TY - JOUR
T1 - Biologically Active Taxol Analogues with Deleted A-Ring Side Chain Substituents and Variable C-2′ Configurations
AU - Swindell, Charles S.
AU - Krauss, Nancy E.
AU - Horwitz, Susan B.
AU - Ringel, Israel
PY - 1991/3/1
Y1 - 1991/3/1
N2 - Taxol (1), a potent inhibitor of cell replication, enhances the assembly of tubulin into stable microtubules and promotes the formation of microtubule bundles in cells. In addition to its unique mechanism of action, taxol exhibits unusual promise as an antitumor agent, but its application in cancer chemotherapy is hampered by its limited availability. In order to better define the structure-activity profile of taxol for the design of more accessible drugs and to provide insight into the chemical features of the taxol-microtubule interaction, taxol analogues 3-8, with deleted A-ring side chain substituents and both R and S C-2′ configurations, were synthesized from baccatin III (2) through esterification at the hindered 13-hydroxyl. Employing an improved hydroxyl protection strategy, lactate analogues 3 and 4 were prepared with reasonable efficiency owing to their simple side-chain structures, while N-benzoylisoserine analogues 7 and 8 were synthesized through esterification reactions whose rates were enhanced greatly by the participation of the amide functionality. Although less biologically active than taxol, analogues 5-7 were found to promote the polymerization of tubulin and to be cytotoxic; 5 and 6 were considerably more effective than 7, whereas 3, 4, and 8 were least active. Interestingly, tubulin polymerization was sensitive to the C-2′ configuration only when the amide substituent was present in the side chain. This observation suggests that the 3′-amide substituent plays an important role in preorganizing the taxol side chain to bind to microtubules.
AB - Taxol (1), a potent inhibitor of cell replication, enhances the assembly of tubulin into stable microtubules and promotes the formation of microtubule bundles in cells. In addition to its unique mechanism of action, taxol exhibits unusual promise as an antitumor agent, but its application in cancer chemotherapy is hampered by its limited availability. In order to better define the structure-activity profile of taxol for the design of more accessible drugs and to provide insight into the chemical features of the taxol-microtubule interaction, taxol analogues 3-8, with deleted A-ring side chain substituents and both R and S C-2′ configurations, were synthesized from baccatin III (2) through esterification at the hindered 13-hydroxyl. Employing an improved hydroxyl protection strategy, lactate analogues 3 and 4 were prepared with reasonable efficiency owing to their simple side-chain structures, while N-benzoylisoserine analogues 7 and 8 were synthesized through esterification reactions whose rates were enhanced greatly by the participation of the amide functionality. Although less biologically active than taxol, analogues 5-7 were found to promote the polymerization of tubulin and to be cytotoxic; 5 and 6 were considerably more effective than 7, whereas 3, 4, and 8 were least active. Interestingly, tubulin polymerization was sensitive to the C-2′ configuration only when the amide substituent was present in the side chain. This observation suggests that the 3′-amide substituent plays an important role in preorganizing the taxol side chain to bind to microtubules.
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U2 - 10.1021/jm00107a042
DO - 10.1021/jm00107a042
M3 - Article
C2 - 1672157
AN - SCOPUS:0025827992
SN - 0022-2623
VL - 34
SP - 1176
EP - 1184
JO - Journal of Medicinal Chemistry
JF - Journal of Medicinal Chemistry
IS - 3
ER -