TY - JOUR A1 - Fayez, Shaimaa A1 - Feineis, Doris A1 - Aké Assi, Laurent A1 - Seo, Ean-Jeong A1 - Efferth, Thomas A1 - Bringmann, Gerhard T1 - Ancistrobreveines A–D and related dehydrogenated naphthylisoquinoline alkaloids with antiproliferative activities against leukemia cells, from the West African liana Ancistrocladus abbreviatus JF - RSC Advances N2 - A unique series of six biaryl natural products displaying four different coupling types (5,10 , 7,10 , 7,80 , and 5,80) were isolated from the roots of the West African liana Ancistrocladus abbreviatus (Ancistrocladaceae). Although at first sight structurally diverse, these secondary metabolites all have in common that they belong to the rare group of naphthylisoquinoline alkaloids with a fully dehydrogenated isoquinoline portion. Among the African Ancistrocladus species, A. abbreviatus is so far only the second one that was found to produce compounds with such a molecular entity. Here, we report on four new representatives, named ancistrobreveines A–D (12–14, and 6). They were identified along with the two known alkaloids 6-O-methylhamateine (4) and entdioncophylleine A (10). The two latter naphthylisoquinolines had so far only been detected in Ancistrocladus species from Southeast Asia. All of these fully dehydrogenated alkaloids have in common being optically active despite the absence of stereogenic centers, due to the presence of the rotationally hindered biaryl axis as the only element of chirality. Except for ent-dioncophylleine A (10), which lacks an oxygen function at C-6, the ancistrobreveines A–D (12–14, and 6) and 6-O-methylhamateine (4) are 6-oxygenated alkaloids, and are, thus, typical ‘Ancistrocladaceae-type’ compounds. Ancistrobreveine C (14), is the first – and so far only – example of a 7,80-linked fully dehydrogenated naphthylisoquinoline discovered in nature that is configurationally stable at the biaryl axis. The stereostructures of the new alkaloids were established by spectroscopic (in particular HRESIMS, 1D and 2D NMR) and chiroptical (electronic circular dichroism) methods. Ancistrobreveine C (14) and 6-O-methylhamateine (4) exhibited strong antiproliferative activities against drug-sensitive acute lymphoblastic CCRF-CEM leukemia cells and their multidrugresistant subline, CEM/ADR5000. KW - chemistry Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201686 VL - 9 IS - 28 ER - TY - JOUR A1 - Mufusama, Jean-Pierre A1 - Feineis, Doris A1 - Mudogo, Virima A1 - Kaiser, Marcel A1 - Brun, Reto A1 - Bringmann, Gerhard T1 - Antiprotozoal dimeric naphthylisoquinolines, mbandakamines B\(_3\) and B\(_4\), and related 5,8′-coupled monomeric alkaloids, ikelacongolines A–D, from a Congolese Ancistrocladus liana JF - RSC Advances N2 - From the leaves of a botanically and phytochemically as yet unexplored Ancistrocladus liana discovered in the rainforests of the Central region of the Democratic Republic of the Congo in the vicinity of the town of Ikela, six new naphthylisoquinoline alkaloids were isolated, viz., two constitutionally unsymmetric dimers, the mbandakamines B\(_3\) (3) and B\(_4\) (4), and four related 5,8′-linked monomeric alkaloids, named ikelacongolines A–D (5a, 5b, 6, and 7). The dimers 3 and 4 are structurally unusual quateraryls comprising two 5,8′-coupled monomers linked via a sterically strongly constrained 6′,1′′-connection between their naphthalene units. These compounds contain seven elements of chirality, four stereogenic centers and three consecutive chiral axes. They were identified along with two known related compounds, the mbandakamines A (1) and B\(_2\) (2), which had so far only been detected in two Ancistrocladus species indigenous to the Northwestern Congo Basin. In addition, five known monomeric alkaloids, previously found in related Central African Ancistrocladus species, were isolated from the here investigated Congolese liana, three of them belonging to the subclass of 5,8′-coupled naphthylisoquinoline alkaloids, whereas two compounds exhibited a less frequently occurring 7,8′-biaryl linkage. The stereostructures of the new alkaloids were established by spectroscopic (in particular HRESIMS, 1D and 2D NMR), chemical (oxidative degradation), and chiroptical (electronic circular dichroism) methods. The mbandakamines B\(_3\) (3) and B\(_4\) (4) displayed pronounced activities in vitro against the malaria parasite Plasmodium falciparum and the pathogen of African sleeping sickness, Trypanosoma brucei rhodesiense. KW - chemistry Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-201141 VL - 9 IS - 21 ER - TY - JOUR A1 - Pimentel-Elardo, Sheila M. A1 - Buback, Verena A1 - Gulder, Tobias A. M. A1 - Bugni, Tim S. A1 - Reppart, Jason A1 - Bringmann, Gerhard A1 - Ireland, Chris M. A1 - Schirmeister, Tanja A1 - Hentschel, Ute T1 - New Tetromycin Derivatives with Anti-Trypanosomal