digitoxopyranose to C-400 of b-D-digitoxopyranose, from H-100 of
b-D-digitoxopyranose to C-40 of b-D-thevetopyranose, and from H-
10 of b-D-thevetopyranose to C-3. The sugar sequence was further
confirmed by the fragment ion peaks at m/z 787.4 [M + Na]+, 657.1
[M-digt + Na]+, and 527.2 [M-digt-digt + Na]+ in the positive ESI
mass spectrum. Thus, the structure of 3 was determined to be
anhydrohirundigenin 3-O-b-D-digitoxopyranosoyl-(1
!4)-b-Ddigitoxopyranosoyl-(
1
!4)-b-D-thevetopyranoside, named cynastauoside
C.
Compounds 1–3 were evaluated the inhibition activities of NO
in peritoneal macrophages of C57bl/6j mouse. Dexamethasone was
used as a positive control substance with the inhibition ratio of
83.5% at a concentration of 1 mM. The results showed that
compounds 2 and 3 containing a trisaccharide moiety at C-3,
exhibited weak inhibitory effect against NO with the inhibition
ratios of 17.0% and 6.9% at a concentration of 10 mM, respectively,
while 1 containing a disaccharide moiety at the same position,
showed no inhibitory effect with the same concentration (see
Table 3).