@article{InduliChelotiWasunaetal.2012,
  author    = {Induli, Martha and Cheloti, Michael and Wasuna, Antonina and Wekesa, Ingrid and Wanjohi, John M. and Byamukama, Robert and Heydenrich, Matthias and Makayoto, Moses and Yenesew, Abiy},
  title     = {Naphthoquinones from the roots of Aloe secundiflora},
  series = {Phytochemistry letters},
  volume    = {5},
  journal   = {Phytochemistry letters},
  number    = {3},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1874-3900},
  doi       = {10.1016/j.phytol.2012.04.014},
  pages     = {506 -- 509},
  year      = {2012},
  abstract  = {Two new naphthoquinones, 5-hydroxy-3,6-dimethoxy-2-methylnaphthalene-1,4-dione and 5,8-dihydroxy-3-methoxy-2-methylnaphthalene-1,4-dione, were isolated from the roots of Aloe secundiflora together with the known compounds chrysophanol, helminthosporin, isoxanthorin, ancistroquinone C, aloesaponarins I and II, aloesaponols I and II, laccaic acid D methyl ester and asphodelin. The structures were elucidated based on spectroscopic evidence. This appears to be the first report on the occurrence of naphthoquinones in the genus Aloe. Aloesaponarin I and 5-hydroxy-3,6-dimethoxy-2-methylnaphthalene-1,4-dione showed anti-bacterial activity against Mycobacterium tuberculosis with MIC values of 21-23 mu g/mL in the Microplate Alamar Blue Assay (MABA) and Low Oxygen Recovery Assay (LORA); 5-hydroxy-3,6-dimethoxy-2-methylnaphthalene-1,4-dione also showed cytotoxicity against the Vero cell line (IC50 = 10.2 mu g/mL).},
  language  = {en}
}
@article{GumulaHeydenreichDereseetal.2012,
  author    = {Gumula, Ivan and Heydenreich, Matthias and Derese, Solomon and Ndiege, Isaiah O. and Yenesew, Abiy},
  title     = {Four isoflavanones from the stem bark of Platycelphium voense},
  series = {Phytochemistry letters},
  volume    = {5},
  journal   = {Phytochemistry letters},
  number    = {1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1874-3900},
  doi       = {10.1016/j.phytol.2011.11.012},
  pages     = {150 -- 154},
  year      = {2012},
  abstract  = {From the stem bark of Platycelphium voense (Leguminosae) four new isoflavanones were isolated and characterized as (S)-5,7-dihydroxy-2 ',4 '-dimethoxy-3 '-(3 ''-methylbut-2 ''-enyl)-isoflavanone (trivial name platyisoflavanone A), (+)-5,7,2 '-trihydroxy-4 '-methoxy-3 '-(3 ''-methylbut-2 ''-enyl)-isoflavanone (platyisoflavanone B), 5,7-dihydroxy-4 '-methoxy-2 ''-(2 '''-hydroxyisopropyl)-dihydrofurano-[4 '',5 '':3 ',2 ']-isoflavanone (platyisoflavanone C) and 5,7,2 ',3 ''-tetrahydroxy-2 '',2 ''-dimethyldihydropyrano-[5 '',6 '':3 ',4 ']-isoflavanone (platyisoflavanone D). In addition, the known isoflavanones, sophoraisoflavanone A and glyasperin F; the isoflavone, formononetin; two flavones, kumatakenin and isokaempferide; as well as two triterpenes, betulin and beta-amyrin were identified. The structures were elucidated on the basis of spectroscopic evidence. Platyisoflavanone A showed antibacterial activity against Mycobacterium tuberculosis in the microplate alamar blue assay (MABA) with MIC = 23.7 mu M, but also showed cytotoxicity (IC50 = 21.1 mu M) in the vero cell test.},
  language  = {en}
}
@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{ReyesVazquezZeidaetal.2016,
  author    = {Reyes, Anibal M. and Vazquez, Diego S. and Zeida, Ari and Hugo, Martin and Dolores Pineyro, M. and Ines De Armas, Maria and Estrin, Dario and Radi, Rafael and Santos, Javier and Trujillo, Madia},
  title     = {PrxQ B from Mycobacterium tuberculosis is a monomeric, thioredoxin-dependent and highly efficient fatty acid hydroperoxide reductase},
  series = {Free radical biology and medicine : the official journal of the Oxygen Society, a constituent member of the International Society for Free Radical Research},
  volume    = {101},
  journal   = {Free radical biology and medicine : the official journal of the Oxygen Society, a constituent member of the International Society for Free Radical Research},
  publisher = {Elsevier},
  address   = {New York},
  issn      = {0891-5849},
  doi       = {10.1016/j.freeradbiomed.2016.10.005},
  pages     = {249 -- 260},
  year      = {2016},
  abstract  = {Mycobacterium tuberculosis (M. tuberculosis) is the intracellular bacterium responsible for tuberculosis disease (TD). Inside the phagosomes of activated macrophages, M. tuberculosis is exposed to cytotoxic hydroperoxides such as hydrogen peroxide, fatty acid hydroperoxides and peroxynitrite. Thus, the characterization of the bacterial antioxidant systems could facilitate novel drug developments. In this work, we characterized the product of the gene Rv1608c from M. tuberculosis, which according to sequence homology had been annotated as a putative peroxiredoxin of the peroxiredoxin Q subfamily (PrxQ B from M. tuberculosis or MtPrxQ B). The protein has been reported to be essential for M. tuberculosis growth in cholesterol-rich medium. We demonstrated the M. tuberculosis thioredoxin B/C-dependent peroxidase activity of MtPrxQ B, which acted as a two-cysteine peroxiredoxin that could function, although less efficiently, using a one-cysteine mechanism. Through steady-state and competition kinetic analysis, we proved that the net forward rate constant of MtPrxQ B reaction was 3 orders of magnitude faster for fatty acid hydroperoxides than for hydrogen peroxide (3x10(6) vs 6x10(3) M-1 s(-1), respectively), while the rate constant of peroxynitrite reduction was (0.6-1.4) x10(6) M-1 s(-1) at pH 7.4. The enzyme lacked activity towards cholesterol hydroperoxides solubilized in sodium deoxycholate. Both thioredoxin B and C rapidly reduced the oxidized form of MtPrxQ B, with rates constants of 0.5x10(6) and 1x10(6) M-1 s(-1), respectively. Our data indicated that MtPrxQ B is monomeric in solution both under reduced and oxidized states. In spite of the similar hydrodynamic behavior the reduced and oxidized forms of the protein showed important structural differences that were reflected in the protein circular dichroism spectra.},
  language  = {en}
}