@article{ZalaStruszczykPeter2001, author = {Zala, Eva and Struszczyk, Marcin Henryk and Peter, Martin G.}, title = {Effects of preparation methods for chitosan films on their properties}, year = {2001}, language = {en} } @article{YenesewTwinomuhweziKiremireetal.2009, author = {Yenesew, Abiy and Twinomuhwezi, Hannington and Kiremire, Bernard T. and Mbugua, Martin N. and Gitu, Peter M. and Heydenreich, Matthias and Peter, Martin G.}, title = {8-Methoxyneorautenol and radical scavenging flavonoids from Erythrina abyssinica}, issn = {1011-3924}, year = {2009}, abstract = {A new pterocarpan (named 8-methoxyneorautenol) was isolated from the acetone ext. of the root bark of Erythrina abyssinica. In addn., the known isoflavonoid derivs. eryvarin L, erycristagallin and shinpterocarpin were identified for the first time from the roots of this plant. The structures were detd. on the basis of spectroscopic evidence. The new compd. showed selective antimicrobial activity against Trichophyton mentagrophytes. The acetone ext. of the root bark of E. abyssinica showed radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The pterocarpenes, 3-hydroxy-9-methoxy-10-(3,3-dimethylallyl)pterocarpene and erycristagallin, were the most active constituents of the roots of this plant and showing dose-dependent activities similar to that of the std. quercetin. [on SciFinder (R)]}, language = {en} } @article{YenesewMushibeIndulietal.2005, author = {Yenesew, Abiy and Mushibe, E. K. and Induli, M. and Derese, Solomon and Midiwo, Jacob O. and Kabaru, Jacques M. and Heydenreich, Matthias and Koch, Andreas and Peter, Martin G.}, title = {7a-O-methyldeguelol, a modified rotenoid with an open ring-C, from the roots of Derris trifoloata}, issn = {0031-9422}, year = {2005}, abstract = {From the acetone extract of the roots of Derris trifoliata an isollavonoid derivative, named 7a-O- methyldeguelol, a modified rotenoid with an open ring-C, representing a new sub-class of isollavonoids (the sub-class is here named as rotenoloid), was isolated and characterised. In addition, the known rotenoids, rotenone, deguelin and alpha-toxicarol, were identified. The structures were determined on the basis of spectroscopic evidence. Rotenone and deguelin were identified as the larvicidal principles of the acetone extract of the roots of Derris trifoliata. (c) 2005 Elsevier Ltd. All rights reserved}, language = {en} } @article{YenesewMidiwoMeisneretal.1998, author = {Yenesew, Abiy and Midiwo, Jacob O. and Meisner, M. and Heydenreich, Matthias and Peter, Martin G.}, title = {Two prenylated flavanones from stem bark of erythrina burttii}, year = {1998}, language = {en} } @article{YenesewMidiwoHeydenreichetal.2000, author = {Yenesew, Abiy and Midiwo, Jacob O. and Heydenreich, Matthias and Schanzenbach, Dirk and Peter, Martin G.}, title = {Two Isoflavanones from the Stem Bark of Erythrina sacleuxii}, year = {2000}, abstract = {From the stem bark of Erythrina sacleuxii two new isoflavanones, (R)-5,7-dihydroxy-2',4',5'- trimethoxyisoflavanone (trivial name, (R)-2,3-dihydro-7-demethylrobustigenin) and (R)-5-hydroxy- 2',4',5'-trimethoxy-2'',2''- dimethylpyrano[5'',6'':6,7]isoflavanone (trivial name, (R)-saclenone) were isolated. In addition the known compounds shinpterocarpin, 2,3-dehydrokievitone, abyssinone V, abyssinone V-4'-methyl ether, erythrinasinate and 4'-O-methylsigmoidin B were isolated. The structures were determined on the basis of spectroscopic evidence.}, language = {en} } @article{YenesewMidiwoHeydenreichetal.1998, author = {Yenesew, Abiy and Midiwo, Jacob O. and Heydenreich, Matthias and Peter, Martin G.}, title = {Four isoflavanones from stem bark of erythrina sacleuxii}, year = {1998}, language = {en} } @article{YenesewMidiwoGuchuetal.2002, author = {Yenesew, Abiy and Midiwo, Jacob O. and Guchu, S. M. and Heydenreich, Matthias and Peter, Martin G.