Plaxenone A and B: Cytotoxic halogenated monoterpenes from the South African red seaweed Plocamium maxillosum
- Knott, Michael G, de la Mare, Jo-Anne, Edkins, Adrienne L, Zhang, Angel, Stillman, Martin J, Bolton, John J, Antunes, Edith M, Beukes, Denzil R
- Authors: Knott, Michael G , de la Mare, Jo-Anne , Edkins, Adrienne L , Zhang, Angel , Stillman, Martin J , Bolton, John J , Antunes, Edith M , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164446 , vital:41119 , https://doi.org/10.1016/j.phytol.2018.12.009
- Description: The endemic South African red seaweed Plocamium maxillosum (Poiret) Lamouroux produces two unusual isomeric dichlorinated cyclohexenone monoterpenes, plaxenone A and B (1 and 2). The structures of the isolated compounds were determined from spectroscopic data and their absolute configuration was determined by comparison of the experimental and calculated ECD spectra. Compounds 1 and 2 inhibit the growth of MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2019
- Authors: Knott, Michael G , de la Mare, Jo-Anne , Edkins, Adrienne L , Zhang, Angel , Stillman, Martin J , Bolton, John J , Antunes, Edith M , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164446 , vital:41119 , https://doi.org/10.1016/j.phytol.2018.12.009
- Description: The endemic South African red seaweed Plocamium maxillosum (Poiret) Lamouroux produces two unusual isomeric dichlorinated cyclohexenone monoterpenes, plaxenone A and B (1 and 2). The structures of the isolated compounds were determined from spectroscopic data and their absolute configuration was determined by comparison of the experimental and calculated ECD spectra. Compounds 1 and 2 inhibit the growth of MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2019
Semi-synthesis and evaluation of sargahydroquinoic acid derivatives as potential antimalarial agents:
- Munedzimwe, Tatenda C, van Zyl, Rovyn L, Heslop, Donovan C, Edkins, Adrienne L, Beukes, Denzil R
- Authors: Munedzimwe, Tatenda C , van Zyl, Rovyn L , Heslop, Donovan C , Edkins, Adrienne L , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163456 , vital:41040 , DOI: 10.3390/medicines6020047
- Description: Malaria continues to present a major health problem, especially in developing countries. The development of new antimalarial drugs to counter drug resistance and ensure a steady supply of new treatment options is therefore an important area of research. Meroditerpenes have previously been shown to exhibit antiplasmodial activity against a chloroquinone sensitive strain of Plasmodium falciparum (D10). In this study we explored the antiplasmodial activity of several semi-synthetic analogs of sargahydroquinoic acid.
- Full Text:
- Date Issued: 2019
- Authors: Munedzimwe, Tatenda C , van Zyl, Rovyn L , Heslop, Donovan C , Edkins, Adrienne L , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163456 , vital:41040 , DOI: 10.3390/medicines6020047
- Description: Malaria continues to present a major health problem, especially in developing countries. The development of new antimalarial drugs to counter drug resistance and ensure a steady supply of new treatment options is therefore an important area of research. Meroditerpenes have previously been shown to exhibit antiplasmodial activity against a chloroquinone sensitive strain of Plasmodium falciparum (D10). In this study we explored the antiplasmodial activity of several semi-synthetic analogs of sargahydroquinoic acid.
- Full Text:
- Date Issued: 2019
Isolation, characterization and antiproliferative activity of new metabolites from the South African endemic red algal species Laurencia alfredensis
- Dziwornu, Godwin A, Caira, Mino R, de la Mare, Jo-Anne, Edkins, Adrienne L, Bolton, John J, Beukes, Denzil R, Sunassee, Suthananda N
- Authors: Dziwornu, Godwin A , Caira, Mino R , de la Mare, Jo-Anne , Edkins, Adrienne L , Bolton, John J , Beukes, Denzil R , Sunassee, Suthananda N
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59963 , vital:27715 , https://doi:10.3390/molecules22040513
- Description: The marine red algae of the genus Laurencia have been widely studied for their structurally diverse and biologically active secondary metabolites. We report here the natural product investigation of the organic extract of a newly identified South African endemic species, Laurencia alfredensis. A sequence of column chromatography, preparative TLC and normal phase HPLC resulted in the isolation of eleven compounds comprising three labdane-type diterpenes (1-3), four polyether triterpenes (4-7), three cholestane-type ecdysteroids (8-10) and a glycolipid (11). Compounds 1-3, 5-8 and 10 have not previously been reported, while compound 9 is reported here for the first time from a natural source and the known compound 11 isolated for the first time from the genus Laurencia. The structural elucidation and the relative configuration assignments of the compounds were accomplished by extensive use of ID- and 2D-NMR, HR-ESI-MS, UV and IR spectroscopic techniques, while the absolute configuration of compound 1 was determined by single-crystal X-ray diffraction analysis. All compounds were evaluated against the MDA-MB-231 breast and HeLa cervical cancer cell lines. Compound 2 exhibited low micromolar antiproliferative activity (IC50 = 9.3 gM) against the triple negative breast carcinoma and compound 7 was similarly active (IC50 = 8.8 gM) against the cervical cancer cell line.
