Chemical Constituents of Macaranga occidentalis, Antimicrobial and Chemophenetic Studies

Viviane Flore Kamlo Kamso; Christophe Colombe Simo Fotso; Ines Michèle Kanko Mbekou; Billy Tchegnitegni Tousssie; Bruno Ndjakou Lenta; Fabrice Fekam Boyom; Norbert Sewald; Marcel Frese; Bonaventure Tchaleu Ngadjui; Ghislain Wabo Fotso

doi:10.3390/molecules27248820

Chemical Constituents of Macaranga occidentalis, Antimicrobial and Chemophenetic Studies

Molecules. 2022 Dec 12;27(24):8820. doi: 10.3390/molecules27248820.

Affiliations

¹ Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon.
² Department of Chemistry, Faculty of Science, University of Buea, Buea P.O. Box 63, Cameroon.
³ Department of Biochemistry, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon.
⁴ Department of Chemistry, Faculty of Science, University of Dschang, Dschang P.O. Box 67, Cameroon.
⁵ Department of Chemistry, Higher Teacher Training College, University of Yaoundé I, Yaoundé P.O. Box 47, Cameroon.
⁶ Department of Chemistry, Organic and Bioorganic Chemistry, University of Bielefeld, 33501 Bielefeld, Germany.

Abstract

Medicinal plants are known as sources of potential antimicrobial compounds belonging to different classes. The aim of the present work was to evaluate the antimicrobial potential of the crude extract, fractions, and some isolated secondary metabolites from the leaves of Macaranga occidentalis, a Cameroonian medicinal plant traditionally used for the treatment of microbial infections. Repeated column chromatography of the ethyl acetate and n-butanol fractions led to the isolation of seventeen previously known compounds (1-17), among which three steroids (1-3), one triterpene (4), four flavonoids (5-8), two stilbenoids (9 and 10) four ellagic acid derivatives (11-14), one geraniinic acid derivative (15), one coumarine (16), and one glyceride (17). Their structures were elucidated mainly by means of extensive spectroscopic and spectrometric (1D and 2D NMR and, MS) analysis and comparison with the published data. The crude extract, fractions, and isolated compounds were all screened for their antimicrobial activity. None of the natural compounds was active against Candida strains. However, the crude extract, fractions, and compounds showed varying levels of antibacterial properties against at least one of the tested bacterial strains, with minimal inhibitory concentrations (MICs) ranging from 250 to 1000 μg/mL. The n-butanol (n-BuOH) fraction was the most active against Escherichia coli ATCC 25922, with an MIC value of 250 μg/mL. Among the isolated compounds, schweinfurthin B (10) exhibited the best activity against Staphylococcus aureus NR 46003 with a MIC value of 62.5 μg/mL. In addition, schweinfurthin O (9) and isomacarangin (6) also exhibited moderate activity against the same strain with a MIC value of 125 μg/mL. Therefore, pharmacomodulation was performed on compound 6 and three new semisynthetic derivatives (6a-c) were prepared by allylation and acetylation reactions and screened for their in vitro antimicrobial activity. None of the semisynthetic derivatives showed antimicrobial activity against the same tested strains. The chemophenetic significance of the isolated compounds is also discussed in this paper.

Keywords: Macaranga occidentalis; antimicrobial activity; chemophenetic significance; pharmacomodulation; prenylated flavonoids; stilbenes.

MeSH terms

1-Butanol
Anti-Bacterial Agents / chemistry
Anti-Infective Agents* / chemistry
Anti-Infective Agents* / pharmacology
Euphorbiaceae*
Microbial Sensitivity Tests
Plant Extracts / chemistry

Substances

1-Butanol
Plant Extracts
Anti-Infective Agents
Anti-Bacterial Agents

Grants and funding

57316173/YaBiNaPA