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In
vitro antibacterial, antioxidant activity and total phenolic content of some
essential oils
Upma Srivastava,
Swati Ojha, N.N. Tripathi and Pooja Singh*
Department of
Botany, DDU Gorakhpur University, Gorakhpur-273 009, India
*Corresponding
Author E-mail: pooja.ddu@gmail.com
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Publication
Data
Paper received:
21 May 2014
Revised received:
17 December 2014
Re-revised received:
23 January 2015
Accepted:
20 March 2015
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Abstract
In
vitro antibacterial activity of 16 essential oils was investigated by disc
diffusion method against two Gram positive bacteria Bacillus subtilis
and Staphylococcus aureus and two Gram negative bacteria, Shigella
flexneri and Escherichia coli. Oils of Cymbopogon citratus
and Ocimum basilicum showed highest antibacterial activity. Gram
positive bacteria were found to be more sensitive than Gram negative.
Antioxidant activities were tested by 2,2-diphenyl-1-picrylhydrazyl (DPPH)
radical scavenging assay and ABTS radical cation decolourization assay while
Folin-Ciocalteu method was used to determine the total phenolic content. In
DPPH assay, highest antioxidant activity was observed in O. basilicum oil
followed by Azeratum conyzoides, A. marmelos and C. citratus,
with percent inhibition and IC50 value ranging from 66.11-71.93%
and 14.10-17.92 ?l ml-1 respectively. In ABTS assay, similar
results were obtained but with higher percent inhibition which ranged from
67.48-76.23% and lower IC50 value (12.12-17.21 ?l ml-1).
Moreover, radical scavenging activity of essential oils was lower than that
observed for the synthetic antioxidant BHA and BHT. The total phenolic
content of the essential oils as GAE in mg 100?l-1 of EO was found
to be highest in O. basilicum (0.406) oil followed by A. conyzoides
(0.322), A. marmelos (0.238) and C. citratus (0.231). The
results provide evidence that the oils of C. citratus and O.
basilicum can be further recommended for treatment of infections caused
by these bacterial pathogens and are potential source of natural antioxidants
having appreciable amount of total phenolic content. ????
Key
words
Antibacterial,
Antibiotic susceptibility, Antioxidant, Phenolic content
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