Browsing by Author "Atlabachew Minaleshewa"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Analytical Method Development for the Compositional Investigation of Khat (Catha Edulis Forsk) Leaves With Respect to its Active Constituents, Selected Secondary Metabolites and Inorganic Nutrients
    (Addis Ababa University, 2013-01-01) Atlabachew Minaleshewa; Chandravanshi B.S. (Professor); Redi Mesfin (PhD)
    The rapid growth of khat use and misuse in the countries of its origin and other parts of the world has led to the development of methods for extraction, clean-up, detection and quantification of its psychoactive alkaloids and other nutrients. However, the extraction and clean-up methods reported so far have a number of drawbacks and there is paucity of quality data with regard to the concentrations of its psychoactive alkaloids, phenolic compounds and mineral nutrients of Ethiopian khat accessions. Thus, this study addressed some of the challenges facing researchers in the area, such as the need to use easily accessible, simple, fast and plausible sample preparation techniques for khat alkaloids and tannins analysis. Furthermore, total polyphenols, selected essential and non-essential elements and fluoride accumulation in various khat cultivars were also investigated. Matrix solid phase dispersion (MSPD), molecularly imprinted polymer for solid phase extraction (MIP-SPE) and the modified quick, easy, cheap, effective, rugged and safe (QuEChERS) based methods were investigated for extraction and clean-up of khat alkaloids prior to HPLC-DAD detection. Under optimum conditions, good recoveries, selectivity and reproducibility were obtained. There was an assertion that drying khat leaves could significantly (if not completely) decompose cathinone to cathine. However, this study demonstrated that cathinone was persistently existed in dried plant material and it is wrong to assume that sun or oven drying the leaves could completely convert cathinone to cathine. This study also presents the quantitative determination of total phenolic compounds, flavonoids, tannins and their related in-vitro antioxidant activities of the young leaves, matured leaves and tips of tender stem near the young shoots. Simplified, rapid and robust method was also developed for the analysis of total tannins using egg albumin as a precipitating agent and Folin Denis reagent and FeCl3 solution for color developing moieties for spectrophotometric assay. In addition, the concentrations of selected major, minor and toxic metals as well as fluoride distribution in various khat cultivars and the corresponding soil samples were investigated by flame atomic absorption spectrometry and fluoride ion-selective electrode potentiometry, respectively. It was noticed that khat leaves could be a good sources of most of essential mineral nutrients and free from toxic metals like Pb and Cd. Analysis of fluoride in the edible portion of the khat leaves resolved the equivocal information about khat chewing and dental staining due to fluoride. It was found that the plant accumulated significantly lower concentrations of fluoride compared with similar stimulant plants.
  • No Thumbnail Available
    Item
    Studies on Commercially available Enset (Ensete ventricosum (Welw.), Cheesman) food Products (Kocho and Bulla) for Major, Minor and Trace Elements
    (Addis Ababa Universty, 2007-07) Atlabachew Minaleshewa; Chandravanshi B.S. (Professor)
    Kocho and Bulla are starchy foods obtained from fermenting edible part of the leaf sheath and corm of enset plant (Ensete ventricosum (Welw.), Cheesman). In the present study the level of selected metals (Na, Mg, Mn, Ni, Pb, K, Ca, Fe, Zn, Cu, Co, Cr, Cd) in Kocho and Bulla sampled from different supermarkets of Woliso (Oromiya region) and Welkite (SNNPRG) of Ethiopia were analyzed. Known weight of oven dried Kocho and Bulla samples were digested by wet digestion using 2 mL of HNO3 and 2 mL of HCLO4 for 2 h at variable temperature (120 - 270 oC). The contents of the minerals in the digests were analysed using flame atomic absorption spectrometer. The following concentration ranges (μg/g) were recorded in Kocho and Bulla, respectively: K (2753 – 4380) and (708 – 875); Na (462 – 688) and (402 – 442); Ca (498 - 584) and (385 - 446) ; Mg (180 - 290) and (58.4 - 89.5); Fe (92.5 -135) and (36.5 - 59.8); Zn (31 - 32.08) and (22 -44.3); Cu (3.4 – 4.3) and (2.01 - 3.53); Mn (8.58 -10.13) and (1.0 - 4.98); Ni (≤ 5.61) and (<4.0]; Cr (5.96 - 6.42) and (≤ 5.38); Co (5.5 - 6.1) and (5.0 - 5.01). Where as Cd and Pb were not detected in both types of food stuffs. The concentration of K was highest followed by Ca, Na and Mg in both food stuffs. From trace elements analysed, Zn was found to be highest next to Fe. Generally Kocho contained higher concentration compared to Bulla for the majority of the mineral nutrients identified. In general, Kocho and Bulla are rich in Ca and Zn compared to other similar food stuffs and contains comparable concentration of Cu, Fe and Mn. Beside Kocho and Bulla are free of heavy metal (Cd and Pb) contaminations compared to others. Key Words: Kocho, Bulla, Amicho, SNNPRG, Oromia, Enset, FAAS, Wolkite, Woliso, Major, Minor, Trace, Element