and Protease Inhibitory Activities JF - Marine drugs N2 - Four new tetromycin derivatives, tetromycins 1-4 and a previously known one, tetromycin B (5) were isolated from Streptomyces axinellae Pol001(T) cultivated from the Mediterranean sponge Axinella polypoides. Structures were assigned using extensive 1D and 2D NMR spectroscopy as well as HRESIMS analysis. The compounds were tested for antiparasitic activities against Leishmania major and Trypanosoma brucei, and for protease inhibition against several cysteine proteases such as falcipain, rhodesain, cathepsin L, cathepsin B, and viral proteases SARS-CoV M(pro), and PL(pro). The compounds showed antiparasitic activities against T. brucei and time-dependent inhibition of cathepsin L-like proteases with K(i) values in the low micromolar range. KW - cysteine protease KW - drugs KW - streptomyces KW - discovery KW - anti-trypanosomal KW - protease inhibition KW - Streptomyces axinellae KW - marine sponge KW - tetromycin Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-141171 VL - 9 IS - 10 ER - TY - JOUR A1 - Fayez, Shaimaa A1 - Feineis, Doris A1 - Mudogo, Virima A1 - Awale, Suresh A1 - Bringmann, Gerhard T1 - Ancistrolikokines E-H and related 5,8\('\)-coupled naphthylisoquinoline alkaloids from the Congolese liana \(Ancistrocladus\) \(likoko\) with antiausterity activities against PANC-1 human pancreatic cancer cells JF - RSC Advances N2 - A striking feature of the metabolite profile of \(Ancistrocladus\) \(likoko\) (Ancistrocladaceae) is the exclusive production of 5,8\('\)-linked naphthylisoquinoline alkaloids varying in their OMe/OH substitution patterns and in the hydrogenation degree in their isoquinoline portions. Here we present nine new compounds of this coupling type isolated from the twigs of this remarkable Central African liana. Three of them, the ancistrolikokines E (9), E\(_2\) (10), and F (11), are the first 5,8\('\)-linked naphthyldihydroisoquinolines found in nature with \(R\)-configuration at C-3. The fourth new metabolite, ancistrolikokine G (12), is so far the only representative of the 5,8\('\)-coupling type that belongs to the very rare group of alkaloids with a fully dehydrogenated isoquinoline portion. Moreover, five new \(N\)-methylated naphthyltetrahydroisoquinolines, named ancistrolikokines A\(_2\) (13), A\(_3\) (14), C\(_2\) (5), H (15), and H\(_2\) (16) are presented, along with six known 5,8\('\)-linked alkaloids, previously identified in related African \(Ancistrocladus\) species, now found for the first time in \(A.\) \(likoko\). The structural elucidation was achieved by spectroscopic analysis (HRESIMS, 1D and 2D NMR) and by chemical (oxidative degradation) and chiroptical (electronic circular dichroism) methods. The new ancistrolikokines showed moderate to good preferential cytotoxic activities towards pancreatic PANC-1 cells in nutrient-deprived medium (NDM), without causing toxicity under normal, nutrient-rich conditions, with ancistrolikokine H\(_2\) (16) being the most potent compound. KW - chemistry KW - Ancistrocladus likoko KW - alkaloids KW - bioactive compound KW - anti-cancer-agent KW - pancreatic cancer KW - naphthylisoquinoline alkaloid KW - spectroscopic analysis Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-172008 VL - 7 IS - 85 ER - TY - JOUR A1 - Pimentel-Elardo, Sheila M. A1 - Buback, Verena A1 - Gulder, Tobias A. M. A1 - Bugni, Tim S. A1 - Reppart, Jason A1 - Bringmann, Gerhard A1 - Ireland, Chris M. A1 - Schirmeister, Tanja A1 - Hentschel, Ute T1 - New Tetromycin Derivatives with Anti-Trypanosomal and Protease Inhibitory Activities N2 - Four new tetromycin derivatives, tetromycins 1–4 and a previously known one, tetromycin B (5) were isolated from Streptomyces axinellae Pol001T cultivated from the Mediterranean sponge Axinella polypoides. Structures were assigned using extensive 1D and 2D NMR spectroscopy as well as HRESIMS analysis. The compounds were tested for antiparasitic activities against Leishmania major and Trypanosoma brucei, and for protease inhibition against several cysteine proteases such as falcipain, rhodesain, cathepsin L, cathepsin B, and viral proteases SARS-CoV Mpro, and PLpro. The compounds showed antiparasitic activities against T. brucei and time-dependent inhibition of cathepsin L-like proteases with Ki values in the low micromolar range. KW - Biologie KW - tetromycin KW - anti-trypanosomal KW - protease inhibition KW - Streptomyces axinellae KW - marine sponge Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75465 ER - TY - CHAP A1 - Burschka, Christian A1 - Bringmann, Gerhard A1 - Busse, Holger A1 - Guessregen, Stefan A1 - Schoener, Bernd A1 - Zagst, Rainer T1 - Structure and dynamics of free and metallated benzonaphthopyranones and -pyrans N2 - First calculations of the structures of metal-free and complexed biaryl lactones and their confrrmation by X-ray crystaIlography, the search for the transition states of their heIimerization processes, and the spectroscopic determination of the heIimerization barriers of related cyclic ethers by DNMR are reported. Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-46858 ER - TY - JOUR A1 - Bringmann, Gerhard A1 - Hartung, Thomas A1 - Goebel, Lothar A1 - Schupp, Olaf A1 - Ewers, Christian L. J. A1 - Schoener, Bernd A1 - Zagst, Rainer A1 - Peters, Karl A1 - Von Schnering, Hans Georg A1 - Burschka, Christian T1 - Novel concepts in directed biaryl synthesis, IX: Synthesis and structure of benzonaphthopyranones, useful bridged model precursors for stereoselective biaryl syntheses N2 - A practicable two-step procedure for the preparation of a series of lactone-type bridged biaryls 7 as favorable substrates for subsequent atropisomer-selective ring-opening reactions is described. Due to the efficiency of the coupling step, which tolerates even a telt·butyl group next to the biaryl axis and avoids problems of regioselectivity, a variety of differently substituted representatives is prepared. These cover a broad range of steric hindrance and thus molecular distortion. The structures are investigated mainly by NMR spectroscopy and X-ray diffraction, showing the lactones 7 to be helically distorted, depending on the size of the residues R. KW - Chemie Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-46635 ER - TY - JOUR A1 - Wang, Hui A1 - Li, Min-Yi A1 - Katele, Félix Zongwe A1 - Satyanandamurty, Tirumani A1 - Wu, Jun A1 - Bringmann, Gerhard T1 - Decandrinin, an unprecedented \(C_9\)-spiro-fused 7,8-\( seco-ent\)-abietane from the Godavari mangrove \(Ceriops\ decandra\) JF - Beilstein Journal of Organic Chemistry N2 - Decandrinin (1), an unprecedented \(C_9\)-spiro-fused 7,8-\(seco-ent\)-abietane, was obtained from the bark of an Indian mangrove, \(Ceriops\ decandra\), collected in the estuary of Godavari, Andhra Pradesh. The constitution and the relative configuration of 1 were determined by HRMS (ESI) and extensive NMR investigations, and the absolute configuration by circular dichroism (CD) and optical-rotatory dispersion (ORD) spectroscopy in combination with quantum-chemical calculations. Decandrinin is the first 7,8-\(seco-ent\)-abietane. KW - ceriops decandra KW - abietane KW - absolute configuration KW - circular dichroism KW - decandrinin KW - rhizophoraceae Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119983 SN - 1860-5397 VL - 10 ER - TY - JOUR A1 - Messi, Bernadette Biloa A1 - Ndjoko-Ioset, Karine A1 - Hertlein-Amslinger, Barbara A1 - Lannang, Alain Meli A1 - Nkengfack, Augustin E. A1 - Wolfender, Jean-Luc A1 - Hostettmann, Kurt A1 - Bringmann, Gerhard T1 - Preussianone, a New Flavanone-Chromone Biflavonoid from Garcinia preussii Engl. JF - Molecules N2 - A new flavanone-chromone biflavonoid, preussianone (1), has been isolated from the leaves of Garcinia preussii, along with four known biflavonoids. The absolute stereostructures were elucidated by chemical, spectroscopic, and chiroptical methods. The biological properties of the new biflavonoid against several bacterial strains were evaluated. KW - multiflora KW - minimal inhibitory concentration KW - absolute configuration KW - circular dichroism KW - C-13 NMR KW - guttiferae KW - flavenoids KW - extractives KW - biflavanoids KW - livingstonei KW - high-temperature NMR KW - antibacterial activity KW - Garcinia biflavonoids Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130881 VL - 17 IS - 5 ER - TY - JOUR A1 - Jansen, Nils A1 - Ohlendorf, Birgit A1 - Erhard, Arlette A1 - Bruhn, Torsten A1 - Bringmann, Gerhard A1 - Imhoff, Johannes F. T1 - Helicusin E, Isochromophilone X and Isochromophilone XI: New Chloroazaphilones Produced by the Fungus Bartalinia robillardoides Strain LF550 JF - Marine Drugs N2 - Microbial studies of the Mediterranean sponge Tethya aurantium led to the isolation of the fungus Bartalinia robillardoides strain LF550. The strain produced a number of secondary metabolites belonging to the chloroazaphilones. This is the first report on the isolation of chloroazaphilones of a fungal strain belonging to the genus Bartalinia. Besides some known compounds (helicusin A (1) and deacetylsclerotiorin (2)), three new chloroazaphilones (helicusin E (3); isochromophilone X (4) and isochromophilone XI (5)) and one new pentaketide (bartanolide (6)) were isolated. The structure elucidations were based on spectroscopic analyses. All isolated compounds revealed different biological activity spectra against a test panel of four bacteria: three fungi; two tumor cell lines and two enzymes. KW - tethya aurantium KW - marine natural product KW - azaphilone KW - pentaketide KW - bartalinia robillardoides Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-129649 VL - 11 IS - 3 ER -