Keywords: inductively coupled plasma mass spectrometry, sequential filtration, medicinal plants, 15 trace elements, hot water extraction 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

No abstract

This study is focusing on a novel approach to screen a large number of medicinal plants from Kenya regarding their contents and availability of selected metals potentially relevant for treatment of diabetes patients. For this purpose, total levels of zinc, chromium, manganese, and copper were determined by flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry as well as BCR sequential extraction to fractionate the elemental species in anti-diabetic medicinal plants collected from five natural locations in two sub counties in Nyamira County, Kenya. Solanum mauense had the highest zinc level of 123.0 ± 3.1 mg/kg while Warburgia ugandensis had the lowest level of 13.9 ± 0.4 mg/kg. The highest level of copper was in Bidens pilosa (29.0 ± 0.6 mg/kg) while the lowest was in Aloe vera (3.0 ± 0.1 mg/kg). Croton macrostachyus had the highest manganese level of 1630 ± 40 mg/kg while Clerodendrum myricoides had the lowest (80.2 ± 1.2 mg/kg). The highest level of chromium was in Solanum mauense (3.20 ± 0.06 mg/kg) while the lowest (0.04 ± 0.01 mg/kg) were in Clerodendrum myricoides and Warburgia ugandesis among the medicinal plants from Nyamira and Borabu, respectively. The levels of the elements were statistically different from that of other elements while the level of a given element was not statistically different in the medicinal plants from the different sub counties. Sequential extraction was performed to determine the solubility and thus estimate the bioavailability of the four investigated essential and potentially therapeutically relevant metals. The results showed that the easily bioavailable fraction (EBF) of chromium, manganese, zinc, and copper ranged from 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 50.1 to 67.6%, 32.2 to 48.7%, 23.0 to 41.1%, and 34.6 to 53.1%, respectively. Bidens pilosa, Croton macrostachyus, Ultrica dioica, and Solanum mauense medicinal plants used to treat diabetes by 80 % of the herbalists in Nyamira County were found to be rich in chromium, manganese, copper, and zinc. The EBF of zinc, manganese, and chromium constitutes adequate amounts recommended for daily intake not exceeding the ADI and delivered a low percentage of RDA when estimating daily intake during therapy from typically applied doses. The plants did not show any significant differences at p < 0.05 in terms of concentrations of the elements between the two study areas though the levels of the different elements were statistically significant. Another major observation was that high total levels of the metals in a given plant did not necessarily translate to high bioavailable levels, and hence the need to determine bioavailable form as it is the one accessible to the patient.

Anaemia is a blood disorder which is widespread among populations of the world. In this study, seven medicinal plants used by one hundred and sixty herbalists from Nyamira County to manage anaemia were evaluated for iron and copper bio-accessibility. The competence of four hundred herbalists was assessed, of which 160 participated in the study. Twenty-one different medicinal plants were reported to be used by various herbalists to manage a number of ailments afflicting their communities in three sub-counties in Kenya. A total of ten different medicinal plants were found to be used by the herbalists to manage anemia which is endemic in the country. Seven of the medicinal plants, Aloe Vera, Carissa edulis, Croton macrostachyus, Clerodendrum myricoides, Melia azedrach, Toddalia asiatica and Warburgia ugandensis, were studied by all herbalists. The seven medicinal plants were prepared according to the herbalists&#039; procedure and analyzed for iron and copper through flame atomic absorption spectrophotometer. The mean iron level in Carissa edulis from Borabu was the highest (2635.48 ± 17.33 mg/kg), while that in Warburgia ugandensis from the Nyamira study area was the lowest (175.76 ± 5.03 mg/kg). The highest mean copper level (9.2 ± 1.24 mg/kg) was reported in Melia azedrach from Ekerenyo, while the lowest (2.12 ± 0.02 mg/kg) was reported in Carissa edulis from the Nyamira study area. Fractionation results indicated that the proportion of iron potentially released (bio-accessible) from all the medicinal plants was quite small. Clerodendrum myricoides had the highest mean iron release and solubility (16.4 mg/kg), while Warburgia ugandensis had the lowest (5.94 mg/kg) among the medicinal plants. More iron and copper were extracted enzymatically as compared to the aqueous extraction. The amount of iron extracted in the intestinal mimicked phase was more than that extracted in the gastric phase, while the reverse was observed for copper. The levels of bio-accessible iron and copper from the medicinal plants, especially those released in enzymatic extraction are quite high and the plants can be used in the management of anaemia.

