A total of 12 new
cycloartane- and lanostane-type triterpenoids
including 16-deoxyargentatin A (
1
), 16-deoxyisoargentatin
A (
2
), 7-oxoisoargentatin A (
3
), 24-
epi
-argentatin H (
4
), 24-
O
-
p
-anisoylargentatin C (
5
), 24-
O
-
trans
-cinnamoylargentatin C (
6
), 16-dehydroargentatin C (
7
), 16,17(20)-didehydroargentatin
C (
8
), isoargentatin C (
9
), isoargentatin
H (
10
), 3-
epi
-quisquagenin (
11
), and isoquisquagenin (
12
) together with 10 known triterpenoids
(
13
–
22
) were isolated from the resin
of
Parthenium argentatum
AZ-2 obtained
as a byproduct of Bridgestone guayule rubber production. The structures
of new triterpenoids
1
–
12
and argentatin
H (
13
), which has previously been characterized as its
diacetate (
23
), were elucidated by extensive analysis
of their spectroscopic data and chemical conversions, and the known
compounds
14
–
22
were identified by
comparison of their spectroscopic data with those reported. Of these,
13
,
14
, and
18
exhibited weak cytotoxic
activity for several cancer cell lines.
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