Publications

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In Press
2017
Aldhaher A, Langat M, Ndunda B, Chirchir D, Midiwo JO, Njue A, Schwikkard S, Carew M, Mulholland D. "Diterpenoids from the roots of Croton dichogamus Pax." Phytochemistry. 2017;144:1-8. AbstractFull text

Four previously undescribed diterpenoids including two crotofolanes, crotodichogamoin A and B, and two halimanes, crothalimene A and B, a new sesquiterpenoid, and fifteen previously reported compounds, including the crotofolane, crotohaumanoxide, the casbane, depressin, a further seven furanohalimane diterpenoids, three patchoulane and two further cadinane sesquiterpenoids and aleuritolic acid were isolated from the root of Croton dichogamus. Crotodichogamoin B is an important biosynthetic intermediate of the crotofolane class and this is the first report of patchoulene sesquiterpenoids from the genus. Compounds were tested at one concentration, 1 × 10−5 M, in the NCI59 cell one-dose screen but did not show significant activity snd were also evaluated for their cytotoxicity against Caco-2 cell lines using the neutral red assay. 10-epi-Maninsigin D reduced Caco-2 cell viability at 10, 30 and 100 μM, with values of decreased viability of 28%, 48% and 43% respectively. None of the other tested compounds showed significant activity.
Keywords
Croton dichogamusEuphorbiaceaeCrotofolaneCrotodichogamoin BCrothalimene ACrothalimene BPatchoulaneCaco-2 cell viability

Soares ACF, Cabral MMW, Martins CHG, Ferreira AE, Bergamo PAS, Omosa LK, Midiwo JO, Parreira RLT, Heleno VCG. "Study of Anti-Tuberculosis Activity Behaviour of Natural Kaurane and Trachylobane Diterpenes Compared with Structural Properties Obtained by Theoretical Calculations." Natural Product Communications. 2017;12(5):763-769. AbstractFull text

A set of seven diterpenes, three kauranes and four trachylobanes, isolated from the African plant Psiadia punctulata were assayed against Mycobacterium tuberculosis and reached activity comparable with cycloserine, a second line drug used to treat tuberculosis (TB). Several structural properties of those diterpenes, such as lipophilicity, HOMO and LUMO energies, charge density, and intramolecular hydrogen bond (IHB) formation, were obtained by theoretical calculations and compared with their activities. Peculiar correlations were observed, especially between activity, lipophilicity and IHB formation.

Study of anti-tuberculosis activity behaviour of natural kaurane and trachylobane diterpenes compared with structural properties obtained by theoretical calculations (PDF Download Available). Available from: https://www.researchgate.net/publication/317750342_Study_of_anti-tuberculosis_activity_behaviour_of_natural_kaurane_and_trachylobane_diterpenes_compared_with_structural_properties_obtained_by_theoretical_calculations [accessed Sep 25, 2017].

2014
Omosa LK, Amugune B, Ndunda B, Milugo TK, Heydenreich M, Yenesew A, Midiwo JO. "Antimicrobial flavonoids and diterpenoids from Dodonaea angustifolia." South African Journal of Botany. 2014. Abstract

