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Articles by Alemayehu Mekonnen
Total Records ( 2 ) for Alemayehu Mekonnen
  Atitegeb Abera , Alemayehu Mekonnen and Tesfaye Tebeka
  Traditionally, Plumbago zeylanica Linn. is used for the treatments of intestinal warms and skin diseases in Ethiopia. The main objective of this study was to investigate the antioxidant and antimicrobial activities of the crude extract of Plumbago zeylanica root. In this study, two different antioxidant activity quantification methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH) and reducing power, FRAP including total phenolic, TPC assays of crude extract of P. zeylanica root were performed. The extracts showed significant activities in all antioxidant assays in a concentration dependent manner. Crude extract was found to possess higher ferric reducing activity (ascorbic acid equivalents 227.011±0.042 mg AA/100 g) and DPPH activity of 156.00±0.048 mg AAE/100 g. Strong correlation of TPC with AEACDPPH and AEACFRAP (R = 0.9745 and R = 0.96652, respectively) implied that compounds in the extract were capable of scavenging the DPPH free radical and reducing ferric ions. The free radical scavenging activity and the reducing capacity of the extract in the present study may serve as a significant indicator of its potential antioxidant activity. Antimicrobial activities evaluation of crude extract against S. aureus ATCC, MRSA, S. pneumoniae ATCC, S. pneumoniae (clinical) (gram positive bacteria), K. pneumoniae (clinical), S. boydii ATCC, E. coli ATCC, E. coli (clinical) (gram negative bacteria) and antifungal activity against C. albicans (clinical) (fungus) were also showing a higher antimicrobial activity of the crude extract. The findings of this study support the view that P. zeylanica plant is a promising source of potential antioxidants and may be effective as preventive agent in the pathogenesis of some diseases.
  Kedir Ebrahim and Alemayehu Mekonnen
  Background and Objective: Salvadora persica (S. persica) is a medicinal plant which has many traditional uses against infections and related disorders. The main objective of this study was to estimate total flavonoid and polyphenol contents, antioxidant and antimicrobial activities of ethanol extracts of root and stem parts of the Salvadora persica plant. Materials and Methods: The extraction was done using maceration method. Total phenolic content, total flavonoid content and antioxidant activity of S. persica extracts were evaluated using the Folin ciocalteu, the aluminum chloride colorimetric and reducing power (FRAP) assays, respectively. The agar well diffusion method was used for the determination of antibacterial activity. Results were subjected to analysis of variance (one-way ANOVA) by applying Duncan’s post hoc test using SPSS. Results: Antioxidant activity of root and stem extracts of S. persica was expressed as ascorbic acid equivalent (206.593±17.5771 and 168.931±12.9975, respectively). Total phenol contents of root and stem extracts were also expressed in terms of gallic acid and gave values of 91.0 and 70.5 GAE/100 g of dry weight, respectively. About 40.528 and 2.6225 mg of QE per 100 g of dry weights of a sample were recorded for root and stem extracts when flavonoid contents of the extracts were determined, respectively. Antibacterial activity of both stem and root samples were assessed and Staphylococcus aureus was not inhibited by either of the two extracts. However antibacterial activity of root showed a positive result against Streptococcus pneumoniae, Shiegella flexneri and Escherichia coli (E. coli ). The stem also gave similar result except it strongly inhibits Shiegella flexneri. Conclusion: Salvadora persica root and stem extracts were found to contain noticeable amount of total phenols and small amount of flavonoids which play major role in controlling oxidation. Furthermore, this study proves the effectiveness of Salvadora persica root and stem extracts for its excellent antioxidant and antimicrobial activities.
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