Effect of Plectranthus glandulosus and Ocimum gratissimum Essential Oils on Growth of Aspergillus flavus and Aflatoxin B1 Production

Essential oils of Ocimum gratissimum and Plectranthus glandulosus leaves were extracted by steam distillation and analysed by GC-MS, and their effects on growth and aflatoxin B1 production by Aspergillus flavus were tested at five levels (i.e 200, 400, 600, 800 and 1000 mg/l) using SMKY agar medium. The main components of O. gratissimum were thymol (47.7%) and -terpinene (14.3%) whereas those of P. glandulosus were represented by -terpinene (30.8%) and terpinolene (25.2%). After 8 days of incubation on essential oil-supplemented medium, growth of A. flavus was totally inhibited by 800 mg/l of O. gratissimum essential oil and by 1000 mg/l of P. glandulosus essential oil. The effect of essential oils on aflatoxin B1 synthesis was evaluated in SMKY broth. The medium supplemented with different essential oil concentrations, was inoculated with A. flavus mycelium and incubated at 25 °C. At 2, 4, 6 and 8 days, aflatoxin B1 concentrations in the supernatant were estimated using Enzyme Linked Immuno-Sorbent Assay (ELISA). Results showed that aflatoxin B1 synthesis was inhibited by 1000 mg/l of both essential oils of O. gratissimum and P. glandulosus after 8 days of incubation. Results obtained in the present study indicate the possibility of exploiting O. gratissimum and P. glandulosus essential oils in the fight against strains of A. flavus responsible for biodeterioration of stored food products

Evaluation of antidiarrhoeal activity of the stem bark of Cylicodiscus gabunensis (mimosaceae)

The ethyl acetate (EA) extract of the stem bark of Cylicodiscus gabunensis (CG) (Mimosaceae) was analysed for its anti-diarrhoeal activity. Like loperamide (3 mg/Kg body weight), a single oral dose of C.gabunensis ethyl acetate extract (CG-EA) (375, 750 mg/Kg body weight) produced a significant decrease in the severity of diarrhoea. To understand the mechanism of its anti-diarrhoeal activity, its effect was further evaluated on intestinal transit, castor oil induced intestinal fluid accumulation(enteropooling) and electrolyte concentration in the small intestinal fluid. CG-EA produced a decrease in intestinal transit (10.26-30.75%), and unlike atropine, it significantly inhibited castor oil induced enteropooling. However, it did not alter the electrolyte concentration in intestinal fluid as compared tocastor oil-treated rat

Occurrence and functioning of phosphate solubilizing microorganisms from oil palm tree (Elaeis guineensis) rhizosphere in Cameroon

Phosphorus replenishment, particularly in smallholder agriculture, remains a challenge as it is mainly fertilizer dependent. While the use of soluble mineral phosphate fertilizers is the obvious best means tocombat phosphate deficiency in Cameroon, their use is limited by their high cost and availability at farmer’s level. This study was aimed at maintaining the fertility of Cameroon soils by biological means,in order to improve agricultural production, using low inputs technology. Isolates were obtained from oil palm tree (Elaeis guineensis) root fragments and rhizospheric soils and their activity in mobilizingphosphate from insoluble sources was evaluated on agar plates and liquid culture media containing sparingly soluble phosphates. At the end of incubation time, it appeared that, phosphate solubilizationresulted from a combined effect of pH decrease of the media and organic acids production. Furthermore, each of the tested isolates was able to produce at least one of the most important organic acids such as citrate, malate and tartrate. Among the ten isolates tested, three were identified as Pseudomonas fluorescens and would be considered as potential biofertilizers

Evaluation of acute and subacute toxicities of aqueous ethanolic extract of leaves of Senna alata (L.) Roxb (Ceasalpiniaceae)

