David K. Kariuki

First Comprehensive Study on Total Contents and Hot water Extractable Fraction of selected elements in 19 Medicinal Plants from Various Locations in Nyamira County, Kenya.

A large number of medicinal plants is traditionally known in Kenya and used for treatment of various diseases, for example diabetes, where metals are supposed to be involved in pathogenesis and therapy. Therefore, detailed investigation of the concentration of a large number of metals in medicinal plants is required for improved understanding and optimisation of the therapeutic role of metals and also to exclude potentially toxic effects. Our study focused on the determination of 30 selected elements in 19 medicinal plant species each collected from 3 sampling locations in Nyamira County, Kenya. The obtained comprehensive data set showed large variability and multivariate data analysis revealed that the differences in the elemental composition were stronger dependent on the plant species than on the sampling location. In addition, hot water extractions were performed to mimic the traditional preparation of medicine from the plants. It was found that the mean extraction efficiencies were below 20% except for B, Mg, P, K, Mn, Co, Ni, Cu, Zn, Rb, Mo, Cd and Tl, which are mostly essential elements apart from Cd and Tl. Sequential (ultra)filtration of the extracts was applied as novel approach for molecular size-fractionation of the extracted elemental species. The results indicate more than 50% low molecular weight species (<3kDa) for Mg, Mn, Co, Ni and Zn while predominantly larger size-fractions (>3kDa up to<5μm) were detected for V, Cu, Al and Fe.

Zinc oxide photocatalytic decolourization of black tea (camellia sinensis) wastewater from processing factories in Kenya

* Patrick K.Tum 1 , David K. Kariuki 1 , Fredrick D.O. Oduor 1 and John K. Wanyoko 2 . 1. University of Nairobi, School of Physical Sciences, Department of Chemistry, P.O Box 30197-00100 Nairobi, Kenya. 2. Tea Research Institute of Kenya, P.O Box 861-20200, Kericho, Kenya. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Phytochemical and analgesic evaluation of Mondia whytei (hook.f) root

Mondia whytei is a forest floor plant that belongs to Asclepidaceae family. The roots are widely used in African traditional medicine to treat various diseases and conditions that include pain, swelling, postpartum hemorrhage, diabetes mellitus among many other claims. Phytochemical tests were carried out to determine the different chemical constituents of the root skeels of M. whytei. Analgesic activity of the root powder was evaluated using acetic acid induced writhing test. Phytochemical screening revealed the presence of carotenoids, flavonoids, steroids and tannins. The root skeels significantly (p < 0.05) reduced the number of writhes in acetic acid induced writhing test. This reduction was dosedependent. Therefore, the use of the plant by traditional medical practitioners in the treatment of pain may be justified.