@article{AtilawDuffyHeydenreichetal.2017,
  author    = {Atilaw, Yoseph and Duffy, Sandra and Heydenreich, Matthias and Muiva-Mutisya, Lois and Avery, Vicky M. and Erdelyi, Mate and Yenesew, Abiy},
  title     = {Three Chalconoids and a Pterocarpene from the Roots of Tephrosia aequilata},
  series = {Molecules},
  volume    = {22},
  journal   = {Molecules},
  number    = {2},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1420-3049},
  doi       = {10.3390/molecules22020318},
  pages     = {11},
  year      = {2017},
  abstract  = {In our search for new antiplasmodial agents, the CH2Cl2/CH3OH (1:1) extract of the roots of Tephrosia aequilata was investigated, and observed to cause 100\% mortality of the chloroquine-sensitive (3D7) strain of Plasmodium falciparum at a 10 mg/mL concentration. From this extract three new chalconoids, E-2,6-dimethoxy-3,4-(2,2-dimethyl)pyranoretrochalcone (1, aequichalcone A), Z-2,6-dimethoxy-3,4-(2,2-dimethyl)pyranoretrochalcone (2, aequichalcone B), 4-ethoxy-3-hydroxypraecansone B (3, aequichalcone C) and a new pterocarpene, 3,4:8,9-dimethylenedioxy-6a,11a-pterocarpene (4), along with seven known compounds were isolated. The purified compounds were characterized by NMR spectroscopic and mass spectrometric analyses. Compound 1 slowly converts into 2 in solution, and thus the latter may have been enriched, or formed, during the extraction and separation process. The isomeric compounds 1 and 2 were both observed in the crude extract. Some of the isolated constituents showed good to moderate antiplasmodial activity against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum.},
  language  = {en}
}
@article{MuthauraKerikoMutaietal.2017,
  author    = {Muthaura, Charles N. and Keriko, Joseph M. and Mutai, Charles and Yenesew, Abiy and Heydenreich, Matthias and Atilaw, Yoseph and Gathirwa, Jeremiah W. and Irungu, Beatrice N. and Derese, Solomon},
  title     = {Antiplasmodial, cytotoxicity and phytochemical constituents of four maytenus species used in traditional medicine in Kenya},
  series = {The natural products journal},
  volume    = {7},
  journal   = {The natural products journal},
  number    = {2},
  publisher = {Bentham Science Publ.},
  address   = {Sharjah},
  issn      = {2210-3155},
  doi       = {10.2174/2210315507666161206144050},
  pages     = {144 -- 152},
  year      = {2017},
  abstract  = {Background: In Kenya, several species of the genus Maytenus are used in traditional medicine to treat many diseases including malaria. In this study, phytochemical constituents and extracts of Maytenus undata, M. putterlickioides, M. senegalensis and M. heterophylla were evaluated to determine compound/s responsible for antimalarial activity. Objective: To isolate antiplasmodial compounds from these plant species which could be used as marker compounds in the standardization of their extracts as a phytomedicine for malaria. Methods: Constituents were isolated through activity-guided fractionation of the MeOH/CHCl3 (1:1) extracts and in vitro inhibition of Plasmodium falciparum. Cytotoxicity was evaluated using Vero cells and the compounds were elucidated on the basis of NMR spectroscopy. Results: Fractionation of the extracts resulted in the isolation of ten known compounds. Compound 1 showed promising antiplasmodial activity with IC50, 3.63 and 3.95 ng/ml against chloroquine sensitive (D6) and resistant (W2) P. falciparum, respectively and moderate cytotoxicity (CC50, 37.5 ng/ml) against Vero E6 cells. The other compounds showed weak antiplasmodial (IC50 > 1.93 mu g/ml) and cytotoxic (CC50 > 39.52 mu g/ml) activities against P. falciparum and Vero E6 cells, respectively. Conclusion: (20 alpha)-3-hydroxy-2-oxo-24-nor-friedela-1(10),3,5,7-tetraen-carboxylic acid-(29)-methyl-ester (pristimerin) (1) was the most active marker and lead compound that warrants further investigation as a template for the development of new antimalarial drugs. Pristimerin is reported for the first time in M. putterlickioides. 