We investigated the acute and subacute toxicities of hydro-ethanolic extract of leaves of Senna alata (L.) Roxb. in Swiss mice and Wistar albino rats. The mice were divided into 6 groups of 10 animals and each group received once by intra gastric gavages 0, 4, 8, 12, 16, 20 times 1000 mg/kg dose of extract. Distilled water served as the control. For the subacute toxicity, three groups of 10 rats (5 males and 5 females) were treated per os with distilled water (control), 500 or 1000 mg/kg of extract every 48 h for 26 days. At the end of treatment blood sample and 20% liver homogenates were collected for biochemical analyses. The results indicated that the medium lethal dose (LD50) was about 18.50 g/kg of body weight. Significant variation (P<0.05) of the body weight was observed after 26 days of treatment, in some biochemicals index of serum and 20% liver homogenates (glutathione , alkaline phosphatase (APL), aspartate aminotransferase (AST)), haematological parameters (platelet) also in the female relative weight of heart of rat. Some of parameter investigated in this study showed dose responsive. The histopatological study of the liver did not show any features after the treatment but, the extract seems to ameliorate the liver architecture.Keywords: Acute toxicity, alkaline phosphatase, hematological and histopatological stud

Variation in nodulation and growth of groundnut (Arachis hypogaea L.) on oxisols from land use systems of the humid forest zone in southern Cameroon

Improving biological nitrogen fixation through legume nodulating bacteria (LNB) inoculation requires knowledge on the abundance and effectiveness of indigenous population in the ferralsols. Nodulation of groundnut was examined under pots experiment in four location sites of the Humid-forest zone: Bertoua in the East; Ebolowa in the South; Bokito and Yaoundé in the Centre Regions of Cameroon and within each of the locations, in four land use systems (LUSs) of different levels of disturbance: mixed farming (1 to 3 years old); fallows (3 to 5 years old); cocoa plantation (> 20 years old); forest (> 30 years old). Results indicate that, soils under investigation are acidic with pH ranging from 3.68 in the Ebolowa forest to 6.92 in mixed farming at Bokito. Groundnut formed nodules in all the four LUSs. Soils from plantations and forests were poorly nodulated, whereas those from mixed farming and fallows were highly nodulated, with a positive and significant correlation (r 0.406; p < 0.0001) observed between nodulation and plant biomass in all the studied sites. These results suggest a high variation in groundnut nodulating bacteria density in soils from diverse LUSs of the humid forest zone of Cameroon; although, there was a site effect.Key words: Acid soil, Arachis hypogaea, biomass, land use systems, multilocal, nodulation

Activit&#233 antifongique des extraits de quelques plantes m&#233dicinales Camerounaises

No Abstract.Nigerian Journal of Natural Products and Medicine Vol. 10 () 2006: pp.94-9

Evaluation of antimicrobial activity of the stem bark of Cylicodiscus gabunensis (mimosaceae)

Ethyl acetate(EA) extract of the stem bark of Cylicodiscus gabunensis (CG) was analysed phytochemically and evaluated for its antimicrobial activity against 17 pathogenic species isolated from patient: Escherichia coli, Klebsiella pneumoniae, Shigella dysenteriae, Shigella flexneri, Morganella morganii, Proteus vulgaris, Proteus mirabilis, Salmonella typhi, Citrobacter freundii, Enterobacter cloacae, Enterobacter agglomerans, Staphylococcus aureus, Streptococcus feacalis, Pseudomonas aeruginosa, Bacillus cereus T, Candida albicans and Candida glabrata. Flavonoids, saponins, tannins, polyphenols, coumarins, triterpenes and/or sterols and reducing sugars were detected in the (EA) extract of CG. The best MIC and MBC values for the microorganisms sensitive to the extract were 0.00078 and 0.00315 mg/ml respectively. The greater and remarkable antimicrobial activity of the (EA) extract of CG was recorded with Staphylococcus aureus, Proteus vulgaris and Bacillus cereus T. These results provide a rationalization for the traditional use of this plant for the treatment of infections diseases. Keywords: Antimicrobial activity; Cylicodiscus gabunensisThe African Journal of Traditional, Complementary and Alternative Medicines Vol. 4 (1) 2007: pp. 87-9

