Hydantion indolinones as AANAT inhibitors

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Neuroscience

Background:

• Arylalkylamine N-acetyltransferase (AANAT) is vital for melatonin biosynthesis and circadian rhythm regulation.
• Dysregulation of melatonin pathways is implicated in mood disorders, including seasonal affective disorder (SAD).
• Previous AANAT inhibitors based on a rhodanine scaffold had stability limitations.

Purpose of the Study:

• To design and synthesize novel hydantoin indolinone-based inhibitors of AANAT.
• To develop more stable and potent alternatives to existing AANAT inhibitors.
• To explore structure-activity relationships for improved AANAT inhibition.

Main Methods:

• Structure-based drug design utilizing docking studies.
• Systematic modification of four key molecular regions.
• Synthesis and in vitro testing of novel hydantoin indolinone derivatives.
• Kinetic mechanism studies with acetyl-CoA and serotonin.

Main Results:

• Hydantoin indolinone scaffolds were successfully developed as AANAT inhibitors.
• Substitution at the 5-position of the indolinone ring significantly enhanced inhibitory activity.
• Compound 5g demonstrated a 19-fold improvement in potency (IC₅₀ = 1.1 μM) over the parent compound.
• Kinetic studies provided insights into inhibitor binding mechanisms.

Conclusions:

• The novel hydantoin indolinone derivatives represent a promising new class of AANAT inhibitors.
• These compounds offer improved stability and potency compared to previous scaffolds.
• The findings provide a strong foundation for developing chemical probes to study melatonin's role in biological systems.