Emmanuel Talla

Antipyretic and antinociceptive effects of Nauclea latifolia root decoction and possible mechanisms of action.

Context: Nauclea latifolia Smith (Rubiaceae) is a small tree found in tropical areas in Africa. It is used in traditional medicine to treat malaria, epilepsy, anxiety, pain, fever, etc. Objective: The aim of this study was to investigate the effects of Nauclea latifolia roots decoction on the peripheral and central nervous systems and its possible mechanisms of action. Materials and methods: The analgesic investigation was carried out against acetic acid-induced writhing, formalin-induced pain, hot-plate and tail immersion tests. The antipyretic activity was studied in Brewer’s yeast-induced pyrexia in mice. Rota-rod test and bicuculline-induced hyperactivity were used for the assessment of locomotor activity. Results: Nauclea latifolia induced hypothermia and had antipyretic effects in mice. The plant decoction produced significant antinociceptive activity in all analgesia animal models used. The antinociceptive effect exhibited by the decoction in the formalin test was reversed by the systemic administration of naloxone, Nω-l-nitro-arginine methyl ester or glibenclamide. In contrast, theophylline did not reverse this effect. Nauclea latifolia (antinociceptive doses) did not exhibit a significant effect on motor coordination of the mice in Rota-rod performance. Nauclea latifolia protected mice against bicuculline-induced behavioral excitation. Discussion and conclusion: Overall, these results demonstrate that the central and peripheral effects of Nauclea latifolia root decoction might partially or wholly be due to the stimulation of peripheric opioid receptors through the action of the nitric oxide/cyclic monophosphate guanosin/triphosphate adenosine (NO/cGMP/ATP)-sensitive- K+ channel pathway and/or facilitation of the GABAergic transmission.

Evaluation of antinociceptive effects of Crassocephalum bauchiense Hutch (Asteraceae) leaf extract in rodents.

ETHNOPHARMACOLOGICAL RELEVANCE The leaves of Crassocephalum bauchiense have long been used in traditional Cameroonian medicine for the treatment of epilepsy, pain, inflammatory disorders, arthritis and intestinal pain. AIM OF THE STUDY In this study, we attempted to identify the possible antinociceptive action of the aqueous extract and the alkaloid fraction prepared from the leaves of Crassocephalum baucheiense. MATERIALS AND METHODS Using acetic acid induced abdominal constrictions, formalin-, capsaisin- and glutamate-induced nociception, and hot plate assay procedures, the antinociceptive effects of the aqueous extract and the alkaloid fraction was assessed after oral administration in mice. Morphine sulfate was used as reference analgesic agent. Mice were submitted to the rota-rod task and open-field test in order to assess any non-specific muscle-relaxant or sedative effects of the extracts of Crassocephalum bauchiense. Male and female Swiss mice were used to assess acute toxicity of these extracts. RESULTS The aqueous extract and the alkaloid fraction of Crassocephalum bauchiense produced a significant antinociceptive effects in the acetic acid, formalin, glutamate, capsaicin and hot plate tests. These antinociceptive effects of Crassocephalum bauchiense were significantly attenuated by pretreatment with naloxone. The extracts of Crassocephalum bauchiense did not alter the locomotion of animals in the open-field or rotarod tests, which suggest a lack of a central depressant effect. The animals did not exhibit any acute toxicity to the aqueous extract and the alkaloid fraction, so it was not possible to calculate the LD(50). CONCLUSION The results confirm the popular use of Crassocephalum bauchiense as an antinociceptive, and contribute to the pharmacological knowledge of this species because it was shown that the aqueous extract and the alkaloid fraction of Crassocephalum bauchiense produced dose related antinociception in models of chemical and thermal nociception through mechanisms that involve an interaction with opioidergic pathway.

