Endophytic Fungi from Alstonia boonei De Wild and Greenwayodendron suaveolens (Engl. and Diels) Verdc. subsp. Suaveolens Possess Inhibitory Activity against Pneumonia Causing Bacteria

Paola Cynthia Emoh Demeni; Patrick Hervé Diboue Betote; Christelle Wayoue Kom; Eric Ngalani Tchamgoue; Esther Del Florence Ndedi Moni; Jacqueline Saurelle Foumane Maniepi; Gabriel A Agbor; Maximilienne Ascension Nyegue

doi:10.1155/2021/9966323

Endophytic Fungi from Alstonia boonei De Wild and Greenwayodendron suaveolens (Engl. and Diels) Verdc. subsp. Suaveolens Possess Inhibitory Activity against Pneumonia Causing Bacteria

Evid Based Complement Alternat Med. 2021 Aug 5:2021:9966323. doi: 10.1155/2021/9966323. eCollection 2021.

Authors

Paola Cynthia Emoh Demeni¹, Patrick Hervé Diboue Betote^{1

2

3}, Christelle Wayoue Kom², Eric Ngalani Tchamgoue¹, Esther Del Florence Ndedi Moni¹, Jacqueline Saurelle Foumane Maniepi³, Gabriel A Agbor², Maximilienne Ascension Nyegue^{1

4}

Affiliations

¹ Laboratory of Microbiology, Department of Microbiology, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon.
² Laboratory of Pharmacology, Centre for Research on Medicinal Plants and Traditional Medicine, Institute of Medical Research and Medicinal Plants Studies, P.O. Box 13033, Yaoundé, Cameroon.
³ Multidisciplinary Laboratory, Department of Galenical Pharmacy and Pharmaceutical Law, Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon.
⁴ Equipe Glyco et Nanovecteurs Pour le Ciblage Thérapeutique, Université of Montpellier, IBMM UMR 5247 CNRS-UM. 15 Avenue Charles Flahault, BP 14491, FR-34093 Montpellier Cedex 5, France.

Abstract

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 were isolated, identified, and stored. These endophytic fungi possessed antibacterial activity against the selected bacterial strains with inhibition zones ranging from 7.00 to 25.00 mm. The endophytic fungi GS₁₅ and AB₂₄ have presented the inhibitions zones of 20.33 mm and 25.00 mm, respectively, and these were better than the ones obtained for Levofloxacin®. The endophytes with inhibition zones greater than 10 mm were used for extraction of their secondary metabolites. The endophytic fungi extracts showed antibacterial activity with the minimum inhibitory concentrations (MICs) ranging from 6.25 × 10^-4 to 2 × 10^-2 g/L and the minimum bactericidal concentrations (MBCs) ranging from 2.5 × 10^-3 to 2 × 10^-2 g/L. The endophytic fungi GS₁₅ extract was the most effective extract; it showed bactericidal effects on the tested bacterial strains. The phytochemical screening of the extracts revealed the presence of secondary metabolites classes, responsible for causing the obtained antibacterial activity. Thus, the endophytic fungi methanolic extracts from A. boonei and G. suaveolens have the potential to inhibit the growth of bacteria responsible for nosocomial pneumonia.