Antioxidant and Free Radical Scavenging Activities of Selected Kenyan Leafy Vegetables

C. I. Chepkwony, K. J. Cherutoi, L. W. Munyendo, R. Amdany


Naturally occurring antioxidants found in vegetables and fruits can play a critical role in deactivating free radicals often before they attack biological cells in humans. Indigenous Kenyan vegetables are potential sources of antioxidants due to their richness in phytochemicals. The study investigated free radical scavenging activities of two indigenous vegetables; Solanum nigrum (black night shade) and Gynandropsis gynandra (spider plant), and two exotic vegetables; Brassica olearacea C. (cabbage) and Brassica olearacea A. (kale), during dry and wet seasons. Fresh leaf samples were collected randomly during the two seasons. Burnt Forest (BF), Elgeyo Border (EB), Kapseret (KSS), Kesses (KS) and Moiben (MB) in Uasin Gishu County, Kenya, were used as sampling areas. Sample processing was carried out in the laboratory prior to analysis using UV-Vis spectroscopy. Radical scavenging potential values for the vegetable samples were 89% (black night shade), 79% (spider plant), 55% (kale) and 35% (cabbage). All species exhibited a 2, 2- diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity with Solanum nigrum and Gynandropsis gynandra demonstrating greater antioxidant potential. It was also observed that extracts of black night shade and spider plant exhibited higher reducing capacities than their exotic counterparts (kale and cabbage) with values ranging from 38.9±3.3 to 937.3±16.5 µmol Fe2+ g-1 for cabbage and black night shade, respectively. The order of increasing reducing capacities of samples followed the trend: cabbage, kale, spider plant and black night shade. It was concluded that indigenous vegetables demonstrated better reducing potential capacities as shown by their higher DPPH radical scavenging values compared to the exotic vegetables and this is indicative of their superior antioxidative power. The agroclimatic conditions of a sampling site also influenced the antioxidant potential of a vegetable.


Free Radical, Scavenging Activity, Leafy Vegetables, Antioxidants

Full Text:



Akubugwo, I. E., Obasi, A. N. and Ginika, S. C. (2007). Nutritional Potential of the Leaves and Seeds of Black Nightshade Solanum nigrum L. Var virginicum from Afikpo-Nigeria. Pakistan Journal of Nutrition, 6(4), 323-326.

Cadenas, S. E. (1989). Biochemistry of oxygen toxicity. Annual Reviews of Biochemistry, 58, 79–110.

Chai, T. T. and Wong, F. C. (2012), Whole-plant profiling of total phenolic and flavonoid contents, antioxidant capacity and nitric oxide scavenging capacity of Turnera subulata. Journal of Medicinal Plants Research, 6:1730–1735.

Chao, P., Lin, S., Lin, K., Liu, Y., Hsu, J., Yang, C. and Lai, J. (2014). Antioxidant Activity in Extracts of 27 Indigenous Taiwanese Vegetables. Nutrients, 6, 2115-2130.

Chebii, Z. (2014). The role of media in conflict management: the case of electoral conflict in Uasin Gishu County, Kenya. Unpublished Thesis.

Chweya, J. A. and Eyzaguirre, P. B. (1999). The Biodiversity of Traditional Leafy Vegetables. International Plant Genetic Resources Institute, Rome, Italy.

Ferreira, V., da Silva, T., Couto, S. and Srur, A. (2015). Total Phenolic Compounds and Antioxidant Activity of Organic Vegetables Consumed in Brazil. Food and Nutrition Sciences, 6, 798-804. doi: 10.4236/fns.2015.69083.

Francisca, I. S. and Eyzaguirre, P. (2007). African leafy vegetables: Their role in the World Health Organizat ion’s global fruit and vegetables initiative. African Journal of Food Agriculture Nutrition and Development, 7, 3-12.

Grubben, G. J. H. and Denton, O. A. (2004). Plant resources of tropical Africa 2. Vegetables. PROTA Foundation, Wageningen, The Netherlands; Backhuys Publishers, Leiden, The Netherlands; CTA, Wageningen, The Netherlands, pp. 191-200.

Huyut, Z., Beydemir, S. and Gülçin, I. (2017). Antioxidant and Antiradical Properties of Selected Flavonoids and Phenolic Compounds, Biochemistry Research International, PMC5660747.

Khan, M. E., Yakubu, U. D. and Kubmarawa, D. (2015).

Determination of Mineral Composition, Anti-microbial Activity and Anti-nutrient Screening of Cleome gynandra (Cat’s Whiskers). British Journal of Applied Science and Technology, 5(4), 396-402.

Kruger, M., Sayed, N., Langenhoven, M. and Holing, F. (1998). Composition of South African foods: Vegetables and fruits. Medical Research Council, Cape Town, South Africa.

Meda N. T. R., Bangou M. J., Bakasso S., Millogo-Rasolodimby J. and Nacoulma, O. G. (2013). Antioxidant activity of phenolic and flavonoid fractions of Cleome gynandra and Maerua angolensis of Burkina Faso. Journal of Applied Pharmaceutical Science, 3(2), 36-42.

Mibei, E. K. (2011). Nutritional, phytochemical and in vitro antimicrobial screening of some indigenous leafy vegetables. Unpublished, MSc. Thesis, Jomo Kenyatta University of Technology, Kenya.

Mitic, V., Jovanovic, V. S., Dimitrijevic, M., Cvetkovic, J. and Stojanovic, G. (2013). Effect of Food Preparation Technique on Antioxidant Activity and Plant Pigment Content in Some Vegetables Species. Journal of Food and Nutrition Research, 1(6), 121-127.

Odhav, B., Beekrum, S., Akula, U. S. and Baijnath, H. (2007). Preliminary assessment of nutritional value of traditional leafy vegetables in Kwa-Zulu Natal, South Africa. Journal of Food Composition and Analysis, 20, 430-435.

Orech, F. O., Christensen, D. L., Larsen, T., Friis, H., Aagaard-Hansen, J. and Estambale, B. A. (2007). Mineral content of traditional leafy vegetables from western Kenya. J. International Journal of Food Science and Nutrition, 58, 595-602.

Pakade, V. E. (2012). Development and application of Imprinted polymers for Selective adsorption of metal ions and flavonols in complex samples. Unpublished, PhD Thesis, University of Witwatersrand, South Africa.

Pezzuto, J. M. and Park, E. J. (2002). Autooxidation and antioxidants. In: Swarbrick, J. and Boylan, J.C., (Eds) Encyclopedia of pharmaceuticals technology. Vol 1, 2nd ed, New York, Marcel Dekker Inc., 97-113.

Rodriguez-Amaya, D. B. (2003). Food carotenoids: analysis composition and alterations during storagege and processing of foods. Forum Nutrition, 56, 35-37.

Sairam, R., Deshmukh, P. and Saxena D. C. (1998). Role of antioxidant systems in wheat genotypes tolerance to water stress. Journal of Plant Biology, 41, 387–394.

Silué, D. (2009). Spider plant: An indigenous species with many uses, The World Vegetable Center Regional Center for Africa, Arusha, Tanzania.


  • There are currently no refbacks.

© 2015 School of Environmental Studies all rights reserved. Permission should be sought from the publishers before any of this work or part of it is reproduced, transmitted in any form or by any means, electronic or mechanical, microfilming and recording, or by any information storage and retrieval system.