflammatory cytokines and in vivo protection from D-galactosamine/LPS -mediated liver injury by the medicinal plant Sclerocarya birrea

Sclerocarya birrea is a medicinal plant used for the treatment of inflammatory- and bacterial-related diseases. The present study investigated in vitro and in vivo the effects of the stem bark methanol extract of S. birrea. Nitrite, TNF, IL-1beta, IL-6 and IL-12p40 production by bone marrow-derived macrophages (BMDM) pre-incubated with or without S. birrea, and stimulated with Lipopolysaccharide (LPS) or infected with live Mycobacterium bovis Bacillus Calmette Guérin (BCG) was evaluated. S. birrea extract inhibited, in a concentration-dependent manner, nitrite, TNF, IL-1beta, IL-6 and IL-12p40 production by BMDM stimulated with LPS or infected with live BCG. The iNOS expression was reduced by S. birrea after stimulation of BMDM with LPS. In addition, S. birrea inhibited the nuclear factor kB (NF-kB) activation by both LPS and BCG. The effects of the plant extract were also evaluated in an in vivo model of liver injury induced by D-galactosamine/LPS (D-GalN/LPS) administration in mice. S. birrea limited D-GalN/LPS-liver injury as assessed by a reduction in transaminases and TNF, IL-1beta, IL-6 serum levels, and translocation of NF-kB to the nucleus. Taken together, our data indicate that stem bark methanol extract of S. birrea possesses anti-inflammatory properties by inhibiting NF-kB activation and cytokine release induced by inflammatory or infectious stimuli.

Hypoglycaemic effects of Mammea africana (Guttiferae) in diabetic rats

AIM OF THE STUDY

The stem bark of Mammea africana Sabine (Guttiferae) is used in African rain forest to treat various diseases, including diabetes mellitus. We investigated whether Mammea africana extract induced hypoglycaemic activity in rats.

MATERIALS AND METHODS

We tested the effects of acute (5h) and sub-acute (21 days) oral administrations of the CH(2)Cl(2)-MeOH stem bark extract of Mammea africana (19-300 mg/kg body weight) on blood glucose levels of normal and streptozotocin (STZ)-induced type 1 diabetic rats. The effects were compared with those of glibenclamide.

RESULTS

Acute administration reduced blood glucose in the diabetic rats only (33.87%, P<0.01). Sub-acute treatment for 21 days also reduced blood glucose level in diabetic rats (73.29%, P<0.01). A reduction or stabilization in total serum protein, triglyceride, cholesterol and alanine amino transferase levels was also observed. No effect was observed on body weight loss but food and water intakes were significantly reduced (P<0.01) in diabetic rats. The maximal anti-diabetic effect was obtained with the dose of 75 mg/kg and was more important than that of glibenclamide.

CONCLUSION

It can be concluded that extracts of Mammea africana exhibited a significant anti-hyperglycaemic activity and improved the metabolic alterations in STZ-diabetic rats. These results provide a rationale for the use of Mammea africana to treat diabetes mellitus and hypercholesterolemia.

Hypertensive effects of oral administration of the aqueous extract of Solanum torvum fruits in L-NAME treated rats: evidence from in vivo and in vitro studies

ETHNOPHARMACOLOGICAL RELEVANCE

Solanum torvum fruits are commonly used in Cameroonian traditional medicine for treatment of arterial hypertension. It has been previously shown that intravenous administration of aqueous extract from dried fruits (AEST) reduced blood pressure.

AIM

The present work evaluates acute toxicity and effects of oral administration of AEST in chronic arterial hypertension induced by L-NAME. Effects of AEST were also evaluated on isolated aorta.

MATERIALS AND METHODS

AEST (200 mg/kg/day, p.o.) was given solely or concomitantly with L-NAME (40 mg/kg/day, p.o.) for 30 consecutive days. Animal body weight, systolic blood pressure and heart rate were measured before stating the treatment and at the end of each week. Urinary volume and urinary sodium and potassium contents were quantified before and at days 1, 15 and 30 of the treatment. Aorta from treated animals was tested for their sensitivity to noradrenaline and carbachol. Aorta from normal untreated rats was used to evaluate the in vitro vascular effect of AEST.

