Bio

Publications


2019

Catherine, K, Fidahusein DS, Wanjiru LC, Maina WJ, Carla K, Hahn D, Serge F, Paul G, Thomas S.  2019.  Effect of Vernodalol, a Sesquiterpene Lactone, on Economically Important Agricultural Fungi. International Journal of Innovative Science and Research Technology. 4(3):685-694. Abstract

The status of food insecurity in the world is devastating and fungal based diseases are a major cause that result in approximately 40-60% crop yield loss. Although synthetic chemical fungicides have been the preferred immediate method for management of fungal diseases, they have undesirable effects on human and animal health; causes environmental hazards, and are expensive. This study investigated whether the natural products from Vernonia glabra (Asteraceae) could be used as alternative biofungicide against disease causing agricultural fungi. Fractions were separated from V. glabra methanolic flower crude extract, using bioassay-guided fractionation. The single pure fraction yielded was selected for bioassay tests, and was isolated and characterized using chromatographic and spectrometric methods. In vitro bioassay test was performed against spore germination of Fusarium graminearum, F. oxysporum, F. verticillioides, Zymoseptoria tritici, Ustilago maydis, and Pyricularia oryzae. A known sesquiterpene lactone, Vernodalol was identified using high resolution mass spectrometry. In vitro bioassay results revealed that spores of Z. tritici were the most susceptible to Vernodalol, (42% spore inhibition) at 33 μg/100 μL compared to Azoxystrobin, a standard fungicide, (100% inhibition) against the fungus at 0.005 μg/100 μL. Vernodalol sprayed on 7 days old wheat seedlings that were inoculated with spores of Zymosepteria tritici, Puccinia triticina, and Helminthosporium sativum, at 50 and 200 ppm did not exhibit any disease control under greenhouse conditions. Azoxystrobin exhibited 90-100% disease control. V. glabra extracts have sesquiterpene lactones which are antifungal, however Vernodalol needs further research on its structural modification to increase efficacy against fungal pathogens.
Keywords:- Plant Fungal Diseases; Alternative Biofungicides; Sesquiterpene Lactones; Food Security.

Kitonde, C, Dossaji SF, Lukhoba CW, WAGACHA JOHNMAINA, Klittich C, Hahn D, Fotso S, Graupner P, Slanec T, Xiong Q.  2019.  In vitro studies of 3-O-Methylquercetin against phytopathogenic fungi of major cereals. Journal of Agricultural Science and Practice. 4(4):102-112. Abstract

Maize, wheat, and rice are major cereal crops in the world, which provide more caloric energy than any other type of cereal class. In recent years, the yield of these cereal grains has stagnated due to a myriad of constraints, including infestation by pests and pathogens. Plant pathogens, especially agricultural phytopathogenic fungi, may be resistant to the available chemical fungicides which may have detrimental effects and are expensive. This study investigated whether natural products isolated from Linzia glabra Steetz of family Asteraceae could be used as alternative antifungals for control of cereal diseases caused by agricultural fungi. A single pure fraction was separated and identified from L. glabra methanolic flower crude extract using high performance liquid chromatography and high resolution mass spectrometry methods. The pure fraction isolated was tested for inhibition of spore germination in vitro against Fusarium graminearum, Fusarium oxysporum, Fusarium verticillioides, Zymoseptoria tritici, Ustilago maydis, and Pyricularia oryzae. The fraction was identified as a flavonol, 3-O-Methylquercetin using high resolution mass spectrometry. Among the fungi tested, spores of Z. tritici were the most susceptible to 3-O-Methylquercetin (44% spore inhibition), followed by F. oxysporum (33% inhibition) at 27 μg/mL. Azoxystrobin, a standard commercialized fungicide, gave a complete inhibition of 100% against Z. tritici and 58% inhibition against F. oxysporum at 5 μg/mL. L. glabra contains flavonols with antifungal activity, but the modest and weak antifungal activity of 3-O-Methylquercetin compared to a standard such as azoxystrobin demonstrates the challenge to produce highly potent natural product fungicides. There is need for continued search for antifungals with new modes of action as solutions to challenges in agricultural production.