Evaluation of the Sedative and Anticonvulsant Properties of Three Cameroonian Plants

Millettia thonningii, Ocinum sanctum and Securitaca longepedunculaca are used in traditional medicine in Cameroon to treat epilepsy, insomnia and headaches. Animal models of epilepsy (maximal electroshock (MES), n-methyl-d-aspartate (NMDA), pentylenetetrazol (PTZ), isonicotinic hydrazide acid (INH), picrotoxine (PIC) and strychnine (STR)-induced convulsions or turning behavior were used to evaluate anticonvulsant activity while diazepam-induced sleep test was used to evaluate sedative activity of the plants. Four doses of extracts were used for each plant (100, 200, 500 and 1000 mg/kg). At a dose of 1000 mg/kg, Millettia thonningii protected 60 and 90% of mice against MES and PTZ-induced convulsions, respectively. At the same dose, Millettia thonningii also protected 80% of mice against NMDA-induced turning behavior. At a dose of 1000 mg/kg, Ocinum sanctum provided complete protection against MES, PIC and STR- induced convulsions and 83.3% of protection in PTZ test. Securitaca longepedunculata completely protected (100%) mice in PIC test at a dose of 200 mg/kg, in MES test at a dose of 500 mg/kg and in PTZ test at a dose of 1000 mg/kg. 66.7% of mice were protected against STR-induced convulsions. All the three plants showed also sedative properties for they increased significantly and in a dose dependent manner the total sleep time induced by diazepam. The total sleep time of the control groups was multiplied by a factor of 3 at least by each extract. The presence of sedative and anticonvulsant activity in the three plants could explain their use in traditional medicine in the treatment of epilepsy and insomnia in Cameroon.

Hypolipidemic and anti-atherogenic effect of aqueous extract leaves of Ficus glumosa (Moraceae) in rats

Leaves of Ficus glumosa are used in northern Cameroon and southern Chad for the treatment of cardiovascular diseases, as food and as a stimulant for milk production in both women and animals. Atherosclerosis is a disease in which frequency increases with age. The first lesions appear at the young subject during adolescence. Atherosclerosis lesions appear very precociously and worsen with age. They interest the levels chronologically aortic, coronary then carotid. Age is a risk factor in that it reflects the exposure time of individual to the other risk factors. The frequency of the atherosclerosis increases with age because of the aging of the cells. This study was undertaken to evaluate the hypolipidemic and anti-atherosclerotic properties of aqueous extract of the leaves of F. glumosa in rats with hypercholesterolemia (HC). 60 male rats were fed for 4 weeks with a high-cholesterol diet (1%) and 3 doses (225, 300 and 375 mg/kg) of extract of F. glumosa were used in these experiments. The experiments were conducted under the same conditions with atorvastatin (1 mg/kg), as pharmacological reference substance. The effects of F. glumosa on weight gain, water and food consumption, levels of serum lipids and lipoprotein lipid oxidation and stress markers in the blood and liver were examined. The administration of F. glumosa extract prevented significant (P<0.05) elevation in TC, LDL-c, VLDL-c, hepatic and aortic TG and TC. The atherogenic, triglyceride, and lipid peroxidation (TBARS) indexes were also decreased in the rats treated with the extract. F. glumosa favored the performance of fecal cholesterol. It also significantly inhibited the changes and the formation of aortic atherosclerotic plaques. These results revealed the hypolipidemic and antiatherosclerotic effects of F. glumosa extract and support the traditional use of the extract of this plant in the treatment of hypertension and diabetes.

New mono-ether of glycerol and triterpenes with DPPH radical scavenging activity from Cameroonian propolis

Abstract The extracts of some propolis samples were analysed by GC-MS and then purified by column chromatography. The latter led to the isolation of a new mono-ether of glycerol, 1′-O-eicosanyl glycerol and a new triterpene, methyl-3β,27-dihydroxycycloart-24-en-26-oate together with known triterpenoids namely betulin, 3β-hydroxylanostan-9,24-dien-21-oic acid, mangiferonic acid, a mixture of ambolic acid and β-sitosterol, 3β-hydroxycycloartan-12,24(25)-diene and 27-hydroxymangiferonic acid. The DPPH radical scavenging potential of some extracts and compounds were measured. The radical scavenging activity varied from Hexane extract of Foumban propolis (IC50 = 5.6 mg/mL) to Methanol extract of Foumban propolis (IC50 = 1.07 mg/mL) for the extracts and from 3β-hydroxylanostan-9,24-dien-21-oic acid (IC50 = 1.22 mg/mL) to 1′-O-eicosanyl glycerol (IC50 = 0.93 mg/mL) for the compounds. Activities of samples were moderate as they remained closer to those of the standard antioxidants Gallic acid (IC50 = 0.30 mg/mL) and vitamin C (IC50 = 0.80 mg/mL), especially 1′-O-eicosanyl glycerol, the most active compound.

