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Effect of Extraction Solvents on Total Phenolic Contents and in vitro Antioxidant Activity of the Leaves of Lippia adoensis var. Koseret Sebsebe
Get PDFLippia. adoensis var. koseret is an endemic herb to Ethiopia and is traditionally used as food flavoring and traditional medicine. This paper reported the total phenolic and flavonoid contents, and in vitro antioxidant activity of various extracts from the dried leaf of this herb. Aqueous: methanol (20:80, v/v) extract contained highest amount of total phenolic (67.61 ± 9.89 mg of gallic acid equivalent/g). Total flavonoid contents were highest in acetone extract (25.24 ± 0.43 mg of quercetin equivalent/g). An increase in the extracted concentration resulted in an increase of antioxidant power for all the extracts. The aqueous: methanol (20:80, v/v) extract showed highest DPPH radical scavenging (IC50 = 10.96 ± 0.42 mg/ml) iron reducing power (IC50 = 123.97 ± 3.23 mg/ml), total antioxidant activity (105.32 ± 10.67 mg ascorbic acid equivalent/g), and iron chelating activity (IC50 = 81.31 ± 15.94 mg/ml) than other four solvents used. Total phenolics well correlated with DPPH (R2 = 0.88, p < 0.05) and Ferric reducing power (R2 = 0.77 p < 0.05). Whereas, total flavonoid content well correlated with total antioxidant (R2 = 0.73 p < 0.05). The study showed the antioxidants activities of the crude extract were variable when extracted by different solvents indicating a high potential to be used as natural antioxidants in preventing various oxidative stresses and as food preservatives. Keywords: Antioxidant; α- Amylase; Phenolic compounds; Herbs; Lippia adoensis var. koseret DOI: 10.7176/FSQM/94-04 Publication date: February 29th 202
Effect of Traditional Fermentation Time on Total Phenolic Content and In vitro Antioxidant Activity of Kocho: Ethiopian Fermented Food from Enset (Ensete ventricusum welw. Chessman)
Get PDFEnsete ventricusum, locally known as Enset, is the main crop of a sustainable food source that ensures food security in Central ,South and South West Ethiopia. It has been used as a food and local medicine for thousands of years. Kocho is a product of matured Enset prepared traditionally by fermenting (for few weeks to some months) a mixture of pulverized pseudostem and corm in pit. The objective of this study was to evaluate the effect of traditional fermentation period on the total phenolic content and antioxidant activity of Kocho. The sample was fermented in the pit for 15, 30, 45, 60, 75, 90, 105 and 120 days. Oven dried Kocho powder was extracted with methanol followed by water. Total phenolic content of the extract was determined by the Folinciocalteu method. Antioxidant activities of the extracts were evaluated with 2, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and total antioxidant activity using phosphomolybdenum assay. The results revealed that Kocho showed greater total phenolic content and antioxidant activities than unfermented product. Methanol extract of Kocho fermented for 45 days showed the highest amount of total phenolic content (9.27 ± 0.44 milligram of gallic acid equivalent per gram of dried extract). In comparison of DPPH scavenging and total antioxidant, methanol extracts were also superior to aqueous extracts. Methanol extract of Kocho fermented for 60 days exhibited the strongest DPPH scavenging activity (IC50 = 0.15 ± 0.02 mg/mL) and total antioxidant activity (0.43 ± 0.04 milligram of ascorbic acid equivalent per gram of dried extract). Thus fermentation offers a tool to further increase the bioactive compounds and antioxidant potential of Kocho. Keywords: antioxidant activity, Ensete ventricusun, , fermentation, Kocho, total phenolic DOI: 10.7176/FSQM/91-05 Publication date:October 31st 2019
Studies on Phenolic Contents and Biofunctional Activities of Selected Ethiopian Spices and Herbs
No full textSpices and herbs have been added to foods since ancient times, not only as flavoring agents, but
also as folk medicine and food preservatives. They show potential health benefits as they possess
antioxidant and biologically active phytochemicals. In Ethiopia, people use dietary spices and
herbs to flavor different cultural foods and also as folk medicine. Thymus schimperi (TS), Lippia
adoensis var koseret (LAK), Lippia adoensis var. adoensis (LAA), Aframomum corrorima (AC),
and Coriandrum sativum leaf (CSL), Coriandrum sativum fruit (CSF), and Coriandrum sativum
seed (CSS) have been used as an important food flavoring agents in Ethiopia, and are also
claimed to have various health benefits. TS, LAK, and LAA are endemic herbs to Ethiopia. In
this study, the phenolic contents, the in vitro antioxidant activities and the effects of heat
treatments on total phenolic content (TPC) and antioxidant potentials from the leaves extract of
TS, LAK, LAA, CSL, fruit extract of CSF and seed extracts of CSS and AC were reported.The
in vitro antidiabetic activity of TS and T. vulgaris (TV) and antiproliferative activity of AC on
liver cancer HepG2 cell lines were evaluated. LAK, LAA, AC, CSL, CSF, and CSS were
collected from Sidama Zone South Ethiopia. The TS was collected from North Shoa, Ethiopia.