}, title = {Three iosoflav-3-enes and a 2-arylbenzofuran from the root bark of Erythrina burttii}, year = {2002}, abstract = {From the root bark of Erythrina burttii three new isoflav-3-enes, 7,4'-dihydroxy-2'-methoxy-6- (1'',1''-dimethylallyl)isoflav-3-ene (trivial name, burttinol-A), 4'-hydroxy-2'- methoxy-(2'',2''-dimethylpyrano[5'',6'':8,7]isoflav-3-ene (trivial name, burttinol-B), 7,4'-dihydroxy-2'-methoxy-8-(3'',3''-dimethylallyl)isoflav-3-ene (trivial name, burttinol-C), and a new 2-arylbenzofuran, 6,4'-dihydroxy-2'-methoxy-5- (1'',1''-dimethylallyl)-2-arylbenzofuran (trivial name, burttinol-D) were isolated. In addition, the known compounds, abyssinone V-4'-methyl ether, bidwillol A, calopocarpin, erybraedin A, erythrabyssin II, isobavachalcone, phaseollidin and phaseollin were identified. The structures were determined on the basis of spectroscopic evidence.}, language = {en} } @article{YenesewKiplagatDereseetal.2006, author = {Yenesew, Abiy and Kiplagat, John T. and Derese, Solomon and Midiwo, Jacob O. and Kabaru, Jacques M. and Heydenreich, Matthias and Peter, Martin G.}, title = {Two unusual rotenoid derivatives, 7a-O-methyl-12a-hydroxydeguelol and spiro-13-homo-13-oxaelliptone, from the seeds of Derris trifoliata}, doi = {10.1016/j.phytochem.2006.01.002}, year = {2006}, abstract = {The crude methanol extract of the seeds of Derris trifoliata showed potent and dose dependent larvicidal activity against the 2nd instar larvae of Aedes aegypti. From this extract two unusual rotenoid derivatives, a rotenoloid (named 7a-O-methyl-12a-hydroxydeguelol) and a spirohomooxarotenoid (named spiro-13-homo-13-oxaelliptone), were isolated and characterised. In addition a rare natural chromanone (6,7-dimethoxy-4-chromanone) and the known rotenoids rotenone, tephrosin and dehydrodeguelin were identified. The structures were assigned on the basis of spectroscopic evidence. The larvicidal activity of the crude extract is mainly due to rotenone. (c) 2006 Elsevier Ltd. All rights reserved}, language = {en} } @article{YenesewIrunguDereseetal.2003, author = {Yenesew, Abiy and Irungu, Beatrice and Derese, Solomon and Midiwo, Jacob O. and Heydenreich, Matthias and Peter, Martin G.}, title = {Two prenylated flavonoids from the stem bark of Erythrina burttii}, year = {2003}, abstract = {From the stem bark of Erythrina burttii, a new isoflavone, 5,2',4'-trihydroxy-7-methoxy-6-(3- methylbut-2-enyl)isoflavone (trivial name, 7-O-methylluteone) and a new flavanone, 5,7-dihydroxy-4'-methoxy- 3'-(3-methylbutadienyl)-5'-(3-methylbut-2-enyl)flavanone (trivial name, burttinonedehydrate) along with three known isoflavonoids (8-prenylluteone, 3-O-methylcalopocarpin and genistein) were isolated. The structures were detd. on the basis of spectroscopic evidence.}, language = {en} } @article{YenesewInduliDereseetal.2004, author = {Yenesew, Abiy and Induli, M. and Derese, Solomon and Midiwo, Jacob O. and Heydenreich, Matthias and Peter, Martin G. and Akala, Hoseah M. and Wangui, Julia and Liyala, Pamela and Waters, Norman C.}, title = {Anti-plasmodial flavonoids from the stem bark of Erythrina abyssinica}, issn = {0031-9422}, year = {2004}, abstract = {The ethyl acetate extract of the stem bark of Erythrina abyssinica showed anti-plasmodial activity against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC50 values of 7.9 +/- 1.1 and 5.3 +/- 0.7 mug/ml, respectively. From this extract, a new chalcone, 2,3,4,4'-tetrahydroxy-5- prenylchalcone (trivial name 5-prenylbutein) and a new flavanone, 4',7-dihydroxy-3'-methoxy-5'- prenylflavanone (trivial name, 5-deoxyabyssinin II) along with known flavonoids have been isolated as the anti- plasmodial principles. The structures were determined on the basis of spectroscopic evidence. (C) 2004 Elsevier Ltd. All rights reserved}, language = {en} } @article{YenesewDereseMidiwoetal.2005, author = {Yenesew, Abiy and Derese, Solomon and Midiwo, Jacob O. and Bii, Christine C. and Heydenreich, Matthias and Peter, Martin G.