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Tietjen I.,University of British Columbia | Tietjen I.,Simon Fraser University | Ntie-Kang F.,University of Buea | Mwimanzi P.,Simon Fraser University | And 13 more authors.
PLoS ONE | Year: 2015

The continued burden of HIV in resource-limited regions such as parts of sub-Saharan Africa, combined with adverse effects and potential risks of resistance to existing antiretroviral therapies, emphasize the need to identify new HIV inhibitors. Here we performed a virtual screen of molecules from the pan-African Natural Product Library, the largest collection of medicinal plant-derived pure compounds on the African continent. We identified eight molecules with structural similarity to reported interactors of Vpu, an HIV-1 accessory protein with reported ion channel activity. Using in vitro HIV-1 replication assays with a CD4+ T cell line and peripheral blood mononuclear cells, we confirmed antiviral activity and minimal cytotoxicity for two compounds, ixoratannin A-2 and boldine. Notably, ixoratannin A-2 retained inhibitory activity against recombinant HIV-1 strains encoding patient-derived mutations that confer resistance to protease, non-nucleoside reverse transcriptase, or integrase inhibitors. Moreover, ixoratannin A-2 was less effective at inhibiting replication of HIV-1 lacking Vpu, supporting this protein as a possible direct or indirect target. In contrast, boldine was less effective against a protease inhibitor-resistant HIV-1 strain. Both ixoratannin A-2 and boldine also inhibited in vitro replication of hepatitis C virus (HCV). However, BIT-225, a previously-reported Vpu inhibitor, demonstrated antiviral activity but also cytotoxicity in HIV-1 and HCV replication assays. Our work identifies pure compounds derived from African plants with potential novel activities against viruses that disproportionately afflict resourcelimited regions of the world. Copyright: © 2015 Tietjen et al. Source


Djoumessi A.V.B.,University of Yaounde I | Sandjo L.P.,University of Yaounde I | Sandjo L.P.,Johannes Gutenberg University Mainz | Liermann J.C.,Johannes Gutenberg University Mainz | And 8 more authors.
Tetrahedron | Year: 2012

Three new cyclopropanic oleanane triterpenoids and ten known compounds were obtained from Donella ubanguiensis using chromatographic methods. The structures were established on the basis of mass spectrometric and NMR data and by comparison with values reported in the literature. The structures of the new compounds were confirmed by X-ray crystallography. A part of the isolated compounds was evaluated for cytotoxic and antimicrobial activities. © 2012 Elsevier Ltd. All rights reserved. Source


Schindel D.E.,Smithsonian Institution | Bubela T.,University of Alberta | Rosenthal J.,Fogarty International Center | Castle D.,University of Victoria | And 24 more authors.
Nature Conservation | Year: 2015

The entry into force of the Nagoya Protocol of the Convention on Biological Diversity will lead to new legislation and regulations that could change international collaborative research in biology. This article suggests a new approach that researchers can use in negotiating international Access and Benefit Sharing agreements under the Protocol. Research on medicinal plants is used as a case study because it is a domain with many competing stakeholders involving non-commercial and commercial research, as well as national and international commercial markets. We propose a decision-based framework to aid all participants as they negotiate ABS agreements for non-commercial biodiversity research. Our proposed approach promotes transparency and builds trust, reflects the principles in the Convention on Biological Diversity, and respects and protects the interests of biodiversity rich developing countries. This approach is an alternative to often-used adversarial approaches. Copyright David E. Schindel et al. Source


Tambama P.,University of Zimbabwe | Abegaz B.,African Academy of science | Mukanganyama S.,University of Zimbabwe
BioMed Research International | Year: 2014

Cancer is a major public health burden in both developed and developing countries. The quinone moiety has been shown to possess antitumor activity and several cancer drugs in clinical use contain this entity. The effect of isofuranonaphthoquinone isolated from Bulbine frutescens on Jurkat T cells was determined. Cells were exposed to the isofuranonaphthoquinone (IFNQ) at different concentrations. Significant antiproliferative effects were observed which were comparable to that of the anticancer drug 1,3-bis(2-chloroethyl)-1- nitrosourea (BCNU). A combination of IFNQ with BCNU produced synergistic effects which were observed after 72 hrs. It was also observed that combining IFNQ with reduced glutathione abolished the anticancer activity of the compound. It is, therefore, proposed that the isofuranonaphthoquinone may exert part of its effect by producing reactive oxygen species resulting in death of the cells as the effects of this compound were antagonized by reduced glutathione. An investigation on the effects of isofuranonaphthoquinone on glutathione transferase (GST) activity and drug efflux pumps showed that this compound exhibited inhibitory effects on both the GST and the drug efflux pumping activities. Thus, the isofuranonaphthoquinone showed cytotoxicity, works through inhibition of some cellular mechanisms, and could present a potential source of lead compounds for anticancer drug development. © 2014 Penelope Tambama et al. Source


Awoussong P.K.,University of Yaounde I | Awoussong P.K.,University of Medicine and Pharmacy, Cluj-Napoca | Zaharia V.,University of Medicine and Pharmacy, Cluj-Napoca | Ngameni B.,University of Yaounde I | And 5 more authors.
Medicinal Chemistry Research | Year: 2015

Chalcones and their derivatives have been shown to have potent anticancer activity. A series of aldehydes A 1-4 and thiazolic chalcones C 1-20 were synthesized and evaluated for their in vitro cytotoxic activity against three human cancer cell lines. In addition, this work led to the synthesis of 12 new thiazolic chalcones using a base-catalyzed Claisen-Schmidt condensation reaction. Compounds C 10 and C 12 were found to be the most promising biologically active samples with IC50 values below or around 10 μM on both DU-145 and THP-1 cancer cell lines. © 2014 Springer Science+Business Media New York. Source

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