The Structural Transformation of Gardenoside and Its Related Iridoid Compounds by Acid and β-Glucosidase

In the course of studies on the metabolism of iridoid compounds, three new compounds derived from 6alpha-hydroxygeniposide and 6beta-hydroxygeniposide, obtained from gardenoside by the hydrochloric acid treatment, were isolated after the hydrolysis with beta-glucosidase. The aglycone of 6beta-hydroxygeniposide was elucidated as 6beta-hydroxygenipin. On the other hand, the aglycones of 6alpha-hydroxygeniposide were identified as the mixture of stereoisomers, 6alpha-hydroxygenipin and 6alpha-hydroxy-1- EPI-genipin.