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Full
Length Research Paper
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Characterization of
antioxidant and antimicrobial compounds of cinnamon and
ginger essential oils
G.
S. El-Baroty1, H. H Abd El-Baky2,
R. S. Farag1 and M. A. Saleh3
1Department
of Biochemistry, Faculty of Agriculture, Cairo University, Cairo, Egypt.
2Department
of Plant
Biochemistry, National Research Centre, Dokki,
Cairo, Egypt.
3Department
of Chemistry, Texas Southern University, Houston, Texas, USA.
*Corresponding author. E-mail:
abdelbakyh@hotmail.com.
Accepted 6 May, 2010. |
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Abstract |
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Essential oils obtained from the bark of Cinnamomum
zeylanicum (cinnamon) and the rhizomes of Zingiber
officinale (ginger) were characterized by analytical TLC
and GC/MS, and their antimicrobial and antioxidant compounds
were detected by TLC-bio-autography assays. Essential oil of
cinnamon bark (CEO) was found to be a unique aromatic
monoterpene-rich natural source, with trans-cinnamaldehyde
(45.62%) as the major constituents. Ginger oil (GEO) was
characterized by high content of sesquiterpene hydrocarbons,
including β-sesquiphellandrene (27.16%), caryophyllene
(15.29%), zingiberene (13.97%), α-farnesene (10.52%)
and ar-curcumin (6.62%). CEO and GEO oils showed
significant inhibitory activity against selected strains of
bacteria and pathogenic fungi, with MIC values ranging from
20 to 120 µg/ml depending upon the microbial species.
Cinnamaldehyde (CA) and
eugenol in cinnamon bark oil and β-sesquiphellandrene,
caryophyllene and zingiberene in ginger rhizome oil were
identified as the most active antibacterial components, with
the aid of bioautography on TLC and GC-MS. Also, both oil
exhibited appreciable in vitro antioxidant activity
as assessed by 2, 2'-diphenyl-1-picrylhydrazyl (DPPH)
radical scavenging and β-carotene bleaching methods,
compared to α-tocopherol, BHT and BHA. Guided isolation
through TLC-autography using 0.05% DPPH and β-carotene/linoleic
acid as a detection reagent led to identified CA and eugenol
as main active antioxidant compounds in CEO. The significant
antimicrobial and antioxidant activities of both oils
suggest that it could serve as a source of compounds with
preservative phenomenon.
Key words:
Antimicrobial, bioautographic assay, antioxidant, essential
oils, ginger, cinnamon.
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