No abstract

Analysis of essential and toxic elements is vital analytical process that could employ different analytical instruments depending on the analytical procedures. This paper presents the results of comparison of ICP-MS and FAAS as methods of quantification of the essential elements in the medicinal plants.  The essential elements in nineteen commonly used medicinal plants in Nyamira County, Kenya were quantified using the ICP-MS and FAAS techniques.  It was revealed that the results obtained by the two methods were statistically not different. The correlation coefficient values for the results of the two techniques in two study areas were close to unit indicating very strong positive relationship between the elemental levels determined by the two methods, though ICP-MS gave slightly higher values. However, any of the two methods could be used for the analytical quantification of the mineral elements in plants and since FAAS is cheap to purchase, maintain and provides reliable results it can be used in the analysis of various elements in plant, environmental and soil samples.

In this study, total and bio-available levels of cadmium (Cd), Lead (Pb), arsenic (As) and Thallium (Tl) in 19 Kenya plants from two study sites (Manga and Borabu) were evaluated. ICP-MS technique was used to determine total Cd, Pb, As and Tl contents, while ultra-filtration and physiological extraction tests evaluated bio-accessibility of these elements. The plants had low concentrations; Cd (0.27±0.02 and 0.26±0.02), As (0.32±0.02 and 0.48±0.04), Tl (0.07± 0.02 and 0.06±0.01) and Pb (1.23±0.11 and 1.16±0.10) mg/kg in Manga and Borabu sites. However, sequential ultra-filtration showed more than 70% high molecular weight species (>10 kDa) predominated with Pb, Cd and Tl. The physiological based tests showed Cd, Pb, As and Tl extracted enzymatically were significantly higher (0.45±0.11, 0.46±0.12, 0.37±0.10 and 0.81±0.19µg/g) than aquatically extracted (0.32±0.07, 0.34±0.11, 0.26±0.08 and 0.50±0.27) µg/g, (p<0.05). Low bio-accessibility levels of these elements in medicinal plants justifies their use therapeutically.

Background: In this study, the total and bio-accessible levels of cadmium (Cd), lead (Pb), and arsenic (As) in 19 Kenyan medicinal plants from two regions (Manga and Borabu) are presented. Methods: Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the total and bio-accessed heavy metals in plants. The NIST 1647 plant reference material was used to study the performance of the method. The method offered excellent quality parameters in terms of detection and quantification limits of 0.08 and 0.24 µg/kg, 0.5 and 1.5 µg/kg, and 3.1 and 9.5 µg /kg, linearity (r2 > 0.997) and recoveries of 95%, 99% and 93% for Cd, Pb, and As, respectively. Results: The dry weights of the plants from Manga and Borabu showed low concentrations of Cd (270 ± 20 and 260 ± 20), As (320 ± 20 and 480 ± 40), and Pb (1230 ± 110 and 1160 ± 100) µg/kg. Significantly higher mean concentrations of Cd, Pb, and As (0.45 ± 0.11, 0.46 ± 0.12 and 0.37 ± 0.10 µg/kg) than (0.32 ± 0.07, 0.34 ± 0.11 and 0.26 ± 0.08 µg/kg) were bioaccessible enzymatically than aquatically from dry weight (p<0.05). The percentage bioaccessibility of the elements from the plants ranged from 0.08 to 10.66% and 0.02 to 2.56% for the enzymatic and aquatic procedures, respectively.  Conclusion: The low bioaccessible concentrations of heavy (toxic) elements in plants justify their therapeutic use.