The surface exudates of the leaves of Dodonaea angustifolia from Ngong forest population (6 km from Nairobi city center, Kenya) demonstrated antimicrobial activity against Gram-negative (Escherichia coli), Gram-positive (Staphylococcus aureus and Bacillus pumilus) bacteria and the fungus Sacchromyces cerevisiae. Chromatographic separation of the exudates yielded eight methylated flavonoids; 5-hydroxy-3, 4′,7-trimethoxyflavone (1), 3,5-dihydroxy-4′,7-dimethoxyflavone (2), santin (3), kumatakenin (4), rhamnocitrin (5), isokaempferide (6), 3,4′,5,7, tetrahydroxy-6-methoxyflavone (7), pinocembrin (8); two clerodanes, dodonic acid (9) and 2β-hydroxyhardwickiic acid (10) and one labdane; (ent-3β,8α)-15,16-epoxy-13(16),14-labdadiene-3,8-diol (11) diterpenoids. The flavonoid aglycones; 6, 7 and the clerodane diterpenoids; 9 and 10 and labdane diterpenoid, 11 were isolated for the first time from this plant species. The structures of the isolated compounds were identified using ultraviolet (UV), mass spectroscopy (MS), one dimension (1D) and two dimension (2D) nuclear magnetic resonance (NMR) spectroscopy and by comparison of the spectral data with literature. The quercetin derivative, 3,4′,5-trihydroxy-3′,7-dimethoxyflavone (12) showed broad spectrum antibacterial activities against E. coli and B. pumilus with minimum inhibition concentration (MIC) values less than 31.25 μg/well and against S. aureus with MIC below 62.5 μg/well. This compound showed poor antifungal activity against S. cerevisiae (MIC < 500 μg/well). Good antifungal activities were observed for 5,4′-dihydroxy-7-methoxyflavanone (13) and hautriwaic acid lactone (14) against S. cerevisiae with MIC values less than 7.8 μg/well. The most active antifungal compound was 5,7-dihydro-3,4′,6-trimethoxyflavone (3, santin) with an MIC value less than 3.9 μg/well against S. cerevisiae. The rest of the compounds exhibited weak to moderate activities. For comprehensive structure activity relationship studies (SAR), hautriwaic acid lactone (14), hautriwaic acid (15), penduletin (16) isolated from the surface exudates of D. angustifolia from Voi (200 km from Mombasa city center, Kenya) and 12 and 13 from Senecio roseiflorus isolated earlier were included in the bioassays.

2013
Machumi F, Midiwo JO, Jacob MR, Khan SI, Tekwani BL, Walker LA, Muhammad I. "Phytochemical, Antiparasitic and Antimicrobial Investigations of Terminalia brownii.". 2013. AbstractPhytochemical, Antiparasitic and Antimicrobial Investigations of Terminalia brownii

Terminalia brownii is an African medicinal plant used to treat parasitic and microbial infections [1]. Chromatographic separations on the stem bark extract aimed at identifying the active components led to isolation of a new oleanane-type triterpenoid, along with seven known oleanane-type triterpenoids and seven ellagic acid derivatives. The new compound was identified using spectroscopic methods as 3β,24-O-ethylidenyl-2α,19α-dihydroxyolean-12-en-28-oic acid (1). The compounds were evaluated for their antiplasmodial, antileishmanial and antimicrobial activities giving the most potent antiplasmodial activity with IC50 values of 2.76 µg/mL for 23-galloylarjunolic acid (2) against P. falciparum W2 strain and the most potent antimicrobial activity with IC50 values of 0.32 µg/mL for diellagic lactone (3) against C. glabrata.

2012
Machumi F, Yenesew A, Midiwo JO, Heydenreich M, Kleinpeter E, Khan S, Tekwani BL, Walker LA, Muhammad I. "Antiparasitic and anticancer carvotacetone derivatives from Sphaeranthus bullatus.". 2012.Website
2011
2010
Dr. Derese S, Omosa LK, Midiwo JO, Yenesew A, Peter MG, Heydenreich. M. "neo-Clerodane diterpenoids from the leaf exudate of Dodonaea angustifolia.". 2010. Abstractneo-Clerodane diterpenoids from the leaf exudate of Dodonaea angustifolia

Phytochemical investigation of the leaf surface exudate of Dodonaea angustifolia L.f. yielded two new neo-clerodane diterpenes, neo-clerodan-3,13-dien-16,15:18,19-diolide (mkapwanin) and 15-methoxy-neo-clerodan-3,13-dien-16,15:18,19-diolide (15-methoxymkapwanin). In addition, ten known compounds were identified. The structures were determined on the basis of spectroscopic evidence. This additional chemical information could contribute towards solving the taxonomical controversy that exists between Dodonaea angustifolia and Dodonaea viscosa Jacq., which are morphologically similar