}, title = {Antimicrobial flavonoids from the stem bark of Erythrina burttii}, issn = {0367-326X}, year = {2005}, abstract = {The chloroform extract of the stem bark of Erythrina burttii showed antifungal and antibacterial activities using the disk diffusion method. Flavonoids were identified as the active principles. Activities were observed against fungi and Gram(+) bacteria, but the Gram(-) bacteria Escherichia coli was resistant. (c) 2005 Elsevier B.V. All rights reserved}, language = {en} } @article{WanjohiYenesewMidiwoetal.2005, author = {Wanjohi, John M. and Yenesew, Abiy and Midiwo, Jacob O. and Heydenreich, Matthias and Peter, Martin G. and Dreyer, M. and Reichert, M. and Bringmann, Gerhard}, title = {Three dimeric anthracene derivatives from the fruits of Bulbine abyssinica}, issn = {0040-4020}, year = {2005}, abstract = {From the fruits of Bulbine abyssinica three new dimeric anthracene derivatives, (P)-8,9,1',8'- tetrahydroxy-3,3'-dimethyl[10,7'-bianthracene]-1,4,9',10'- tetraone (trivial name abyquinone A), (10R)-1,4,8,1',8-pentahydroxy-3,3'-dimethyl-[10,7'-bianthracene]9,9',10' (10H)-trione (trivial name abyquinone B), and (10R)-3,4'-dihydro-1,4,8,3',8',9'-hexahydroxy-3,3'- dimethyl-[10,7'-biant hracene]9,1'(10H,2'H)-dione (trivial name abyquinone Q were isolated. Despite their structural differences, these three compounds are connected to each other by the apparently biomimetic conversion of abyquinone C (a preanthraquinonylanthrone with two stereogenic centers) into B (an anthraquinonylanthrone with one stereogenic center) and finally into A (an axially chiral bianthraquinone) under mild conditions, involving a highly efficient center-to-axis chirality transfer. In addition, the known anthraquinones islandicin and chrysophanol were identified. The structures were determined on the basis of spectroscopical evidences, chemical transformations, and quantum chemical CD calculations. (C) 2005 Elsevier Ltd. All rights reserved}, language = {en} } @article{VijayakrishnanIssareeCoriloetal.2011, author = {Vijayakrishnan, Balakumar and Issaree, Arisara and Corilo, Yuri E. and Ferreira, Christina Ramires and Eberlin, Marcos N. and Peter, Martin G.}, title = {MSn of the six isomers of (GlcN)(2)(GlcNAc)(2) aminoglucan tetrasaccharides (diacetylchitotetraoses) rules of fragmentation for the sodiated molecules and application to sequence analysis of hetero-chitooligosaccharides}, series = {Carbohydrate polymers : an international journal devoted to scientific and technological aspects of industrially important polysaccharides}, volume = {84}, journal = {Carbohydrate polymers : an international journal devoted to scientific and technological aspects of industrially important polysaccharides}, number = {2}, publisher = {Elsevier}, address = {Oxford}, issn = {0144-8617}, doi = {10.1016/j.carbpol.2010.04.041}, pages = {713 -- 726}, year = {2011}, abstract = {The six possible isomers of di-N-acetylchitotetraoses [AADD, ADDA, ADAD, DADA, DAAD, and DDAA, where D stands for 2-amino-2-deoxy-3-D-glucose (GlcN) and A for 2-acetamido-2-deoxy-beta-D-glucose (GlcNAc)] were analyzed by ESI(+)-MSn. Collision induced dissociation via MSn experiments were performed for the sodiated molecules of m/z 769 [M+Na](+) for each isomer, and fragments were generated mainly by glycosidic bond and cross-ring cleavages. Rules of fragmentation were then established. A reducing end D residue yields the (O.2)A(4) cross-ring [M-59+Na](+) fragment of m/z 710 as the most abundant, whereas isomers containing a reducing end A prefer to lose water to form the [M-18+Na](+) ion of m/z 751, as well as abundant (O.2)A(4) cross-ring [M-101+Na](+) fragments of m/z 668 and B-3 [M-221+Na](+) ions of m/z 548. MS3 of C- and Y-type