Recovery of Saponins, Phenolic Compounds and Antioxidant Capacity from Curculigo orchioides Gaertn Rhizomes by Different Extraction Methods

This study aimed to investigate the effects of the solvent type, extraction time, extraction temperature and solvent-to-material ratio on the recovery of the total saponin content (TSC), the total phenolic content (TPC) and the antioxidant activity from the rhizomes of Curculigo orchioides Gaertn. The extraction efficiency of the bioactive compounds by ultrasound-assisted extraction (UAE) was also evaluated. Extraction with 80% ethanol achieved the highest extraction yields, and the optimal conditions for the extraction of TSC were 60 min, 57 °C and an 80 mL/g solvent-to-material ratio. The optimal conditions for the recovery of TPC were 178 min, 45 °C and a solvent-to-material ratio of 68 mL/g. The highest antioxidant activity of the extracts from Curculigo orchioides Gaertn rhizomes was obtained with the optimal conditions of 180 min, 40 °C and an 80 mL/g solvent-to-material ratio. The actual extraction yields obtained from the optimal conditions were 11.33 mg aescin equivalents (AE)/g dry weight (DW) for TSC, 23.58 mg gallic acid equivalents (GAE)/g DW for TPC and DPPH antioxidant activity of 133.45 µM Trolox equivalents (TE)/g DW. UAE using the same type and amount of solvent for only 10 min could result in comparable extraction yields of TSC, TPC and DPPH antioxidant activity to the 180 min conventional extraction process. These promising results suggest the potential for the development of effective extraction processes to recover bioactive compounds from Curculigo orchioides Gaertn rhizomes in practical production.