Design and Synthesis of Bis-Chalcones as Curcumin Simplified Analogs and Assessment of Their Antiproliferative Activities Against Human Lung Cancer Cells and Trypanosoma cruzi Amastigotes

Abstract

Background: Anticancer therapies represent the primary treatment option for a significant number of cancer patients globally; however, many of these treatments are associated with severe side effects as they target molecular structures present in both cancerous and healthy cells. In a similar context, the treatment of Chagas disease, a neglected tropical illness, is hindered by the high toxicity of the currently available drugs. Researchers are increasingly focusing on the development of safer and more selective alternatives, with natural compounds being studied as potential starting points for the creation of more effective drug candidates with a favorable therapeutic index. Objectives: The aim of this study was to design simplified curcumin-derived structures that preserved or enhanced their therapeutic activity against human lung cancer cell lines and T. cruzi, while also improving bioavailability and minimizing toxicity. Methods: In this study, curcumin and two natural curcuminoids inspired the synthesis of a chalcone and a set of bis-chalcones, compound classes known for their enhanced stability compared with their natural parent derivatives. The synthetic strategy used was the acid-catalyzed aldol condensation reaction. The stability profiles, IC₅₀ values against A549 and H460 tumor cell lines, and trypanocidal activity against T. cruzi amastigotes of these derivatives were assessed. Results: The synthesized derivatives exhibited improved stability compared with the parent compounds, along with lower IC₅₀ values in both A549 and H460 tumor cell lines. Additionally, one of the new analogs showed promising trypanocidal activity against T. cruzi amastigotes. Conclusions: This study provides a potential pathway toward the development of more effective and less toxic treatments for both cancer and Chagas disease. The simplified curcumin derivatives represent a promising foundation for designing new therapeutic agents with improved bioavailability and efficacy.

Keywords: Chagas disease; antiparasitic drugs; antitumor drugs; chemotherapy; molecular simplification.

Figure 1

The main natural curcuminoids are from turmeric (Curcuma longa rhizomes).

Figure 2

Degradation products of CUR are generated in a basic medium (entry 1), in an acidic medium (entry 2), and in its autooxidation reaction (entry 3) [41,42,43].

Figure 3

Molecular design of structurally simplified CUR analogs (4) and (5).

Figure 4

Synthesis of simplified curcumin analogs 4 and 5. Reaction conditions: ethanol/HCl aq. (37%) 3:1, r.t., 24 h. (4, 61%; 5, 53% yield).

Figure 5

Synthetic approach to the preparation of conformationally restricted analogs. Reaction conditions: a) ethanol/HCl aq. (37%) 3:1, r.t., 24 h (23–96% yield); b) H₂O₂ (40 eq), acetic acid, r.t., 0.5 h (100% yield); c) OXONE^® (8 eq), diethylamine (5 eq), water/acetonitrile 3:1, r.t., 12 h (96% yield).

Figure 6

Stability of CUR 1 (A) and bis-chalcone 4 (B) in PBS (pH 7.4) at 37 °C at times of 0, 15, 30, 60 min, and 24 h, evaluated by HPLC-DAD. The chromatogram (C) shows the profile of bis-chalcone 4 after 24 h in PBS. All experiments were monitored at two wavelengths (254 and 380 nm).

Figure 7

Analysis of the effect of curcuminoids with better antitumor activity on cell cycle in A549 cells. The cell cycle was measured by incorporating the DNA intercalator PI, allowing the detection of the different cell cycle phases (G0-G1, S, and G2-M). Cells were treated or not for 72 h with the IC₅₀ of the more active curcuminoids on cancer cells. The distribution of cell cycle and sub-G0 phase peaks (an indicator of apoptosis) were examined by flow cytometry assay, as described in the Materials and Methods Section (Section 3)—the representative result of three individual experiments.

Figure 8

Evaluation of the cell death mechanism promoted by bis-chalcone 12, which showed better antitumor activity in A549 cells. To evaluate cell death mechanisms, cells were treated (B) or not (A) for 48 h with 12 in its IC₅₀ concentration. After treatment, the monolayers were trypsinized, and the cells were incubated with Annexin-V and PI and analyzed by flow cytometry.

Figure 9

(A) Electrostatic potential map of p53 with the superposition of the four compounds (4, 8, 11, and 12) with the best antitumoral profile in vitro. (B) Superposition of 1–12 into the catalytic site of p53. The main amino acid residues interact with (C) 4, (D) 8, (E) 11, and (F) 12. (G) Electrostatic potential map of KIT kinase domain with the superposition of 4, 8, 11, and 12. (H) Zoom representation of KIT:4:8 and KIT:11:12 in the presence of the commercial antitumoral drug sunitinib. The main amino acid residues that interact with (I) 4, (J) 8, (K) 11, and (L) 12 are highlighted. Elements’ colors are as follows: oxygen, nitrogen, and sulfur are in red, dark blue, and yellow, respectively. To better visualize, hydrogen atoms were omitted. Black dots and blue lines indicate hydrophobic and hydrogen bond interactions, respectively.