ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Isolation and characterization of antisalmonellal anthraquinones and coumarins from Morinda lucida Benth. (Rubiaceae)

Napoleon A. Mfonku, Alain T. Tadjong, Gabriel T. Kamsu, Norbert Kodjio, Jie Ren, James A. Mbah, Donatien Gatsing, and Jixun Zhan

Department of Chemistry, University of Buea, Buea, Cameroon

E-mail: ajeck.james@ubuea.cm

Received: 9 September 2020  Accepted: 30 November 2020

Abstract:

A new anthraquinone, 1,6-dihydroxy-2-hydroxymethyl-5-methoxy-9,10-anthracenedione (1), along with four known compounds, including 1,2-dimethoxyanthraquinone (2), morindone-5-methylether (3), scopoletin (4), and fraxidin (5) were isolated from the methylene chloride extract of the stem bark of Morinda lucida Benth. Structure elucidation was accomplished by analysis of the 1D and 2D NMR, IR and mass spectra. Compounds 1, 2, 4 and 5 were tested against five Salmonella strains. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were determined. The results indicated that the four compounds have different antibacterial activities, with MIC values ranging from 8 to 256 µg/mL. Among these four compounds, the best activity was observed for compound 4 against Salmonella enterica subsp. enterica serovar Typhimurim (STM), with a MIC value of 8 µg/mL. Compound 1 showed selective antibacterial activity toward the five Salmonella strains, with MICs of 16 µg/mL against STM, 32 µg/mL against S. enteritidis (STE), 64 µg/mL against S. enterica subsp. enterica serovar Typhi (ST) and S. enterica subsp. enterica serovar Typhi (ST566), and 128 µg/mL against S. enteritidis, S. enterica subsp. enterica serovar Typhi ATCC 6539 (STS). Compounds 1, 2, 4, and 5 have bactericidal effects (MBC/MIC ≤ 4) against the tested Salmonella strains, except for compound 4, which is bacteriostatic to STM with a MBC/MIC value of 16.

Keywords: Morinda lucida; Rubiaceae; Anthraquinones; Coumarins; Antisalmonellal activity

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-020-01460-3

Chemical Papers 75 (5) 2067–2073 (2021)