Abstract
Nortopsentins are a vital class of deep-sea sponge metabolites which can be used as leads for antitumor agents. Although their action has been studied in several diseases' contexts, their cytotoxic activity against colorectal carcinoma has not yet been fully investigated. Therefore, a series of 2,6-bis(1H-indol-3-yl)-4-(substituted-phenyl)pyridin-5-carbonitriles 4a-j (nortopsentin analogs) was investigated for their cytotoxic activity against colorectal carcinoma. The analog 4i showed the highest antitumor activity via inducing cell cycle arrest at G1 phase. Cell cycle arrest was induced due to expression downregulation of CDK2, CDK4, and CDK6. In addition, 4i suppressed the enzymatic activity of CDK6. The theoretical study of some basic quantum factors and the geometric shape of compound 4i proved that the compound is stable and a soft molecule, in which the E(HOMO) and E(LUMO) energies were negative and had a small ∆E gap. 4i also demonstrated a high potential for oral bioavailability due to its adherence to Lipinski's rule of five. The molecular docking studies of 4i analog showed good binding mode with CDK6 active pocket through the formation of multiple interactions with its key amino acids.