Browsing by Author "Ele, Estifanos (PhD)"

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    Analysis and Determination of Acrylamide in Roasted Potato Chips (Potato Crisps) from Different Potato Chips Selling Centers In Addis Ababa
    (Addis Ababa University, 2018-06-05) Yihune, Getasew; Ele, Estifanos (PhD)
    Acrylamide or 2-propene amide is an organic compound formed in French fries, potato crisps, bread and coffee when they are fried, roasted or baked at a higher temperature. It is formed from the reaction of reducing sugars such as glucose and fructose with amino acids (asparagine). Many animal studies have shown that acrylamide is a carcinogenic, neurotoxic and genotoxic compound. In this study, GCMS instrument was used to analyze the presence and amount of acrylamide in roasted potato chips. The GCMS method to analyze acrylamide requires bromination type of derivatization to minimize interferences. Roasted potato chips samples were collected from Kebena, Arat kilo, Amist kilo, and Sidist kilo in Addis Ababa in 2018. From each sites light yellow color roasted potato chips (SFOPC) prepared from fresh palm oil and dark brown color roasted potato chips (SBOPC) prepared from the mixture of fresh and reused palm oil were collected. In all samples of roasted potato chips significant amount of acrylamide was investigated by using GCMS. The amount of acrylamide extracted from dark brown color potato chips (SBOPC) prepared from the mixture of fresh and reused palm oil is much higher than light yellow color potato chips (SFOPC) prepared from fresh palm oil. The highest amount was detected in samples collected from Kebena S5FOPC (light yellow potato chips) 10005μg/kg and S5BOPC (dark brown potato chips) 13933μg/kg while the lowest amount was detected in samples collected from Arat kilo S4FOPC (light yellow potato chips) 2511μg/kg and S4BOPC (dark brown potato chips) 7453μg/kg, respectively. Generally, to investigate the presence of acrylamide in roasted potato chips in this study samples were collected, grounded, extracted, purified by Solid phase extraction (SPE), brominated and 1 μL sample solution of 2-bromopropene amide (2-BPA) were injected and analyzed by GCMS.
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    Determination of 2,4-Dichlorophenoxyacetic Acid in Water Sediment and Soil Using High Performance Liquid Chromatography
    (Addis Ababa University, 2021-07-09) James, Stella; Ele, Estifanos (PhD)
    2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide throughout the world to control broad-leaved herbs in various crops. Despite widespread use in a number of countries, studies have revealed that 2,4-D is a possible carcinogen and has a number of neurotoxic effects. The purpose of this study was to develop a method for extracting and determining 2,4-D acid from the soil, sediment, and water, as well as to investigate the compound's stability in water. The analysis was performed using high-performance liquid chromatography with UV detection at 230 nm. The performance of the developed analytical method was evaluated by extracting the analyte from spiked soil and water samples; recoveries ranged from 88 to 100%. A calibration curve for the method using known concentrations of 1, 10, 20, 40, 60, 80, and 100 mg/L of the analyte showed good linearity (R2 ≥ 0.9996). The LOD of the developed method was determined to be 0.45 μg/mL while the LOQ was 2 μg/mL. From the analysis of the samples, no 2,4-D was detected in sediment or soil samples from the Wafiko or Kontola sites, respectively. 2,4-D concentrations in soil samples from Bochessa and water samples from Wafiko and Sher site were generally high and exceeded USEPA regulatory agency standards. On the nature of the compound in water, a 45-day experiment on spiked water samples from Lake Koka demonstrated that the acidic form of 2,4-D is stable in water. An average recovery 73.46 ± 2.00% was achieved in this study. Thus, this study suggests that the developed method can be used to quantitatively extract 2,4-D residues and other chemical pollutants with similar physicochemical properties from contaminated samples originating from various sources.
