Synthesis and Biological Evaluation of Harmirins, Novel Harmine–Coumarin Hybrids as Potential Anticancer Agents

Abstract

As cancer remains one of the major health burdens worldwide, novel agents, due to the development of resistance, are needed. In this work, we designed and synthesized harmirins, which are hybrid compounds comprising harmine and coumarin scaffolds, evaluated their antiproliferative activity, and conducted cell localization and cell cycle analysis experiments. Harmirins were prepared from the corresponding alkynes and azides under mild reaction conditions using Cu(I) catalyzed azide–alkyne cycloaddition, leading to the formation of the 1H-1,2,3-triazole ring. Antiproliferative activity of harmirins was evaluated in vitro against four human cancer cell lines (MCF-7, HCT116, SW620, and HepG2) and one human non-cancer cell line (HEK293T). The most pronounced activities were exerted against MCF-7 and HCT116 cell lines (IC50 in the single-digit micromolar range), while the most selective harmirins were 5b and 12b, substituted at C-3 and O-7 of the β-carboline core and bearing methyl substituent at position 6 of the coumarin ring (SIs > 7.2). Further experiments demonstrated that harmirin 12b is localized exclusively in the cytoplasm. In addition, it induced a strong G1 arrest and reduced the percentage of cells in the S phase, suggesting that it might exert its antiproliferative activity through inhibition of DNA synthesis, rather than DNA damage. In conclusion, harmirin 12b is a novel harmine and coumarin hybrid with significant antiproliferative activity and warrants further evaluation as a potential anticancer agent.

Harmicens, Novel Harmine and Ferrocene Hybrids: Design, Synthesis and Biological Activity

“…Thus, compound 28 possibly targeted both nuclear DNA and cytoplasmic targets ( Figure 2 ). This was contrary to our previous finding that harmine derivatives did not enter the cell nuclei [ 34 ]. A longer incubation period did not improve the fluorescence signal, while the 5-fold higher concentration disrupted the cell morphology (data not shown).…”

“…Numerous studies have shown that harmine significantly influences the cell cycle of various cancer cell lines, including HCT116, via induction of G2/M cell cycle arrest, intercalation into DNA and induction of DNA fragmentation; upregulation of p53 and p21 expression; and downregulation of cyclin B1, p-cdc2, cdc2, cdc25, and p-cdc25 expression necessary for G2/M transition [ 47 , 48 , 49 ]. In our previous paper, we also confirmed that the parent compound harmine induced arrest in the G1 phase of MCF-7 cells already after 24 h, along with a reduction in cells in the S phase and an additional accumulation of cells in the G2/M phase after 48 h. The O-7-substituted TT harmine–coumarin derivative, which was synthesized by our research group, caused even more prominent G1 arrest than harmine, accompanied by a drastic reduction in the percentage of cells in the S phase, which also persisted after 48 h [ 34 ]. Harmicene 28 , also an O-7-substituted TT-harmine derivative, had an even more pronounced effect on the HCT116 cell cycle.…”

“…Our previous work on harmine hybrids, i.e., harmicines, harmirins, and harmiquins, demonstrated that the development of hybrids is indeed a valid strategy for obtaining biologically active compounds that exhibit more pronounced activity than the parent compounds [ 31 , 32 , 33 , 34 , 35 ]. Encouraged by the literature data, which clearly show the potential of organometallic compounds as anticancer and antimalarial therapeutics [ 36 , 37 , 38 , 39 , 40 , 41 ], we set out to prepare harmicens—hybrids in which ferrocene is covalently bound to harmine/β-carboline ( Figure 1 ), and to investigate their antiproliferative and antiplasmodial activities.…”

Anticancer Potential of β‐Carboline Alkaloids: An Updated Mechanistic Overview

“…The cytoplasm is the only location for the unique harmine and coumarin hybrid known as Harmirin. Moreover, harmirin generated a significant G1 arrest and decreased the proportion of cells in the S phase, indicating that it may impede DNA synthesis rather than DNA damage to exert its antiproliferative action [89] …”

The anti‐breast cancer therapeutic potential of 1,2,3‐triazole‐containing hybrids

“…[ 97 ] Coumarin‐1,2,3‐triazole‐harmine hybrids 138 (IC 50 : 1.9–13.3 µM, MTT assay) demonstrated considerable antiproliferative activity against MCF‐7 breast cancer cells, and the most active hybrids 138a,b (IC 50 : 2.2 and 1.9 µM) were more potent than 5‐fluorouracil (IC 50 : 23.9 µM) and harmine (IC 50 : 13.5 µM). [ 177 ] 1,2,3‐Triazole tethered coumarin‐pyrimidinone/β‐lactam hybrids only showed weak to moderate antiproliferative activity against MCF‐7 breast cancer cells, revealing that pyrimidinone and β‐lactam were not suitable pharmacophores to combine with coumarin through 1,2,3‐triazole. [ 178,179 ]…”