African Journal of Agricultural Research Vol. 5(18), pp. 2570-2575, 18 September, 2010 Available online at http://www.academicjournals.org/AJAR ISSN 1991-637X ©2010 Academic Journals Full Length Research Paper Distribution of total phenolics and antioxidant activity in fruit, leaf, stem and root of Monsonia burkeana N. D. Mamphiswana 1 , P. W. Mashela 1 * and L. K. Mdee 2 1 School of Agricultural and Environmental Sciences, University of Limpopo, Private Bag X 1106, Sovenga 0727, South Africa. 2 School of Health Sciences, University of Limpopo, Private Bag X 1106, Sovenga 0727, South Africa. Accepted 12 August, 2010 Monsonia burkeana, widely used as ‘special tea’, is harvested unsustainably due to insufficient information on the accumulative abilities of its organs on the secondary metabolites. Using phenolics and antioxidants as focus chemical compounds, an investigation was carried out to (1) determine the accumulative abilities of organs of M. burkeana on phenolic and antioxidant compounds, and (2) determine whether phenolic acids and antioxidants in M. burkeana had density-dependent relationship patterns. Ten plants per plot, with three replicates, were harvested whole, oven-dried, separated into the four organs and quantified for phenolics and antioxidant components using the Folin Ciocalteau method and the Trolox Equivalent Antioxidant Capacity (TEAC) assay, respectively. Generally, reproductive and vegetative organs had high levels of phenolic and antioxidant compounds when compared to roots. The saturation factor suggested that more than 90% antioxidants were derivatives of the phenolic compounds. Optimum levels of antioxidant activity were attained at 5.39, 5.49, 4.36 and 4.13 mg/ 100 g of phenolics in fruit, leaf, stem and root, respectively. In conclusion, vegetative and reproductive organs are good sources of phenolic and antioxidant compounds in M. burkeana. Key words: Phenolic, antioxidant, saturation factor, optimum. INTRODUCTION Interest has increased considerably in finding naturally occurring antioxidants for use in foods, medicinal materials or plant protection to replace synthetic compounds which are being restricted due to their carcinogenicity and environment-unfriendliness (Velioglu et al., 1998). Herbal teas are receiving much attention as functional medicinal beverages, because of their natural nutritive values that encompass essential nutrient elements such as N, P, K, Ca, Zn, Fe, vitamins, phenolics and antioxidant compounds. In most medicinal plants, for a particular organ to be considered as a harvestable organ, it must have a high accumulative ability for the focus chemical compound. Generally, when in doubt of which organ contains the highest concentration of the desired chemical compound; the entire plant is harvested - which is not sustainable. The accumulative abilities of organs on essential nutrient elements and secondary *Corresponding author. E-mail: Mashelap@ul.ac.za and Tel. + 27152682190. metabolites follow the density-dependent pattern, which is expounded by the saturation factor model (Salisbury and Ross, 1992). In this model, as the independent factor increases the dependent factor also increases to reach a threshold above which it begins to have an effect. Thereafter, the response increases sigmoidally, until the system becomes saturated, and as the stimulus continues to increase, the response remains constant and then begins to decrease if the stimulus at its high levels becomes inhibitory. Monsonia burkeana Planch. ex Harv. (Family Geraniaceae), is native to Southern Africa (Venter, 1979). Decoctions from this herb, referred to as ‘special tea’, are widely used in marginal communities that comprised former homeland areas of the Republic of South Africa. Most users of this herb believe that it has chemical pro- perties that range from blood cleansing, amelioration of erectile dysfunction and improvement of libido (IKS). The organ in which medicinal properties in M. burkeana is concentrated is not documented, resulting in locals harvesting and using the whole plant in preparation of decoctions. The objective of this study was to determine