Structure activity relationship of brevenal hydrazide derivatives

Area of Science:

• Marine Natural Products Chemistry
• Neuroscience
• Pharmacology

Background:

• Brevenal, a polyether from Karenia brevis, antagonizes brevetoxins, which cause respiratory and gastrointestinal issues.
• Brevenal demonstrates therapeutic potential, notably increasing tracheal mucosal velocity in asthmatic sheep, suggesting Cystic Fibrosis treatment applications.

Purpose of the Study:

• To elucidate brevenal's mechanism of action and binding site.
• To develop second-generation brevenal drug candidates with improved therapeutic profiles.

Main Methods:

• Synthesis of brevenal derivatives via modification of the aldehyde moiety, including aliphatic, aromatic, and heteroaromatic hydrazides.
• In vitro synaptosome binding assays to assess derivative displacement of brevetoxin and brevenal from receptors.
• A sheep inhalation model to evaluate derivative-induced bronchoconstriction.

Main Results:

• Small modifications to the brevenal structure were tolerated, preserving receptor affinity.
• Larger structural modifications resulted in a loss of affinity for the brevenal receptor.
• Significant structural changes in brevenal derivatives led to undesirable bronchoconstriction in the sheep model.

Conclusions:

• Structural integrity is crucial for brevenal's beneficial activity and receptor binding.
• Further drug development requires careful consideration of substituent size to avoid adverse effects like bronchoconstriction.