ions shows analogous fragmentation behaviour that allows identification of the reducing end next-neighbour residue. Due to gas-phase anchimeric assistance, B-type cleavage between the glycosidic oxygen and the anomeric carbon atom is favoured when the glycon is an A residue. Relative ion abundances are generally in the order B >> C > Y, but may vary depending on the next neighbour towards the non-reducing end. These fragmentation rules were used for partial sequence analysis of hetero-chitooligosaccharides of the composition D(2)A(3), D(3)A(3), D(2)A(4), D(4)A(3), and D(3)A(4).}, language = {en} } @article{vanAaltenKomanderSynstadetal.2002, author = {van Aalten, Daan M. F. and Komander, David and Synstad, Bjoenar and Gaseidnes, Sigrid and Peter, Martin G. and Eijsink, Vincent G. H.}, title = {Structural Insights into the catalytic mechanism of a family 18 exochitinase}, year = {2002}, abstract = {Chitinase B (ChiB) from Serratia marcescens is a family 18 exochitinase whose catalytic domain has a TIM-barrel fold with a tunnel-shaped active site. We have solved structures of three ChiB complexes that reveal details of substrate binding, substrateassisted catalysis, and product displacement. The structure of an inactive ChiB mutant (E144Q) complexed with a pentameric substrate (binding in subsites 22 to 13) shows closure of the ''roof'' of the active site tunnel. It also shows that the sugar in the 21 position is distorted to a boat conformation, thus providing structural evidence in support of a previously proposed catalytic mechanism. The structures of the active enzyme complexed to Allosamidin (an analogue of a proposed reaction intermediate) and of the active enzyme soaked with pentameric substrate show events after cleavage of the glycosidic bond. The latter structure shows reopening of the roof of the active site tunnel and enzyme-assisted product displacement in the 11 and 12 sites, allowing a water molecule to approach the reaction center. Catalysis is accompanied by correlated structural changes in the core of the TIM barrel that involve conserved polar residues whose functions were hitherto unknown. These changes simultaneously contribute to stabilization of the reaction intermediate and alternation of the pKa of the catalytic acid during the catalytic cycle.}, language = {en} } @article{VaajeKolstadVasellaPeteretal.2004, author = {Vaaje-Kolstad, G. and Vasella, A. and Peter, Martin G. and Netter, C. and Houston, Douglas R. and Westereng, B. and Synstad, Bjoenar and Eijsink, Vincent G. H. and van Aalten, Daan M. F.}, title = {Interactions of a family 18 chitinase with the designed inhibitor HM508 and its degradation product, chitobiono- delta-lactone}, issn = {0021-9258}, year = {2004}, abstract = {We describe enzymological and structural analyses of the interaction between the family 18 chitinase ChiB from Serratia marcescens and the designed inhibitor N,N'-diacetylchitobionoxime-N-phenylcarbamate (HM508). HM508 acts as a competitive inhibitor of this enzyme with a K-i in the 50 muM range. Active site mutants of ChiB show K-i values ranging from 1 to 200 muM, providing insight into some of the interactions that determine inhibitor affinity. Interestingly, the wild type enzyme slowly degrades HM508, but the inhibitor is essentially stable in the presence of the moderately active D142N mutant of ChiB. The crystal structure of the D142N-HM508 complex revealed that the two sugar moieties bind to the -2 and -1 subsites, whereas the phenyl group interacts with aromatic side chains that line the +1 and +2 subsites. Enzymatic degradation of HM508, as well as a Trp-->Ala mutation in the +2 subsite of ChiB, led to reduced affinity for the inhibitor, showing that interactions between the phenyl group and the enzyme contribute to binding. Interestingly, a complex of enzymatically degraded HM508 with the wild type enzyme showed a chitobiono-delta- lactone bound in the -2 and -1 subsites, despite the fact that the equilibrium between the lactone and the hydroxy acid forms in solution lies far toward the latter. This shows that the active site preferentially binds the E-4 conformation of the -1 sugar, which resembles the proposed transition state of the reaction}, language = {en} } @article{TsukamotoHaebelValencaetal.2008, author = {Tsukamoto, Junko and Haebel, Sophie and Valenca, Gustavo P. and Peter, Martin G. and FRanco, Telma T.