Papers by Maximilienne Nyegue
This work assessed the combined effect of Drypetes gossweileri essential oil (EO) and three organ... more This work assessed the combined effect of Drypetes gossweileri essential oil (EO) and three organic acids (Na+ benzoate, Na+ lactate and Sorbic acid) on the inhibition of germination and growth of Bacillus spores. The test consisted of inoculating activated spores of each Bacillus species in 4 ml of nutrient broth under the combined effect of D. gossweileri EO (0.62, 5.31 and 10 µg/ml), each organic acid (0.01, 0.05 and 0.1 %) at different pH levels (4.5, 5.75 and 7.0) taken as independent variable. After incubating for 48 hours, the inhibition percentages of spores germination were used to generate the polynomial model: Y (%) = β0 - β1 X1 + β2 X2 + β3 X3 + β1,1 X12 + β1,2 X1X2 + β1,3 X1X3 + β2,2 X22 + β2,3 X2X3 + β2,3 X32 . The ANOVA test was used to determine how significant (p ˂ 0.05) of each factor, their interactions and the validity of the final models. The results showed that the determination coefficient (R2) and the adjusted coefficients (R2adj) were generally close. For ea...
We describe here three urea-based soluble epoxide hydrolase (sEH) inhibitors from the root of the... more We describe here three urea-based soluble epoxide hydrolase (sEH) inhibitors from the root of the plant Pentadiplandra brazzeana. The concentration of these ureas in the root was quantified by LC-MS/MS, showing that 1, 3-bis (4-methoxybenzyl) urea (MMU) is the most abundant (42.3 μg/g dry root weight). All of the ureas were chemically synthesized, and their inhibitory activity toward recombinant human and recombinant rat sEH was measured. The most potent compound,MMU, showed an IC50 of 92 nM via fluorescent assay and a Ki of 54 nM via radioactivity-based assay on human sEH.MMU effectively reduced inflamma-tory pain in a rat nociceptive pain assay. These compounds are among the most potent sEH inhibitors derived from natural sources. Moreover, inhibition of sEH by these compounds may mechanistically explain some of the therapeutic effects of P. brazzeana.
Thymus vulgaris, Cinnamomum zeylanicum and Ocimum gratissimum are spices widely used as aroma enh... more Thymus vulgaris, Cinnamomum zeylanicum and Ocimum gratissimum are spices widely used as aroma enhancers and food preservatives. This work assessed the chemical composition, antioxidant and antimicrobial effect of their essential oils on some food pathogenic bacteria, namely, Staphylococcus aureus, Citrobacter freundii, Enterobacter cloacae, Morganella morganii, Escherichia coli, Salmonella typhimurium, Proteus vulgaris and Shigella flexineri. After chemical analyses of the essential oils by gas chromatography and gas chromatography coupled to mass spectroscopy, the antimicrobial effects were subsequently assessed by disk and microdilution methods, while the antioxidant evaluations were performed by free radical scavenging activity. T. vulgaris essential oil composed of p-cymene (45.90%) and thymol (23.72%) which exhibited the highest inhibitory diameters of 20.33±0.58 and 18.00±1 mm, respectively, on the growth of S. aureus and C. freundii. O. gratissimum essential oil with thymol a...
International Journal of Pharmacy and Pharmaceutical Sciences, 2020
Objective: This study aims to evaluate the in vitro antioxidant, anti-inflammatory activities of ... more Objective: This study aims to evaluate the in vitro antioxidant, anti-inflammatory activities of the aqueous and hydroethanolic extracts recipe of Alchornea cordifolia and Antrocaryon klaineanum. A preliminary phytochemical screening was carried out. Methods: The total phenols content was determined by the Folin Ciocalteu reagent method, while the antioxidant activity of both extracts was characterized by the 2-2diphenyl-1-picrilhidrazil (DPPH) and β-carotene assays. The anti-inflammatory activity of the extracts was evaluated as the inhibition of Bovine Serum Albumin (BSA) denaturation and antiproteinase activity. Results: The aqueous extracts of Alchornea cordifolia and Antrocaryon klaineanum contained more polyphenols [270 mg Ascorbic acid equivalent (AAE)/g dry weight (dw)] than the hydroethanolic recipe extract (262.41 mg AAE/g dw) at the same concentration level. On the other hand, the aqueous and hydroethanolic recipe extract had the same radical scavenging activity with the ...
