title: 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.
abstract: 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.
authors.affiliation: Central Institute for Engineering, Electronics and Analytics, Analytics (ZEA-3), Forschungszentrum Juelich, 52425 Juelich, Germany. Electronic address: v.nischwitz@fz-juelich.de.
authors.forename: Volker
authors.initials: V
authors.lastname: Nischwitz
authors.affiliation: Chemistry Department, The University of Nairobi, P.O. Box 100, 30197 Nairobi, Kenya.
authors.forename: Richard
authors.initials: R
authors.lastname: Mogwasi
authors.affiliation: Central Institute for Engineering, Electronics and Analytics, Analytics (ZEA-3), Forschungszentrum Juelich, 52425 Juelich, Germany.
authors.forename: Salim
authors.initials: S
authors.lastname: Zor
authors.affiliation: Chemistry Department, Chuka University, P.O. Box 109, 60400 Chuka, Kenya.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Getenga
authors.affiliation: Chemistry Department, The University of Nairobi, P.O. Box 100, 30197 Nairobi, Kenya.
authors.forename: David K
authors.initials: DK
authors.lastname: Kariuki
authors.affiliation: Institut für Ernährungs- und Lebensmittelwissenschaften, Rheinische Friedrich-Wilhelms-Universität Bonn, Endenicher Allee 11-13, 53115 Bonn, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Günther
mesh_terms: D006358:Hot Temperature; D007630:Kenya; D010936:Plant Extracts / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D014131:Trace Elements / Q000032:analysis*; D014867:Water / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D014131:Trace Elements; D014867:Water
keywords: Hot water extraction; Inductively coupled plasma mass spectrometry; Medicinal plants; Sequential filtration; Trace elements