Rob W. M. van Soest
University of Amsterdam
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Featured researches published by Rob W. M. van Soest.
Bioorganic & Medicinal Chemistry | 2010
Triana Hertiani; RuAngelie Edrada-Ebel; Sofia Ortlepp; Rob W. M. van Soest; Nicole J. de Voogd; Victor Wray; Ute Hentschel; Svetlana Kozytska; Werner E. G. Müller; Peter Proksch
Chemical investigation of Indonesian marine sponges Agelas linnaei and A. nakamurai afforded 24 alkaloid derivatives representing either bromopyrrole or diterpene alkaloids. A. linnaei yielded 16 bromopyrrole alkaloids including 11 new natural products with the latter exhibiting unusual functionalities. The new compounds include the first iodinated tyramine-unit bearing pyrrole alkaloids, agelanesins A-D. These compounds exhibited cytotoxic activity against L5178Y mouse lymphoma cells with IC(50) values between 9.25 and 16.76 muM. Further new compounds include taurine acid substituted bromopyrrole alkaloids and a new dibromophakellin derivative. A. nakamurai yielded eight alkaloids among them are three new natural products. The latter include the diterpene alkaloids (-)-agelasine D and its oxime derivative and the new bromopyrrole alkaloid longamide C. (-)-Agelasine D and its oxime derivative exhibited cytotoxicity against L5178Y mouse lymphoma cells (IC(50) 4.03 and 12.5 microM, respectively). Furthermore, both agelasine derivatives inhibited settling of larvae of Balanus improvisus in an anti-fouling bioassay and proved to be toxic to the larvae. (-)-Agelasine D inhibited the growth of planktonic forms of biofilm forming bacteria S. epidermidis (MIC<0.0877 microM) but did not inhibit biofilm formation whereas the oxime derivative showed the opposite activity profile and inhibited only biofilm formation but not bacterial growth. The structures of the isolated secondary metabolites were elucidated based on extensive spectroscopic analysis involving one- and two-dimensional NMR as well as mass spectrometry and comparison with literature data.
Organic Letters | 2008
Marianne D. Sadar; David E. Williams; Nasrin R. Mawji; Brian O. Patrick; Thamrin Wikanta; Ekowati Chasanah; Hari Eko Irianto; Rob W. M. van Soest; Raymond J. Andersen
The new chlorinated peptides sintokamides A to E (1-5) have been isolated from specimens of the marine sponge Dysidea sp. collected in Indonesia. Their structures were elucidated by a combination of spectroscopic and single-crystal X-ray diffraction analyses. Sintokamide A (1) is an inhibitor of N-terminus transactivation of the androgen receptor in prostate cancer cells.
Biochemical Systematics and Ecology | 1992
Jean Claude Braekman; Désiré Daloze; Catherine Stoller; Rob W. M. van Soest
The secondary metabolite content of four different species of Agelas (Porifera) from the West Indies has been studied. All the compounds isolated are already known metabolites whose identification was confirmed by comparison of their spectral properties with those reported in the literature. They pertain to two different classes of compounds: terpenoids and pyrrole-2-carboxylic acid derivatives. The chemotaxonomic value of these secondary metabolites has been evaluated. Their distribution amongst the Porifera, as well as that of isocyanide derivatives, suggests a close relationship between the Agelasidae, the Axinellidae and the Halichondriidae.
Toxicon | 2009
Reiko Ueoka; Akihiro Ito; Miho Izumikawa; Satoko Maeda; Motoki Takagi; Kazuo Shin-ya; Minoru Yoshida; Rob W. M. van Soest; Shigeki Matsunaga
Azaspiracid-2 was isolated from a marine sponge Echinoclathria sp. collected off Amami-Oshima as the predominant cytotoxic constituent. A combination of HPLC using ODS, GS320, and Phenylhexyl stationary phases permitted the purification without using acid or inorganic additives in the mobile phase. Azaspiracid-2 exhibited potent cytotoxicity against P388 cells with an IC50 value of 0.72 ng/mL and caused S phase arrest on the cell cycle.
Marine Biotechnology | 2007
Dirk Erpenbeck; Rob W. M. van Soest
In addition to their pharmaceutical applications, sponges are an important source of compounds that are used to elucidate classification patterns and phylogenetic relationships. Here we present a review and outlook on chemosystematics in sponges in seven sections: Secondary metabolites in sponges; Further applications of bioactive compound research in sponges; Sponge chemotaxonomy; Pitfalls of sponge chemotaxonomy; The chemotaxonomic suitability of sponge compounds; Potential synapomorphic markers in sponges; and The future of sponge chemotaxonomy.