RESULTS

The results showed that AEST did induce neither mortality nor visible signs of toxicity. When given solely or in co-administration with L-NAME, AEST significantly reduced animal's body weight. It amplified the hypertensive and cardiac hypertrophy effect of L-NAME and did not affect these parameters in normotensive animals. AEST increased the sensitivity to noradrenaline in normotensive and significantly reduced it in hypertensive animals. AEST significantly increased urinary volume and sodium excretion in L-NAME treated animals while reducing the sodium excretion in normotensive. In vitro, AEST induced a potent partial endothelium-dependent contraction of aortic ring; contractions that were partially antagonized by prazosin and verapamil and were not relaxed by carbachol.

CONCLUSION

These results suggest that oral chronic administration of AEST induced potentiation of arterial hypertension and cardiac hypertrophy in L-NAME treated rats. These effects may result from a reduction in sensitivity to vasorelaxant agents and increase in hypersensitivity to contractile factors. AEST possess potent in vitro vasocontractile activity that may result from activation of both alpha(1)-adrenergic pathway and calcium influx.

Anti-oxidative and anti-inflammatory activities of some isolated constituents from the stem bark of Allanblackia monticola Staner L.C (Guttiferae)

Stem bark of Allanblackia monticola has been used in association with others plant in the Cameroonian folk medicine for the treatment of various diseases such amoebic dysentery, diarrhoea, lung infections, and skin diseases. The methylene chloride fraction, its isolated compounds like alpha-mangostin, lupeol and acid betulinic were screened for antioxidant activity using free radical scavenging method. These isolated compounds were further tested for anti-inflammatory properties using carrageenan-induced model. Methylene chloride fraction, showed concentration-dependent radical scavenging activity, by inhibiting 1,1-diphenyl-1-picryl-hydrazyl radical (DPPH) with an IC(50) value of 14.60 microg/ml. alpha-Mangostin and betulinic acid (500 microg/ml), showed weak radical scavenging activity with a maximum inhibition reaching 38.07 microg/ml and 26.38 microg/ml, respectively. Betulinic acid, lupeol and alpha-mangostin (5 mg/kg and 9.37 mg/kg) showed anti-inflammatory activity with a maximum inhibition of 57.89%, 57.14% and 38.70%, respectively. Methylene chloride fraction of Allanblackia monticola and some derivatives, have antioxidant and anti-inflammatory activities.

Anti-hypertensive effects of the methanol/methylene chloride stem bark extract of Mammea africana in l-NAME-induced hypertensive rats

AIM OF THE STUDY

The methanol/methylene chloride (CH(3)OH/CH(2)Cl(2)) extract from the stem bark of Mammea africana was showed to possess vasodilating effect in the presence and the absence of N(omega)-nitro-l-arginine methyl ester (l-NAME). The present study was designed to evaluate the effects of the methanol/methylene chloride from the stem bark of Mammea africana.

MATERIALS AND METHODS

The extract (200 mg/(kg day)) was administered orally in rats treated concurrently with l-NAME (40 mg/(kg day)). l-Arginine (100 mg/(kg day)) and captopril (20 mg/(kg day))were used as positive controls. Bodyweight, systolic arterial blood pressure and heart rate were measured weekly throughout the experiment period (28 days). At the end of treatment, animals were killed and the cardiac mass index evaluated. The aorta was used to evaluate the endothelium-dependant relaxation to carbachol. The aorta contraction induced by noradrenalin was also examined and expressed as a percentage of that induced by KCl.

RESULTS

The extract neither affected the body weight nor the heart rate. The extract as captopril completely prevented the development of arterial hypertension. Both the substances failed to restore the endothelium-dependent vascular relaxation and increased the vascular contraction to norepinephrine in relation to KCl contraction. They also significantly reduced the left ventricular hypertrophy induced by l-NAME.