The leaf of TV was collected from campus of Dalhousie Agricultural College, Canada. Each
dried sample was extracted with five solvents (petroleum ether, water, acetone, methanol, and
aqueous: methanol, 20: 80, v/v). The antioxidant activity was determined using 2, 2-dipheny-l-2-
picryl-hydrazyl (DPPH) assay method, ferric ion reducing, phosphmolybdenum, ferric ion
chelating, and lipid peroxidation assays. The effects of thermal treatments (heated at 100 oC, 150
oC, and 180 oC for 1 and 2 h) on TPC and antioxidant capacity were investigated. The in vitro
antiproliferation activity of petroleum ether and aqueous: methanol (20:80, v/v) extracts of AC
on liver cancer HepG2 cell lines was conducted using [3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] assay. Based on α–
amylase and α–glucosidase inhibitions, the in vitro anti-diabetic activity of hot water and
aqueous: methanol (20:80, v/v) extracts of TS and TV was evaluated.
The TPC ranged from 6.39 ± 0.62 mg GAE/g dried extract up to 122.04 ± 11.59 mg GAE/g of
dried extract, while the TFC varied between 0.02 ± 0.01 and 45.11 ± 5.09 mg QE/g of dried
extract. Five flavan-3-ols, seven phenolic acids, six flavonols, two dihydrochalcones, and two
aliphatic organic acids were identified and quantified. Highest concentrations of total flavonols
and phenolic acids were found in TS. Highest flavan-3-ols were found in CSS and highest
aliphatic carboxylic acid levels were found in CSL. Q3-Rut was the most abundant flavonol and
hydroxycinnamic acid was the most abundant phenolic acid in TS. Catechin (Cat) was the most
abundant flavan-3-ols in CSS.
The antioxidant activity was concentration dependent. The aqueous: methanol (20:80, v/v)
extract of LAA showed highest DPPH radical scavenging (IC50 = 7.96 ± 2.11 g/mL), reducing
power (IC50 = 79.55 ± 6.32 mg AAE/g of dried extract), and total antioxidant activity (1.98 ±
0.14 mg BHTE/g dried extract). Water extract of CSS showed the strongest iron chelating
activity (IC50 = 53.95 ± 1.22 g/mL), the leaf methanol extract of CSL had the highest
percentage of linoleic peroxidation (78.30 ± 2.50%) and CSS showed the highest (82.64 ±
2.47%) inhibition of secondary lipid decomposition products. There were positive relationships
(R2 = 0.55–0.95) between TPC and DPPH scavenging activity (%) of the tested plant extracts but
negatively correlated with ferrous chelating activity (%).
The TPC and DPPH scavenging activity (%) of most of these dietary spices and herbs were
increased with the increasing heating temperature and prolong heating time. But LAK and LAA showed reduction in TPC and antioxidant activities when heated at high temperatures and others
showed different variation in all the activities. The DPPH scavenging activity (%) was strongly
correlated (R2 = 0.86, R2 = 0.80) with TPC whereas the total antioxidant activity was moderately
correlated (R2 = 0.59, R2 = 0.45) for all spices and herbs heated at different heating temperatures
for 1 and 2 h, respectively.