Journal of Advances in Microbiology
Aims: The general objective of this work was to highlight the physiopathological and sociological... more Aims: The general objective of this work was to highlight the physiopathological and sociological factors linked to uro-genital infections with Mycoplasma hominis (Mh) and Ureaplasma urealyticum (Uu), in patients who come to the consultation at the Military Hospital Region N ° 1 in Yaoundé. Place and Duration of Study: The research was carried out at at the Military Hospital Region N°1 in Yaoundé between 2017 and 2019 Methodology: Patients whose mycoplasma examination was done, were included in the retrospective study (2017 and 2018) and patients obtained in 3 months (January to march 2019) during the prospective study were also included. Parameters of patients were collected. These parameters were analyzed using SPSS 23 software and graphs were plotted using GraphPad Prism 7 software. Results: From the 231 patients included, 152 (65.80%) were infected with MUG. The pathophysiological factors associated with Mh and Uu infections are young people aged 25 to 31 (39.47%), women (98.68 ...
The aim of this work was to determine the chemical profile and assess in vitro the antibacterial ... more The aim of this work was to determine the chemical profile and assess in vitro the antibacterial activity of the leaves, resin and stem-barks of Dacryodes edulis. The essential oils were analyzed simultaneously by Gas Chromatography and Gas Chromatography coupled to Mass Spectrometry. Agar diffusion well and microdilution methods were used to assay the antibacterial activity. The resin essential oil contained p-cymene (30.32%), αthujene (28.58%), α-phellandrene (27.14%) and β-phellandrene (10.16%) as the main components; the stembarks essential oil had as abundant components p-cymene (35.14%), trans-carveol (22.60%), α-thujene (14.86%), β-phellandrene (8.65%) and β-elemene (5.22%). The leaves essential oil was distinct with elemol (29.22%), caryophyllene oxide (15.26%), trans-carveol (11.80%) and spathulenol (6.28%) as major components. The leaves essential oil was the most active with MIC and MBC value of 18.75 mg/mL on B. cereus; the most susceptible strain. The stem-barks essenti...
A chemical study of the volatile components obtained by applying the hydrodistillation and reflux... more A chemical study of the volatile components obtained by applying the hydrodistillation and reflux processes to <i>Pentadiplandra brazzeana</i> roots was performed by GC-FID and GC-MS. The hydrodistillation process showed a total yield of 0.97% with 0.11% of essential oil and 0.86% of volatile compounds from the aqueous reaction medium; in the reflux process, the volatile extract yield was 1.03%. Benzylic-type isothiocyanates were the major degradation products of glucosinolates in the essential oil (95.0%); the CH<sub>2</sub>Cl<sub>2</sub> extracts obtained from the aqueous solutions were characterised by alcohols and amines in both processes. This study has shown that during hydrodistillation, only 10% of the glucosinolate degradation products are recovered in the essential oil whereas 90% remain in the aqueous medium, being converted into alcohols and amines. The relative percentages of the different chemical classes recovered in our experimenta...
African Journal of Traditional, Complementary and Alternative Medicines, 2015
Background: Many fungal infections are responsible for human skin damages, to control their negat... more Background: Many fungal infections are responsible for human skin damages, to control their negative action, some aromatic and medicinal plants are traditionally used by local population in Cameroon. The present study was carried out to determine the chemical composition of essential oils of Eugenia caryophylla and Mentha sp cf piperita and their antifungal activity on some human pathogenic fungi. Materials and methods: Essential oils from Eugenia caryophylla and Mentha sp cf piperita were extracted by steam distillation using Clevenger apparatus and the antifungal activity was evaluated on six human pathogenic fungal strains; two yeasts (Candida albicans 1 and Candida albicans 2) and four dermatophytes (Tricophyton rubrum 1, T. rubrum 2, T. violaceum, and T. soudanensis) using modified broth microdilution method M27-A3 and M38-A respectively. Results: The essential oils obtained yielded of 5.9 for Eugenia caryophylla and 0.2% Mentha sp cf piperita respectively. The chemical composi...