CONCLUSION

These findings are in agreement with the traditional use of Mammea africana in the treatment of arterial hypertension and indicate that it may have a beneficial effect in patients with NO deficiency but will be unable to improve their endothelium-dependent vasorelaxation.

Maternal and developmental toxicity evaluation of Acanthus montanus leaves extract administered orally to Wistar pregnant rats during organogenesis

Acanthus montanus is a plant used in Cameroon to treat pains and threatened abortion. The aim of this study was to evaluate the influence of methanol/methylene chlorides leaves extract from Acanthus montanus on Wistar pregnant rats and identify the substance(s) essential for these actions. Dams were treated orally from days 6 to 15 of the pregnancy at the dose levels of 0, 250, 500 and 1000 mg/(kgday). They were sacrificed on day 20 or allowed to deliver and wean. Various parameters were assessed. The F(1) generation offsprings were allowed to give birth to F(2) generation and a number of parameters assessed. The results showed that there was no maternal or organs toxicity. Embryotoxicity was observed during organogenesis manifested by reduction in foetal body weight, crown-rump and tail lengths and reduced ossification of extremities bones. However after delivery, these signs of growth retardation were seen before day 5, and henceforth, the treated pups regained all their parameters to normality. All others parameters for F(1) and F(2) generations were insignificant. beta-Sitosterol was the major chemical component of the extract and its role on these results could not be ignored. The MeOH/CH(2)Cl(2) extract of this plant is embryotoxic peri-natally at high doses but this failed to manifest after 5 days of post-natal survival. beta-Sitosterol may be central in the observed effects of the extract. This extract can be tolerated by pregnant patients.

Vasorelaxant effects of Brillantaisia nitens Lindau (Acanthaceae) extracts on isolated rat vascular smooth muscle

Brillantaisia nitens Lindau (Acanthaceae) is traditionally used in Cameroon for the treatment of many diseases including cardiovascular disorders. We have studied its vasorelaxant effects in rat vascular smooth muscle. In this study, aqueous, methylene chloride, methanol, and methylene chloride/methanol leaves extracts of Brillantaisia nitens were tested for their relaxing ability in vitro. Strips of rat aorta, with or without intact endothelium, were mounted in tissue baths, contracted with KCl (60mM) or norepinephrine (10(-4)M), and then exposed to the plant extracts. These extracts exhibited concentration-dependent vasorelaxations of norepinephrine-induced contractions of intact aortic strips. The EC(50) were 0.42+/-0.01mg/ml (aqueous extract), 0.63+/-0.02mg/ml (methylene chloride extract), 0.73+/-0.02mg/ml (methanol extract) and 0.36+/-0.02mg/ml (methylene chloride/methanol extract). The methylene chloride/methanol (CH(2)Cl(2)/CH(3)OH) extract was the most potent relaxing extract. It caused a concentration-dependent and endothelium-independent relaxation of the rat aortic strips contracted by KCl or norepinephrine. On the NE-induced contraction, its maximal relaxant activity (109%) due to the dose of 1.5mg/ml, was not significantly modified by the pretreatment of aortic strips with indomethacin (89%, P>0.05) or with l-NAME (103%, P>0.05). This suggests that the vasorelaxation elicited by CH(2)Cl(2)/CH(3)OH extract was not mediated via endothelium-derived prostacyclin or nitric oxide. In contrast, this relaxation was markedly reduced by tetraethylammonium, a blocker of non-selective K(+) channels and glibenclamide, a blocker of ATP-sensitive K(+) channels. The CH(2)Cl(2)/CH(3)OH extract significantly inhibited Ca(2+)-induced concentration-contraction and the Ca(2+) influx in aortic strips incubated with 60mM KCl. These results indicate that the vasorelaxant effect of the CH(2)Cl(2)/CH(3)OH extract of Brillantaisia nitens is due to an inhibition of Ca(2+) influx, possibly via the activation of ATP-sensitive K(+) channels.

