Seunghyun Ahn

Polyphenols bearing cinnamaldehyde scaffold showing cell growth inhibitory effects on the cisplatin-resistant A2780/Cis ovarian cancer cells.

Ovarian carcinoma remains the most lethal among gynecological cancers. Chemoresistance is a clinical problem that severely limits treatment success. To identify potent anticancer agents against the cisplatin-resistant human ovarian cancer cell line A2780/Cis, 26 polyphenols bearing a cinnamaldehyde scaffold were synthesized. Structural differences in their inhibitory effect on clonogenicity of A2780/Cis cells were elucidated using comparative molecular field analysis and comparative molecular similarity indices analysis. Structural conditions required for increased inhibitory activity can be derived based on the analysis of their contour maps. The two most active compounds (16 and 19) were selected and further characterized their biological activities. We found that compounds 16 and 19 trigger cell cycle arrest at the G2/M phase and apoptotic cell death in cisplatin-resistant A2780/Cis human ovarian cancer cells. The molecular mechanism of compound 16 was elucidated using in vitro aurora A kinase assay, and the binding mode between the compound 16 and aurora A kinase was interpreted using in silico docking experiments. The findings obtained here may help us develop novel plant-derived polyphenols used for potent chemotherapeutic agents. In conclusion, compounds 16 and 19 could be used as promising lead compounds for the development of novel anticancer therapies in the treatment of cisplatin-resistant ovarian cancers.

Anticancer and structure-activity relationship evaluation of 3-(naphthalen-2-yl)-N,5-diphenyl-pyrazoline-1-carbothioamide analogs of chalcone.

To identify new potent chemotherapeutic agents, we synthesized compounds with 3-(naphthalen-2-yl)-N,5-diphenyl-pyrazoline-1-carbothioamide (NDPC) skeletons and evaluated their cytotoxicities using a clonogenic long-term survival assay. Their half-maximal cell growth inhibitory concentrations ranged from a few hundred nanomolars to a few micromolars. Further biological experiments including flow cytometry and western blotting analysis were performed with the derivative showing the best cytotoxicity. To identify a target protein of the selected compound, an in vitro kinase assay was carried out, which revealed that aurora kinases A and B were inhibited by the test compound, and this was confirmed using western blot analysis. The molecular binding mode between the selected compound and the kinases was elucidated using in silico docking. The structural conditions required for good cytotoxicity were identified based on the quantitative relationships between the physicochemical properties of the derivatives and their cytotoxicities.

1H and 13C NMR spectral assignments of novel flavonoids bearing benzothiazepine

Benzothiazepine is a heterocyclic compound containing nitrogen and sulfur. A variety of derivatives can be designed by modifying the positions of the double bond and benzene ring. 2,3-Dihydro1,5-benzothiazepine (also known as 2,3-dihydro[b][1,4]thiazepine) derivatives show diverse biological activities, including inhibitory effects on alpha-glucosidase, urease, cholinesterase, and butyrylcholinesterase, and agonistic activity toward the transient receptor potential ankyrin 1 (TRPA1) receptor (Fig. 1(A)). When two benzene rings are attached at the C-2 and C-4 positions, 2,4-diphenyl2,3-dihydro-1,5-benzothiazepine containing a C6-C3-C6 skeleton can be derived (Fig. 1(B)). Flavonoids are found in various plants as their secondary metabolites and are composed of C6-C3-C6 skeletons (Fig. 1(C)). Because methoxylation and naphthalenyl groups can increase cellular compartmentation and cell permeability, we designed and synthesized methoxylated 4-(1-hydroxy-naphthalen-2-yl)-2-phenyl-2,3-dihydro-1,5-benzothiazepine derivatives (Fig. 1(D)). However, flavonoids bearing a benzothiazepine skeleton have rarely been reported, even though their design and synthesis are of interest because of their biological diversity. Furthermore, because the 1H and 13C NMR, and high resolution mass spectrometric (HR/MS) data can be used as references for further study, herein, we report the NMR and MS data of 27 novel flavonoids bearing benzothiazepine skeletons.

