Biology subjects

Joseph Arsene, M. M.

Publications and source records attributed to Joseph Arsene, M. M..

3 recordsLinked to original sources

bioRxiv2021

Screening of antimicrobial activity of aqueous and ethanolic extracts of some medicinal plants from Cameroon and assessment of their synergy with common antibiotics against multidrug-resistant uropathogenic bacteria.

Background and aimThe Cameroonian flora abounds in plants with multidimensional therapeutic virtues which can play an important role in the fight against resistance to antibiotics and the search for new antimicrobials. This study aimed to screen the antimicrobial potential of aqueous and ethanolic extracts of thirteen (13) samples (Bark, leaf, seed) of eight (8) plants from Cameroon against 3 reference pathogens and to evaluate their synergy with conventional antibiotics against eleven (11) multiresistant uropathogenic (MRU) bacteria. MethodBioactive compounds were extracted from leaves of Leucanthemum vulgare, Cymbopogon citratus (DC.) Stapf, Moringa oleifera Lam and Vernonia amygdalina Delile; barks of Cinchona officinalis and Enantia chlorantha Oliv; barks and seeds of Garcinia lucida Vesque and leaves and seeds of Azadirachta indica (Neem) using distilled water and ethanol as solvents. The extracts were tested against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538 and Candida albicans 10231 using the well diffusion method and the microdilution method. The synergistic effect was assessed (using disc diffusion method and the checkerboard method) against MRU bacteria namely Achromobacter xylosoxidans 4892, Citrobacter freundii 426, Enterococcus avium 1669, Escherichia coli 1449, Klebsiella oxytoca 3003, Kocuria rizophilia. 1542, Moraxella catarrhalis 4222, Morganella morganii 1543, Pseudomonas aeruginosa 3057, Staphylococcus aureus 1449 and Streptococcus agalactiae 3984. ResultsWe found that distilled water extracted a more important mass of phytochemical compounds (7.9-21.2%) compared to ethanol (5.8-12.4%). Except C. officinalis and G. lucida leaves, the rest of extracts were active with inhibition diameters (ID) ranging from 5 to 36 mm. Both ethanolic (EE) and aqueous extract (AE) of E. chloranta bark (ECB) were the most active against all pathogens with the mean ID of 17 and 36 mm vs S. aureus ATCC 6538, 23 and 14 mm vs E. coli ATCC 25922 and 36 and 19 mm vs C. albicans ATCC 10231. Only the EE of E. chloranta bark (ECB) had a strong activity against all the microorganisms tested (MIC <2 mg / ml); L. vulgare leaves (LVL) and G. lucida seed (GLS) had moderate (average MIC of 8 mg/ml) while all other extracts showed very weak antimicrobial activity. In addition, the fractional inhibitory concentration (FIC) ranged from 0.125 to 0.750. No antagonism (FIC> 4) or indifference (1[≤] FIC[≤]4) was noted between the extracts and the antibiotics, but the best synergies were found with ECB which well-modulated Kanamycin (FIC = 0.125 against S. aureus and 0.250 against E. coli), nitrofurantoin (FIC = 0.250 against S. aureus and 0.188 against E. coli) and ampicillin (FIC = 0.125 against E. coli). Similarly, compared to other extracts, ECB, LVL and GLS also well-modulated ampicillin, ceftazidime, tetracycline, nitrofurantoin, and trimethoprim against all the above-mentioned resistant uropathogenic bacteria with important increase in fold area (IFA). ConclusionThis study show that E. chlorantha bark, L. vulgare leaves G. lucida seed, have good antimicrobial activity against both bacteria (Gram positive and Gram negative) and fungi (C. albicans); and should be more investigated for their possible use to the fight against MDR and MRU microorganisms.

microbiology↗

bioRxiv2021

Assessment of antimicrobial activity of ethanolic and aqueous extracts of Aesculus hippocastanum L. (horse chestnut) bark against bacteria isolated from urine of patients diagnosed positive to urinary tract infections.

