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

BACKGROUND: Multidrug 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. METHODS: The 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. RESULTS: The 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). CONCLUSIONS: The 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.International Foundation for Science (IFS-Grant F/4579-2 to VK), TWAS for financial support for ICCBSTWAS fellowship at the H.E.J. Research Institute of Chemistry, International Center of Chemical Sciences, University of Karachi, Pakistan on year 2010 (HF).http://www.biomedcentral.com/bmccomplementalternmedam201

Cytotoxic Compounds from the Leaves of Garcinia polyantha

Lannang AM, Tatsimo SJN, Fouotsa H, Dzoyem JP, Saxena AK, Sewald N. Cytotoxic Compounds from the Leaves of Garcinia polyantha. Chemistry & Biodiversity. 2014;11(6):975-981.A new compound, named banganxanthone C (=12-(1,1-dimethylprop-2-en-1-yl)-5,10-dihydroxy-9-methoxy-2-methyl-2-(4-methylpent-3-en-1-yl)-2H, 6H-pyrano[3,2-b]xanthen-6-one; 4), together with five known compounds, were isolated from the leaves of Garcinia polyantha. The structures of the compounds were elucidated on the basis of 1D- and 2D-NMR spectroscopy. Among the known compounds, two were xanthones, one was a pentacyclic triterpene, one sterol, and one benzophenone derivative. Isoxanthochymol (2) and 4-[(2E)-3,7-dimethylocta-2,6-dien-1-yl]-1,5,8-trihydroxy-3-methoxy-9H-xanthen-9-one (3) exhibited significant antiproliferative activity against the leukemia cell line TPH-1 with IC50 inhibition values of 1.5 and 2.8 mu g/ml, respectively. The cytotoxic activity was found to be related to apoptosis induction

Anti-inflammatory activity of benzophenone and xanthone derivatives isolated from Garcinia (Clusiaceae) species

Dzoyem JP, Lannang AM, Fouotsa H, et al. Anti-inflammatory activity of benzophenone and xanthone derivatives isolated from Garcinia (Clusiaceae) species. Phytochemistry Letters. 2015;14:153-158.Species of the genus Garcinia have been the source of many benzophenone and xanthone derivatives. Recent data regarding potent biological properties of natural compounds in Garcinia species led us to investigate the in vitro anti-inflammatory effect of three known xanthones, lichexanthone (1), 1,3,6,7-tetrahydroxyxanthone (2), 1,3,5,6-tetrahydroxyxanthone (3), two new xanthones 1-hydroxy-3,6,7-tri-O, O, O-triprenylxanthone (4), 1,6-dihydroxy-3,7-di-O, O-diprenylxanthone (5) and two benzophenones isoxanthochymol (6), guttiferone E (7), isolated from Garcinia nobilis and Garcinia punctata. The Griess assay was used for the measurement of nitric oxide (NO) production in RAW264.7 macrophages and the ferrous oxidation-xylenol orange assay was used to determine the 15-lipoxygenase (15-LOX) inhibitory activity. All the compounds had inhibitory effect on 15-LOX activity to different extents. Compound (7) had the highest anti-LOX activity with an IC50 value of 43.05 mu g/mL. At the highest studied concentration (25 mg/mL), compound (4) had the most potent inhibitory activity against NO release with a% of inhibition of 95.42% and less cytotoxic effect on RAW264.7 cells (% of cell viability of 81.40). The results presented here suggest that 1,3,5,6-tetrahydroxyxanthone (3) and guttiferone E (7) are promising inhibitors of NO production and 15-LOX activity. Further studies should be considered in order to elucidate the mechanism by which these compounds exert their inhibitory activities. (C) 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved

A new xanthone derivative from twigs of Garcinia nobilis

Fouotsa H, Tatsimo SJN, Neumann B, et al. A new xanthone derivative from twigs of Garcinia nobilis. Natural Product Research. 2014;28(14):1030-1036.Phytochemical investigation of the twigs of Garcinia nobilis led to the isolation of a new xanthone, named l-hydroxy-2,5-dimethoxyxanthone (1), together with 15 known compounds (2-16). The structures of the new and known compounds were established by means of spectroscopic methods and by comparison with previously reported data. The structure of compound 1 was confirmed by X-ray diffraction data. Compounds 1-16 were tested for their cytotoxic activity against human cervix carcinoma cell line KB-3-1. Compounds 5 and 11 showed moderate activity while others showed weak biological activity in these cytotoxicity assays. Compounds 4 and 9 were found to be inactive

Antiproliferative activity of a new xanthone derivative from leaves of Garcinia nobilis Engl.

A new xanthone, mboudiexanthone (1), together with five known compounds, euxanthone (2), isogarcinol (3), garcinol (4), betulinic acid (5) and zeorin (6) were isolated from the leaves of Garcinia nobilis Engl. The structures were determined by 1D and 2D NMR techniques and X-ray diffraction for 6. The in vitro antiproliferative properties of isolated compounds were evaluated against the human breast cancer cell line MCF-7. All compounds showed an antiproliferative activity with an IC50 value down to ∼11 µM for isogarcinol.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Antiproliferative activity of a new xanthone derivative from leaves of <i>Garcinia nobilis</i> Engl

A new xanthone, mboudiexanthone (1), together with five known compounds, euxanthone (2), isogarcinol (3), garcinol (4), betulinic acid (5) and zeorin (6) were isolated from the leaves of Garcinia nobilis Engl. The structures were determined by 1D and 2D NMR techniques and X-ray diffraction for 6. The in vitro antiproliferative properties of isolated compounds were evaluated against the human breast cancer cell line MCF-7. All compounds showed an antiproliferative activity with an IC50 value down to about 11 mM for isogarcinol

Antibacterial and Antioxidant Xanthones and Benzophenone from Garcinia smeathmannii

Fouotsa H, Lannang AM, Dzoyem JP, et al. Antibacterial and Antioxidant Xanthones and Benzophenone from Garcinia smeathmannii. Planta Medica. 2015;81(7):594-599.A new prenylated xanthone, 1,3,5,8-tetrahydroxy-2-(3-methybut-2-enyl)-4-(3,7-dimethylocta-2,6-dienyl) xanthone (1), and a new benzophenone (2), together with four known xanthone derivatives, cheffouxanthone (3), smeathxanthone A (4), smeathxanthone B (5), ananixanthone (6), and two pentacyclic triterpenes, epi-friedelinol (7) and friedelin (8), were isolated from the stem bark of Garcinia smeathmannii. The structures of the compounds were elucidated on the basis of 1D and 2DNMR experiments, and compound 2 was further characterized and confirmed by single X-ray analysis. Compounds 1, 2, and 3 exhibited the most prominent antibacterial activity against gram-positive Enterococcus faecalis with minimal inhibitory concentration values of 8, 8, and 2 mu g/mL, respectively, while compounds 1, 3, 4, and 6 showed the capacity to scavenge free radicals

Xanthones inhibitors of alpha-glucosidase and glycation from Garcinia nobilis

Fouotsa H, Lannang AM, Mbazoa CD, et al. Xanthones inhibitors of alpha-glucosidase and glycation from Garcinia nobilis. Phytochemistry Letters. 2012;5(2):236-239