Keywords: Alternative antifungals, cereal crops, flavonoid concentration, flavonols, plant diseases, Linzia glabra Steetz.

2014

Kitonde*, CK, Fidahusein DS, Lukhoba CW, Jumba MM.  2014.  Antimicrobial Activity and Phytochemical Screening of Senna didymobotrya used to treat bacterial and fungal infections in Kenya. International Journal of Education and Research. 2(1):1-12.
Kitonde*, CK, Fidahusein DS, Lukhoba CW, Jumba MM.  2014.  Phytochemistry and Utilization of Vernonia glabra (Steetz) Oliv. & Hiern. in Management of Food Spoilage and Poisoning Pathogens, in Kenya. European International Journal of Science and Technology. 3(1):65-72.

2013

*Kitonde, C.K., Dossaji, S. F., Lukhoba, C.W., Jumba, M.M..  2013.  Antimicrobial Activity and Phytochemical Study of Vernonia glabra (Steetz) Oliv. & Hiern. in Kenya.. African Journal of Traditional, Complementary and Alternative Medicines.. 10(1):149-157.

2012

Kitonde, CK.  2012.  Antimicrobial activity and phytochemical screening of three selected medicinal plants used to treat bacterial and fungal infections in Kenya. , Nairobi: University of Nairobi Abstract

Infectious diseases are prevalent and life threatening in Kenya. The majority of the sick are
seeking herbal remedies in search of effective, safe, and affordable treatments. This study
investigated the antimicrobial activity and presence of alkaloids, terpenoids, sapogenins,
flavonoids and quinones in different parts of Vernonia glabra, Senna didymobotrya, and
Kigelia africana. Traditionally, these medicinal plants are used to treat microbial infections in
Kenya. The plants were selected based on the available traditional medical knowledge and
literature and collected in January 2010 in Machakos and Kisumu Counties. Different parts
were dried at room temperature under shade, ground into powder and extracted in
dichloromethane: methanol (1:1) and water. The crude extracts were tested against
Staphylococcus aureus (gram positive), Escherichia coli (gram negative) bacteria, Candida
albicans (yeast fungus), and Aspergillus niger (filamentous fungus) for antimicrobial activity
and Minimum Inhibitory Concentrations (MICs) determined using disc diffusion technique
under sterile conditions. Discs impregnated with standard antibiotics (Streptomycin for
bacteria and Nystatin for fungi) were used as positive controls while the extraction solvents
were used as negative controls. Antimicrobial activity was determined by measuring the
diameter of the clear inhibition zones around the paper discs using a transparent ruler (cm)
after 24 to 48 hours for bacteria and yeast fungus, and up to 72 hours for filamentous fungus.
Thin Layer Chromatography (TLC) was used to determine the chemical compounds present
in selected active crude extracts. Results showed that, organic extracts of V. glabra leaf
(Mean inhibition zone of 1.85 cm) and flower (MIZ of 1.78 cm) recorded the highest activity
against S. aureus than the standard antibiotic (Streptomycin MIZ of 1.30 cm). Organic extract
of V. glabra flower showed significant activity only against S. aureus, with the lowest MIC
of 1.5625 mg/100 mL compared to streptomycin at high MIC of 6.25 mg/100 mL. Qualitative
spray reagents on TLC plates, showed the V. glabra and S. didymobotrya flavonoids highly
present; terpenoids, sapogenins and quinones sufficiently present and V. glabra flower
alkaloids greatly present. The results of this study suggest that the three plants have
significant antimicrobial properties and justify their use in traditional herbal medicine for the
management of microbial based diseases. The presence of chemical compounds in most
extracts of V. glabra indicates its potential to produce novel compounds. Bioassay-guided
fractionations are recommended to identify the compounds responsible for antimicrobial
activity. Cytotoxicity assays are highly recommended for V. glabra in order to verify,
validate and document its safety in medicine.
Key words: Microbial infections, Vernonia glabra, Senna didymobotrya, Kigelia africa

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