Synthesis, biologic properties, and molecular modeling studies of bis-indole based thiosemicarbazones

The Schiff base condensation reaction of thiosemicarbazides and methylene bridged 2,2 '-bisindolylmethanes, prepared from the acid-catalyzed condensation of 3-aryl-4,6-dimethoxyindole-7-carbaldehydes and formaldehyde, produced a series of the targeted bis-indole based thiosemicarbazones. To explore the biological potential of the newly synthesized compounds, antidiabetic, anticholinesterase, and antioxidant activities were investigated. The structural derivatization carried out by the addition of bromophenyl ring at C3 position of the indole backbone increased the enzyme potency towards the anticholinesterase activity. Some of the targeted compounds showed selective the alpha-glucosidase enzyme inhibition activity. In addition to that, the inhibition concentrations were found to lower that the standard acarbose showing that they may be more efficient agents. Although most of the compounds were effective for the metal chelation capacities (CUPRAC), a couple of examples were found to be favorable for DPPH and ABTS assays. The presence of methyl substituted thiosemicarbazone tail with different indole back bones individually detected as promising targets for ABTS and DPPH activities. The compound methyl substituted thiosemicarbazone was also determined as the most potent agent with the 6 mu M inhibition concentration toward CUPRAC assay. Molecular docking study was performed to support the experimental results.