Optimization of extraction methods for total polyphenolic compounds obtained from rhizomes of Zingiber officinale

In an alternative medicine, aqueous extracts and decoctions of the ginger root (Ginger- Zingiber officinale Roscoe L., Ginger family Zingiberaceae) are used as antibacterial, diaphoretic, analgesic, anti-emetic and anti-inflammatory drugs. The aim of this study was to determine the optimal method and conditions of total polyphenolic compounds (TPC) extraction from ginger roots using ethanol as the solvent. The ethanol extracts were obtained by several extraction methods involving maceration, Soxhlet apparatus and ultrasound. TPC and total flavonoids (TF) were determined spectrophotometrically using the Folin-Ciocalteu method. It was found that the highest content of TPC and TF is obtained after sonication followed by subsequent maceration for a period of ten for TPC and seven days for TF, with a yield of 2.48 ± 0.029% and 1.3 ± 0.08% (per 1 g of dry substance), respectively. Optimal extraction conditions were found with ethanol (70%) and a ratio raw material/solvent of 1:1.