Abstract
Introduction
Cancer, a serious disease in which abnormal cells grow uncontrollably, spreads to other parts of the body, and kills normal cells, has been known as the second leading cause of death after cardiovascular disease in the world. Thus, considerable attention has been paid to the discovery of potential anticancer agents, such as podophyllotoxin derivatives.1-4 Although podophyllotoxins are good tubulin polymerization inhibitors, with antitumor activities, they mostly failed in clinical studies and caused many side effects.
5
Semisynthetic derivatives of podophyllotoxin, such as etoposide (

Some potent podophyllotoxin derivatives.
A series of novel podophyllotoxin–naphthoquinones has been prepared and evaluated for their anticancer activity against 5 cancer cell lines.9-11,27 4-Azapodophyllotoxin analogs (
Results and Discussion
In our previous study, we found that 3-component reactions of 2-amino-naphthoquinone, fluorinated aromatic aldehydes, and tetronic acid using p-toluenesulfonic acid (p-TsOH) as an acid catalyst and gl. AcOH as a solvent under microwave irradiation furnished fluorinated podophyllotoxin derivatives in high yield.
27
Accordingly, in this study, the synthesis of 2 new potent 4-azapodophyllotoxin containing fluorine atoms was conducted under the same optimized reaction conditions (outlined in Scheme 1). Upon completion of the reactions (20 min), 11-(3-fluoro-4-hydroxyphenyl)-4,11-dihydrobenzo[g]furo[3,4-b]quinoline-1,5,10(3H)-trione (

Synthesis of fluorinated podophyllotoxin–naphthoquinone derivatives
The cytotoxic activities of the 2 products
Cytotoxicity of
On the grounds of biological evaluation, it is of interest studying the interactions between products against potential anticancer dual targets, such as tubulin and topoisomerase. In this study, as a standard protocol, colchicine and etoposide (

Redocked poses (green) compared to original poses (yellow) of (A) colchicine in tubulin and (B) etoposide (
After validating the docking protocol for each target,

Interactions between compounds
Binding Energy and Interaction Between the Docked Compounds With the Amino Acids in the Active Site of Tubulin and Topoisomerase.
On the other hand, etoposide (