- Full Text:
- Date Issued: 2017
- Authors: Dziwornu, Godwin A , Caira, Mino R , de la Mare, Jo-Anne , Edkins, Adrienne L , Bolton, John J , Beukes, Denzil R , Sunassee, Suthananda N
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59963 , vital:27715 , https://doi:10.3390/molecules22040513
- Description: The marine red algae of the genus Laurencia have been widely studied for their structurally diverse and biologically active secondary metabolites. We report here the natural product investigation of the organic extract of a newly identified South African endemic species, Laurencia alfredensis. A sequence of column chromatography, preparative TLC and normal phase HPLC resulted in the isolation of eleven compounds comprising three labdane-type diterpenes (1-3), four polyether triterpenes (4-7), three cholestane-type ecdysteroids (8-10) and a glycolipid (11). Compounds 1-3, 5-8 and 10 have not previously been reported, while compound 9 is reported here for the first time from a natural source and the known compound 11 isolated for the first time from the genus Laurencia. The structural elucidation and the relative configuration assignments of the compounds were accomplished by extensive use of ID- and 2D-NMR, HR-ESI-MS, UV and IR spectroscopic techniques, while the absolute configuration of compound 1 was determined by single-crystal X-ray diffraction analysis. All compounds were evaluated against the MDA-MB-231 breast and HeLa cervical cancer cell lines. Compound 2 exhibited low micromolar antiproliferative activity (IC50 = 9.3 gM) against the triple negative breast carcinoma and compound 7 was similarly active (IC50 = 8.8 gM) against the cervical cancer cell line.
- Full Text:
- Date Issued: 2017
Sarqaquinoic acid and related synthetic naphthoquinones inhibit the function of Hsp90
- Chiwakata, M, de la Mare, Jo-Anne, Edkins, Adrienne L, Beukes, Denzil R
- Authors: Chiwakata, M , de la Mare, Jo-Anne , Edkins, Adrienne L , Beukes, Denzil R
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66324 , vital:28933 , https://doi.org/10.1055/s-0036-1596751
- Description: publisher version , Heat shock protein 90 (Hsp90) is of critical importance in the proper folding of numerous proteins, including those involved in cancer. Consequently, there is significant interest in the discovery and development of Hsp90 inhibitors as anticancer drugs. In this study, we investigated the ability of sargaquinoic acid (SQA) and selected naphthoquinone derivatives to inhibit Hsp90 function. SQA was isolated and purified from Sargassum incisifolium while the naphthoquinones were synthesised via a straightforward sequence incorporating a Diels-Alder reaction between benzoquinone derivatives and myrcene followed by coupling with substituted alkyl or arylamines. Hsp90 inhibition was assessed by a client protein degradation assay. At a concentration of 1µM, SQA showed almost complete inhibition of Hsp90 but only moderate antiproliferative effects (IC50 658µM) against a Hs578T breast cancer carcinoma cell line. Interestingly, the most potent synthetic aminonaphthoquinone inhibited Hsp90 function by 50% at a concentration of 1µM but showed much improved activity against the Hs578T cell line (IC50 0.32µM). Furthermore, unlike geldanamycin, none of the compounds tested upregulates Hsp70 suggesting that these compounds may bind to the C-terminal end of Hsp90.