}, title = {Enzymatic direct synthesis of acrylic acid esters of mono- and disaccharides}, issn = {0268-2575}, year = {2008}, abstract = {Background: There is an increased need to replace materials derived from fossil sources by renewables. Sugar- cane derived carbohydrates are very abundant in Brazil and are the cheapest sugars available in the market, with more than 400 million tons of sugarcane processed in the year 2007. The objective of this work was to study the prepn. of sugar acrylates from free sugars and free acrylic acid, thus avoiding the previous prepn. of protected sugar derivs., such as glycosides, or activated acrylates, such as vinyl acrylate. Results: Lipase catalyzed esterification of three mono- and two disaccharides with acrylic acid, in the presence or absence of mol. sieves was investigated. The reactions were monitored by high-performance liq. chromatog. (HPLC) and the products were analyzed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. The main products are mono- and diacrylates, while higher esters are formed as minor products. The highest conversion to sugar acrylates was obsd. for the D-glucose and D- fructose, followed by D-xylose and D-maltose. Mol. sieves had no pronounced effect on the conversion. Conclusions: A feasible method is described to produce and to characterize sugar acrylates, including those contg. more than two acrylate groups. The process for prodn. of these higher esters could potentially be optimized further to produce mols. for crosslinking in acrylate polymn. and other applications. The direct enzymic esterification of free carbohydrates with acrylic acid is unprecedented. [on SciFinder (R)].}, language = {en} } @article{ThieleRottmannGermeretal.2002, author = {Thiele, Gabriela and Rottmann, Antje and Germer, Antje and Kleinpeter, Erich and Spindler, Klaus-Dieter and Synstad, Bjoenar and Eijsink, Vincent G. H. and Peter, Martin G.}, title = {Synthesis and conformational analysis of pseudosugar analogues of chitotriose}, year = {2002}, abstract = {In this article, the synthesis of analogs of N,N',N''-triacetylchitotriose in which the central sugar residue was replaced by a succinic acid is presented. Mol. modeling calcns. revealed that the pseudotrisaccharides exist in low energy extended conformations which show similar space filling as N,N',N''-triacetylchitotriose. Of the N,N',N''-triacetylchitotriose pseudosugar analogs tested as chitinase inhibitors, none showed any appreciable competition (numerical data not presented). The conformational anal. along with further synthetic efforts will hopefully lead to more efficient pseudosaccharides as chitinase inhibitors.}, language = {en} } @article{StruszczykRatajskaBoryniecetal.1997, author = {Struszczyk, Marcin Henryk and Ratajska, M. and Boryniec, Stefan and Peter, Martin G. and Loth, Fritz}, title = {The determination of the degree of N-acetylation of chitosan}, year = {1997}, language = {en} } @article{StruszczykPospiesznySchanzenbachetal.2001, author = {Struszczyk, Marcin Henryk and Pospieszny, Henryk and Schanzenbach, Dirk and Peter, Martin G.}, title = {Biodegradation of various chitosans using Aspergillus fumigatus}, year = {2001}, language = {en} } @article{StruszczykLothPospiesznyetal.2001, author = {Struszczyk, Marcin Henryk and Loth, Fritz and Pospieszny, Henryk and Peter, Martin G.