130
Fig. 54 Diterpenoids
[255]. This means that the conformation of the lactone ring must be distorted and so
the NMR data obtained should be checked carefully. The differences in the chemical constituents between these two samples were clear, and so the study of additional L. rumicifolia specimens would be advisable.
3.15 Ligularia songarica (Fischer) Y. Ling
Four samples of L. songarica were collected in the Xinjiang Autonomous Region,
China (Table 18). Sample 1 produced 2-hydroxyplatyphyllide (121), a 10H-lactone
(369), two bisabolanes (680 and 698), and a cadinane-type sesquiterpenoid (808)
[99]. Seven bisabolanes (666, 681, 700, 701, 702, 703, and 704) were isolated from
sample 2 [227]. Sample 3 produced seven oplopane sesquiterpenoids, namely, songaricalarins A (754), B (748), C (738), D (737), E (733), 736 (major constituent),
and 734 [237]. The structure of songaricalarin A (754) was determined by X-ray
diffraction analysis. Intriguingly, this compound later was reported again using
M. Tori and C. Kuroda
Fig. 54 Diterpenoids
[255]. This means that the conformation of the lactone ring must be distorted and so
the NMR data obtained should be checked carefully. The differences in the chemical constituents between these two samples were clear, and so the study of additional L. rumicifolia specimens would be advisable.
3.15 Ligularia songarica (Fischer) Y. Ling
Four samples of L. songarica were collected in the Xinjiang Autonomous Region,
China (Table 18). Sample 1 produced 2-hydroxyplatyphyllide (121), a 10H-lactone
(369), two bisabolanes (680 and 698), and a cadinane-type sesquiterpenoid (808)
[99]. Seven bisabolanes (666, 681, 700, 701, 702, 703, and 704) were isolated from
sample 2 [227]. Sample 3 produced seven oplopane sesquiterpenoids, namely, songaricalarins A (754), B (748), C (738), D (737), E (733), 736 (major constituent),
and 734 [237]. The structure of songaricalarin A (754) was determined by X-ray
diffraction analysis. Intriguingly, this compound later was reported again using
M. Tori and C. Kuroda