Extraction of hydrolysable tannins from Phyllanthus niruri Linn.: Effects of solvents and extraction methods

Effects of solvent types and extraction methods (solvent extraction (SE), supercritical fluid extraction (SFE) and pressurized water extraction (PWE)) were investigated for effective recovery of bioactive hydrolysable tannins from Phyllanthus niruri Linn. Various organic and aqueous solvents screened by Soxhlet method showed that the gallic acid and ellagic acid contents increased with water content whereas corilagin yield reached a maximum value at 30% (v/v) ethanol in water. At a fixed temperature, solvent extraction by Soxhlet is the best method for gallic and ellagic acid extractions, whereas pressurized methods are better for the corilagin extraction. Even though exhaustive extraction is achieved fastest by PWE, SFE with the addition of ethanol–water cosolvent is superior in terms of low liquid solvent consumption and component fractionation produced. Solvent polarity, solvent-to-solid ratio and contact time play significant roles in determining the most efficient method for tannin extraction.