Specification of Trace Elements in Selected Medicinal Plants From Nyamira County (Kenya)

Abstract

In this study medicinal plants used by herbalist in Nyamira County, Kenya were evaluated and characterized for their elemental species. Experienced herbalists and the medicinal plants they use to treat different diseases were assessed. Elemental species in medicinal plants were determined and correlated to the diseases they treat. A questionnaire was administered to four hundred herbalists in four Sub-Counties, Borabu, Ekerenyo, Manga and Nyamira that comprise Nyamira County. Seventy six herbalists in each sub-county were randomly selected using the questionnaires. The herbalists were established by mapping their clinics using geographical position system (GPS). A total of three hundred and four medicinal plants were sampled from the herbalists and analyzed for various trace and macro elements. The questionnaires were analyzed to establish the demographics and social status of the herbalists, the predominant diseases treated and medicinal plants used by the herbalists. Total levels of magnesium, copper, zinc, iron, manganese and chromium in the medicinal plants were determined by flame Atomic absorption spectrometry using acetylene at 2000oC and inductively coupled plasma- mass spectrometry. Sequential Extractions was used to fractionate iron, chromium, manganese, zinc and copper in the medicinal plants. One hundred and sixty herbalists were found to treat predominantly malaria and diabetes and with high treatment success rates. Twelve medicinal plants were used to treat diabetes and ten medicinal plants were found to treat malaria. A total of 19 medicinal plants were used in the treatment of malaria and diabetes. The four mostly used medicinal plants to treat malaria with 100% usage were Aloe vera, Clerodendrum myricoides, Toddalia asiatica and Warburgia ugandensis while those used to treat diabetes were Bidens pilosa, Solanum indicum, Magnifera indica and Erythrina abyssinica. The macro elements found in the medicinal plants were calcium, magnesium, potassium and phosphorus whose concentration ranges were 2.4 to 39.04 g/Kg, 0.43 to 6.23 g/Kg, 3 to 59 g/Kg and 0.29 to 5.90 g/Kg respectively. The trace elements in the medicinal plants were zinc, copper, manganese, chromium and iron. The highest zinc level of 123.00 mg/Kg was found in Solanum mauense while the lowest level, 3.90 mg/Kg was found in Acacia hockii. The highest copper level of 29.00 mg/Kg was found in Bidens pilosa while the lowest level, 1.56 mg/Kg was found in Acacia hockii. The highest manganese level of 2990 mg/Kg was found in Croton macrostachyus while the lowest, 18.20 mg/Kg was in Acacia hockii. The highest chromium level of 3.20 mg/Kg were in Solanum mauense and Clerodendrum myricoides while the lowest, 0.04 mg/Kg was in Acacia hockii among the medicinal plants from Nyamira County. The iron levels in the medicinal plants (Carissa edulis, Clerodendrum myricoides, Melia azedarach, Toddalia asiatica) ranged from 1150 to 4700 mg/Kg. The results of the sequential extraction showed that the easily bioavailable fraction (EBF) of iron, chromium, manganese, zinc and copper, ranged from 0.2 to 0.4%, 6.7 to 13.8 %, 4.1 to 10%, 2.4 to 10.2% and 3.2 to 12.0 % while the potentially bioavailable fraction (PBF) ranged from 1.6 to 1.9%, 50.1 to 67.6 %, 32.2 to 48.7%, 23.0 to 41.1 % and 34.6 to 53.1% respectively. Acacia hockii had 4.47 mg/Kg of iron while Melia azedarach had 67.454 mg/Kg of iron extracted. 0.12 mg/Kg of chromium, 83.35 mg/Kg of manganese, 2.42mg/Kg of zinc and 2.53 mg/Kg of copper were extracted from Warburgia ugandensis. 1.75 mg/Kg of chromium from Solanum mauense, 745.63 mg/Kg of manganese from Croton macrostachyus, 29.31 mg/Kg of zinc from Solanum mauense and 7.12mg/Kg of copper from Bidens pilosa were extracted. Molecular size fractionation of elemental characterization showed that the percentage distribution across the fractions (<3 kDa, 3 kDa-10 kDa, 10 kDa-0.45 μm and 0.45μm-5 μm) was strongly dependent on the specific element. Bidens pilosa, Croton macrostachyus, Ultrica dioica and Solanum mauense which were used to treat diabetes by at least eighty percent (80%) of the herbalists in vi Nyamira County were found to be rich in chromium, magnesium, manganese, copper and zinc. Melia azedarach, Aloe vera, Clerodendrum myricoides and Tabernaemontana stapfiana which were used to treat malaria by at least ninety percent (90%) of the herbalists had bioavailale iron levels ranging from 67.454 to 11.053 mg/Kg. This is evidence that the herbalists are able to manage malaria and diabetes by use of their choice medicinal plants.