}, title = {Biodegradation of films and paper sheets containing chitosan}, year = {2001}, language = {en} } @article{StruszczykLothPeter1998, author = {Struszczyk, Marcin Henryk and Loth, Fritz and Peter, Martin G.}, title = {Analysis of deacetylation deree in chitosans from various sources}, year = {1998}, language = {en} } @article{StruszczykLothPeter1998, author = {Struszczyk, Marcin Henryk and Loth, Fritz and Peter, Martin G.}, title = {Calibration of methods for the determination of the degree of decatetylation of chitosan}, year = {1998}, language = {en} } @article{StruszczykLothPeter2000, author = {Struszczyk, Marcin Henryk and Loth, Fritz and Peter, Martin G.}, title = {Properties of microcrystalline chitosan gel-like dispersion and formed films}, year = {2000}, language = {en} } @article{StruszczykLothPeter1999, author = {Struszczyk, Marcin Henryk and Loth, Fritz and Peter, Martin G.}, title = {Preparation of paper sheets containing microcrystalline chitosan}, isbn = {3-9806494-5-8}, year = {1999}, language = {en} } @article{StruszczykLothPeter1999, author = {Struszczyk, Marcin Henryk and Loth, Fritz and Peter, Martin G.}, title = {Method of microcrystalline chitosan-protein films preparation}, year = {1999}, language = {en} } @article{StruszczykLothKoehleretal.1998, author = {Struszczyk, Marcin Henryk and Loth, Fritz and K{\"o}hler, L. A. and Peter, Martin G.}, title = {Characterization of chitosan}, year = {1998}, language = {en} } @article{StruszczykHalwegPeter1999, author = {Struszczyk, Marcin Henryk and Halweg, R. and Peter, Martin G.}, title = {Comparative analysis of chitosans from insects and crustacea}, isbn = {3-9806494-5-8}, year = {1999}, language = {en} } @article{StrefferKaatzBaueretal.1998, author = {Streffer, Katrin and Kaatz, Helvi and Bauer, Christian G. and Makower, Alexander and Schulmeister, Thomas and Scheller, Frieder W. and Peter, Martin G. and Wollenberger, Ursula}, title = {Application of a sensitive catechol detector for determination of tyrosinase inhibitors}, year = {1998}, language = {en} } @article{SchumacherWanderslebPetersenPeter1994, author = {Schumacher-Wandersleb, Michael H. M. G. and Petersen, Stefan and Peter, Martin G.}, title = {Preparation of the N-Acetylglucosaminidase inhibitor 1-Acetamido-1,2,5-tride oxy-2,5-imino-D-glucitol from methyl a-D-Mannopyranoside}, year = {1994}, language = {en} } @article{SchumacherWanderslebPeter1995, author = {Schumacher-Wandersleb, Michael H. M. G. and Peter, Martin G.}, title = {Synthesis of chitobiosyl pyrrolidines}, year = {1995}, language = {en} } @article{SchanzenbachPeter1997, author = {Schanzenbach, Dirk and Peter, Martin G.}, title = {NMR spectroscopy of chito-oligosaccharides}, year = {1997}, language = {en} } @article{SchanzenbachPeter1997, author = {Schanzenbach, Dirk and Peter, Martin G.}, title = {Chromatography of chito-oligosaccarides}, year = {1997}, language = {en} } @article{SchanzenbachMaternPeter1997, author = {Schanzenbach, Dirk and Matern, Christa-Maria and Peter, Martin G.}, title = {Cleavage of chitin by means of sulfurice acid/acetc anhydride and isolation of peracetylated chito- oligosaccharides}, year = {1997}, language = {en} } @article{SchanzenbachMaternPeter1997, author = {Schanzenbach, Dirk and Matern, Christa-Maria and Peter, Martin G.}, title = {Synthesis of glycosylamines and glycopeptides}, year = {1997}, language = {en} } @article{RusuNgWilkeetal.2005, author = {Rusu, Viorel Marin and Ng, C. H. and Wilke, Max and Tiersch, Brigitte and Fratzl, Peter and Peter, Martin G.