Evaluation of antidiarrhoeal activity of the fruit-rind of Picralima nitida (Apocynaceae)

The methanol (M) extract of the fruit-rind of Picralima nitida (PN) (Apocynaceae) was tested for its anti-diarrhoeal activity. Like loperamide (3 mg/kg body weight), a single oral dose of PN-M (375, 750 mg/kg body weight) produced a significant decrease in the frequency of defecation and severity of diarrhoea. To understand the mechanism of its anti-diarrhoeal activity, its effect was further evaluated on intestinal transit; castor oil-induced intestinal fluid accumulation (enteropooling) and electrolyte concentration in the small intestinal fluid. PN-M produced a decrease in intestinal transit (18.81-21.86%) as compared to castor oil treated animals. Unlike atropine, PN-M significantly inhibited castor oil-induced enteropooling. However it did not alter the electrolyte concentration in intestinal fluid as compared to castor oil treated rats. Keywords: Picralima nitida, antidiarrhoeal activity, castor oil African Journal of Traditional, Complementary and Alternative Medicines Vol. 3(4) 2006: 66-7

Activités antibactérienne et cytotoxique In vitro de différents extraits des écorces du tronc de Diospyros canaliculata (Ebenaceae)

In this study, we have evaluated the antimicrobial and cytotoxic activities of the aqueous, Hexane, ethyl acetate and methanolic extracts of Diospyros canaliculata. The study of the antimicrobial activity has been achieved by the Agar well diffusion method for the determination of the the inhibition zones and the liquide dilution method for the determination of the minimal inhibition concentraion of the different extracts on ten bacterial strains implicated in several human infections. Brine Shrimp lethality bioassay was used in the cytotoxicity investigations. The results showed a weak inhibitory activity of the aqueous extract, on 9 of the 10 microbial strains. Ethyl acetate and methanolic extracts also presented a weak inhibitory effects though active on all the tested bacterial strains. On the other hand a strong antibacterial activity of the hexane extrat was observed on all the tested pathogenic agents. Cytotoxic assay showed that the different extracts were non toxic. The LD50 has been determined only for the ethyl acetate extract. It was of 495.156 μg/ml. The results of this study indicated that this plants could be used in the control of the pathology implicated bacteria.Keywords: Diospyros canaliculata, antibacterial activity, cytotoxicityR ésum é Dans cette tude, nous avons valu les activits antimicrobienne et cytotoxique des extraits l\'eau, l\'hexane, l\'actate d\'thyle et au mthanol de Diospyros canaliculata. L\'tude de l\'activit antimicrobienne a t ralise par les techniques de diffusion par puits sur glose pour la dtermination des diamtres des zones d\'inhibition et de dilution en milieu liquide pour la dtermination des concentrations minimales inhibitrices (CMI) des diffrents extraits sur dix souches bactriennes impliques dans plusieurs infections humaines. La cytotoxicit de ces extraits a quant elle t dtermine sur les crevettes par la technique de dilution l\'eau sale. Les rsultats ont montr une faible activit inhibitrice de l\'extrait aqueux, actif sur 9 des 10 souches microbiennes. Les extraits l\'actate d\'thyle et au mthano ont galement prsent un faible effet inhibiteur bien qu\'actif sur toutes les souches bactriennes testes. Par contre une forte activit de l\'extrait l\'hexane a t observe sur les agents pathognes. Les tudes cytotoxiques ont montres que les diffrents extraits taient non toxiques. La DL 50 n\'a pu tre dtermine que pour l\'extrait l\'acate d\'ethyle. Elle tait de 495,156 μg/ml. Les rsultats obtenus dans cette tude ont montr que cette plante pouvait tre utilise dans le contrle des pathologie lies aux bactries.Mots cls: Diospyros canaliculata, activit antibactrienne, cytotoxicitWest African Journal of Pharmacology and Drug Research Vol. 20(1&2) 2005: 22-2