Analgesic and anticonvulsant effects of extracts from the leaves of Kalanchoe crenata (Andrews) Haworth (Crassulaceae)

Kalanchoe crenata Andr. (Crassulaceae) is a fleshy herbaceous plant used in the African traditional medicine as remedies against otitis, headache, inflammations, convulsions and general debility. In the present work, the analgesic effects of methylene chloride/methanol (1:1) (CH(2)Cl(2)/CH(3)OH) extract and its hexane, methylene chloride (CH(2)Cl(2)), ethyl acetate, n-butanol fractions and aqueous residue have been evaluated using acetic acid, formalin and pressure test. The anticonvulsant effects of the CH(2)Cl(2)/CH(3)OH extract were also investigated on seizures induced by pentylenetetrazol (PTZ 70 mg/kg), strychnine sulphate (STN 2.5 mg/kg) and thiosemicarbazide (TSC 50 mg/kg). CH(2)Cl(2)/CH(3)OH extract and its fractions, administered orally at the doses of 150 and 300 mg/kg, exhibited protective effect of at least 30% on the pain induced by acetic acid. The CH(2)Cl(2) fraction at 300 mg/kg showed a maximal effect of 78.49%. The CH(2)Cl(2)/CH(3)OH extract and its CH(2)Cl(2) fraction at the doses of 150 and 300 mg/kg significantly reduced the first phase of pain induced by formalin while the second phase was completely inhibited. The CH(2)Cl(2) fraction produced more than 45% reduction in the sensitivity to pain induced by pressure. The CH(2)Cl(2)/CH(3)OH extract of Kalanchoe crenata significantly increased the latency period in seizures induced by PTZ and significantly reduced the duration of seizures induced by the three convulsant agents. The extract protected 20% of animals against death in seizures induced by TSC and STN. These results suggest a peripheral and central analgesic activities as well as an anticonvulsant effect of the leaves of Kalanchoe crenata.

Methanol extract of Terminalia superba induces endothelium-independent relaxation of rat thoracic aorta

Terminalia superba is highly regarded in some parts of Cameroon in traditional medical practice. We have studied the vasorelaxant effects of the stem bark methanol extract of T. superba on rat vascular smooth muscle. The results demonstrated that T. superba extract provoked a time-dependent relaxation of aortic rings precontracted with norepinephrine (10(-6) M). The vasorelaxant effect of the plant extract was not affected by endothelium removal or by pretreatment with indomethacin or N(W)-nitro-Larginine methyl ester (L-NAME). T. superba extract did not significantly, affect the contraction induced by 30 mM or 60 mM KCl as compared to those induced by NE. Relaxations elicited by T. superba extract were markedly reduced by glibenclamide, a putative blocker for K(ATP) channels and by tetraethylammonium, the non-specific K+ channel inhibitor. T. superba caused a time- and concentration-dependent relaxation of the rat aortic rings that were inhibited by charybdotoxin and iberotoxin but not by apamin. These finding indicate that T. superba extract at least partially relaxes the rat aorta by activating K+ channels, mainly KATP channels and large-conductance Ca2+ -activated K+ channels in rat aorta.

Anti-diabetic activity of methanol/methylene chloride stem bark extracts of Terminalia superba and Canarium schweinfurthii on streptozotocin-induced diabetic rats

