# Tricyclic Isatin Derivatives as Anti-Inflammatory Compounds with High Kinase Binding Affinity

## TL;DR

This study shows that tricyclic isatin oximes can reduce inflammation and bind to multiple kinases, making them promising for anti-inflammatory and neuroprotective drug development.

## Contribution

The study introduces new tricyclic isatin oxime derivatives with high kinase binding affinity and anti-inflammatory activity.

## Key findings

- Compounds 5a and 5d inhibited NF-κB/AP-1 activity and IL-6 production in monocytic cells.
- These compounds showed nanomolar/submicromolar binding affinity to 12 kinases, including DYRK1A and PIM1.
- Molecular modeling confirmed the binding modes of the compounds in kinase catalytic sites.

## Abstract

Oximes have been reported to exhibit useful pharmaceutical properties, including compounds with anticancer, anti-arthritis, antibacterial, and neuroprotective activities. Many oximes are kinase inhibitors and have been shown to inhibit various kinases. Herein, a panel of oxime derivatives of tricyclic isatins was synthesized and evaluated for inhibition of cellular inflammatory responses and binding affinity to several kinases. Compounds 5a and 5d (a.k.a. NS-102), which have an unsubstituted oxime group, inhibited lipopolysaccharide (LPS)-induced nuclear factor-κB/activating protein 1 (NF-κB/AP-1) transcriptional activity in human THP-1Blue monocytic cells and interleukin-6 (IL-6) production in human MonoMac-6 monocytic cells, with IC50 values in the micromolar range. These compounds also inhibited LPS-induced production of several other proinflammatory cytokines, including IL-1α, IL-1β, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor (TNF) in MonoMac-6 cells. Compounds 5a and 5d exhibited nanomolar/submicromolar binding affinity toward several kinase targets. The most potent inhibitor, 5d (3-(hydroxyimino)-5-nitro-1,3,6,7,8,9-hexahydro-2H-benzo[g]indol-2-one), demonstrated high binding affinity for 12 kinases, including DYRK1A, DYRK1B, PIM1, Haspin, HIPK1-3, IRAK1, NEK10, and DAPK1-3. Molecular modeling suggested modes of binding interaction of selected compounds in the DYRK1A and PIM1 catalytic sites that agreed with the experimental binding data. Our results demonstrate that tricyclic isatin oximes could be potential candidates for developing anti-inflammatory drugs with neuroprotective effects for treating neurodegenerative diseases.