}, title = {Size-controlled hydroxyapatite nanoparticles as self-organized organic-in organic composite materials}, issn = {0142-9612}, year = {2005}, abstract = {This paper presents some results concerning the size-controlled hydroxyapatite nanoparticles obtained in aqueous media in a biopolymer matrix from soluble precursors salts. Taking the inspiration from nature, where composite materials made of a polymer matrix and inorganic fillers are often found, e.g. bone, shell of crustaceans, shell of eggs, etc., the feasibility on making composite materials containing chitosan and nanosized hydroxyapatite was investigated. A stepwise co-precipitation approach was used to obtain different types of composites by means of different ratio between components. The synthesis of hydroxyapatite was carried out in the chitosan matrix from calcium chloride and sodium dihydrogenphosphate in alkaline solutions at moderate pH of 10-11 for 24 h. Our research is focused on studying and understanding the structure of this class of composites, aiming at the development of novel materials, controlled at the nanolevel scale. The X-ray diffraction technique was employed in order to study the kinetic of hydroxyapatite formation in the chitosan matrix as well as to determine the HAp crystallite sizes in the composite samples. The hydroxyapatite synthesized using this route was found to be nano-sized (15-50nm). Moreover, applying an original approach to analyze the (002) XRD diffraction peak profile of hydroxyapatite by using a sum of two Gauss functions, the bimodal distribution of nanosized hydroxyapatite within the chitosan matrix was revealed. Two types of size distribution domains such as cluster-like (between 200 and 400 nm), which are the habitat of "small" hydroxyapatite nanocrystallites and scattered-like, which are the habitat of "large" hydroxyapatite nanocrystallites was probed by TEM and CSLM. The structural features of composites suggest that self-assembly processes might be involved. The composites contain nanosized hydroxyapatite with structural features close to those of biological apatites that make them attractive for bone tissue engineering applications. (c) 2005 Elsevier Ltd. All rights reserved}, language = {en} } @article{RukungaMuregiOmaretal.2008, author = {Rukunga, G. M. and Muregi, F. W. and Omar, S. A. and Gathirwa, J. W. and Muthaura, C. N. and Peter, Martin G.}, title = {Anti-plasmodial activity of the extracts and two sesquiterpenes from Cyperus articulatus}, issn = {0367-326X}, year = {2008}, abstract = {Two sesquiterpenes, corymbolone and mustakone, isolated from the chloroform extract of the rhizomes of Cyperus articulatus, exhibited significant anti-plasmodial properties. Mustakone was approximately ten times more active than corymbolone against the sensitive strains of the Plasmodium falciparum.}, language = {en} } @article{RottmannSynstadThieleetal.1999, author = {Rottmann, Antje and Synstad, Bjoenar and Thiele, G. and Schanzenbach, Dirk and Eijsink, Vincent G. H. and Peter, Martin G.}, title = {Approaches towards the design of new chitinase inhibitors}, isbn = {3-9806494-5-8}, year = {1999}, language = {en} } @article{RottmannSynstadEijsinketal.1999, author = {Rottmann, Antje and Synstad, Bjoenar and Eijsink, Vincent G. H. and Peter, Martin G.}, title = {Synthesis of N-acetylglucosaminyl and diacetylchitobiosyl amides of heterocyclic carboxylic acids as potential chitinase inhibitors}, year = {1999}, language = {en} } @article{RatajskaStruszczykBoryniecetal.1997, author = {Ratajska, M. and Struszczyk, Marcin Henryk and Boryniec, Stefan and Peter, Martin G. and Loth, Fritz}, title = {The degree of acetylation of chitosan : optimization of the IR Method}, year = {1997}, language = {en} } @misc{PeterYenesewTwinomuhwezietal.2009, author = {Peter, Martin G. and Yenesew, Abiy and Twinomuhwezi, Hannington and Kabaru, Jacques M. and Akala, Hoseah M. and Kiremire, Bernard T. and Heydenreich, Matthias and Eyase, Fredrick and Waters, Norman C. and Walsh, Douglas S.