Diuretic Activity of the Aqueous Extract Leaves of Ficus glumosa Del. (Moraceae) in Rats

Experiments were carried out to validate the use of F. glumosa extract as a diuretic in the treatment of hypertension as claimed by traditional healers. The experiments were performed under the same conditions with two synthetic pharmacological diuretics considered as check (Furosemide and Amiloride hydrochlorothiazide). The aqueous extract leaves of F. glumosa accelerated the elimination of overloaded fluid. At the maximum of diuretic response, urinary osmolarity decreased significantly when compared with controls. The single dose treatment of the aqueous extract leaves of F. glumosa has significantly increased urine volume 24 h after administration of the extract. The stability of aldosterone level, the absence of correlation with the plasma levels of sodium, and the increased clearance of free water in the animals receiving the extract show that increased diuresis and natriuresis moderate elevation are tubular in origin. The increase in Na+, K+, and Cl− induced by the extract caused alkalinization of the urine and showed a strong inhibitory effect of carbonic anhydrase and saluretic. These effects were mainly observed at the dose of 375 mg/kg. These observations confirm the traditional use in the treatment of hypertension and support the importance of the conservation of local knowledge as well as the conservation of Cameroonian biodiversity.

Nitric oxide-dependent vasodilation and Ca2+signalling induced by erythrodiol in rat aorta

Abstract Objective To evaluate the pharmacological property of erythrodiol, a natural triterpenoid contained in propolis, as vasodilatory agent, and to determine its mechanism of action. Methods Rats aortic rings were isolated and suspended in organ baths, and the effects of erythrodiol were studied by means of isometric tension recording experiments. Nitric oxide (NO) was detected by ozone-induced chemiluminescence. The technique used to evaluate changes in intracellular Ca 2+ concentration in intact endothelium was opened aortic ring and loaded with 16 μmol Fura-2/AM for 60 min at room temperature, washed and fixed by small pins with the luminal face up. In situ , ECs were visualized by an upright epifluorescence Axiolab microscope (Carl Zeiss, Oberkochen, Germany) equipped with a Zeiss×63 Achroplan objective (water immersion, 2.0 mm working distance, 0.9 numerical apertures). ECs were excited alternately at 340 and 380 nm, and the emitted light was detected at 510 nm. Results In aortic rings with intact endothelium pre-contracted with norepinephrine (10 −4 mol/L), the addition of erythrodiol (10 −8 −10 −4 mol/L) induced vasorelaxation in a concentration-dependent manner; in endothelium-denuded rings, the relaxant response induced by erythrodiol was almost completely abolished suggesting that vasorelaxation was endothelium-dependent. They had almost no relaxant effect on depolarised or endothelium-denuded aortic segments. The relaxation was significantly attenuated by pre-treatment with the NO synthase inhibitor Nv-nitro-L-arginine-methylester. Erythrodiol (10 −4 mol/L) was able to significantly increase NOx levels. This effect was completely abolished after removal of the vascular endothelium. Erythrodiol (100 μmol/L) caused a slow, long-lasting increase in intracellular Ca 2+ concentration. These results further supported the hypothesis that erythrodiol can induce activation of the NO/soluble guanylate cyclase/cyclic guanosine monophosphate pathway, as suggested by functional studies. Conclusions The present results suggest that the mechanism of relaxation seems to be mainly mediated by the endothelial production of NO. Such a vasorelaxation was an endothelium-dependent effect, via the NO/soluble guanylate cyclase/cyclic guanosine monophosphate pathway. This result also suggests that erythrodiol causes a slow influx of extracellular Ca 2+ release from the intracellular Ca 2+ stores and an inhibition of Ca 2+ extruding mechanism. It can be concluded that erythrodiol may have interesting therapeutic potential as a new vasodilator drug, for protecting the cardiovascular system.

Vitellaroside, A New Cerebroside from Vitellaria paradoxa (Sapotaceae) and its Bioactivities

