THE RELATIONSHIP BETWEEN THE ANTIOXIDANT ACTIVITY WITH DIFFERENT AMOUNTS OF PHENOLIC COMPOUNDS

The aim of this study was to evaluate and compare the antioxidant activity and
the collecting rate of free radicals in the environment of in vitro, by utilizing the methanol’s extracts
from different parts of the plants such as Plantago major, Trifolium subterraneum, Boswellia thurifera,
Juglans regia (walnut).
Materials & Methods: Antioxidant and antiradical activities were determined using reducing power,
ferric-reducing antioxidant potential (FRAP) ability to scavenge DPPH radical assays and ABTS
methods. Moreover, the phenol and flavonoid contents were determined using UV/Vis
spectrophotometric methods.
Results: The results showed that the rate of IC50 in the inhibition of (DPPH) stable radical for the
extracts of walnuts inner shell was 2.93. The assessment of ABTS and FRAP also showed that the
extracts of walnuts inner shells, green shells cover of walnut and plantago in compared with the other
extracts were more active and showed the higher level of antioxidant activity. The results of total phenol
and flavonoid contents also showed that the extract of plantago contains the highest level of flavonoid,
and also all of extracts excluding Boswellia contain the highest level of phenolic compounds. On the
other hand, Trifolium despite of the high levels of phenolic compounds showed the lower level of the
antioxidant activity.
Conclusion: Results showed a significant relationship between the phenol content and the antioxidant
activity of the extracts. Also the phenolic compounds with different structure have shown various
antioxidant activities. Therefore the antioxidant activity of the plant’s extracts could not be explained
just on the basis of their phenolic content but also required other characterization. Consequently, there
is not a conclusive and direct relationship between the antioxidant activity and the phenol and flavonoid
contents.