@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{MengibarGananMirallesetal.2011,
  author    = {Mengibar, M. and Ganan, M. and Miralles, B. and Carrascosa, A. V. and Martinez-Rodriguez, Adolfo J. and Peter, Martin G. and Heras, A.},
  title     = {Antibacterial activity of products of depolymerization of chitosans with lysozyme and chitosanase against Campylobacter jejuni},
  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.2010.04.042},
  pages     = {844 -- 848},
  year      = {2011},
  abstract  = {Chitosan has several biological properties useful for the food industry, but the most attractive is its potential use as a food preservative of natural origin due to its antimicrobial activity against a wide range of food-borne microorganisms. Among food-borne pathogens, Campylobacter jejuni and related species are recognised as the most common causes of bacterial food-borne diarrhoeal disease throughout the world. Recently, it has been demonstrated that campylobacters are highly sensitive to chitosan. Even though chitosan is known to have important functional activities, poor solubility makes them difficult to use in food and biomedical applications. Unlike chitosan, the low viscosity and good solubility of chitosan oligosaccharides (COS) make them especially attractive in an important number of useful applications. In the present work, the effect of different COS on C. jejuni was investigated. Variables such as the physicochemical characteristics of chitosan and the enzyme used in COS preparation were studied. The COS had been fractioned using ultrafiltration membranes and each fraction was characterized regarding its FA and molecular weight distribution. It has been demonstrated that the biological properties of COS on Campylobacter depend on the composition of the fraction analysed. COS prepared by enzymatic hydrolysis with chitosanase were more active against Campylobacter that lysozyme-derived COS, and this behaviour seems to be related with the acetylation of the chains. On the other hand. the 10-30 kDa fraction was the most active COS fraction, independently of the enzyme used for the hydrolysis. These results have shown that COS could be useful as antimicrobial in the control of C. jejuni.},
  language  = {en}
}
@article{JumaAkalaEyaseetal.2011,
  author    = {Juma, Wanyama P. and Akala, Hoseah M. and Eyase, Fredrick L. and Muiva, Lois M. and Heydenreich, Matthias and Okalebo, Faith A. and Gitu, Peter M. and Peter, Martin G. and Walsh, Douglas S. and Imbuga, Mabel and Yenesew, Abiy},
  title     = {Terpurinflavone an antiplasmodial flavone from the stem of Tephrosia Purpurea},
  series = {Phytochemistry letters},
  volume    = {4},
  journal   = {Phytochemistry letters},
  number    = {2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1874-3900},
  doi       = {10.1016/j.phytol.2011.02.010},
  pages     = {176 -- 178},
  year      = {2011},
  abstract  = {The stem extract of Tephrosia purpurea showed antiplasmodial activity against the D6 (chloroquine-sensitive) and W2 (chloroquine-resistant) strains of Plasmodium falciparum with IC(50) values of 10.47 +/- 2.22 mu g/ml and 12.06 +/- 2.54 mu g/ml, respectively. A new prenylated flavone, named terpurinflavone, along with the known compounds lanceolatin A, (-)-semiglabrin and lanceolatin B have been isolated from this extract. The new compound, terpurinflavone, showed the highest antiplasmodial activity with IC(50) values of 3.12 +/- 0.28 mu M (D6) and 6.26 +/- 2.66 mu M (W2). The structures were determined on the basis of spectroscopic evidence.},
  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{MenezesGrigolonTodorovicetal.2009,
  author    = {Menezes, Bruno M. and Grigolon, Lisanne and Todorovic, Zoran and Peter, Martin G. and Franco, Telma T.},
  title     = {On the depolymerization of chitosan by papain : a re-assessment},
  year      = {2009},
  language  = {en}
}
@article{IssareeVijayakrishnanAbdelnuretal.2009,
  author    = {Issaree, Arisara and Vijayakrishnan, Balakumar and Abdelnur, Patricia V. and Corilo, Yuri E. and Riccio, Maria F. and Sanvido, Gustavo B. and Eberlin, Marcos N. and Peter, Martin G.},
  title     = {Mass spectrometry of aminoglucan oligosaccharides using electrospray ionization MS/MS and MS/MS/MS},
  year      = {2009},
  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}
}
@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{FettkePeikowPeteretal.2009,
  author    = {Fettke, Anja and Peikow, Dirk and Peter, Martin G. and Kleinpeter, Erich},
  title     = {Synthesis and conformational analysis of glycomimetic analogs of thiochitobiose},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2009.03.067},
  year      = {2009},
  abstract  = {The synthesis of six analogs of N,N;-diacetylchitobiose is reported, including a novel transglycosylation reaction for the preparation of S-aryl thioglycosides. The conformations of the compounds were studied by a combination of NMR spectroscopy and molecular modeling, using force field calculations. In the case of the S-aryl thioglycosides with exclusively S-glycosidic linkages, dihedral angles of the disaccharidic S-glycosidic bonds, ;; and ;; and of the S-arylglycoside bonds, ; and ;, were found to be similar, whereas they were different in mixed glycosides and in a thiazoline derivative. An adequate correlation between the calculated H,H-distances of the local minima and the measured NOE contacts was achieved by applying population-weighted averages over participating conformers based on weighted relative energies.},
  language  = {en}
}
@misc{BringmannMutanyattaComarMaksimenkaetal.2008,
  author    = {Bringmann, Gerhard and Mutanyatta-Comar, Joan and Maksimenka, Katja and Wanjohi, John M. and Heydenreich, Matthias and Brun, Reto and M{\"u}ller, Werner E. G. and Peter, Martin and Midiwo, Jacob O. and Yenesew, Abiy},
  title     = {Joziknipholones A and B : the First Dimeric Phenylanthraquinones, from the Roots of Bulbine frutescens},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-42638},
  year      = {2008},
  abstract  = {From the roots of the African plant Bulbine frutescens (Asphodelaceae), two unprecedented novel dimeric phenylanthraquinones, named joziknipholones A and B, possessing axial and centrochirality, were isolated, together with six known compounds. Structural elucidation of the new metabolites was achieved by spectroscopic and chiroptical methods, by reductive cleavage of the central bond between the monomeric phenylanthraquinone and -anthrone portions with sodium dithionite, and by quantum chemical CD calculations. Based on the recently revised absolute axial configuration of the parent phenylanthraquinones, knipholone and knipholone anthrone, the new dimers were attributed to possess the P-configuration (i.e., with the acetyl portions below the anthraquinone plane) at both axes in the case of joziknipholone A, whereas in joziknipholone B, the knipholone part was found to be M-configured. Joziknipholones A and B are active against the chloroquine resistant strain K1 of the malaria pathogen, Plasmodium falciparum, and show moderate activity against murine leukemic lymphoma L5178y cells.},
  language  = {en}
}