Interactions between compounds
Conclusions
The efficient and straightforward preparation of 2 new fluorinated podophyllotoxin–nạpthoquinones is described, using a microwave-assisted multicomponent approach employing 2-amino-1,4-naphthoquinone, fluorinated benzaldehydes, and tetronic acid. Subsequent cytotoxic assessment in KB, HepG2, A549, MCF7, and Hek-293 cell lines, together with the investigation of their interactions with the amino acids in the active site of tubulin and topoisomerase implied their potential for further elaboration toward novel anticancer agents.
Materials and Methods
The synthesis procedure for compounds
11-(3-Fluoro-4-Hydroxyphenyl)-4,11-dihydrobenzo[g]furo[3,4-b]Quinolin-1,5,10(3H)-Trione (8a )
Yield 275 mg (73%), orange solid, mp. 302°C. IR (KBr) νmax/cm−1 3351, 3102, 3037, 2948, 1745, 1667, 1629, 1589, 1517, 1493, 1478, 1439, 1397, 1340, 1297, 1194, 1113, 1024, 1000, 932, 792, 771, 730, 601, 577. 1H NMR (DMSO-d6, 600 MHz): δ 10.58 (1H, s, -NH), 9.66 (1H, s, -OH), 8.05 (1H, dd, J = 7.8, 1.2 Hz, H-6), 7.90 (1H, dd, J = 7.8, 1.2 Hz, H-9), 7.83 (1H, td, J = 7.8, 1.2 Hz, H-8), 7.80 (1H, td, J = 7.8, 1.2 Hz, H-7), 7.05 (1H, dd, J = 12.6, 2.4 Hz), 6.93 (1H, dd, J = 8.4, 2.4 Hz), 6.81 (1H, t, J = 8.4 Hz), 4.97 (1H, d, J = 16.8 Hz, H-3a), 4.91 (1H, s, H-11), 4.88 (1H, dd, J = 16.8, 1.2 Hz, H-3b). 13C NMR (DMSO-d6, 125 MHz) δ 182.1 (C-10), 179.5 (C-5), 171.1 (C-1), 155.8 (C-3a), 151.7 (1C, d, J = 238.75 Hz, C-3’), 143.5 (1C, d, J = 11.25 Hz, C-4’), 139.2 (C-4a), 136.0 (1C, d, J = 5.0 Hz, C-1’), 134.9 (C-8), 133.3 (C-7), 131.9 (C-9a), 130.3 (C-5a), 125.9 (C-6), 125.7 (C-9a), 124.1 (C-6’), 118.1 (C-10a), 117.3 (1C, d, J = 2.5 Hz, C-5’), 115.7 (1C, d, J = 18.75 Hz, C-2’), 101.8 (C-11a), 66.1 (C-3), 34.0 (C-11). HRESIMS (ESI): Found m/z 378.0775 [M + H]+, calcd. for [C21H13FNO5]+: 378.0773, and m/z 395.1042 [M+NH4]+, calcd. for [C21H16FN2O5]+: 395.1038.
11-(4-(Difluoromethoxy)-3-Hydroxyphenyl)-4,11-
dihydrobenzo[g]furo[3,4-b]Quinolin-1,5,10(3H)-Trione (8b )
Yield 289 mg (68%), orange solid, mp. 175°C. IR (KBr) νmax/cm−1 3311, 2971, 2942, 2900, 2710, 1742, 1653, 1601, 1570, 1502, 1433, 1393, 1349, 1301, 1264, 1236, 1194, 1115, 1049, 1023, 1001, 957, 828, 788, 724, 678, 552. 1H NMR (DMSO-d6, 600 MHz): δ 10.65 (1H, s, -NH), 9.78 (1H, s, -OH), 8.06 (1H, dd, J = 7.8, 1.2 Hz, H-6), 7.91 (1H, dd, J = 7.8, 1.2 Hz, H-9), 7.83 (1H, td, J = 7.2, 1.2 Hz, H-8), 7.81 (1H, td, J = 7.2, 1.2 Hz, H-7), 6.97 (1H, d, J = 7.8 Hz), 6.94 (1H, d, J = 1.8 Hz, H-2’), 6.93 (1H, t, J = 75 Hz, H-7’), 6.74 (1H, dd, J = 8.4, 2.4 Hz), 4.97 (1H, d, J = 16.2 Hz, H-3a), 4.91 (1H, s, H-11), 4.90 (1H, dd, J = 16.2, 0.6 Hz, H-3b). 13C NMR (DMSO-d6, 150 MHz) δ 182.0 (C-10), 1179.5 (C-5), 171.1 (C-1), 155.8 (C-3a), 148.4, 142.7, 139.3 (C-4a), 137.2 (1C, d, J = 3.0 Hz, C-4’), 135.0 (C-8), 133.4 (C-7), 131.8 (C-9a), 130.2 (C-5a), 126.0 (C-6), 125.8 (C-9a), 121.5, 118.9, 118.2 (C-10a), 116.8, 116.6 (1C, t, J = 256.5 Hz, C-7’), 101.9 (C-11a), 66.1 (C-3), 34.4 (C-11). HRESIMS (ESI): Found m/z 426.0800 [M + H]+, calcd. for [C22H14F2NO6]+: 426.0784, and m/z 443.1070 [M+NH4]+, calcd. for [C22H17F2N2O6]+: 443.1050.
The HRESIMS and NMR spectra for products
Supplemental Material
sj-doc-1-npx-10.1177_1934578X231153733 - Supplemental material for Synthesis, Molecular Docking, and Cytotoxic Evaluation of Fluorinated Podophyllotoxin Derivatives
Supplemental material, sj-doc-1-npx-10.1177_1934578X231153733 for Synthesis, Molecular Docking, and Cytotoxic Evaluation of Fluorinated Podophyllotoxin Derivatives by Nguyen Ha Thanh, Le Quang Bao, Hai Pham-The, Dang Thi Tuyet Anh and Phan Van Kiem in Natural Product Communications
Footnotes
Acknowledgements
The authors are indebted to Vietnam Academy of Science and Technology (code: CT0000.03/22-23).
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Vietnam Academy of Science and Technology (grant number CT0000.03/22-23).
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References
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