Design, synthesis, <i>in vitro</i> antiproliferative activity and apoptosis-inducing studies of 1-(3′,4′,5′-trimethoxyphenyl)-3-(2′-alkoxycarbonylindolyl)-2-propen-1-one derivatives obtained by a molecular hybridisation approach
Creators: name: Preti, Delia
name: Romagnoli, Romeo
name: Rondanin, Riccardo
name: Cacciari, Barbara
name: Hamel, Ernest
name: Balzarini, Jan
name: Liekens, Sandra
name: Schols, Dominique
name: Estévez-Sarmiento, Francisco
name: Quintana, José
name: Estévez, Francisco
Publisher: name: Taylor & Francis
Year: 2018
Subjects: subject: Biochemistry
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Cell Biology
subject: Molecular Biology
subject: Pharmacology
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Cancer

description: Inhibition of microtubule function using tubulin targeting agents has received growing attention in the last several decades. The indole scaffold has been recognized as an important scaffold in the design of novel compounds acting as antimitotic agents. Indole-based chalcones, in which one of the aryl rings was replaced by an indole, have been explored in the last few years for their anticancer potential in different cancer cell lines. Eighteen novel (3′,4′,5′-trimethoxyphenyl)-indolyl-propenone derivatives with general structure <b>9</b> were synthesized and evaluated for their antiproliferative activity against a panel of four different human cancer cell lines. The highest IC<sub>50</sub> values were obtained against the human promyelocytic leukemia HL-60 cell line. This series of chalcone derivatives was characterized by the presence of a 2-alkoxycarbonyl indole ring as the second aryl system attached at the carbonyl of the 3-position of the 1-(3′,4′,5′-trimethoxyphenyl)-2-propen-1-one framework. The structure–activity relationship (SAR) of the indole-based chalcone derivatives was investigated by varying the position of the methoxy group, by the introduction of different substituents (hydrogen, methyl, ethyl or benzyl) at the <i>N</i>-1 position and by the activity differences between methoxycarbonyl and ethoxycarbonyl moieties at the 2-position of the indole nucleus. The antiproliferative activity data of the novel synthesized compounds revealed that generally <i>N</i>-substituted indole analogues exhibited considerably reduced potency as compared with their parent <i>N</i>-unsubstituted counterparts, demonstrating that the presence of a hydrogen on the indole nitrogen plays a decisive role in increasing antiproliferative activity. The results also revealed that the position of the methoxy group on the indole ring is a critical determinant of biological activity. Among the synthesized derivatives, compound <b>9e</b>, containing the 2-methoxycarbonyl-6-methoxy-<i>N</i>-1<i>H</i>-indole moiety exhibited the highest antiproliferative activity, with IC<sub>50</sub> values of 0.37, 0.16 and 0.17 μM against HeLa, HT29 and MCF-7 cancer cell lines, respectively, and with considerably lower activity against HL-60 cells (IC<sub>50</sub>: 18 μM). This derivative also displayed cytotoxic properties (IC<sub>50</sub> values ∼1 μM) in the human myeloid leukemia U-937 cell line overexpressing human Bcl-2 (U-937/Bcl-2) via cell cycle progression arrest at the G<sub>2</sub>-M phase and induction of apoptosis. The results obtained also demonstrated that the antiproliferative activity of this molecule is related to inhibition of tubulin polymerisation. The presence of a methoxy group at the C5- or C6-position of the indole nucleus, as well as the absence of substituents at the <i>N</i>-1-indole position, contributed to the optimal activity of the indole-propenone-3′,4′,5′-trimethoxyphenyl scaffold.