Bioorganic & Medicinal Chemistry | 2009
Mudit Mudit; Mohammad A. Khanfar; Anbalagan Muralidharan; Shibu Thomas; Girish V. Shah; Rob W. M. van Soest; Khalid A. El Sayed
The Red Sea sponge Hemimycale arabica afforded the known (Z)-5-(4-hydroxybenzylidene)-hydantoin (1), (R)-5-(4-hydroxybenzyl)hydantoin (2), and (Z)-5-((6-bromo-1H-indol-3-yl)methylene)-hydantoin (3). The natural phenylmethylene hydantoin (PMH) 1 and the synthetic (Z)-5-(4-(ethylthio)benzylidene)-hydantoin (4) showed potent in vitro anti-growth and anti-invasive properties against PC-3M prostate cancer cells in MTT and spheroid disaggregation assays. PMHs 1 and 4 also showed significant anti-invasive activities in orthotopic xenograft and transgenic mice models. To study the effect of electronic and lipophilic parameters on the activity, a wide array of several substituted aldehydes possessing electron-withdrawing (+sigma), lipophilic (+pi), electron-donating (-sigma), and less lipophilic substituents (-pi) were used to synthesize several PMHs. Few des-phenylmethylenehydantoins and 2-thiohydanoins were also synthesized and the anti-invasive activities of all compounds were evaluated. Comparative molecular field analysis (CoMFA) was then used to study the 3D QSAR. Predictive 3D QSAR model with conventional r(2) and cross validated coefficient (q(2)) values up to 0.910 and 0.651 were established. In conclusion, PMH is a novel antimetastatic lead class with potential to control metastatic prostate cancer.
Journal of Natural Products | 2002
M. Salmoun; C. Devijver; Désiré Daloze; Jean Claude Braekman; Rob W. M. van Soest
Indonesian specimens of the marine sponges Hyrtios erectus and H. reticulatus were found to contain 5-hydroxytryptamine-derived alkaloids. Their structures were determined on the basis of their spectral properties. H. erectus contained hyrtiosulawesine (4), a new beta-carboline alkaloid, together with the already known alkaloids 5-hydroxyindole-3-carbaldehyde (1), hyrtiosin B (2), and 5-hydroxy-3-(2-hydroxyethyl)indole (3). H. reticulatus contained the novel derivative 1,6-dihydroxy-1,2,3,4-tetrahydro-beta-carboline (11) together with serotonin (5), 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline (7), and 6-hydroxy-3,4-dihydro-1-oxo-beta-carboline (9).
Journal of Organic Chemistry | 2009
Reiko Ueoka; Yoichi Nakao; Shizuka Kawatsu; Junko Yaegashi; Yoshitsugu Matsumoto; Shigeki Matsunaga; Kazuo Furihata; Rob W. M. van Soest; Nobuhiro Fusetani
Three new antiprotozoan compounds, gracilioethers A-C (1-3), have been isolated from the marine sponge Agelas gracilis. Their structures were elucidated on the basis of spectroscopic and chemical methods. Gracilioethers A-C showed antimalarial activity against Plasmodium falciparum with IC(50) values of 0.5-10 microg/mL, whereas gracilioether B (2) also showed antileishmanial activity.
Tetrahedron Letters | 2000
Kinzo Watanabe; Yuichiro Tsuda; Yoshihisa Yamane; Haruko Takahashi; Kazuo Iguchi; Hideo Naoki; Tsuyoshi Fujita; Rob W. M. van Soest
Three new cytotoxic long-chain acetylenic alcohols, strongylodiols A, B and C, were isolated from the Okinawan marine sponge of the genus Strongylophora. Their gross structures were elucidated based on spectroscopic analysis. During the process for determination of the absolute stereochemistry at C-6 using the modified Moshers method, these acetylenic alcohols were each found to be an enantiomeric mixture with a different ratio; 91:9 for strongylodiol A, 97:3 for strongylodiol B and 84:16 for strongylodiol C. The R configuration for each major enantiomer was established by the modified Moshers method. Each enantiomer was separated and fully characterized.
Bioorganic & Medicinal Chemistry Letters | 2008
Sachiko Tsukamoto; Tomoharu Takeuchi; Henki Rotinsulu; Remy E. P. Mangindaan; Rob W. M. van Soest; Kazuyo Ukai; Hisayoshi Kobayashi; Michio Namikoshi; Tomihisa Ohta; Hideyoshi Yokosawa
A compound that inhibits the formation of a complex composed of the ubiquitin E2 enzyme Ubc13 and Uev1A was isolated from the marine sponge Leucetta aff. microrhaphis. The compound was identified as leucettamol A (1) by spectroscopic analysis. Its inhibition of Ubc13-Uev1A interaction was tested by the ELISA method, revealing an IC(50) value of 50 microg/mL. The compound is the first inhibitor of Ubc13-Uev1A interaction, that is, that of the E2 activity of Ubc13. Such inhibitors are presumed to be leads for anti-cancer agents that upregulate activity of the tumor suppressor p53 protein. Interestingly, hydrogenation of 1 increased its inhibitory activity with an IC(50) value of 4 microg/mL, while its tetraacetate derivative was inactive, indicating that the hydroxy and/or amino groups of 1 are required for the inhibition.