A new cerebroside (2R)-2-hydroxy-N-[(Z,2S,3S,4R)-1-O-β-D-glucopyranosyl-3,4-dihydroxynonadec-8-en-2-yl] nonacosanamide (1) was isolated from the wood of roots of V. paradoxa along with six known compounds including catechin (2), quercetin (3), spinasterol 3-O-β-D -glucopyranoside (6), gallic acid (7) and a mixture of β-sitosterol (4) and stigmasterol (5). The structure of the new compound was established by 1D (1H and 13C NMR) and 2D NMR (COSY and HSQC) spectroscopy, extensive mass spectrometry and by comparison with published data. The antibacterial, α-glucosidase and alkaline phosphatase (AP) inhibitory activities of all the pure compounds were evaluated. The antibacterial activities were evaluated against three gram negative bacteria (Escherichia coli; Salmonella typhimurium and Pseudomonas aeruginosa) while APs inhibitory activities were evaluated on h-TNAP and h-IAP. Significant antibacterial activity was recorded for quercetin (3) against P. aeruginosa. Most of the compounds except 1 and 6 were found to be inhibitors of α-glucosidase. The highest inhibitory potential being recorded for quercetin (3) with IC50 value of 4.30 ± 0.01 μM, 55 fold higher than the standard drug acarbose (IC50=234.6 ± 2.01 μM). All tested compounds exhibited moderate inhibitory activities against APs. h-TNAP inhibitory values were ranged between 41.24 ± 1.33 μM and 312.54 ± 6.44 μM while h-IAP inhibitory values were in the range of 47.95 ± 0.35 μM and 777.47 ± 18.55 μM. Quercetin (3) was found to be the most active h-IAP inhibitor (IC50=47.95 ± 0.35 mM), whereas, spinasterol 3-O-β-D-glucopyranoside (6) was found to be the most active h-TNAP inhibitor (IC50=41.24 ± 1.33 mM). The new compound (1) showed moderate inhibition on h-IAP (78.11 ± 3.70 μM) and on h-TNAP (88.84 ± 2.70 μM).

Lipids constituents from Gardenia aqualla Stapf & Hutch

Abstract Gardenia aqualla a plant of the Rubiaceae family is being used extensively in Africa, particularly in Cameroon as an herbal medicine. Therefore it is necessary to have knowledge of the constituents of the plant of our native species. Thus, the aim of the present study was to investigate chemical constituents of this herbal medicine. Nine compounds, including one alkane, n-Nonacosane (1), two aliphatic alcohols n-heptatriacontanol (2) and n-Docosanol(3), one fatty ester, Heptadecyl heptacosanoate (4), two sugars, D-mannitol (5) and D-mannitol acetate (6), and a mixture of three phytosterols, β-sitosterol (7), stigmasterol (8) and fucosterol (9), have been isolated and purified from the stem barks of Gardenia aqualla Stapf & Hutch. Their structures were elucidated using spectroscopic analyses, including 1D and 2D NMR and ESI-MS. The fatty acid ester, heptadecyl heptacosanoate (4) is reported here for the first time. All the isolated compounds were tested for their antimicrobial activities against four Gram negative bacteria (Salmonella Typhimurium ATCC6539, Pseudomonas aeruginosa ATCC9721, Escherichia coli, and S. Typhi) and four yeasts (Candida albicans ATCC9002, Candida parapsilosis ATCC22019, Candida krusei and C. albicans).

DPPH antiradical scavenging, anthelmintic and phytochemical studies of Cissus poulnea rhizomes

Objective: To investigate the phytochemical constituents, antioxidant and anthelmintic activities of the crude methanol extract of Cissus populnea (C. populnea) rhizomes. Methods: Phytochemical screening was performed using standard protocols, and column chromatography of silica gel was used for the compounds isolation. DPPH antiradical scavenging assay was performed in order to evaluate the antioxidant activity. Total phenolic content was evaluated using the Folin–Ciocalteu assay. The anthelmintic activity was screened on the bovine adult male forms of parasitic nematode Onchocerca ochengi, by the in vitro evaluation of the inhibition of adult worm motility and mortality. Worms were incubated in the presence of different concentrations of the plant extract and effects on survival were monitored after 24 and 48 h. Results: The preliminary phytochemical screening revealed the presence of phenolic compounds, saponins, steroids, tannins, and terpenoids. Bergenin and a mixture of phytosterol, β -sitosterol and stigmasterol were isolated from this extract and were identified by nuclear magnetic resonance, mass spectrometry and by comparison with published data. The crude methanol extract of C. populnea rhizomes showed a strong DPPH antiradical activity with a good amount of total phenolic content ((20.69±2.13) g gallic acid equivalent/100 g of extract) and significant anthelmintic activity comparable to the standard drug ivermectin. Bergenin was found to be inactive even after 72 h of incubation. Conclusions: This study constitutes the first report on the anthelmintic activity of this plant and supports the traditional use of C. populnea as a natural antioxidant and anthelmintic.