Midiwo JO, Yenesew A, Juma BF, Omosa KL, Omosa IL, Mutisya D. "Phytochemical Evaluation of So me Kenyan Medicinal Plants.". 2010. AbstractPhytochemical Evaluation of So me Kenyan Medicinal Plants

11 th NAPRECA Symposium Book of Proceedings, Antananarivo, Madagascar Pages 9-19 Midiwo et al. 9 Phytochemical Evaluation of So me Kenyan Medicinal Plants J. Ogweno Midiwo, A. Yenesew, B.F. Juma Kerubo L Omosa, Irene L Omosa, Daniel Mutisya. Department of Chemistry, University of Nairobi, P.o. Box 30197, Nairobi. Kenya. E-mail: jmidiwo@uonbi.ac.ke Abstract There are more than 1200 described medicinal pl ants in Kenya from a flora of approximately 10,000 members. Strong cross-medical informati on from the 42 ethnic groups points to the high potential of some of these species. The Myrsinaceae are well established ethno-anthel mintics and anti-bacterials. They are harbingers of long alkyl side chain benzoquinones which clearly have a protective function from their histochemical disposition. The main benzoqui none in the sub-family Myrsinodae is embelin while for the Maesodae it is maesaquinone together with its 5-acetyl derivative; the distribution of these benzoquinones by their alkyl side chain le ngth or the presence / absence of 6-methyl group is in accord with morphological sub-fam ily de-limitation. The benzoquinones showed anti- feedant, anti-microbial, phytotoxic, acaricidal, in secticidal and nematicidal activity. Many other benzoquinones of medium and mi nor concentration were also isolated and characterised. Some plants belonging to the Polygonaceae which are widely used as ethno-anthelmintics have been studied. The common anthelmintic anthraquinones were obtained from all five Rumex species while the naphthalenic acetogenin deriva tive, nepodin was more selectively distributed. The leaf of Polygonum senegalense is upto 17% surface exudate; about thirteen non polar flavonoid derivatives (chalcones, di hydrochalcones, flavanones and a flavone) have been isolated from it. From the internal aerial tissues of this plant, the major flavonoids were common flavonoids, quercetin, kaempferol, luteolin a nd their glycosides. The only unique compound isolated from this plant was 2'-glucosy l-6'-hydroxy-4'-methoxychalcone whose aglycone, uvangolatin is part of the exuda te mixture. Other leaf exuda te plants studied included the stomach-ache medicine, Psiadia punctulata (Compositae) from which novel methylated flavonoids, kaurene and trachyloba n diterpenes have been found.

2009
Martin PG, Yenesew A, Heydenreich M, Guchu SM, lrungu B, Derese S, Midiwo JO. "Flavonoids and isoflavonoids of Erythrina burttii.". 2009.isoflavanoes_...0001.pdfWebsite
2008
2007
2006
Andayi AW, Yenesew A, Derese S, Midiwo JO, Gitu PM, Jondiko OJI, Akala H, Liyala P. "Antiplasmodial Flavonoids from Erythrina sacleuxii.". 2006.Website
2005
ABIY PROFYENESEW, O PROFMIDIWOJACOB. "Antimicrobial flavonoids from the stem bark of Erythrina burttii.". In: Fitotherapia, 469-472.; 2005. Abstract
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2004
2003
2002
Gikonyo NK, Hassanali A, Njagi PGN, Peter M, Midiwo JO. "Odor Composition of Preferred (Buffalo and Ox) and Nonpreferred (Waterbuck) Hosts of Some Savanna Tsetse Flies.". 2002. Abstracthttp://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/36947

