Objective: To design and synthesize a series of squamosamide cyclic analogues and to test their antioxidation activity.
Methods: Eleven 3-substituted indole-2-one derivatives were designed and synthesized through 9 steps with p-hydroxyphenylacetic acid as the starting material and their structures were confirmed by nuclear magnetic resonance and mass spectrometry.
Results: Eleven compounds showed antioxidation activity and the activities of compounds 9 and 13 matches the positive control FLZ-52.
Conclusion: Cyclic reconstruction with FLZ-52 as the lead compound have some antioxidation activity.