}, title = {Antiplasmodial and larvicidal flavonoids from Derris trifoliata}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44614}, year = {2009}, abstract = {From the dichloromethane-methanol (1:1) extract of the seed pods of Derris trifoliata, a new flavanone derivative (S)-lupinifolin 4´-methyl ether was isolated. In addition, the known flavonoids lupinifolin and rotenone were identified. The structures were determined on the basis of spectroscopic evidence. Lupinfolin showed moderate in vitro antiplasmodial activity against the D6 (chloroquine-sensitive) and W2 (chloroquineresistant) strains of Plasmodium falciparum. The different parts of this plant showed larvicidal activities against Aedes aegypti and rotenoids were identified as the active principles.}, language = {en} } @article{PeterWollenberger1997, author = {Peter, Martin G. and Wollenberger, Ursula}, title = {Phenol-oxidizing enzymes : mechanisms and applications}, year = {1997}, language = {en} } @misc{PeterMuivaYenesewetal.2009, author = {Peter, Martin G. and Muiva, Lois M. and Yenesew, Abiy and Derese, Solomon and Heydenreich, Matthias and Akala, Hoseah M. and Eyase, Fredrick and Waters, Norman C. and Mutai, Charles and Keriko, Joseph M. and Walsh, Douglas S.}, title = {Antiplasmodial β-hydroxydihydrochalcone from seedpods of Tephrosia elata}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44437}, year = {2009}, abstract = {From the seedpods of Tephrosia elata, a new β-hydroxydihydrochalcone named (S)-elatadihydrochalcone was isolated. In addition, the known flavonoids obovatachalcone, obovatin, obovatin methyl ether and deguelin were identified. The structures were determined on the basis of spectroscopic evidence. The crude extract and the flavonoids obtained from the seedpods of this plant showed antiplasmodial activities. The literature NMR data on β-hydroxydihydrochalcones is reviewed and the identity of some of the compounds assigned β-hydroxydihydrochalcone skeleton is questioned.}, language = {en} } @article{PeterMerz1995, author = {Peter, Martin G. and Merz, A.}, title = {Stereoselective benzylic deprotonation in the enzymatic rearrangement of N-acetyldopamine derived o-Quinone to the p-Quinone methide}, issn = {0957-4166}, year = {1995}, language = {en} } @article{PeterLeyPetersenetal.1994, author = {Peter, Martin G. and Ley, J. P. and Petersen, Stefan and Londershausen, M. and Schumacher-Wandersleb, Michael H. M. G. and Spindler, Klaus-Dieter and Spindler-Barth, Margarethe and Turberg, Andreas}, title = {Synthesis of chitinase inhibitors}, year = {1994}, language = {en} } @article{PeterAndersen1994, author = {Peter, Martin G. and Andersen, S. O.}, title = {The molecular architecture of the insect exoskeleton}, year = {1994}, language = {en} } @article{Peter2002, author = {Peter, Martin G.}, title = {Chitin and Chitosan from Animal Sources}, isbn = {3-527-30227-1}, year = {2002}, abstract = {A review on the chem. and biochem. of chitin and the chem. and application of chitosan. The following topics were discussed: structure of chitin and chitosan; occurrence and physiol. functions of chitin; detection of chitin in animals and anal. of chitin and chitosan; biosynthesis and biodegrdn. of chitin in animals; prodn. of chitin and chitosan; properties of chitin and chitosan; and applications of chitin and chitosan.}, language = {en} } @article{Peter2002, author = {Peter, Martin G.}, title = {Chitin and Chitosan from Fungi}, isbn = {3-527-30227-1}, year = {2002}, language = {en} } @article{Peter1995, author = {Peter, Martin G.}, title = {Applications and environmental aspects of chitin and chitosan}, issn = {0022-233X}, year = {1995}, language = {en} } @article{Peter1995, author = {Peter, Martin G.}, title = {The Bio-organic chemistry of melanogenesis}, year = {1995}, language = {en} } @article{Peter1995, author = {Peter, Martin G.}, title = {Chemie i Biochemia Zewnetrznego Szkieletu Owadow : (Chemistry and biochemistry of the insect exoskeleton)}, year = {1995}, language = {en} }