150
N. N. Win and H. Morita
OH
OAc
AcO
58 (norcaesalpinin MA) R = H
59 (norcaesalpinin MB) R = OAc
R
OH O
O
O
AcO
OAc
56 (caesalpinin ME)
OH
HO
57 (caesalpinin ML)
O
OH
OAc
OAc
O
60 (norcaesalpinin MC) R = α-OAc, β-H,
61 (norcaesalpinin MD) R = O
R
Fig. 12 Structures of new cassane-type diterpenes 56 and 57 without a C-5 hydroxy substituent
and furan ring, and of 16-norcassane-type diterpenes 58 and 59 and 17-norcassane-type diterpenes
60 and 61 from the seed kernels of C. crista
20 unprecedented cassane-type diterpenes (42–53), including 14 cassane-type furanoditerpenes, named caesalpinins MA–MD (42–45), MF–MK (46–51), and MM–
MP (52–55) (Fig. 11); two cassane-type diterpenes without any C-5 hydroxy group
substituent or furan ring (caesalpinins ME (56) and ML (57)); two 16-norcassanetype diterpenes (norcaesalpinins MA (58) and MB (59)), and two 17-norcassane-type
diterpenes (norcaesalpinins MC (60) and MD (61)) (Fig. 12). Also identified were
27 known cassane-type furanoditerpenes, caesalmin C (62) [59], 1-deacetoxy-1oxocaesalmin C (63), 1-deacetylcaesalmin C (64) [64], caesalpinins C (65) and F
(66) [58], 14(17)-dehydrocaesalmin F (67) [65], caesalpinin J (68) [66], ζ-caesalpin
(69) [67], caesalmin E (70) [59], caesalpinin E (71) [58], caesalpinins K (72), M
(73), and N (74) [66], bonducellpin C (75) [68], 7-acetoxybonducellpin C (76) [68]
(Fig. 13), caesalmins B (77) [69] and G (78) [59], caesalpinins D (79) [58], H (80),
I (81), and O (82) [66], norcaesalpinins B (83) [57] and E (84) [58], caesaldekarin e
(85) [70], 2-acetoxycaesaldekarin E (86) [65], 2-acetoxy-3-deacetoxycaesaldekarin e
(87) [71], and 6-acetoxy-3-deacetoxycaesaldekarin e (88) [72] (Fig. 14). Caesalpinin
MC (44) was found to be the first example of a cassane-type furanoditerpene with
a dihydrofuran ring. Furthermore, caesalpinins MM (52) and MN (53) are the first
members of a rare group of cassane-type furanoditerpenes with a rearranged carbon
skeleton, for which no additional representatives have been reported subsequently.
The chemical constituents of C. crista from Myanmar also include 1-deacetoxy-1oxocaesalmin C (63) and 1-deacetylcaesalmin C (64), which are natural products
that were previously synthesized.
Interestingly, significant inhibition of the growth of the malaria parasite P. falciparum FCR-3/A2 clone in vitro (IC 50 value of 0.21 μg/cm
3 ) was reported from the
N. N. Win and H. Morita
OH
OAc
AcO
58 (norcaesalpinin MA) R = H
59 (norcaesalpinin MB) R = OAc
R
OH O
O
O
AcO
OAc
56 (caesalpinin ME)
OH
HO
57 (caesalpinin ML)
O
OH
OAc
OAc
O
60 (norcaesalpinin MC) R = α-OAc, β-H,
61 (norcaesalpinin MD) R = O
R
Fig. 12 Structures of new cassane-type diterpenes 56 and 57 without a C-5 hydroxy substituent
and furan ring, and of 16-norcassane-type diterpenes 58 and 59 and 17-norcassane-type diterpenes
60 and 61 from the seed kernels of C. crista
20 unprecedented cassane-type diterpenes (42–53), including 14 cassane-type furanoditerpenes, named caesalpinins MA–MD (42–45), MF–MK (46–51), and MM–
MP (52–55) (Fig. 11); two cassane-type diterpenes without any C-5 hydroxy group
substituent or furan ring (caesalpinins ME (56) and ML (57)); two 16-norcassanetype diterpenes (norcaesalpinins MA (58) and MB (59)), and two 17-norcassane-type
diterpenes (norcaesalpinins MC (60) and MD (61)) (Fig. 12). Also identified were
27 known cassane-type furanoditerpenes, caesalmin C (62) [59], 1-deacetoxy-1oxocaesalmin C (63), 1-deacetylcaesalmin C (64) [64], caesalpinins C (65) and F
(66) [58], 14(17)-dehydrocaesalmin F (67) [65], caesalpinin J (68) [66], ζ-caesalpin
(69) [67], caesalmin E (70) [59], caesalpinin E (71) [58], caesalpinins K (72), M
(73), and N (74) [66], bonducellpin C (75) [68], 7-acetoxybonducellpin C (76) [68]
(Fig. 13), caesalmins B (77) [69] and G (78) [59], caesalpinins D (79) [58], H (80),
I (81), and O (82) [66], norcaesalpinins B (83) [57] and E (84) [58], caesaldekarin e
(85) [70], 2-acetoxycaesaldekarin E (86) [65], 2-acetoxy-3-deacetoxycaesaldekarin e
(87) [71], and 6-acetoxy-3-deacetoxycaesaldekarin e (88) [72] (Fig. 14). Caesalpinin
MC (44) was found to be the first example of a cassane-type furanoditerpene with
a dihydrofuran ring. Furthermore, caesalpinins MM (52) and MN (53) are the first
members of a rare group of cassane-type furanoditerpenes with a rearranged carbon
skeleton, for which no additional representatives have been reported subsequently.
The chemical constituents of C. crista from Myanmar also include 1-deacetoxy-1oxocaesalmin C (63) and 1-deacetylcaesalmin C (64), which are natural products
that were previously synthesized.
Interestingly, significant inhibition of the growth of the malaria parasite P. falciparum FCR-3/A2 clone in vitro (IC 50 value of 0.21 μg/cm
3 ) was reported from the