Synthesis, cytotoxicity evaluation and molecular docking studies on 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone derivatives

2',4'-Dihydroxy-6'‑methoxy-3',5'-dimethylchalcone and its amino acid-conjugated derivatives induce G0/G1 cell cycle arrest and apoptosis via BAX/BCL2 ratio upregulation and in silico insight in SiHa cell lines

We modified the chemical structure of 2',4'-dihydroxy-6'‑methoxy-3',5'-dimethylchalcone (DMC, 1), a phytochemical found in the seed of Syzygium nervosum A.Cunn. ex DC., by conjugation with the amino acid L-alanine (compound 3a) or L-valine (compound 3b) to enhance anticancer activity and water solubility. Compounds 3a and 3b had antiproliferative activity in human cervical cancer cell lines (C-33A, SiHa and HeLa), with half-maximal inhibitory concentrations (IC₅₀) of 7.56 ± 0.27 and 8.24 ± 0.14 µM, respectively in SiHa cells; these values were approximately two-fold greater than DMC. We investigated the biological activities of compounds 3a and 3b based on a wound healing assay, a cell cycle assay and messenger RNA (mRNA) expression analysis to determine the possible mechanism of anticancer activity. Compounds 3a and 3b inhibited SiHa cell migration in the wound healing assay. After treatment with compounds 3a and 3b, there was an increase in SiHa cells in the G1 phase, indicative of cell cycle arrest. Moreover, compound 3a showed potential anticancer activity by upregulating TP53 and CDKN1A that resulted in upregulation of BAX and downregulation of CDK2 and BCL2, leading to apoptosis and cell cycle arrest. The BAX/BCL2 expression ratio was increased after treatment with compound 3avia the intrinsic apoptotic pathway. In silico molecular dynamics simulation and binding free energy calculation shed light on how these DMC derivatives interact with the HPV16 E6 protein, a viral oncoprotein associated with cervical cancer. Our findings suggest that compound 3a is a potential candidate for anti-cervical cancer drug development.

Discovery of Natural Bisbenzylisoquinoline Analogs from the Library of Thai Traditional Plants as SARS-CoV-2 3CLPro Inhibitors: In Silico Molecular Docking, Molecular Dynamics, and In Vitro Enzymatic Activity

The emergence of SARS-CoV-2 in December 2019 has become a global issue due to the continuous upsurge in patients and the lack of drug efficacy for treatment. SARS-CoV-2 3CL^Pro is one of the most intriguing biomolecular targets among scientists worldwide for developing antiviral drugs due to its relevance in viral replication and transcription. Herein, we utilized computer-assisted drug screening to investigate 326 natural products from Thai traditional plants using structure-based virtual screening against SARS-CoV-2 3CL^Pro. Following the virtual screening, the top 15 compounds based on binding energy and their interactions with key amino acid Cys145 were obtained. Subsequently, they were further evaluated for protein-ligand complex stability via molecular dynamics simulation and binding free energy calculation using molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) approaches. Following drug-likeness and ADME/Tox assessments, seven bisbenzylisoquinolines were obtained, including neferine (3), liensinine (4), isoliensinine (5), dinklacorine (8), tiliacorinine (13), 2'-nortiliacorinine (14), and yanangcorinine (15). These compounds computationally showed a higher binding affinity than native N3 and GC-373 inhibitors and attained stable interactions on the active site of 3CL^pro during 100 ns in molecular dynamics (MD) simulation. Moreover, the in vitro enzymatic assay showed that most bisbenzylisoquinolines could experimentally inhibit SARS-CoV-2 3CL^Pro. To our delight, isoliensinine (5) isolated from Nelumbo nucifera demonstrated the highest inhibition of protease activity with the IC₅₀ value of 29.93 μM with low toxicity on Vero cells. Our findings suggested that bisbenzylisoquinoline scaffolds could be potentially used as an in vivo model for the development of effective anti-SARS-CoV-2 drugs.

Synthesis and Characterization of Novel Heterocyclic Chalcones from 1-Phenyl-1H-pyrazol-3-ol

An efficient synthetic route to construct diverse pyrazole-based chalcones from 1-phenyl-1H-pyrazol-3-ols bearing a formyl or acetyl group on the C4 position of pyrazole ring, employing a base-catalysed Claisen–Schmidt condensation reaction, is described. Isomeric chalcones were further reacted with N-hydroxy-4-toluenesulfonamide and regioselective formation of 3,5-disubstituted 1,2-oxazoles was established. The novel pyrazole-chalcones and 1,2-oxazoles were characterized by an in-depth analysis of NMR spectral data, which were obtained through a combination of standard and advanced NMR spectroscopy techniques.

Effects of 2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone from Syzygium nervosum Seeds on Antiproliferative, DNA Damage, Cell Cycle Arrest, and Apoptosis in Human Cervical Cancer Cell Lines

2′,4′-Dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC), a natural product derived from Syzygium nervosum A. Cunn. ex DC., was investigated for its inhibitory activities against various cancer cell lines. In this work, we investigated the effects of DMC and available anticervical cancer drugs (5-fluorouracil, cisplatin, and doxorubicin) on three human cervical cancer cell lines (C-33A, HeLa, and SiHa). DMC displayed antiproliferative cervical cancer activity in C-33A, HeLa, and SiHa cells, with IC₅₀ values of 15.76 ± 1.49, 10.05 ± 0.22, and 18.31 ± 3.10 µM, respectively. DMC presented higher antiproliferative cancer activity in HeLa cells; therefore, we further investigated DMC-induced apoptosis in this cell line, including DNA damage, cell cycle arrest, and apoptosis assays. As a potential anticancer agent, DMC treatment increased DNA damage in cancer cells, observed through fluorescence inverted microscopy and a comet assay. The cell cycle assay showed an increased number of cells in the G₀/G₁ phase following DMC treatment. Furthermore, DMC treatment-induced apoptosis cell death was approximately three- to four-fold higher compared to the untreated group. Here, DMC represented a compound-induced apoptosis for cell death in the HeLa cervical cancer cell line. Our findings suggest that DMC, a phytochemical agent, is a potential candidate for antiproliferative cervical cancer drug development.