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Phenolic compounds are able to act as reducing agents,
hydrogen donors and scavengers of reactive oxygen species as it classified as a
common secondary metabolites characterized by the presence of an aromatic ring
bearing free hydroxyl groups or engaged with a carbohydrate (Mason et al., 1996; Pandey & Rizvi, 2009;
Ivanova et al., 2005). Plants
polyphenols are play important role in defense against different types of
stress by offering protection against reactive oxygen and nitrogen species, UV
light, pathogens, parasites and plant predators (Balasundram et al., 2006). Moreover it also playing
important role in prevention
of chronic diseases, such as cardiovascular diseases, neurodegenerative
disorders, cancer, type II diabetes and osteoporosis (Alothman et al., 2009; Scalbert et al., 2005).

There are many method to extract the polyphenols
from the plant such as Accelerated Solvent Extraction (ASE), Supercritical
Fluid Extraction (SFE), Soxhlet Extraction (SE), Ultrasound Assisted Extraction
(UAE) and others. However, the extraction processes are a major variability
factor in the antioxidant properties of extracts. Indeed, different antioxidant
capacities depending on the factors and affinities between factors used in the
extraction such as solvent types, extraction times, extraction temperature,
particle size of samples and the method adopted for the influence for
extraction influence significantly the composition of the extract (Ksouri et al., 2009; Hayouni et al., 2007) . Extracting polyphenols
from biological materials by conventional method such as SE is time consuming.
By using new method or modern techniques such as Microwaves Assisted Extraction
(MAE) or UAE is intended to overcome this time consuming problem and additional
can increase extraction efficiency, selectivity and kinetics. UAE using
ultrasound or sonication to break the cell membranes and reducing the extraction
time and increasing the extract yield. This application happened by disrupting
the cell wall structure and accelerates the diffusion through membranes thus it
facilitates the release of cell contents (Mason et al., 1996). 

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