Effect of Harvest Time on Saponins in Yam (Dioscorea pseudojaponica Yamamoto)
JAU-TIEN LIN1, SU-LIN CHEN2, SHIH-CHUAN LIU2 AND DENG-JYE YANG2*
1. Department of Applied Chemistry, Chung Shan Medical University, Taichung , Taiwan (R.O.C.)
2. School of Health Diet and Industry Management, Chung Shan Medical University, Taichung, Taiwan (R.O.C.)
(Received: May 29, 2008; Accepted: December 15, 2008)
ABSTRACT
Steroidal saponins including furostanol and spirostanol glycosides are the important bioactive compounds in yams. In the study, the content of individual saponin in varied organs of yam (Dioscorea pseudojaponica Yamamoto) harvested from November to March of the next year (the harvest season) were determined. Results showed that total saponin levels in yam organs (except rhizophor) harvested at various time were in the order: January > December > February > November > March. Saponin contents in rhizophor gathered in December were higher than those obtained in January. The highest total amounts of saponins among various organs were in the order: tuber cortex (619.79 μg/g dw) > tuber flesh (247.84 μg/g dw) > rhizophor (32.19 μg/g dw) > leaf (26.57 μg/g dw) > vine (25.06 μg/g dw).
Key words: furostanol glycoside, spirostanol glycoside, steroidal saponin, yam (Dioscorea spp), harvest time