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    Determination of Methanol, Ethanol, Solid, Acid Content and Other Quality Parameters of Ethiopian Traditional Fermented, Distilled and Factory Produced Alcoholic Beverages
    (Addis Ababa University, 2018-10-05) Tadesse, Seferu; Ele, Estifanos (PhD); Zewge, Feleke (PhD)
    The Ethiopian traditional fermented alcoholic beverages including (‘Tella’, ‘Tej’, ‘Shameta’,‘Bordie’ and ‘Korefie’), traditional distilled alcohols (‘Wheat Berkrakie Areki, ‘Wheat Sharata Areki’, ‘Dagusa Arefa Areki’, ‘Dagussa Sharata Areki’, ‘Dagim Areki’, ‘Gibto Areki’, ‘Wheat Arefa Areki’, ‘Mixed Areki’, ‘Koso Areki’ and ‘Yemar Areki’) and factory produced alcoholic beverages (‘Vodka Areki’, ‘Lomie Areki’, ‘Ananas Areki’, ‘Ouzo Areki’ and ‘Dry Gin Areki’) were collected from Addis Ababa, Ethiopia for the measurement of their ethanol, methanol, solid, salinity contents, acid value, pH value and electrical conductivity. The overall average values of pH value, ethanol% (v/v), acidic content (g/L), solid content (mg/L), conductivity (μS/cm) and salinity (%) found in all of the beverages studied were in the range of 4.6 - 7.5, 2.80 - 51.2, 0.02 - 105, 0.00 - 20328, 5.87- 8391 and 0.1 - 4.6, respectively. The methanol contents of the beverages were determined using GC-MS. The results showed that the level of methanol in some of the studied traditional and factory alcoholic beverages were found in the range between 0.867 - 0.979% (v/v). No methanol was observed in all of the analyzed traditional fermented beverages. Hence, contrary to the general assumptions, the levels of methanol observed in the analyzed drinks do not pose any health threat to the human. However, the normal alcohol health risk associated with high consumption remains a problem.
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    Investigation of Chemical Constituents and Anti- Oxidant Activities of the Essential Oils of Lippia Adoensis and Ocimum Sanctum L.
    (Addis Ababa University, 2020-07-24) Fikadu, Yemisrach; Ele, Estifanos (PhD)
    In this study essential oils of Lippia adoensis leaf, Ocimum sanctum L. leaf and stem (together without separation) and the mixture of the two plants from Bishoftu and Debre Berhan sample area was analyzed using Gas chromatography mass spectrometry (GC-MS) and its antioxidant activities were assessed using UV-Vis spectroscopy. Ocimum sanctum L. from Bishoftu sample area showed 12 compounds. The detected major compounds were -bisabolene (31.38%), 4- [(1E)-1,5-dimethyl-1,4-hexadien-1-yl]-1-methyl-Cyclohexen (25.56%), eucalyptol (17.12%). The essential oil from stem and leaf of Ocimum sanctum L. from Debre Berhan sample area showed 20 compounds. The major compounds were -bisabolene (24.45%), 4-[(1E)-1,5- dimethyl-1,4-hexadien-1-yl]-1-methylcyclohexen (19.61%) and eucalypto (13.42%). Lippia adoensis from Bishoftu sample area showed 15 compounds with major components as linalool (66.60%) and caryophyllene (4.28%) and Lippia adoensis from Debre Berhan sample area showed 12 compounds with major component as linalool (86.11%). The essential oil of the mixture of Lippia adoensis and Ocimum sanctum L. from Bishoftu sample area showed 18 compounds with major components as linalool (62.54%) and from Debre Berhan sample area showed 21 compounds major components as linalool (48.47%) and octadecane (5.47%). The antioxidant activities were assessed using UV-Visible spectroscopy. The radical scavenging activity of the essential oils of Lippia adoensis and Ocimum sanctum L. was assessed using DPPH. The antioxidant activities of the sample were determined by comparing DPPH inhibition and standard ascorbic acid DPPH inhibition. The measured average antioxidant activities for essential oil of Ocimum sanctum L. from Bishoftu and Debre Berhan exhibited DPPH radical scavenging activities of 96.48% and 96.17% at 100μg/mL, respectively. Lippia adoensis from Bishoftu and Debre Berhan sample area exhibited DPPH radical scavenging activities of 92.58% and 93.37% at 100 μg/mL, respectively and the essential oil of mixture of two plants (Lippia adoensis and ocimum sanctum) from Bishoftu and Debre Berhan sample area exhibited DPPH radical scavenging activities of 95.25% and 96.42% at 100μg/mL, respectively, which is comparable to that of ascorbic acid standard that exhibited a 98.08 % at the same concentration.
