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Title
Antioxidant and antibacterial activities of some natural polyphenols
Authors
IOANA IGNAT DANA G. RADU IRINA VOLF ANDREEA I. PAG and VALENTIN I. POPA
Received
March 6, 2013
Published
Volume 47 Issue 5-6 May-June
Keywords
polyphenols, extraction, characterization, HPLC, radical scavenging, antibacterial activity, seed germination
Abstract
The present study provides information on separation and identification of natural bioactive compounds from different
vegetal materials with potential applications as antibacterials and plant growth modulators. Natural extracts were
obtained by alcoholic and water extraction from spruce bark, grape seeds, Crataegus monogyna (hawthorn) and
Asclepias syriaca (milkweed).
HPLC-DAD analysis revealed that gallic acid (12.54 mg/100 g) and catechin (85.52 mg/100 g) were the most abundant
compounds in hawthorn and grape seed extracts, vanillic acid (71.9 mg/100 g) was found in high concentrations in
spruce bark wood, while milkweed extracts were characterized by the presence of hydroxycinnamic acids and
flavonoids. The DPPH assay indicated that the highest radical scavenging activity was registered by grape seeds (EC50
= 45.75 µg) and hawthorn (EC50 = 17.8 µg) alcoholic extracts. The same extracts exhibited antibacterial properties on
Staphylococcus aureus, while the samples obtained from spruce bark and milkweed extracts inhibited the development
of Escherichia coli and Pseudomonas aeruginosa species. Furthermore, the toxicity of the natural extracts was
evaluated by their application in germination tests of Phaseolus vulgaris. The obtained results demonstrated that a high
concentration of polyphenols has an inhibitory effect on plant development, while lower concentrations determine a
considerable stimulation of plantlet elongation.
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