초록
<P>A minor product, rebaudioside M2 (<B>2</B>), from the bioconversion reaction of rebaudioside A (<B>4</B>) to rebaudioside D (<B>3</B>), was isolated and the complete structure of the novel steviol glycoside was determined. Rebaudioside M2 (<B>2</B>) is considered an isomer of rebaudioside M (<B>1</B>) and contains a relatively rare 1<B>→</B>6 sugar linkage. It was isolated and characterized with NMR (<SUP>1</SUP>H, <SUP>13</SUP>C, COSY, HSQC-DEPT, HMBC, 1D-TOCSY, and NOESY) and mass spectral data. Additionally, we emphasize the importance of 1D and 2D NMR techniques when identifying complex steviol glycosides. Numerous NMR spectroscopy studies of rebaudioside M (<B>1</B>), rebaudioside D (<B>3</B>), and mixture of <B>1</B> and <B>3</B> led to the discovery that SG17 which was previously reported in literature, is a mixture of rebaudioside D (<B>3</B>), rebaudioside M (<B>1</B>), and possibly other related steviol glycosides.</P>