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    Phytochemial Investigations and Biological Activities of Smoke Samples Collected from Otostegia Integrifolia, Silene Macrosolen, and Echinops Kebericho Plants
    (Addis Ababa University, 2020-08-06) Zewdu, Tadesse; Ele, Estifanos (PhD)
    The essential oils and smoke collected from leaves of Otostegia integrifolia, S. macrosolen and E.kebericho were investigated using gas chromatography mass spectrometry (GC-MS). Several compounds were identified in the essential oil of Otostegia integrifolia: They were Terpenoids (51.51%) which are monoterpene (12.12%), sesqui terpene (36.36% ), di terpene (3.03%) and phenolic compounds ( 13.60% ). From smoke trapped in hexane a group of compound such as phenolic (43.73%), alkane (21.88% ), terpene (9.3%) were identified. In smoke trapped by methanol, alkenes (62.50%), and phenolic compounds were detected. From smoke of S. macrosolen trapped in hexane and methanol phenolic compounds 54.00% and 70.37% respectively were identified. From smoke of E.kebericho trapped in hexane and methanol phenolic compound 57.89% and 65.20% respectively were identified. The antioxidant activities were evaluated using reducing power (FRAP), by UV-Vis absorption spectroscopy. The results revealed that the Silene macrosolon exhibited the highest anti-oxidant activity compared to Echinops kebercho and Otostegia integrifolia. The antioxidant concentration in Hexane trapped smoke of all sample under this study was negligible. The insecticidal activity tests (both repellent and mortality) were conducted using cockroach as a test insect. The repellant activity of insect was tested by O. integrifolia leaves extract and, the recorded results of repellency at 60 minutes were 100% by hexane and 91.47% by methanol trapped smokes. The maximum mortality of cockroach at the maximum time by E. kebericho, S. macrosolen and O. integrifolia smoke extract were 100.00 , 40.00 , 13.2% respectively.
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    Phytochemical Investigation and Antioxidant Analysis of Seeds and Aerial Parts of Coriander (Coriandrum Sativum L.) Cultivated in Ethiopia
    (Addis Ababa University, 2021-08-31) Assefa, Mekides; Ele, Estifanos (PhD)
    In this study essential oils extracted from coriander seed and aerial parts of the samples collected from Sululta, Jimma and Wolaita Sodo were analyzed using GC-MS. Similarly, fatty acids from the coriander seeds were extracted and analyzed in their methyl ester form. The antioxidant activities of the crude extracts of coriander aerial parts were evaluated using a UV-Vis spectrophotometer. The optimum time for extraction of essential oil was determined to be 5 h. The concentration of each fatty acid component was evaluated based on an external standard prepared from linoleic acid ethyl ester. From the analyzed data, the sample collected from Sululta showed the highest number of compounds and a higher amount of Petroselinic acid (107.53 μg/mL) compared to Wolaita Sodo (41.12 μg/mL) and Jimma (20.41μg/mL). In this study, 18.24-22.37% linoleic acid (omega-6) was determined. The P/S index values were calculated for all oil and found to be between 1.69 and 2.39. The total number of compounds identified in the essential oils extracted from seeds collected from Jimma, Sululta and Wolaita Sodo were 7, 9 and 15 with combined percent areas of 99.64, 75.14 and 96.68, respectively. The essential oils were dominated by linalool, which accounts for 36.72%-88.50% of the total amount. From the aerial parts of the plants collected from Jimma, Wolaita Sodo and Sululta, 45, 21 and 19 different compounds were identified, respectively. Decanal and (E)-2-decenal were the major components of the essential oils. The crude methanol extract of coriander aerial parts from all three sample areas showed good radical scavenging activities with values ranging from 91.091% to 92.295% at a concentration of 500 μg/mL.
