@article{MutaiHeydenreichThoithietal.2013, author = {Mutai, Peggoty and Heydenreich, Matthias and Thoithi, Grace and Mugumbate, Grace and Chibale, Kelly and Yenesew, Abiy}, title = {3-Hydroxyisoflavanones from the stem bark of dalbergia melanoxylon - isolation, antimycobacterial evaluation and molecular docking studies}, series = {Phytochemistry letters}, volume = {6}, journal = {Phytochemistry letters}, number = {4}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1874-3900}, doi = {10.1016/j.phytol.2013.08.018}, pages = {671 -- 675}, year = {2013}, abstract = {Two new 3-hydroxyisoflavanones, (S)-3,4',5-trihydroxy-2',7-dimethoxy-3'-prenylisoflavanone (trivial name kenusanone F 7-methyl ether) and (S)-3,5-dihydroxy-2',7-dimethoxy-2 '',2 ''-dimethylpyrano[5 '',6 '':3',4']isoflavanone (trivial name sophoronol-7-methyl ether) along with two known compounds (dalbergin and formononetin) were isolated from the stem bark of Dalbergia melanoxylon. The structures were elucidated using spectroscopic techniques. Kenusanone F 7-methyl ether showed activity against Mycobacterium tuberculosis, whereas both of the new compounds were inactive against the malaria parasite Plasmodium falciparum at 10 mu g/ml. Docking studies showed that the new compounds kenusanone F 7-methyl ether and sophoronol-7-methyl ether have high affinity for the M. tuberculosis drug target INHA.}, language = {en} } @article{KeruboMidiwoDereseetal.2013, author = {Kerubo, Leonidah Omosa and Midiwo, Jacob Ogweno and Derese, Solomon and Langat, Moses K. and Akala, Hoseah M. and Waters, Norman C. and Peter, Martin and Heydenreich, Matthias}, title = {Antiplasmodial activity of compounds from the surface exudates of senecio roseiflorus}, series = {Natural product communications : an international journal for communications and reviews}, volume = {8}, journal = {Natural product communications : an international journal for communications and reviews}, number = {2}, publisher = {NPC}, address = {Westerville}, issn = {1934-578X}, pages = {175 -- 176}, year = {2013}, abstract = {From the surface exudates of Senecio roseiflorus fourteen known methylated flavonoids and one phenol were isolated and characterized. The structures of these compounds were determined on the basis of their spectroscopic analysis. The surface exudate and the flavonoids isolated showed moderate to good antiplasmodial activity with 5,4'-dihydroxy-7-dimethoxyflavanone having the highest activity against chloroquine-sensitive (D6) and resistant (W2) strains of Plasmodium falciparum, with IC50 values of 3.2 +/- 0.8 and 4.4 +/- 0.01 mu g/mL respectively.}, language = {en} } @article{AbdissaInduliAkalaetal.2013, author = {Abdissa, Negera and Induli, Martha and Akala, Hoseah M. and Heydenreich, Matthias and Midiwo, Jacob O. and Ndakala, Albert and Yenesew, Abiy}, title = {Knipholone cyclooxanthrone and an anthraquinone dimer with antiplasmodial activities from the roots of Kniphofia foliosa}, series = {Phytochemistry letters}, volume = {6}, journal = {Phytochemistry letters}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1874-3900}, doi = {10.1016/j.phytol.2013.02.005}, pages = {241 -- 245}, year = {2013}, abstract = {A new phenylanthrone, named knipholone cyclooxanthrone and a dimeric anthraquinone, 10-methoxy-10,7'-(chrysophanol anthrone)-chrysophanol were isolated from the roots of Kniphofia foliosa together with the rare naphthalene glycoside, dianellin. The structures were determined by NMR and mass spectroscopic techniques. The compounds showed antiplasmodial activities against the chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum with 10-methoxy-10,7'-(chrysophanol anthrone)-chrysophanol being the most active with IC50 values of 1.17 +/- 0.12 and 4.07 +/- 1.54 mu g/ml, respectively.}, language = {en} } @article{SzatmariHeydenreichKochetal.2013, author = {Szatmari, Istvan and Heydenreich, Matthias and Koch, Andreas and Fulop, Ferenc and Kleinpeter, Erich}, title = {Unexpected isomerization of new naphth[1,3]oxazino[2,3-a] isoquinolines in solution, studied by dynamic NMR and supported by theoretical DFT computations}, series = {Tetrahedron}, volume = {69}, journal = {Tetrahedron}, number = {35}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2013.06.094}, pages = {7455 -- 7465}, year = {2013}, abstract = {Through the reactions of 1-aminomethyl-2-naphthol and substituted 1-aminobenzyl-2-naphthols with 3,4-dihydroisoquinoline or 6,7-dimethoxy-3,4-dihydroisoquinoline under microwave conditions, naphth[1,2-e][1,3]oxazino[2,3-a]-isoquinoline derivatives were prepared in good yields. The latter reaction was extended by using 2-aminoarylmethyl-1-naphthols, leading to isomeric naphth-[2,1-e][1,3]oxazino[2,3-a] isoquinolines. Beside the detailed NMR spectroscopic and theoretical study of both stereochemistry and dynamic behaviour of these new conformational flexible heterocyclic ring systems an unexpected dynamic process between two diastereomers was observed in solution, studied by variable temperature H-1 NMR spectroscopy and the mechanism proved by theoretical DFT computations.}, language = {en} }