Both aqueous: methanol (20:80, v/v) and boiling water extracts from TS and TV exhibited
inhibitory activities against α–amylase and α-glucosidase. Aqueous: methanol (20:80, v/v)
extract of TS showed the strongest α-amylase inhibition activity (IC50 = 0.33 ± 0.05 mg/mL),
whereas, the hot water extract exhibited the strongest α-glucosidase inhibition (IC50 = 0.05 ±
0.01 mg/mL) activities. The petroleum ether extract of AC showed stronger inhibition of
proliferation of HepG2 cells (IC50 = 105.36 ± 6.92 g/mL) than that of aqueous: methanol
(20:80, v/v) extract (IC50 = 282.01 ± 43.40 g/mL) treated for 24 h.
The findings suggested that the methanol, acetone, and aqueous: methanol (20:80, v/v) herbal
extracts (CSL, LAK, LAA, and TS) exhibited stronger antioxidant activities than that of spice
(CSS, CSF, and AC) extracts. Except for LAK and LAA, thermal treatment increased the TPC
and DPPH scavenging activities of the plant extracts. There is high potential for the polar solvent
extracts to be utilized as sources of natural antioxidants in preventing various oxidative stresses,
in the control of blood glucose for diabetes and as food preservatives in the functional food
industry. However, on the contrary the nonpolar solvent extracts from the seeds of AC showed
stronger inhibition of proliferation of HepG2 cell lines than polar solvent extracts suggesting that
the nonpolar compounds are also important for their anticancer activity
Quantification of Phenolic Compounds by HPLC-DAD and In vitro Antioxidant Activity of Root Extract of Echinops kebericho Mesfin (Asteraceae)
Get PDFEchinops kebericho Mesfin is wild endemic medicinal herb to Ethiopia and the root is used traditionally for the treatment infectious and non-infectious diseases. This study was designed to identify and quantify the phenolic compounds and in vitro antioxidant activity of the root extracts. Seven phenolic acids, six flavanols, and two aliphatic organic acids were analyzed by high performance liquid chromatography-diode array detector (HPLC-DAD), among which hydroxycinnamic acid (413.14 ± 6.60 µg/g), quercetin-3-O-galactoside (7.07 ± 0.34 µg/g) and succinnic acid (702.95 ± 42.54 µg/g) were the major components. The methanol extract exhibited the highest total phenolics (29.14 ± 0.38 milligram gallic acid equivalent gram of dried extract), total flavonoid content (1.08 ± 0.03 milligram of quercitin equivalent/gram of dried extract), and antioxidant activities followed by ethanol and water extracts. Antioxidant capacity were 99.96 ± 7.53µg/mL and 246.88 ± 15.60µg/mL as determined by the DPPH (IC50), ferric reducing power (IC50) assays, respectively. Total phenolic content (TPC) and total flavonoid content (TFC) were strongly correlated with DPPH (R2 = 0.93, R2 = 0.91) and ferric reducing power (R2 = 0.98, R2 = 0.71), respectively. The study revealed that crude root extract of E. kebericho can be used as natural antioxidants as well as for preventing oxidative stress mediated human disorders. Keywords: Antioxidant activity; DPPH; ferric reducing; Herb; Echinops kebericho; phenols DOI: 10.7176/CPER/62-02 Publication date: January 31st 202
Effect of Extraction Solvents on Antioxidant and α-amylase Inhibition Activities of Spiced Green Chili Paste: An In Vitro Study