1H and 13C NMR spectral assignments of naphthalenyl chalcone derivatives

Cellular homeostasis of reduction and oxidation is maintained by the elimination and generation of reactive oxygen species (ROS). In cancer cells, the amount of ROS produced by glycolysis is higher than that of normal cells. As a result, ROS generation is more lethal to cancer cells than normal cells. This phenomenon has been applied to the development of chemotherapeutic agents. Compounds generating ROS can be potent anticancer drugs and selectively kill cancer cells. ROS consist of hydroxy radicals, hydrogen peroxide, and superoxide. Many ROS-generating natural compounds are known, including curcumin, piperlongumine, chalcone, and cinnamaldehyde (Fig. 1A). All these compounds contain a Michael acceptor moieties, which are known to generate ROS. The ability to generate ROS depends upon the aromatic rings or substituents attached to the α,β-unsaturated carbonyl group, as shown in inset of Fig. 1A. We designed compounds containing α,β-unsaturated carbonyl groups with a 2-hydroxyphenyl substituent attached to the ketone carbon and a naphthalenyl group attached to the beta carbon (Fig. 1B) and synthesized 30 naphthalenyl chalcone derivatives. Their complete H and C Nuclear magnetic resonance (NMR) data and high-resolution mass spectrometric (HRMS) data are reported here as references for identifying newly synthesized derivatives or those isolated from natural sources in the future.

Colorectal anticancer activities of polymethoxylated 3-naphthyl-5-phenylpyrazoline-carbothioamides.

To develop potent chemotherapeutic agents for treating colorectal cancers, polymethoxylated 3-naphthyl-5-phenylpyrazoline-carbothioamide derivatives were designed. Twenty-two novel derivatives were synthesized and their cytotoxicities were measured using a clonogenic long-term survival assay. Of these derivatives, 3-(1-hydroxynaphthalen-2-yl)-N-(3-methoxyphenyl)-5-(4-methoxyphenyl)-pyrazoline-1-carbothioamide (NPC 15) exhibited the best half-maximal cell growth inhibitory concentrations (196.35nM). To explain its cytotoxicity, further biological experiments were performed. Treatment with NPC 15 inhibited cell cycle progression and triggered apoptosis through the caspase-mediated pathway. Its inhibitory effects on several kinases participating in the cell cycle were investigated using an in vitro kinase assay. Its half-maximal inhibitory concentrations for aurora kinases A and B were 105.03μM and 8.53μM, respectively. Further analysis showed that NPC 15 decreased phosphorylation of aurora kinases A, B, and C and phosphorylation of histone H3, a substrate of aurora kinases A and B. Its molecular binding mode for aurora kinase B was elucidated using in silico docking. In summary, polymethoxylated 3-naphthyl-5-phenylpyrazoline-carbothioamides could be potent chemotherapeutic agents.

1H and 13C NMR spectral assignments of 18 novel polymethoxylated hydroxynaphthopyrazolylchalconoids

Among plant-derived polyphenols produced via phenylpropanoids pathway, chalcones are biosynthesized by a combination of 4-coumaroyl-CoA with malonyl-CoA. Chalcones are known as chalconoids (Figure 1A). They consist of two benzene rings connected via the α,β-unsaturated carbonyl group, which may close to form another ring, to give flavonoids with three rings. It was known that chalconoids act as potassium channel blockers and aromatase inhibitors. As reported previously, some chalconoids can be converted to flavonoids easily (Fig. 1B). Therefore, their stabilities remained to be solved to develop as biological active compounds. A substitution of α,β-unsaturated carbonyl group with pyrazoline group (pyrazolylchalconoids) can prevent the conversion of chalconoids to flavonoids (Fig. 1C). Methoxylation increases the cell permeability and stability of many plant-derived polyphenols. We designed hydroxynaphthopyrazolylchalconoids with hydroxynaphthyl A-ring and trimethoxylated B-ring (Fig. 1D), and synthesized 18 derivatives. Their NMR data and mass spectrometric (MS) data can help us to identify plant-derived polyphenols newly synthesized or isolated from natural sources in the future, thus, we report here the complete H and C NMR data and high-resolution MS data.

Investigation of 2-hydroxy-4-methoxy-2′,3′-benzochalcone binding to tubulin by using NMR and in silico docking

Hydroxychalcones act as autophagy inducers and methoxy chalcones induce apoptosis. Additionally, benzoflavones inhibit the hepatitis C virus. Based on these findings, a chalcone derivative, 2-hydroxy-4-methoxy-2′,3′-benzochalcone, was prepared. It showed antimitotic activity through its inhibitory effect on tubulin polymerization. Its molecular binding mode with tubulin was elucidated using in silico docking and nuclear magnetic resonance spectroscopy. In addition, the three-dimensional structure of 2-hydroxy-4-methoxy-2′,3′-benzochalcone was determined by X-ray crystallography.