A previous study on the feeding responses of tsetse flies, Glossina morsitans morsitans, implicated the existence of allomonal barriers, both volatile and nonvolatile, on the nonpreferred host, waterbuck, Kobus defassa. In the present study, electroantennogram-active compounds in odors from waterbuck were compared with those of two preferred hosts of tsetse flies, buffalo, Syncerus caffer, and ox, Bos indicus. Odors from the three bovids were trapped on activated charcoal and/or reverse-phase (octadecyl bonded) silica and analyzed with a gas chromatography-linked electroantennographic detector (GC-EAD) and, where possible, identified by using gas chromatography-linked mass spectrometry (GC-MS) and chromatographic comparisons with authentic samples. The GC-EAD profiles (with G. m. morsitans antennae) of the odors of the two preferred hosts were comparable, comprising medium-chain, saturated or unsaturated aldehydes and phenols, with buffalo emitting a few more EAG-active aldehydes. Waterbuck odor gave a richer profile, consisting of fewer aldehydes but more phenolic components and a series of 2-ketones (C8–C13) and δ-octalactone. This bovid also emits moderate amounts of C5–C9 straight-chain fatty acids, some of which were detected in buffalo and ox only in trace amounts. However, these did not elicit significant GC-EAD responses. Waterbuck profiles from the antennae of G. pallidipes showed broad similarity to those from G. m. morsitans, although the composition of aldehydes and ketones was somewhat different, indicating species-specific difference in the detection of host odors. Certain waterbuck-specific EAG-active components, particularly the 2-ketones and lactone, constitute a candidate allomonal blend in waterbuck odor.

ABIY PROFYENESEW, O PROFMIDIWOJACOB, O PROFMIDIWOJACOB. "Three isoflav-3-enes and a 2-arylbenzofuran from the root bark of Erythrina burttii.". In: Phytochemistry, 59, 337-341.; 2002. Abstract
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2001
2000
Martin PG, Heydenreich M, M. S, Midiwo.' JO, Yenesew A. "Op-37 Flavonoids from erythrina burttii and erythrina sacleuxii.". 2000. AbstractOp-37 Flavonoids from erythrina burttii and erythrina sacleuxii

The root and stem bark of Erythrina species are widely used in traditional medicine for the treatment of microbial infections: In our interest on the phytochemistry of Erythrina species of Kenya, we have isolated several flavonoids, including new flavanones (eg. 1) and isoflav-3-enes (eg 2) from Erythrina burttii; isoflavones (eg. 3) and isoflavanones (eg. '1) from Erythrina sac/euxii. Some of these compounds show antibacterial, anti-fimgal, anti-malarial and anti-oxidant activities. The structure elucidation and biological activities of some of these compounds will be discussed.

Echeverry C, Arredondo F, Abin-Carriquiry JA, Midiwo JO, Ochieng C, Kerubo L, Dajas F. "Pretreatment with Natural Flavones and Neuronal Cell Survival after Oxidative Stress: A Structure−Activity Relationship Study.". 2000. AbstractPretreatment with Natural Flavones and Neuronal Cell Survival after Oxidative Stress: A Structure−Activity Relationship Study

uercetin shows structural features that have been related to the antioxidant potency of flavonoids and also shows neuroprotection in different models of oxidative death. Because only a few studies have focused on the flavonoid structural requirements for neuroprotection, this work evaluated the protective capacity of 13 flavones structurally related to quercetin, isolated from Kenyan plants, to rescue primary cerebellar granule neurons from death induced by a treatment with 24 h of hydrogen peroxide (150 μM). Each flavone (0−100 μM) was applied 24 h prior to the oxidative insult, and neuronal viability was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results suggest that the o-dihydroxy substitution in the B-ring is not necessary to afford neuroprotection and could be partly responsible for neurotoxic effects. Furthermore, the hydroxy substitutions in the positions C3 (C-ring) in C5 and C7 (A-ring) would be important for neuroprotection in this model.