Stem bark extracts of Terminalia superba Engl. and Diels and Canarium schweinfurthii Engl. are used in Africa for the treatment of various ailments, including diabetes mellitus. The anti-diabetic effects of the methanol/methylene chloride extracts of the stem barks on streptozotocin (STZ)-induced diabetes were evaluated on male rats. Through the subcutaneous route, diabetes was induced using 60 mg/mL of streptozotocin. After 2 days, the rats received, by gavage, 150 mg/kg and 300 mg/kg of extract daily for 14 days. At 300 mg/kg, the two extracts (Terminalia superba and Canarium schweinfurthii), significantly showed at least 67.1% and 69.9% reduction in blood glucose level, respectively, while insulin (three units) given subcutaneously and once daily, had 76.8% reduction compared to diabetic untreated control rats. Similarly, the weight gains were 6.6% and 4.9%, respectively, and were comparable to the normal rats, whereas, diabetic untreated rats lost 14.1% body weight. Still with the same dose, there was 68.5% and 58.5% (p < 0.001) significant decrease in food consumption and 79.7% and 64.0% (p < 0.001) in fluid intake by diabetic rats treated with the respective plant extracts. The insulin-treated rats showed 56.4% and 75.8% decrease in food and fluid intake compared to an augmentation for diabetic control rats, 43.0% and 383.8%, respectively, at the end of the second week of experimentation. These results showed that the plant extracts can reverse hyperglycemia, polyphagia and polydipsia provoked by streptozotocin, and thus, they have anti-diabetic properties.

Glucose lowering efficacy of the aqueous stem bark extract of Trema orientalis (Linn) Blume in normal and streptozotocin diabetic rats

The glucose-lowering efficacy of the aqueous stem bark extract of Trema orientalis (Ulmaceae) was evaluated both in normal and streptozotocin-induced diabetic rats. In normoglycemic rats, the single oral administration of the aqueous extract of T. orientalis failed to reduce blood glucose levels while in STZ-diabetic rats, the plant extract (38-300 mg/kg) exhibited significant hypoglycaemic activity with a maximum effect of 29.67%, 5 hours after administration of the 75 mg/kg dose when compared with the diabetic untreated group. Glibenclamide was not able to lower blood glucose in STZ-diabetic rats, while it significantly lowered the blood sugar in normoglycemic rats. The hypoglycaemic property of T. orientalis was also assessed by an oral glucose tolerance test (OGTT) in STZ-diabetic rats. The aqueous extract of T. orientalis and the reference drug, glibenclamide, (10 mg/kg) produced significant blood glucose lowering effects in the diabetic rats when compared to the diabetic controls. One week after repeated administration of T. orientalis extract, blood glucose levels were significantly decreased (p < 0.05) and still remained low after 2 weeks (p < 0.01). The results indicated that T. orientalis stem bark extract significantly reduces blood glucose in STZ-induced diabetic rats by a mechanism different from that of sulfonylurea agents. The present investigation provides pharmacological evidence that the use of this plant extract in traditional medicine for cardiovascular disease can be of benefit particulary in diabetic patients.

Relaxant effects of the neutral extract of the leaves of Bidens pilosa Linn on isolated rat vascular smooth muscle

The long-lasting antihypertensive effect of a neutral extract of Bidens pilosa has been suggested to be due to vasodilation. The present work was undertaken to assess this hypothesis. The vasorelaxant effect of a neutral extract (NBp) of the leaves of B. pilosa was evaluated in vitro on isolated rat aorta contracted with KCl or norepinephrine. NBp induced a concentration-dependent vasorelaxation of the rat aorta precontracted with KCl (60 mM) by 25%-105% at the respective concentrations of 0.25-1.5 mg/mL. The maximal concentration of 1.5 mg/mL provoked 88% relaxation of norepinephrine-induced contractions. There were no significant differences between the effects of the extract on the aorta strips with or without endothelium. In the presence of indomethacin or pyrilamine maleate, the relaxant response induced by the plant extract was significantly inhibited at the lower concentrations. The plant extract was able to reduce the aorta resting tone, inhibit the KCl-induced contractions (90% at 1.5 mg/mL) and the CaCl2-induced contractions by 95% at a concentration of 0.75 mg/mL. These results demonstrate the vasodilating properties of the neutral extract of Bidens pilosa and indicate that it may act as a calcium antagonist.

