ABSTRACT
A series of new taxoids derived from 14 beta-hydroxy-10-deacetylbaccatin III was synthesized by means of the beta-lactam synthon method. Most of the new taxoids thus synthesized possess excellent cytotoxicity against human ovarian (A121), non-small-cell lung (A549), colon (HT-29), and breast (MCF-7) cancer cell lines, and several of these taxoids show subnanomolar IC50 values which are severalfold to 1 order of magnitude better than those of paclitaxel and docetaxel. Modifications at the 3'- and 3'-N-positions exert marked effects on the activity. For the substituents at C-3', the cytotoxicity decreases in the order 2-furyl approximately 2-methyl-1-propenyl > or = 2-methylpropyl > (E)-1-propenyl > or = n-propyl > phenyl > > 2,2-dimethylpropyl. For the 3'-N substituents, the activity decreases in the order t-BuOCO > Ph > n-hexanoyl. A significant increase in the cytotoxicity against the doxorubicin-resistant human breast cancer cell line MCF7-R that expresses the multidrug resistance (MDR) phenotype is observed by the proper modification of the substituent at C-10. The observed remarkable effects of the substituents at C-10 on the activity against MCF7-R can be ascribed to the effective inhibition of the binding of these new taxoids to P-glycoprotein that is responsible for MDR.
Subject(s)
Antineoplastic Agents, Phytogenic/chemical synthesis , Antineoplastic Agents, Phytogenic/pharmacology , Paclitaxel/analogs & derivatives , Taxoids , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Antineoplastic Agents, Phytogenic/chemistry , Antineoplastic Agents, Phytogenic/metabolism , Docetaxel , Drug Resistance, Multiple , Drug Resistance, Neoplasm , Drug Screening Assays, Antitumor , Humans , Magnetic Resonance Spectroscopy , Molecular Conformation , Molecular Structure , Paclitaxel/chemical synthesis , Paclitaxel/chemistry , Paclitaxel/metabolism , Paclitaxel/pharmacology , Structure-Activity Relationship , Tumor Cells, CulturedABSTRACT
A series of pyrazinoic acid esters has been prepared and evaluated for in vitro antimycobacterial activity. Several of the pyrazinoate esters have substantially better activity than the first-line antituberculous agent pyrazinamide against susceptible isolates of Mycobacterium turberculosis as well as activity against pyrazinamide-resistant isolates. The minimal inhibitory concentrations (MICs) were lower for each organism and at each pH than the MICs for pyrazinamide. The esters have activity against Mycobacterium bovis and Mycobacterium kansasii, two species resistant to pyrazinamide, but not against Mycobacterium avium complex.