1) H and (13) C NMR spectral assignments of novel naphthalenylphenylpyrazolines.

Compounds containing pyrazolinyl-1-carbothioamide scaffolds (Fig. 1A) can act as anticancer agents, antimicrobial agents, and monoamine oxidase inhibitors. When ethyl 2-bromoacetate is added to pyrazolinyl-1-carbothioamide, 2-pyrazolin-1-ylthiazol4(5H)-one (Fig. 1B) is produced. Compounds containing thiazolone scaffolds show hepatitis C virus inhibitory effects, antitubercular, antibacterial, and antimicrobial activities. We designed naphthalenylphenylpyrazolinyl-1-carbothioamides (Fig. 1C) and naphthalenylphenyl-2-pyrazolin-1-ylthiazol-4(5H)-ones (Fig. 1D). Five thousand compounds containing pyrazolinyl-1-carbothioamide scaffolds and three thousand compounds containing 2-pyrazolin-1ylthiazol-4(5H)-one scaffolds have been reported. Similar to chalcones (Fig. 1E), naphthalenylphenylpyrazolinyl-1-carbothioamides and naphthalenylphenyl-2-pyrazolin-1-ylthiazol-4(5H)-ones contain a C6C3-C6 skeleton. Chalcones are a group of plant-derived polyphenols. Because of their diverse biological activities, chalcones are still being derivatized. Therefore, the NMR and mass spectrometric (MS) data of the compounds we have designed and synthesized could help us identify newly synthesized derivatives or derivatives isolated from natural sources in the future. We report herein the complete H and C NMR data and high resolution MS data of 13 novel naphthalenylphenylpyrazolinyl-1-carbothioamides and five novel naphthalenylphenylpyrazolinyl-1-thiazol-4(5H)-ones.

A novel hydroxymethoxynaphthochalcone induces apoptosis through the p53-dependent caspase-mediated pathway in HCT116 human colon cancer cells

Flavonoids have always been studied in the context of therapies of human diseases. Among them, chalcone, an openchain flavonoid, has been used as a key precursor for synthetic lead compounds due to its diverse innate biological activity. Additionally, benzoflavone is known to induce xenobiotic-metabolizing enzyme activity, as well as have potent chemopreventive activity. Therefore, the combined structure of these two compounds should be useful for the discovery of new and/or increased biological activity. In this study, a chalcone derivative, 2′-hydroxy-2,4,6-trimethoxy-5′,6′-naphthochalcone (HMNC-74), was synthesized, and its anticancer activity was tested in the HCT116 human colon cancer cell line. An in silico docking study showed that HMNC-74 binds to tubulin. HMNC-74 exhibited the inhibition of clonogenicity of HCT116 cells and cell cycle arrest at the G2/M phase, followed by induction of apoptosis through, at least in part, p53-dependent caspase-7 activation. The results of this study show that HMNC-74 may be an effective chemotherapeutic agent.

Biological evaluation of 2-pyrazolinyl-1-carbothioamide derivatives against HCT116 human colorectal cancer cell lines and elucidation on QSAR and molecular binding modes

In the search of compounds exhibiting anticancer activity, 37 derivatives of 2-pyrazolinyl-1-carbothioamide were designed and synthesized. Clonogenic cell survival assays were adapted to measure the cytotoxicities of the synthetic derivatives against HCT116 human colon cancer cell lines. Half-maximal cell growth inhibitory concentrations (GI50) ranged from 0.49 to 41.22µM. The compound with the lowest GI50 value, 3-(2-hydroxy-4,5-dimethoxyphenyl)-5-(naphthalen-1-yl)-N-(3,4,5-trimethoxyphenyl)-pyrazolinyl-1-carbothioamide, was subjected to further biological studies, including cell viability and apoptosis assays to examine levels of annexin-V in the outer plasma membrane layer and poly ADP-ribose polymerase cleavage. Additionally, in vitro kinase assays were performed, and Abelson murine leukemia viral oncogene homolog 1 (Abl 1) tyrosine kinase demonstrated good inhibitory activity. The binding mode between the compound of interest and Abl 1 was elucidated using in silico docking. The pharmacophores derived for 2-pyrazolinyl-1-carbothioamides based on their quantitative structure-activity relationships will help us design novel chemotherapeutic agents.