The purpose of this study was to evaluate the in-vitro antibacterial activity of hydro-ethanol ex... more The purpose of this study was to evaluate the in-vitro antibacterial activity of hydro-ethanol extracts of stems, barks and leaves of Annona muricata against Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabillis and Bacillus cereus, followed by the evaluation of their antioxidant activities. The sensitivity of the bacteria to extracts was evaluated by the well diffusion method and the inhibition parameters of the bacterial growth were determined by the micro-dilution assay. The Minimum Bactericidal concentrations (MBC) obtained were between 6.25 and 25.00 mg/ml. Pseudomonas aeruginosa was the most sensitive strain with a MBC value of 6.25 mg/ml obtained from leaves extract. The antioxidant activity was evaluated using1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and ferric reducing antioxidant power (FRAP) assay. Hydro-ethanol extract of barks exhibited the highest DPPH scavenging activity of 0.010 ± 0.004 g/mg and the highest reducing power with asco...
The aim of this work was to determine the chemical profile and assess in vitro the antibacterial ... more The aim of this work was to determine the chemical profile and assess in vitro the antibacterial activity of the leaves, resin and stem-barks of Dacryodes edulis. The essential oils were analyzed simultaneously by Gas Chromatography and Gas Chromatography coupled to Mass Spectrometry. Agar diffusion well and microdilution methods were used to assay the antibacterial activity. The resin essential oil contained p-cymene (30.32%), αthujene (28.58%), α-phellandrene (27.14%) and β-phellandrene (10.16%) as the main components; the stembarks essential oil had as abundant components p-cymene (35.14%), trans-carveol (22.60%), α-thujene (14.86%), β-phellandrene (8.65%) and β-elemene (5.22%). The leaves essential oil was distinct with elemol (29.22%), caryophyllene oxide (15.26%), trans-carveol (11.80%) and spathulenol (6.28%) as major components. The leaves essential oil was the most active with MIC and MBC value of 18.75 mg/mL on B. cereus; the most susceptible strain. The stem-barks essenti...
International journal of innovation and scientific research, 2014
This work has been led in view to find the influence of sublethal heat (45°C, 50°C, 60°C) on acid... more This work has been led in view to find the influence of sublethal heat (45°C, 50°C, 60°C) on acid resistance of B. subtilis NCTC 3610 and B. stearothermophilus CNCH 5781 spores. Firstly, we have submitted Bacillus spores to 0.4% acetic acid pH 4.5 during the times of 1, 2 and 3 hours. Then another spores group were preheated at various sublethal temperatures, before be treated with acetic acid. The effect of acetic acid before and after preheat was evaluated by the culture of treated spores on agar medium and the number of colony obtained was compared with that of control culture (neither treated with heat nor acid) and control A culture (only treated with acid). We found that acetic acid was effective on the twice Bacillus spores with more effect on B. stearothermophilus CNCH 5781 spores. Furthermore we have noticed a significant increasing in percentages of recovery of colonies obtained from preheated and acid treated spores compared to those of control and control A cultures. Thi...
African Journal of Pharmacy and Pharmacology, 2015
African Journal of Biotechnology, 2016
The Open Entomology Journal, 2013
Larvicidal and repellent effect of the essential oil from the seeds and leaves of Chenopodium amb... more Larvicidal and repellent effect of the essential oil from the seeds and leaves of Chenopodium ambrosioides Linn were evaluated against the larvae and adults of Anopheles gambiae s.s. mosquitoes at concentrations of 0, 50, 75, 100, 200, 300 and 400 ppm. Total mortality of larvae occurred at 200ppm and 300ppm for the essential oils from seeds and leaves respectively. Alpha-terpinene (73.55% for the seeds; 40.69% for the leaves) and para-cymene (20.05% for the seeds; 45.44% for the leaves) are the principal constituents. There was a 100% repellent effect on adult mosquitoes at 200ppm, with protection time of at least four hours for both seed and leaf essential oils. The findings indicated that C. ambrosioides Linn possess mosquito larvicidal and repellent potentials that might be further exploited in combating malaria through anti-vector intervention.