- Full Text: false
- Date Issued: 2016
- Authors: Chiwakata, M , de la Mare, Jo-Anne , Edkins, Adrienne L , Beukes, Denzil R
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66324 , vital:28933 , https://doi.org/10.1055/s-0036-1596751
- Description: publisher version , Heat shock protein 90 (Hsp90) is of critical importance in the proper folding of numerous proteins, including those involved in cancer. Consequently, there is significant interest in the discovery and development of Hsp90 inhibitors as anticancer drugs. In this study, we investigated the ability of sargaquinoic acid (SQA) and selected naphthoquinone derivatives to inhibit Hsp90 function. SQA was isolated and purified from Sargassum incisifolium while the naphthoquinones were synthesised via a straightforward sequence incorporating a Diels-Alder reaction between benzoquinone derivatives and myrcene followed by coupling with substituted alkyl or arylamines. Hsp90 inhibition was assessed by a client protein degradation assay. At a concentration of 1µM, SQA showed almost complete inhibition of Hsp90 but only moderate antiproliferative effects (IC50 658µM) against a Hs578T breast cancer carcinoma cell line. Interestingly, the most potent synthetic aminonaphthoquinone inhibited Hsp90 function by 50% at a concentration of 1µM but showed much improved activity against the Hs578T cell line (IC50 0.32µM). Furthermore, unlike geldanamycin, none of the compounds tested upregulates Hsp70 suggesting that these compounds may bind to the C-terminal end of Hsp90.
- Full Text: false
- Date Issued: 2016
Assessment of potential anti-cancer stem cell activity of marine algal compounds using an in vitro mammosphere assay:
- de la Mare, Jo-Anne, Sterrenberg, Jason N, Sukhthankar, Mugdha G, Chiwakata, Maynard T, Beukes, Denzil R, Blatch, Gregory L, Edkins, Adrienne L
- Authors: de la Mare, Jo-Anne , Sterrenberg, Jason N , Sukhthankar, Mugdha G , Chiwakata, Maynard T , Beukes, Denzil R , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165184 , vital:41216 , DOI: 10.1186/1475-2867-13-39
- Description: The cancer stem cell (CSC) theory proposes that tumours arise from and are sustained by a subpopulation of cells with both cancer and stem cell properties. One of the key hallmarks of CSCs is the ability to grow anchorage-independently under serum-free culture conditions resulting in the formation of tumourspheres. It has further been reported that these cells are resistant to traditional chemotherapeutic agents.
- Full Text:
- Date Issued: 2013
- Authors: de la Mare, Jo-Anne , Sterrenberg, Jason N , Sukhthankar, Mugdha G , Chiwakata, Maynard T , Beukes, Denzil R , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165184 , vital:41216 , DOI: 10.1186/1475-2867-13-39
- Description: The cancer stem cell (CSC) theory proposes that tumours arise from and are sustained by a subpopulation of cells with both cancer and stem cell properties. One of the key hallmarks of CSCs is the ability to grow anchorage-independently under serum-free culture conditions resulting in the formation of tumourspheres. It has further been reported that these cells are resistant to traditional chemotherapeutic agents.
- Full Text:
- Date Issued: 2013
Halogenated oxindole and indoles from the South African marine ascidian Distaplia skoogi:
- Bromley, Candice L, Parker-Nance, Shirley, de la Mare, Jo-Anne, Edkins, Adrienne L, Beukes, Denzil R, Davies-Coleman, Michael T
- Authors: Bromley, Candice L , Parker-Nance, Shirley , de la Mare, Jo-Anne , Edkins, Adrienne L , Beukes, Denzil R , Davies-Coleman, Michael T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164918 , vital:41184
- Description: The known 3,6-dibromoindole (1), 6-bromo-3-chloroindole (2) and 6-bromo-2-oxindole (3) were isolated from the marine ascidian (sea squirt) Distapia skoogi collected from Algoa Bay, South Africa. Standard spectroscopic techniques were used to elucidate the structures of 1-3. All three compounds were found to be moderately cytotoxic to metastatic MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2013
- Authors: Bromley, Candice L , Parker-Nance, Shirley , de la Mare, Jo-Anne , Edkins, Adrienne L , Beukes, Denzil R , Davies-Coleman, Michael T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164918 , vital:41184
- Description: The known 3,6-dibromoindole (1), 6-bromo-3-chloroindole (2) and 6-bromo-2-oxindole (3) were isolated from the marine ascidian (sea squirt) Distapia skoogi collected from Algoa Bay, South Africa. Standard spectroscopic techniques were used to elucidate the structures of 1-3. All three compounds were found to be moderately cytotoxic to metastatic MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2013
Quinones and halogenated monoterpenes of algal origin show anti-proliferative effects against breast cancer cells in vitro:
