Polyphenolic phytochemical extractions from peel of apples, pears, plums, red and
white grapes were performed using 70% ethanol and 0.9% NaCl (7:3) with ultrasound
assistance and extracts were analyzed for total phenolics, flavonoids, and antioxidant
capacity. In the tested fruit the highest content of flavonoids was found in the red
grapes (4.337±0.218mg/g), followed by the pear and the plum (3.333±0.035 and 3.108±0.157mg/g),
which have almost identical content, and the white grapes and the apples which again
have an approximately equal content of flavonoids (2.126±0.039 and 2.072±0.096mg/g).
The antioxidant capacities of analysed fruit extracts were assayed for antioxidant
activity by DPPH radical scavenging and total reducing power. The percentage of neutralize
DPPH radicals can be reported by EC50 value or by the concentration of extract required
to neutralize 50% of DPPH radicals. The lowest EC50 value, and therefore the highest
antioxidant activity was in the extracts of red grape, followed by the extracts of
pear, apple, white grape, and plum.The highest content of phenolic compounds were
in extract of the red grape (12,884±0,444mg/g), than followed by the pear (9,590±1,031mg/g),
the plums (9,296±0,268mg/g), the apples (3,676±0,135mg/g), and the lowest content
was in the extract of the white grapes (3,009±0,161mg/g).
Acknowledgement:
This work was supported under the projects No.OI 45001 by the Ministry of Science
of the Republic of Serbia.
References: 1. Halliwell B (1997) Nutr Rev 55: S44-S52.
2. Aquino R et al. (2002)J Ethnopharmacol 79: 183–191.
3. Xu BJ, Chang SKC (2007)J Food Sci 72: S159-S166.
