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Synthesis, tubulin binding, antineoplastic evaluation, and structure-activity relationship of oncodazole analogues
L I Kruse1, D L Ladd, P B Harrsch
1Department of Medicinal Chemistry, Smith Kline & French Laboratories, Swedeland, Pennsylvania 19406.
Abstract:
In an attempt to identify a soluble oncodazole analogue that could be easily formulated, a series of substituted oncodazoles was synthesized and evaluated for tubulin binding affinity, in vitro cytotoxicity against cultured mouse B-16 cells, and ability to prolong lifespan at the maximally tolerated dose in the P388 mouse leukemia model. Biological evaluation of all the isomeric methyloncodazoles demonstrated the thiophene 4'-position to be the only site of significant bulk tolerance, although substitution of this position with polar or charged functional groups abolished biological activity. Simple esters of the 4'-carboxymethyloncodazole were shown to have enhanced antitumor activity and tubulin binding affinity relative to oncodazole. Despite a failure of this study to identify a water-soluble oncodazole with antitumor activity, the structure-activity relationship developed led to a derivative with enhanced activity in the P388 leukemia model and facilitated the preparation of a biologically active photolabile analogue.
Insights
Researchers synthesized substituted oncodazoles to find a soluble analogue for cancer treatment. While a water-soluble version wasn't found, structure-activity studies yielded a more potent derivative for leukemia models.
Area of Science:
- Medicinal Chemistry
- Pharmacology
- Cancer Biology
Background:
- Oncodazole analogues are investigated for potential anticancer properties.
- Developing soluble analogues is crucial for effective drug formulation and delivery.
- Understanding structure-activity relationships (SAR) guides the design of improved therapeutic agents.
Purpose of the Study:
- To synthesize and evaluate novel substituted oncodazoles for improved solubility and anticancer activity.
- To identify key structural modifications that enhance tubulin binding affinity and in vitro cytotoxicity.
- To assess the in vivo efficacy of synthesized analogues in a mouse leukemia model.
Main Methods:
- Synthesis of a series of substituted oncodazoles.
- Evaluation of tubulin binding affinity using biochemical assays.
- Assessment of in vitro cytotoxicity against mouse B-16 melanoma cells.
- In vivo efficacy studies in the P388 mouse leukemia model at maximally tolerated doses.
Main Results:
- The thiophene 4'-position was identified as the primary site for bulk tolerance in methyloncodazoles.
- Substitution with polar or charged groups at the 4'-position abolished biological activity.
- Simple esters of 4'-carboxymethyloncodazole exhibited enhanced antitumor activity and tubulin binding compared to oncodazole.
- No water-soluble analogue with significant antitumor activity was identified.
Conclusions:
- The SAR study revealed critical insights into oncodazole modification for enhanced biological activity.
- Despite the lack of a water-soluble analogue, a derivative with improved efficacy in the P388 leukemia model was developed.
- The findings facilitated the creation of a biologically active photolabile oncodazole analogue.