Effects of methylene chloride/methanol leaf extract of Celtis durandii engler (Ulmaceae) on constriction of rat aorta

Celtis durandii is a medicinal plant widely used in some part of Cameroon for the treatment of cardiovascular disorders. The vasorelaxant effects of the methylene chloride/methanol leaf extract of C. durandii were examined on isolated rat thoracic aorta. The relaxant effects of C. durandii on vascular preparation from rat aorta precontracted with KCl or norepinephrine was concentration dependent. This relaxing effect was significantly reduced with KCl-induced contraction following mechanical damage to the aortic endothelium. Relaxation elicited by C. durandii was not significantly affected by glibenclamide (10(-6) M), a selective inhibitor of K-ATP-dependent channels or tetraethylammonium (10(-6) M), a non selective K+ channel blocker. Indomethacin (10(-6) M) significantly inhibited relaxation induced by the plant extract. These findings indicate that the vasorelaxation effect of the methylene chloride/methanol leaf extract of C. durandii may be mediated at least in part by prostacyclin.

Antiinflammatory, lack of central analgesia and antipyretic properties of Acanthus montanus (Ness) T. Anderson

Aqueous leaves extract of Acanthus montanus (Nees) T. Anderson (Acanthaceae) were tested for antiinflammatory, analgesic and antipyretic properties. This was done using standard methodologies following oral administration of the extract. The results showed that the extract significantly reduced the oedema induced by carrageenan within 30 min with 200 mg/kg being the most potent. On the analgesia front, acetic acid writhing test was significant. The extract reduced only the number of paw licks of phase 2 and not phase 1 of formalin test. The results on hotplate and tail immersion tests excluded central acting analgesic properties of the extract. In overall, the analgesic tests conducted revealed that the extract had only peripheral analgesic properties. Its effect on pyresis was also observed to be appreciable. It significantly reduced fever at doses greater than 100 mg/kg within 6 h.

Analgesic properties of the aqueous and ethanol extracts of the leaves ofKalanchoe crenata(Crassulaceae)

The aqueous and ethanol extracts of the dry leaves of Kalanchoe crenata (300 and 600 mg/kg) were evaluated for their analgesic properties on the pain induced by acetic acid, formalin and heat in mice and by pressure on rats. The ethanol extract of K. crenata at a dose of 600 mg/kg produced an inhibition of 61.13% on pain induced by acetic acid and 50.13% for that induced by formalin. An inhibition of 67.18% was observed on pain induced by heat 45 min after the administration of the extract. The aqueous extract administered at a dose of 600 mg/kg produced a maximum effect of 25% on pain induced by pressure. These activities were similar to those produced by a paracetamol-codeine association, while indomethacin exhibited a protective effect only against the writhing test. Our results suggest that the leaves of K. crenata could be a source of analgesic compounds.

Analgesic and antiinflammatory activities of Erigeron floribundus

This study was intended to evaluate the analgesic and antiinflammatory activities of an aqueous extract of Erigeron floribundus (H.B. & K) or (syn": Conyza sumatrensis (Retz) E.K. Walker) (Asteraceae). Phytochemical analysis was carried out using standard methodologies. The analgesic investigations were carried out against two types of noxious stimuli, chemical (formalin-induced pain and acetic acid-induced writhing) and thermal (hotplate and tail immersion tests). The effects following aspirin and naloxone pretreatments were also studied. For the antiinflammatory activities, the carrageenan-induced oedema of the hindpaw of rats was used and the paw volume measured plethysmometrically from 0 to 24 h after injection. This was compared to a standard drug indomethacin (10 mg/kg). The results were subjected to statistical analysis. The plant had saponins, flavonoids, glycosides, alkaloids, oils, phenols and tannins and significantly increased the reaction time of hotplate and immersion tests. It decreased the writhings of acetic acid-induced abdominal contractions and lickings of formalin-induced pain. Aspirin had no effect on hotplate and tail immersion tests but showed an effect on writhing test. These results showed that the plant had both central and peripheral acting effects and this was confirmed by its effect on both phases of formalin-induced pain. The extract also significantly decreased the rat paw oedema volume at 50 mg/kg and above. In conclusion, Erigeron floribundus has central and peripheral analgesic properties as well as antiinflammatory activities.