The search for new antimicrobials is essential to address the worldwide issue of antibiotic resistance which affects all areas requiring the use of antibiotics including the management of diseases such as urinary tract infections (UTIs). AimTo assess the antimicrobial activity of ethanolic and aqueous extract of Aesculus hippocastanum L. (horse chestnut) bark. Material and MethodBioactive compounds were extracted from A. hippocastanum bark using water and ethanol as solvent. The extracts were tested against 10 clinical strains isolated from urine of patients diagnosed positive to urinary tract infections and including five Gram-positive bacteria (Kocuria rhizophila 1542, Enterococcus avium 1669, Staphylococcus simulans 5882, Conybacterium spp 1638, Enterococcus faecalis 5960) and five Gram-negative (Proteus mirabilis 1543, Morganella morganii 543, Citrobacter freundi 426, Acynetobacter baumannii 5841 and Achromobacter xylosoxidans 4892). Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 25922 were used as standard Gram+ and Gram-respectively. The susceptibility of the test strains to antibiotic was assessed using the Kirby Bauer disc diffusion method while the antibacterial activity of the extracts was evaluated using the well diffusion method. We finally determined the Minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) by the microdilution method. ResultsA. hippocastanum bark possessed a dry matter content of 65.73%. The volume yield of the ethanolic and aqueous extract (AE) was 77,77% and 74,07% (v/v), respectively, whereas their mass yields were 13,4% and 24,3% (w/w), respectively. All the bacteria were susceptible to amoxiclav, imipenem and ceftriaxone, both standard bacteria (E. coli ATCC 25922 and S. aureus ATCC 6538) were sensitive to all antibiotics while the clinical strains were resistant to at least one antibiotic. K. rizophilia 1542 and Conybacterium spp 1638 were the most resistant bacteria both with multidrug resistance index of 0.45. Except AE on P. Mirabilis 1543 and E. faecalis 5960 (0 mm), both AE and EE were active against all the microorganisms tested with inhibition diameters (mm) which ranged from 5.5-10.0 for AE and 8.0-14.5 for EE. The MICs of EEs varied from 1-4 mg/ml while those of EAs varied from 4-16 mg/ml. Almost all the MBCs of AEs were indeterminate (>64 mg/ml) while those of EE were successfully determined. The ethanolic extracts (EE) were overall more active than the aqueous ones. ConclusionThe A. hippocastanum bark extracts had overall weak antibacterial activity (MIC [≥]0.625 mg/ml) and bacteriostatic potential (MBC/MIC [≥]16) on both Gram-positive and Gram-negative bacteria. Therefore, studies with other solvents (such as methanol and chloroform), other extraction techniques, and synergy tests with conventional antibiotics are needed to conclude on a potential better antimicrobial activity of this plant material.

microbiology↗

bioRxiv2021

Galleria mellonella as a novel eco-friendly in vivo approach for the assessment of the toxicity of medicinal plants

The evaluation of medicinal plants toxicity is a prerequisite prior their usage. The vertebrate models used for this purpose are often the object of ethical consideration. Though invertebrate models including Galleria mellonella have shown their ability to be used to assess various products toxicity, to our knowledge, G. mellonella has never been exploited to determine the toxicity of medicinal plants. In this study, the toxicity of hydroalcoholic and aqueous extracts of seven (7) Cameroonian medicinal plants namely leaves of Cymbopogon citratus (DC.) Stapf, Moringa oleifera Lam and Vernonia amygdalina Delile; barks of Cinchona officinalis and Enantia chloranta Oliv; barks and seeds of Garcinia lucida Vesque and leaves and seeds of Azadirachta indica (Neem) were evaluated using the larval form of the Greater Wax Moth (Galleria mellonella). The median lethal doses (LD50), 90% lethal doses (LD90) and 100% lethal doses were successfully determined using the spline cubic survival curves and equations from the data obtained on the survival rate of G. mellonella 24h after the injection with the extracts. The LD50 values varied from 3.90 g/kg bw to >166.67 g/kg bw and the pattern of toxicity observed was in accordance with previous investigations on the plant materials concerned. The results obtained in this study suggest that G. mellonella can be used as a sensitive, reliable, and robust eco-friendly model to gauge the toxicity of medicinal plants. Thus, avoid the sacrifice of vertebrate models often used for this purpose to limit ethical concerns.

pharmacology and toxicology↗