Essential oils obtained by hydrodistillation of seeds, pericarps, leaves and rhizomes of Aframomu... more Essential oils obtained by hydrodistillation of seeds, pericarps, leaves and rhizomes of Aframomum dalzielii, A. letestuianum and A. pruinosum grown in Cameroon were analyzed by GC-FID and GC-MS. The seed oils of the three species were characterized by a high content of (E)-(R)-nerolidol (>88.0 %), which was fully characterized by NMR spectroscopy and chiral GC analysis. The main constituents of the pericarp and rhizome oils were monoterpene hydrocarbons, mainly -pinene (0.8%-22.9%) and sabinene (29.0%-42.3%), along with 1,8-cineole (4.5%-23.7%); leaf oils were characterized by sesquiterpenes, namely (E)-β-caryophyllene (18.4%-82.4%) and caryophyllene oxide (4.5%-23.7%). The antibacterial activities of these essential oils and of nine pure compounds (sabinene, -pinene, 1,8-cineole, linalool, racemic (E)-nerolidol, (E)-(R)-nerolidol, (E)-β-caryophyllene, α-humulene and caryophyllene oxide) were assessed against Micrococcus luteus and Escherichia coli. The strongest activities were observed against E. coli. The seed essential oils and their major component, (E)-(R)-nerolidol, exhibited the lowest MIC values (0.19-0.39 µL/mL), justifying their traditional use and their potential application as natural food preservatives.
Evidence-Based Complementary and Alternative Medicine
This study evaluated the antibacterial efficacy of methanolic extracts of isolated endophytic fun... more This study evaluated the antibacterial efficacy of methanolic extracts of isolated endophytic fungi from stem barks and leaves of Alstonia boonei De Wild and Greenwayodendron suaveolens (Engl. and Diels) Verdc. subsp. Suaveolens against Klebsiella pneumoniae ATCC 43816, Haemophilus influenzae ATCC 49247, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 35218, responsible for causing pneumonia. The endophytic fungi were isolated and characterized in the Potato Dextrose Agar (PDA), Sabouraud Dextrose Agar (SDA), and Czapek Dox Agar (CDA) media. The fungi and their methanolic extracts were tested for in vitro antibacterial potential by antagonistic assay for endophytic fungi against bacterial pathogens and microdilution method. The phytochemical screening of extracts was carried out according to the colorimetric and precipitation methods to reveal the presence of secondary metabolites. The results showed that 24 macroscopically and microscopically distinct endophytic fungi ...
Journal of Drug Delivery and Therapeutics
Background: Dissotis multiflora (Sm) Triana and Paullinia pinnata Linn are widely used in Cameroo... more Background: Dissotis multiflora (Sm) Triana and Paullinia pinnata Linn are widely used in Cameroonian traditional medicine to treat infectious diseases. These plants were found to be a reservoir of antioxidant and antimicrobial agents and have the potential to be used in clinic. Objective: To determine the mechanism of action of the ethanolic leaves extracts of Dissotis multiflora and Paullinia pinnata on Escherichia coli. Methodology: The microbroth dilution method was used to determine the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of D. multiflora and P. pinnata ethanolic leaves extracts. The above samples were tested for their rate of killing of E. coli cells at 1 MIC and 2 MICs. Sorbitol protection, outer membrane permeability, loss of 260-nm-absorbing material, fluorescence microscopy, and DNA degradation assay were used to examine the ultrastructural changes in bacteria induced by the extracts. Results: D. multiflora and P. pin...
Journal of Advances in Microbiology
Aims: The present study was carried out to determine the diversity of endophytic fungi that colon... more Aims: The present study was carried out to determine the diversity of endophytic fungi that colonize the leaves of Psidium guajava, and to evaluate their antagonistic activity against Fusarium oxysporum f.sp. cubense and Mycosphaerella fijiensis which are the two main phytopathogens of banana plants. Place and Duration of Study: The research was carried out at Microbiology Laboratory, Faculty of Sciences, University of Yaoundé I and Microbiology Laboratory, Faculty of Biotechnologies, University of Agronomic Sciences and Veterinary Medicine Bucharest, between April 2018 and February 2020. Methodology: Fragments of surface sterilized leaves of Psidium guajava were inoculated on Potato Dextrose Agar supplemented with chloramphenicol. The isolated and purified endophytic fungi were identified based on their macroscopic and microscopic characters using a mycological atlas as guide. The non-sporulating isolates were identified by comparing the ITS regions of their DNA to those of known f...
Journal of Food Processing and Preservation
Microbiology Research Journal International
Aims: The aim of this study was to propose a model describing the relationship between the antimi... more Aims: The aim of this study was to propose a model describing the relationship between the antimicrobial concentration and the inhibition zone diameter during antimicrobial susceptibility testing.
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Papers by Maximilienne Nyegue