- de la Mare, Jo-Anne, Lawson, Jessica C, Chiwakata, Maynard T, Beukes, Denzil R, Blatch, Gregory L, Edkins, Adrienne L
- Authors: de la Mare, Jo-Anne , Lawson, Jessica C , Chiwakata, Maynard T , Beukes, Denzil R , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165165 , vital:41214 , DOI: 10.1007/s10637-011-9788-0
- Description: Red and brown algae have been shown to produce a variety of compounds with chemotherapeutic potential. A recent report described the isolation of a range of novel polyhalogenated monoterpene compounds from the red algae Plocamium corallorhiza and Plocamium cornutum collected off the coast of South Africa, together with the previously described tetraprenylquinone, sargaquinoic acid (SQA), from the brown algae Sargassum heterophyllum. In our study, the algal compounds were screened for anti-proliferative activity against metastatic MDA-MB-231 breast cancer cells revealing that a number of compounds displayed anti-cancer activity with IC50 values in the micromolar range. A subset of the compounds was tested for differential toxicity in the MCF-7/MCF12A system and five of these, including sargaquinoic acid, were found to be at least three times more toxic to the breast cancer than the non-malignant cell line.
- Full Text:
- Date Issued: 2012
- Authors: de la Mare, Jo-Anne , Lawson, Jessica C , Chiwakata, Maynard T , Beukes, Denzil R , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165165 , vital:41214 , DOI: 10.1007/s10637-011-9788-0
- Description: Red and brown algae have been shown to produce a variety of compounds with chemotherapeutic potential. A recent report described the isolation of a range of novel polyhalogenated monoterpene compounds from the red algae Plocamium corallorhiza and Plocamium cornutum collected off the coast of South Africa, together with the previously described tetraprenylquinone, sargaquinoic acid (SQA), from the brown algae Sargassum heterophyllum. In our study, the algal compounds were screened for anti-proliferative activity against metastatic MDA-MB-231 breast cancer cells revealing that a number of compounds displayed anti-cancer activity with IC50 values in the micromolar range. A subset of the compounds was tested for differential toxicity in the MCF-7/MCF12A system and five of these, including sargaquinoic acid, were found to be at least three times more toxic to the breast cancer than the non-malignant cell line.
- Full Text:
- Date Issued: 2012
Ten years of marine natural products research at Rhodes University
- Davies-Coleman, Michael T, Beukes, Denzil R
- Authors: Davies-Coleman, Michael T , Beukes, Denzil R
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6568 , http://hdl.handle.net/10962/d1004131
- Description: Marine invertebrates, algae and microorganisms produce a plethora of structurally unique and biologically active secondary metabolites. The ecological roles of these natural products, although not completely understood, range from chemical defence against predation to intra-specific cues for larval settlement. Surprisingly, a number of these metabolites have also shown potential as new medicines for the treatment of a variety of diseases including cancer. The natural products chemistry of southern Africa’s unique marine flora and fauna is relatively unknown and this review provides an overview of the contribution made by the marine natural products research group at Rhodes University to the isolation, identification and synthesis of biologically active natural products from southern African marine microorganisms, algae, sponges, ascidians, soft corals and molluscs.
- Full Text:
- Date Issued: 2004
- Authors: Davies-Coleman, Michael T , Beukes, Denzil R
- Date: 2004
- Language: English
- Type: Article
- Identifier: vital:6568 , http://hdl.handle.net/10962/d1004131
- Description: Marine invertebrates, algae and microorganisms produce a plethora of structurally unique and biologically active secondary metabolites. The ecological roles of these natural products, although not completely understood, range from chemical defence against predation to intra-specific cues for larval settlement. Surprisingly, a number of these metabolites have also shown potential as new medicines for the treatment of a variety of diseases including cancer. The natural products chemistry of southern Africa’s unique marine flora and fauna is relatively unknown and this review provides an overview of the contribution made by the marine natural products research group at Rhodes University to the isolation, identification and synthesis of biologically active natural products from southern African marine microorganisms, algae, sponges, ascidians, soft corals and molluscs.
- Full Text:
- Date Issued: 2004
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