Possible mechanisms of action of the neutral extract fromBidens pilosa L. leaves on the cardiovascular system of anaesthetized rats

The aim of this study was to investigate the hypotensive and cardiac effects of the neutral extract from Bidens pilosa leaves. Intravenous administration of the extract resulted in a biphasic dose-related hypotensive activity. In normotensive rats (NTR), B. pilosa decreased systolic blood pressure by 18.26%, 42.5% and 30% at doses of 10, 20 and 30 mg/kg, respectively. In spontaneously hypertensive rats (SHR), the decrease in systolic blood pressure was 25.77%, 38.96% and 28.64% at the above doses, respectively. These doses induced hypotension by 27%, 34.13% and 18.73% respectively in salt-loaded hypertensive rats. In NTR, B. pilosa reduced heart rate by 23.68% and 61.18% at doses of 20 and 30 mg/kg, respectively. The force of contraction of the heart was only affected at 30 mg/kg. The initial phase of hypotensive response was partially inhibited by atropine while propranolol increased this effect. These results suggest that B. pilosa exhibited its fi rst hypotensive effects by acting on the cardiac pump efficiency and secondly through vasodilation.

Gastric cytoprotective anti-ulcer effects of the leaf methanol extract of Ocimum suave (Lamiaceae) in rats

The anti-ulcerogenic potential of the leaf methanol extract of Ocimum suave (Lamiaceae) was investigated using four methods of gastric lesion induction in experimental Wistar rats (150-200 g): (1) HCl/ethanol-induced gastric lesions, (2) Absolute ethanol-induced gastric lesions, (3) Indomethacin-HCl/ethanol-induced gastric lesions, (4) Pylorus ligation-induced gastric lesions. Administration of the extract of O. suave to the rats by oral route (75-500 mg/kg) dose-dependently prevented the formation of acute gastric lesions induced using the four experimental techniques. The dose-dependent reduction of lesion formation was in all cases accompanied by significant increases in gastric mucus production. At the dose of 250 mg/kg there was complete inhibition of gastric lesions induced using the HCl/ethanol solution. Pre-treatment, by intraperitoneal route, with indomethacin significantly reduced the ability of the extract to inhibit the formation of HCl/ethanol-induced lesions. When the rats were subjected to pylorus ligation, the dose of 500 mg/kg completely inhibited lesion formation but did not have any effect on gastric acid secretion compared with the controls. The mucus secretion promoting effect of the extract was most significant when the gastric environment was highly acidic. These results suggest that a new anti-ulcer therapy regimen may be formulated which does not require the use of antacids and anti-secretory agents.

In vitro vascular smooth muscle contractile activity of Aspilia africana extract on rat aortic preparations

Aspilia africana is widely used in ethnomedical practice in Africa for its ability to stop bleeding, even from a severed artery, as well as promote rapid healing of wounds and sores, and for the management of problems related to cardiovascular diseases. In the present paper, the methylene chloride/methanol extract of A. africana leaves was tested for its contractile activity in vitro. Rings of rat aorta, with or without an intact endothelium, were mounted in tissue baths, contracted with norepinephrine, and then exposed to the plant extract. The effect of the extract was also assessed on the baseline tension of aortic rings in normal and calcium-free PSS. At the lower doses, A. africana slowly re-inforced contractions induced by norepinephrine and relaxed precontracted tension at the highest concentration. The relaxant activity of the extract was endothelium-independent and was not modified by pre-treatment with Nw-nitro-L-arginine methyl ester or indomethacin, suggesting that its effect was not mediated by either nitric oxide or prostacyclin. A. africana extract induced slow and progressive increase in the basal vascular tone which was partially endothelium-dependent. In calcium-free PSS, a high proportion of the contractile activity was inhibited (77%), suggesting that A. africana contractile activity in vascular tissue depends, in part, on extracellular calcium.

