3.4. Effects of extraction solvents
*Extraction of bioactive compounds is a vital step in accurately quantifying levels from a plant material using various solvent systems. Solvents, such as water, ethanol, methanol, petroleum ether, acetone, chloroform, and ethyl acetate, are routinely used for extraction of polyphenols and other bioactive compounds from plant sources. Previous researches describe acetone and methanol as yielding maximum extraction of phenolic compounds compared to other solvents (Ganesan et al., 2008) and therefore these two solvents were used in this research.Recovery of polyphenols and other antioxidant compounds from plant materials depends greatly on the compound solubility in a particular solvent, the polarity of the solvents, viscosity, and vapor pressure. Thus, solvents, such as methanol or acetone, can easily diffuse into the pores of the plant materials to leach out the active constituents. Among the different factors that contribute to varied results for polyphenols and antioxidant of a single plant source, the chemical nature of the compounds, the extraction solvents used, and the assay employed are the major ones (Bhat et al., 2012; Naczk and Shahidi, 2006). So, the variations observed in the results of antioxidant compounds in the Betel leave can be attributed directly to the polarity and type of used solvent.