Trichothecene analogues. 1. 1,5-Dioxaspiro(2.5)octanes

Area of Science:

• Medicinal Chemistry
• Pharmacology
• Organic Synthesis

Background:

• The "epoxypyran" structure is a key feature of trichothecene sesquiterpenes, known for their tumor-inhibiting properties.
• Understanding the structure-activity relationship of these compounds is crucial for developing new anticancer agents.

Purpose of the Study:

• To synthesize and evaluate the anticancer potential of seven 1,5-dioxaspiro[2.5]octanes.
• To compare the activity and toxicity of these novel compounds against established antitumor agents.

Main Methods:

• Synthesis of seven 1,5-dioxaspiro[2.5]octane derivatives.
• Anticancer screening using the mouse P388 lymphocytic leukemia and Ehrlich ascites tumor models.
• Assessment of skin irritation in rabbits as a measure of toxicity.

Main Results:

• Three synthesized spirooctanes exhibited marginal to moderate activity (74.1-86.3% inhibition) in the Ehrlich ascites screen and low activity (T/C = 126-131) in the P388 screen.
• A carbocyclic analogue, 1-oxaspiro[2.5]octane (9), showed moderate activity in both screens (78.8% inhibition, T/C = 140).
• Compound 9 was significantly less potent than T-2 toxin in the Ehrlich ascites screen and demonstrated a favorable safety profile, with no skin irritation at 10-mg doses, unlike T-2 toxin.

Conclusions:

• The tested 1,5-dioxaspiro[2.5]octanes possess anticancer activity, though generally less potent than T-2 toxin.
• The carbocyclic analogue (9) presents a promising profile with moderate efficacy and reduced toxicity, warranting further investigation.
• These findings contribute to understanding the role of the epoxypyran moiety in antitumor activity and suggest potential for developing safer chemotherapeutic agents.