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    Phytochemical Studies of Cyperus Esculentus Carissa Spinarum Melilotus Officinalis Rhus Glutinosa and Rhus Natalensis
    (Addis Ababa University, 2021-09-12) Assefa, Melaku; Ele, Estifanos (PhD); Mammo, Wendimagegn (Professor)
    In this study, the essential oils obtained from the rhizomes of Cyperus esculentus L. and the roots of Carissa spinarum Linn. together with medicinal smoke obtained from burnt roots of Carissa spinarum were analyzed by GC-MS. The major components of the essential oil of Cyperus esculentus were pinocarveol (11.42%), humulene epoxide II (10.18%), caryophyllene oxide (9.38%) and β-pinene (8.95%). On the other hand, the essential oil obtained from the roots of Carissa spinarum was predominantly 2- hydroxyacetophenone (16, 82.97%). The dominant components of the n-hexane- and MeOH-soluble fractions of the smoke derived from the roots of Carissa spinarum were found to be 2,6-dimethoxyphenol, 2-methoxyphenol and 2-hydroxyacetophenone. The radical scavenging activities of the EtOAc extract of the rhizomes of Cyperus esculentus, the MeOH-soluble fraction of the smoke derived from the roots of Carissa spinarum, the MeOH extract of the seeds of Melilotus officinalis and the EtOAc extracts of the fresh leaves of Rhus glutinosa and Rhus natalensis were also evaluated using the diphenylpicrylhydrazyl (DPPH) method. The smoke derived from the roots of Carissa spinarum and the MeOH-soluble fraction of the seeds of M. officinalis showed 88.48 ± 0.31% and 26.35 ± 0.54% DPPH inhibition at concentration of 50.00 μg/mL, respectively. On the other hand, the EtOAc-soluble fractions of the rhizomes of Cyperus esculentus and III the leaves of R. glutinosa and R. natalensis reduced DPPH radical by 24.53 ± 0.36%, 94.89 ± 0.10% and 94.94 ± 0.29% at 50.00 μg/mL, respectively. At the same concentration, standard ascorbic acid (a known antioxidant) scavenged the DPPH radical by 96.29 ± 0.06%. The seed fatty acid composition of M. officinalis was determined in this study by GC-MS analysis. Hence, the n-hexane extract of the seeds of M. officinalis unveiled twelve compounds with a combined area percentage of 98.33%, the major constituents being (9Z,12Z)-octadecadienoic acid (20.22%, 366.08 ppm), 14-methylpentadecanoic acid (19.52%, 353.45 ppm) and (9E)-octadecenoic acid (15.94%, 288.66 ppm). Four sesquiterpenes, namely, caryophyllene oxide (113), cyperotundone (12), corymbolone (114) and tricyclohumuladiol (115), were also isolated from the EtOAc extract of the rhizomes of Cyperus esculentus. Furthermore, two compounds, namely, cis-coumaric acid- 2-O-β-glucopyranoside (cis-melilotoside, 116) and 1,2-benzopyrone (coumarin, 65), were isolated from the MeOH extract of the seeds of M. officinalis. Twelve compounds, namely, pentacosanol (119), acacetin (120), kaempferol (38), rhusflavanone (121), rhusflavone (122), avicularin (123), quercetin (1), myricetin (2), quercitrin (124), shikimic acid (125), hyperoside (126), and myricetin-3-O-β-galactopyranoside (127) were obtained from R. glutinosa leaves and three compounds, namely, quercetin (1), guaijaverin (131) and vitexin (132) were isolated and characterized from the leaves R. natalensis. Spectroscopic techniques such as NMR, UV-Vis, FTIR, HRESIMS and single X-ray crystallography were used to characterize the isolated compounds.
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    Phytochemical Studies on Premna Schimperi Engl (Lamiaceae)
    (Addis Ababa University, 2021-09-20) Nasir, Mohammedamin; Ele, Estifanos (PhD); Mammo, Wendimagegn (Professor)
    In this study, attempts were made to isolate secondary metabolites from the solvent extracts of the dried leaves of Premna schimperi Engl. The essential oil obtained by hydrodistillation of the dried leaves of P. schimperi was also analyzed by GC-MS. A total of six compounds were isolated from the solvent extracts, of which ent-8,12α-epidioxy-12-hydroxylabda-9(11),13-dien-15-oic acid -lactone (71), 3,5,5'-trihydroxy-6,7,3',4'-tetramethoxyflavone (157) and 3,5,7,5'-tetrahydroxy-6,3',4'-trimethoxyflavone (158) were isolated from the chloroform extract, while a straight chain primary alcohol (165) was isolated from the petroleum ether extract, and luteolin (159) and p-hydroxycinnamic acid (164) were isolated from the ethyl acetate portion of the methanol extract. Per acetylation of compound 157 using acetic anhydride and pyridine gave triacetate 157-Ac. The GC-MS analysis of the essential oil revealed 36 compounds, of which the major compositions were caryophyllene (9), caryophyllene oxide (10), terpinen-4-ol (33), -curcumene (166), eugenol (167), -sesquiphellandrene (168), -gurjunene (169), 2-isopropyl-5-methyl-9-methylene-bicyclo[4.4.0]dec-1-ene (170), -eudesmol (171). The antioxidant activities of the MeOH extract of the leaves of P. schimperi and compound 71 were assessed using the DPPH radical scavenging assay. The MeOH extract reduced the stable DPPH radical by 95.3% whereas compound 71 reduced the stable DPPH radical by 62.2% at 100 μg/mL, which suggested that they are potential radical scavengers.