Biology subjects

Hzounda Fokou, J. B.

Publications and source records attributed to Hzounda Fokou, J. B..

3 recordsLinked to original sources

bioRxiv2026

Larvicidal Potential of Cola nitida Endophytic Bacteria Against Insecticide-Resistant Anopheles gambiae

BackgroundInnovative vector control strategies are urgently needed to combat malaria transmission by Anopheles gambiae, given the limitations of current insecticides--namely resistance, human toxicity, environmental damage, and high costs. This study evaluated the larvicidal efficacy of endophytic bacteria isolated from Cola nitida against third-instar larvae of Anopheles gambiae. MethodsEndophytic bacteria were isolated from nine Cola nitida plant parts (leaves, roots, stems, fruits, flowers, stem bark, branches, root bark, whole plant extracts) using standard surface sterilization and culturing protocols. Thirty-two morphologically distinct strains were purified and screened for larvicidal activity against third-instar An. gambiae larvae using the WHO-recommended turbidity method at McFarland 4 standard. Six active isolates underwent dose-response testing (McFarland 0.5-4) with mortality recorded at 24 and 48 hours. Environmental safety was assessed via Lemna minor growth inhibition, and molecular identification employed the API 20E biochemical gallery. ResultsScreening identified six strains with significant larvicidal activity (LC < McFarland 2). At McFarland 2 concentration, all six strains achieved >50% mortality within 24-48 hours, with Lemna minor EC >100% indicating minimal phytotoxicity. API 20E identification (96-99.99% similarity) revealed three strains (6164, 6211, 6501) matching Photobacterium damselae, two (6186-1, 6512-1) matching Salmonella enterica subsp. arizonae, and one (6600) matching Pseudomonas sp., confirmed by distinctive biochemical profiles. ConclusionThis study provides the first evidence of potent, environmentally safe larvicidal activity from Cola nitida endophytic bacteria against Anopheles gambiae. These strains represent promising biocontrol candidates to address insecticide resistance, offering a sustainable alternative for malaria vector management in endemic regions.

microbiology↗

bioRxiv2025

Antibacterial potential of selected extracts and silver nanoparticles from bacterial endophyte harboured by Cola acuminata and Cola nitida (Sterculiaceae) roots

IntroductionAntimicrobial resistance (AMR) is currently a global health issue in most countries. Harnessing endophytic at present. Antibiotic resistance occurs when bacteria can adapt and grow in the presence of antibiotics. Endophytic microorganisms as bio-factory of natural bioactive compounds, and their potential in nanotechnology remains largely under explored. The aim of this study was to evaluate the antibacterial activity of extracts and silver nanoparticles synthesised using bacterial endophytes isolated from Cola acuminata and Cola nitida roots. MethodologyThe roots of each plant were harvested, washed, cut and surface sterilised. The sterile pieces were placed on the surface of nutrient agar and incubated, after which the microorganisms were sub-cultured until pure colonies were obtained. Secondary metabolite production was then undertaken over a 12-day fermentation period in Mueller Hinton Broth, conducted under stringent aseptic conditions. Each microorganism was fermented in two different tanks. The first was used for the preparation of crude extracts, and the second for the synthesis of nanoparticles. The in vitro antibacterial activity was determined using the broth microdilution method against Pseudomonas aeruginosa, Proteus mirabilis, Acinetobacter sp. and Escherichia coli. The MIC and the time-kill kinetic were used to determine the inhibiting parameters. The endophytes that produced the most promising effects were identified using microscopy and MALDI-TOF techniques. Results22 extracts were obtained from Cola nitida and Cola acuminata endophytes extracts (16 and 6 respectively. Crude extracts and silver nanoparticle). The most active material were the crude extracts from Cola acuminata endophytes were found to be the most active preparations. The MALDI-TOF identification method yielded the designation of NPMRU 6508, NPMRU 6511, NPMRU 7045 and NPMRU 7063 as Bacillus cereus. Furthermore, NPMRU6113 and NPMRU7047 were identified as Brevibacterium sp. ConclusionThis study supports the use of endophytes derived from Cola acuminata and Cola nitida roots to combat four bacterial strains involved in the development of antibiotic resistance.

microbiology↗

bioRxiv2024

Cylicodiscus gabunensis (FABACEAE) aqueous stem bark extract mediated silver nanoparticle enhance anti-inflammation on Wistar rats

IntroductionPlants are a source of bioactive ingredient that can play a key role in development of new drugs. In recent years, plant mediated-biological synthesis of nanoparticles has gained importance due to its simplicity, cost effectiveness and eco-friendly nature. To the best of our readings, nanoparticule from Cylicodiscus gabunensis stem bark is still untaped. This work therefore aimed at assessing the anti-inflammatory properties of the silver nanoparticles obtained from the aqueous extract of the stem bark of Cylicodiscus gabunensis(Cg). MethodologyCylicodiscus gabunensis extract was prepared by infusion-followed by the biosynthesis of silver nanoparticles. The synthesis was monitored by color and UV-Vis spectrophotometry. Infrared spectroscopy aimed at revealing the functional groups present at the surface of the nanoparticles. Structural elucidation was done by powder X-ray crystallography, while microstructure and elemental mapping was performed with scanning electron microscopy and energy dispersive X-ray spectroscopy. In vitro anti-inflammatory test was done using the BSA denaturation based test. The acute toxicity was done using the OEDC 425 guideline. carrageenan-induced rat paw oedema model was used to ascertain the in vivo anti-inflammatory effects. ResultsPhytochemical screening of the aqueous extract of Cylicodiscus gabunensis revealed the presence of polyphenols, flavonoids, alkaloids, coumarins, saponins, triterpenes, steroids, reducing sugar, tannins, and the absence of anthraquinone. The surface Plasmon resonance peak in the UV-Vis spectrum shows absorption spectra between 380 and 550 nm. Stability studies done over time showed that the nanoparticles were stable even after two months of synthesis. IR spectroscopy revealed the presence of O-H, N-H, C{equiv}C, C=C, C-O, and C=O groups. PXRD confirms the formation of silvernanoparticles (AgNPs) while nanograins of various forms were visualized by SEM and EDX. No toxic sign was observed. The maximum inhibitory percentages were 95% at 200 {micro}g/mL and 91% at 400 g/Kg for in vitro and in vivo anti-inflammatory effects, respectively. ConclusionThis paper spot the light on silver nanoparticle from Cylicodiscus gabunensis aqueous stem bark for their anti-inflammatory effect on paw oedema model.

pharmacology and toxicology↗