3-Hydroxyolean-12-en-28-oic acid (oleanolic acid) (5), stigmast-5-en-3-ol (beta-sitosterol) (6), 3-oxo-28-friedelanoic acid (7), olean-12-en-3-ol (beta-amyrin) (8), lup-20(29)-en-3-ol (lupeol) (9) and lup-20(29)-en-3-one (lupenone) (10) are reported for the first time in M. undata.},
  language  = {en}
}
@article{MuivaMutisyaAtilawHeydenreichetal.2018,
  author    = {Muiva-Mutisya, Lois M. and Atilaw, Yoseph and Heydenreich, Matthias and Koch, Andreas and Akala, Hoseah M. and Cheruiyot, Agnes C. and Brown, Matthew L. and Irungu, Beatrice and Okalebo, Faith A. and Derese, Solomon and Mutai, Charles and Yenesew, Abiy},
  title     = {Antiplasmodial prenylated flavanonols from Tephrosia subtriflora},
  series = {Natural Product Research},
  volume    = {32},
  journal   = {Natural Product Research},
  number    = {12},
  publisher = {Routledge, Taylor \& Francis Group},
  address   = {Abingdon},
  issn      = {1478-6419},
  doi       = {10.1080/14786419.2017.1353510},
  pages     = {1407 -- 1414},
  year      = {2018},
  abstract  = {The CH2Cl2/MeOH (1:1) extract of the aerial parts of Tephrosia subtriflora afforded a new flavanonol, named subtriflavanonol (1), along with the known flavanone spinoflavanone B, and the known flavanonols MS-II (2) and mundulinol. The structures were elucidated by the use of NMR spectroscopy and mass spectrometry. The absolute configuration of the flavanonols was determined based on quantum chemical ECD calculations. In the antiplasmodial assay, compound 2 showed the highest activity against chloroquine-sensitive Plasmodiumfalciparum reference clones (D6 and 3D7), artemisinin-sensitive isolate (F32-TEM) as well as field isolate (KSM 009) with IC50 values 1.4-4.6M without significant cytotoxicity against Vero and HEp2 cell lines (IC50>100M). The new compound (1) showed weak antiplasmodial activity, IC50 12.5-24.2M, but also showed selective anticancer activity against HEp2 cell line (CC50 16.9M). [GRAPHICS] .},
  language  = {en}
}
@article{AtilawHeydenreichNdakalaetal.2014,
  author    = {Atilaw, Yoseph and Heydenreich, Matthias and Ndakala, Albert and Akala, Hoseah M. and Kamau, Edwin and Yenesew, Abiy},
  title     = {3-Oxo-14 alpha, 15 alpha-epoxyschizozygine: A new schizozygane indoline alkaloid from Schizozygia coffaeoides},
  series = {Phytochemistry letters},
  volume    = {10},
  journal   = {Phytochemistry letters},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1874-3900},
  doi       = {10.1016/j.phytol.2014.07.003},
  pages     = {28 -- 31},
  year      = {2014},
  abstract  = {The stem bark extract of Schizozygia coffaeoides (Apocynaceae) showed moderate antiplasmodial activity (IC50 = 8-12 mu g/mL) against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the extract led to the isolation of a new schizozygane indoline alkaloid, named 3-oxo-14 alpha, 15 alpha-epoxyschizozygine. In addition, two dimeric anthraquinones, cassiamin A and cassiamin B, were identified for the first time in the family Apocynaceae. The structures of the isolated compounds were deduced on the basis of spectroscopic evidence. The schizozygane indole alkaloids showed good to moderate antiplasmodial activities (IC50 = 13-52 mu m). (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.},
  language  = {en}
}