Antibacterial constituents of three Cameroonian medicinal plants: Garcinia nobilis, Oricia suaveolens and Balsamocitrus camerunensis

Abstract

BackgroundMultidrug resistance is a worrying cause of treatment failure in bacterial infections. The search of bioactive constituents from medicinal plants against multidrug resistant (MDR) bacteria has significantly evolved in the two last decades. In the present study, twenty-two compounds (three terpenoids, eleven phenolics and eight alkaloids) isolated from three Cameroonian medicinal plants, namely Garcinia nobilis, Oricia suaveolens and Balsamocitrus camerunensis, as well as the crude extracts were tested for their antibacterial activities against Mycobacterium tuberculosis and Gram-negative bacteria amongst which were MDR active efflux pumps expressing phenotypes.MethodsThe microplate alamar blue assay (MABA) and the broth microdilution methods were used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of the studied samples.ResultsThe results of the MIC determinations indicate that, the best crude extract was that from G. nobilis (GNB), its inhibitory effects being noted against 12 of the 14 tested bacteria. The extract of GNB also exhibited better anti-tuberculosis (MIC of 128 μg/ml M. tuberculosis against ATCC 27294 strain) and antibacterial (MIC of 64 μg/ml against Escherichia coli ATCC10536) activities compared to the extracts of O. suaveolens and B. camerunensis. Interestingly, 4-prenyl-2-(3,7-dimethyl-2,6-octadienyl)-1,3,5,8-tetrahydroxyxanthone (2), isolated from the most active extract GNB, also showed the best activity amongst compounds, inhibiting the growth of all the fourteen tested microorganisms. The lowest MIC value obtained with compound 2 was 8 μg/ml against M. tuberculosis ATCC 27294 and M. tuberculosis clinical MTCS2 strains. Other compounds showed selective activities with 11 of the 14 tested bacteria being sensitive to the xanthone, morusignin I (5) and the alkaloid, kokusaginine (13).ConclusionsThe results of the present investigation provide evidence that the crude extract from G. nobilis, O. suaveolens and B. camerunensis as well as some of their compounds, and mostly compound 2 (isolated from G. nobilis,) could be considered as interesting natural antibacterial products.

Cytotoxicity and modes of action of three naturally occurring xanthones (8-hydroxycudraxanthone G, morusignin I and cudraxanthone I) against sensitive and multidrug-resistant cancer cell lines

“…We previously reported their isolation and identification from Garcinia nobilis (Fouotsa et al, 2012(Fouotsa et al, , 2013. Doxorubicin and vinblastine were provided by the University Pharmacy of the Johannes Gutenberg University (Mainz, Germany) and dissolved in PBS (Invitrogen, Eggenstein, Germany) at a concentration of 10 mM.…”

New furoquinoline alkaloid and flavanone glycoside derivatives from the leaves ofOricia suaveolens and Oricia renieri(Rutaceae)

“…The known compounds were identified as a stigma-5-en-3-ol (3) and b-sistosterol (4) (Fouotsa et al 2013), g-fagarine (5) (Rapoport & Tjan Gwan Hiem 1960), a-amyrin (6) (Ndom et al 2001), 3b-hydroxy-olean-12-ene (7) (Seo et al 1975), didymin (8) (Mohamed 2004), lupeol (9) (Wansi et al 2008), lupenone (10) (Atta-Ur-Rahman 1994), scoparone (11) (Ulubelen et al 1984), evoxanthidine (12) (Govindanchari et al 1967) and (roeharmine) (13) (Gözler & Shamma 1990) ( Figure S3). …”

Isolation and Characterization of Antimycobacterial Compounds from Fruits of Aegle marmelos (L.) Correa

“…28 On the contrary, imperatorin isolated from Balsamo citruscamerunensis when tested against E. aerogenes , K. pneumonia , P. stuartii, P. aeruginosa did not exhibit any inhibitory activity and was found to be active only against E. coli at a high concentration of 512 µg/ mL. 29 It shows excellent anti-listerial activity with an MIC of 15.62 µg/mL against L. monocytogenes. 30 Imperatorin is also reported to inhibit HIV-1 replication.…”