Synergistic and potentiating effects of ranitidine and two new anti-ulcer compounds from Enantia chlorantha and Voacanga africana in experimental animal models

TN, an alkaloid from the fruit of Voacanga africana and a protoberberine-type alkaloid (7,8-dihydro-8-hydroxypalmatine) (1), obtained from the bark of Enantia chlorantha were tested for ulcer preventive and antisecretory activity in combination with ranitidine. When tested alone (50 and 100 mg/kg, p.o.), TN and 1 achieved their anti-ulcer actions through reduced gastric secretion and improved mucus production. 1:1 combinations of 1 and the antisecretory agents (25/25 and 50/50 mg/kg) resulted in significant reduction of ulceration under highly acidic conditions (50-70 mEq/l), suggesting potentiating effects. A combination of TN and ranitidine led to synergistic antisecretory effects.

Effects of Aframomum melegueta and Piper guineense on sexual behaviour of male rats

The effects of aqueous extracts of Aframomum melegueta and Piper guineense on the sexual behaviour of male rats were studied, considering many criteria, such as penile erection, copulatory behaviour and orientation activities towards themselves (genital grooming) and female rats (ano-genital sniffing, mounting). For 8 days different groups of rats received a daily administration of distilled water (control) or a plant extract: A. melegueta at 115 mg/kg or P. guineense at 122.5 mg/kg. Both plant extracts stimulated male sexual behaviour. In fact, A. melegueta and P. guineense significantly increased penile erection index, and the frequencies of intromission and ejaculation. These plant extracts were found to enhance the orientation of males towards females by increasing mounting and ano-genital investigatory behaviour. Results of this study showed that A. melegueta and P. guineense modified the sexual behaviour of male rats by increasing sexual arousal.

Effects of the aqueous and methylene chloride extracts of Bidens pilosa leaf on fructose-hypertensive rats

We investigated the effects of the aqueous (150-350 mg/kg) and methylene chloride (150-300 mg/kg) extracts of Bidens pilosa on fructose-induced hypertension in rats. Food and liquid intake were measured as well as systolic blood pressure and plasma levels of glucose, insulin, cholesterol, triglycerides and creatinine. Fructose feeding for 6 weeks induced hypertension, hyperinsulinemia and increased plasma triglyceride levels in male Wistar rats. The aqueous and methylene chloride extracts of B. pilosa reversed the high blood pressure and hypertriglyceridemia developed due to fructose feeding but did not have any effects on plasma levels of insulin and glucose. High doses of the extracts reduced plasma creatinine levels and tended to increase plasma cholesterol. These results suggest that the extracts of B. pilosa possess hypotensive effects whose mechanism of action is not related to insulin sensitivity.

Antihypertensive effects of Dorstenia psilurus extract in fructose-fed hyperinsulinemic, hypertensive rats

We examined the effect of methanol/methylene chloride extract of Dorstenia psilurus given by gastric intubation on systolic blood pressure, plasma glucose, insulin, cholesterol, triglycerides and creatinine in rats with fructose-induced hypertension. Male Wistar rats in groups of 6 animals each were fed fructose-rich diets or standard chow for 3 weeks and treated with 100 mg/kg/day or 200 mg/kg/day of plant extract or vehicle for 3 subsequent weeks. Systolic blood pressure was measured every three days using the indirect tail cuff method. Systolic blood pressure was higher in fructose-fed rats (142+/-2 mm Hg, p < 0.01) compared with the controls (112+/-2 mm Hg), and was lower in Dorstenia psilurus-treated groups (127+/-2 and 119+/-1 mm Hg for the dose of 100 and 200 mg/kg, respectively) compared with the fructose-fed rats. Plasma insulin, cholesterol and triglycerides were higher on the fructose-rich diet compared with the controls. Plasma insulin and cholesterol were lower in the Dorstenia psilurus-treated groups. These results suggest that, Dorstenia psilurus treatment could prevent and reverse high blood pressure induced by a diet rich in fructose probably by improvement of plasma insulin levels. The plant extract might prove useful in the treatment and/or prevention of hypertension.