ABIY PROFYENESEW, O PROFMIDIWOJACOB, O PROFMIDIWOJACOB. "Two isoflavanones from stem bark of Erythrina sacleuxii.". In: Phytochemistry, 55, 457-459.; 2000. Abstract
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1999
Yenesew. A, Derese S, Midiwo JO, Peter MG. New isoflavonoids from the stem bark of Erythrina sacleuxii.; 1999.
1998
O PROFMIDIWOJACOB, ABIY PROFYENESEW, O PROFMIDIWOJACOB. "Four Isoflavones from the Stem Bark of Erythrina sacleuxii.". In: Phytochemistry, 49, 1, 247-249.; 1998. Abstract
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O PROFMIDIWOJACOB. "Four Isoflavones from the Stem Bark of Erythrina sacleuxii. Phytochemistry, 49, 1, 247-249.". In: Phytochemistry, 55, 457-459.; 1998. Abstract
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O PROFMIDIWOJACOB, O PROFMIDIWOJACOB. "Two prenylated flavonones from stem bark of Erythrinna burtii.". In: Phytochemistry, 48, 8 1439-1443).; 1998. Abstract
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1997
O PROFMIDIWOJACOB. "Diterpenoids from the leaf exudate of Psiada punctulata .". In: Phytochemistry Vol 45, (1) 117-120.; 1997. Abstract
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O PROFMIDIWOJACOB. "A new flavonol tetraglycoside from Myrsina africana leaves.". In: Natural Products letters, 9, 121-126.; 1997. Abstract
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O PROFMIDIWOJACOB, O PROFMIDIWOJACOB. "A new flavonol tetraglycoside from Myrsina africana leaves.". In: Natural Products letters, 9, 121-126.; 1997. Abstract
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1996
Midiwo JO. "A New Flavonol Tetraglycoside from Myrsine Africana Leaves.". 1996. AbstractA New Flavonol Tetraglycoside from Myrsine Africana Leaves

A new flavonol glycoside, quercetin 3 - glucosyl (1′″ - 4″) rhamnoside - 7 -rhamnosyl (1′″ - 6″″) glucoside (1) together with known flavonol glycosides, quercetin 3 -rhamnoside (2), quercetin 3 - glucoside (3) and myricetin 3 - galactoside (4) have been isolated from methanolic extract of Myrsine africana leaves and identified on the basis of their spectral data.

O PROFMIDIWOJACOB. "A flavonoid glycoside from Myrsine africana leaves.". In: Phytochemistry 43, (5) 1107-1109.; 1996. Abstract
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O PROFMIDIWOJACOB. "Four flavones from seed pods of Milletia dura.". In: Phytochemistry 41(3) pp 951-955.; 1996. Abstract
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O PROFMIDIWOJACOB. "New Dialkyl benzoquinone from fruits of Myrsine africana and Maesa lanceolata, Forsk.". In: Natural Products Letter 8, pp 11-14.; 1996. Abstract
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1995
O PROFMIDIWOJACOB. "Insect Anti-feedant, Growth Inhibiting and Larvicidal Compounds from Rapanea melanphloes (Myrsinaceae).". In: Insect Science Application, 16 (2) pp. 163-166.; 1995. Abstract
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1994
Derese S, Yenesew A, Midiwo JO, Heydenreich, Peter MG. "Anthraquinones, Pre-anthraquinones And Isoeleutherol In The Roots Of Aloe Species."; 1994.
Derese S, Yenesew A, Midiwo JO, Heydenreich, Peter MG. "The Chemotaxonomic Value Of Anthraquinones In Asphodelaceae.". 1994.Website
1993
1992
O PROFMIDIWOJACOB. "Chromatographic separation and spectroscopic analysis of Kenyan Myrsinaceae benzoquinones.". In: The Matsumae International Foundation Fellowship Report,(1992), Vol. 2. 143.; 1992. Abstract
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O PROFMIDIWOJACOB. "Flavonoids of Polygonum senegalense (Meisn) Part II: More surface and Internal Tissue Flavonoid Aglycones.". In: Bull. Chem. Soc. Ethip. (1992, 6(2) 119-122.; 1992. Abstract
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1991
1990
O PROFMIDIWOJACOB. "Anti-feedant effects of surface accumulated flavonoids of Polygonum senegalense.". In: Bull. Chem. Soc. Ethiop. (1990), 4(2), 123.; 1990. Abstract
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O PROFMIDIWOJACOB. "Benzoquinone Pigments in Kenyan Myrsinaceae:.". In: New 2,5-dihydroxyakyl derivatives from Maesa lanceolata. Bull. Chem. Soc. Ethiop. (1990), 4 (1) 71.; 1990. Abstract
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1989
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