Novel d-seco paclitaxel analogues: synthesis, biological evaluation, and model testing

Area of Science:

• Medicinal Chemistry
• Molecular Modeling
• Biochemistry

Background:

• Paclitaxel is a crucial anticancer drug, but its derivatives are explored to improve efficacy and overcome resistance.
• Understanding the structure-activity relationship of paclitaxel analogues is vital for developing new cancer therapies.

Purpose of the Study:

• To synthesize novel D-secopaclitaxel analogues.
• To evaluate the biological activity of these analogues using in vitro assays.
• To refine predictive models of paclitaxel binding to tubulin.

Main Methods:

• Synthesis of four D-secopaclitaxel analogues via D-ring opening using Jones oxidation.
• In vitro cytotoxic assays to determine compound toxicity.
• Tubulin assembly assays to assess microtubule stabilization.
• Minireceptor modeling and conformational analysis to predict and understand binding interactions.

Main Results:

• All synthesized D-secopaclitaxel analogues demonstrated biological inactivity in cytotoxic and tubulin assembly assays.
• Initial minireceptor model predictions of high activity for two analogues were contradicted by experimental results.
• Conformational analysis indicated the 4-acetyl substituent's significant role in A ring conformation, comparable to the oxetane ring.

Conclusions:

• The synthesized D-secopaclitaxel analogues lack cytotoxic and microtubule-stabilizing activity.
• The study highlights limitations in the predictive minireceptor model, specifically regarding steric effects around the oxetane ring.
• Model adjustments incorporating additional amino acids for steric effects led to accurate bioactivity predictions, guiding future drug design.