Get PDFChili pepper (Capsicum frutescens L.) is widely produced and consumed as raw or processed products. Spiced green chili paste, locally known as Datta, is hot spicy paste consumed in South Ethiopia. Under this study, total phenolic contents (TPC), total flavonoid contents (TFC), in vitro antioxidant, and α-amylase inhibition activities of different extracts of green Datta paste were investigated. The TPC and TFC of the extracts were determined by the Folin ciocalteu and aluminum chloride methods, respectively. The antioxidant activities were determined by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging, ferric reducing power, and total antioxidant using phosphomolybdenum methods. In vitro porcine pancreatic α-amylase inhibition activity was evaluated using the dinitrosalicylic acid (DNSA) assay. The acetone extract contained the highest TPC (24.92 ± 2.88 milligram gallic acid equivalent/ gram of dried extract) and TFC (28.05 ± 8.36 milligram catechin equivalent/gram of dried extract). Similarly this extract showed stronger antioxidant capacity, 6.34 ± 1.21 milligram of ascorbic acid equivalent/gram of dried extract, 1.46 ± 0.22 milligram butylated hydroxytoluene equivalent/ gram of dried extract, and 46.99 ± 2.60 mg/mL as determined by ferric reducing power, total antioxidant activity, and DPPH scavenging (IC50) activity, respectively. The same extract also exhibited the strongest α-amylase inhibition activity (IC50 = 0.45 mg/mL). TPC and TFC were strongly correlated with DPPH (R2 = 0.99, R2 = 0.91), reducing power (R2 = 0.86, R2 = 0.97), and total antioxidant activity (R2 = 0.79, R2 = 0.97), respectively. The α-amylase inhibition activity was strongly correlated with TPC (R2 = 0.90) but weakly correlated with TFC (R2 = 0.18). Thus the result indicated promising perspectives for the development and usage of acetone extract of Ethiopian spiced green chili pepper with considerable levels of natural antioxidants which can be used as functional food for preventing oxidative stress mediated human disorders. Keywords: Antioxidant, chili pastes Datta, α-amylase, Phenolic content. DOI: 10.7176/ALST/77-02 Publication date: January 31st 202
In vitro antioxidant and α-amylase inhibition activities of spiced red chili paste (datta) from South Ethiopia
No full textSpiced chili paste (green or red), locally known as Datta, is a traditional popular spicy paste consumed in Ethiopia. This study investigated the total phenolic contents (TPC), total flavonoid contents (TFC), in vitro antioxidant, and α-amylase inhibition activities of water, acetone, petroleum ether, methanol, and 80% methanol extracts of red Datta paste. TPC and TFC of the extracts were determined by the Folin–Ciocalteu and aluminum chloride method, respectively. DPPH scavenging, reducing power, and total antioxidant activities were taken as parameters for the evaluation of antioxidant activity. It was found that acetone extract contained the highest TPC (14.98 ± 0.76 mg of gallic acid equivalent/g of dried extract) and TFC (22.05 ± 0.87 mg of quercetin equivalent/g of dried extract). The acetone extract showed the highest, 2- diphenyl-1 picrylhydrazyl (DPPH) radical scavenging activity (IC50 = 87.30 ± 3.17 g/ml), iron reducing power (11.06 ± 2.10 mg of ascorbic acid equivalent/g dried extract), and total antioxidant activity (0.62 ± 0.13 mg butylated hydroxytoluene equivalent/g of dried extract) than the other four extracts tested. The acetone extract also exhibited the highest percentage of α-amylase inhibition activity (54.31 ± 4.70%). TPC and TFC were strongly correlated with DPPH (r = 0.93, 0.94. p < 0.01), ferric reducing power (r = 0.89, 0.83, p < 0.05), and total antioxidant activity (r = 0.88, 0.85, p < 0.05), respectively. The α-amylase inhibition activity was well correlated with TPC (r = 0.78, p > 0.05) and TFC (r = 0.81, p > 0.05). This indicated that phenolic compounds are the main contributors of antioxidant and α-amylase inhibiting activities in red Datta paste. The study revealed that crude extract of red Datta paste can be used as natural antioxidants as well as for preventing oxidative stress mediated human disorders such as suppressing hyperglycaemia.Keywords: chili pepper, Datta paste, antioxidant, α-amylase, phenolic conten
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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