Ultrasonic Synthesis and Preliminary Evaluation of Anticoronaviral Activity of 6,7-Dimethoxy-4-(4-(4-methoxyphenyl)piperazin-1-yl)-1-methylquinolin-1-ium Iodide
, Peter P. Grozdanov 2, Ivanka Nikolova 2, Valentin S. Lozanov 3 and Meglena I. Kandinska 1,*
Round 1
Reviewer 1 Report
This is an interesting topic from the point of view of the biological properties that the synthesized molecule is expected to have. However, from a chemical point of view, the article is poor and very traditional chemistry. I miss the fact that the synthesis of more derivatives and their subsequent biological study has not been carried out. I approve of the article but I encourage the authors to complete the work as indicated above.
Author Response
Point 1: This is an interesting topic from the point of view of the biological properties that the synthesized molecule is expected to have. However, from a chemical point of view, the article is poor and very traditional chemistry. I miss the fact that the synthesis of more derivatives and their subsequent biological study has not been carried out. I approve of the article but I encourage the authors to complete the work as indicated above.
Response 1: We are very grateful to the esteemed Reviewer for the positive opinion. About the note concerning the “poor and very traditional chemistry” in the present work, we would like to say that this is a desired effect. From more than twenty years we have work on the field of organic synthesis and we believe that the complicated and very expensive multistep synthesis is not very useful when finally some compound reaches the point for scale up and industrial production. Additionally, we are adherents to the Green chemistry principles. The bigger series of similar compounds is already prepared and the synthesis and screening of the antiviral properties of these compounds will be published elsewhere.
Reviewer 2 Report
The manuscript describes the synthesis of two novel quinoline derivatives as well as cytotoxic and antiviral evaluation of one compound. The structures were determined using spectral data (IR, 1H, and 13C NMR) as well as high-resolution mass spectrometry. The melting points are also provided. The attached spectra prove that the purity of the compounds is high. The authors could add retention factors for their TLC analysis. Please, change 'm' in the biological evaluation to capital 'M' - the unit of concentration (mol/L) rather than length (meter). The language should be checked.
I support the paper for its publication in Molbank after minor revision.
Author Response
Reviewer 2: The manuscript describes the synthesis of two novel quinoline derivatives as well as cytotoxic and antiviral evaluation of one compound. The structures were determined using spectral data (IR, 1H, and 13C NMR) as well as high-resolution mass spectrometry. The melting points are also provided. The attached spectra prove that the purity of the compounds is high. The authors could add retention factors for their TLC analysis. Please, change 'm' in the biological evaluation to capital 'M' - the unit of concentration (mol/L) rather than length (meter). The language should be checked.
I support the paper for its publication in Molbank after minor revision.
Point 1: The authors could add retention factors for their TLC analysis.
Response 1: Thank you very much for the positive evaluation of the manuscript and for the valuable recommendations. The ratio of solvents in the selected mobile phase for TLC for both compounds is corrected to DCM:MeOH = 4.5:0.5 (because of technical mistake) and RF values are indicated.
Point 2: Please, change 'm' in the biological evaluation to capital 'M' - the unit of concentration (mol/L) rather than length (meter).
Response 2: The molar concentration symbol is corrected to “M”.
Reviewer 3 Report
M. I. Kandinska and co-workers report a two-step procedure towards the synthesis of the new organic salt 6,7-dimethoxy-4-(4-(4-methoxyphenyl)piperazin-1-yl)-1-methylquinolin-1-ium iodide, as well as preliminary results from biological assays against coronavirus, and cytotoxicity profile against HCT-8 cells. Thus, despite the synthetic route is short and simple, the synthesized compound is a hybrid because it contains the piperazine pharmacophore along with the quinolinium one. The overall yield (i.e. 80%) is good considering the relatively complex structure of the synthesized bis-heterocycle. Cytotoxicity value is lower in comparison to CQ and HCQ. IC50 value against OC-43 of SARS-CoV-2 shows the potential of the synthesized compound for further in vitro and in silico assays. NMR, MS, and IR spectra are Okay. For these positive reasons, I consider this manuscript is suitable to be published by MDPI in the Molbank journal, practically in its present form, as well.
Author Response
Reviewer 3: M. I. Kandinska and co-workers report a two-step procedure towards the synthesis of the new organic salt 6,7-dimethoxy-4-(4-(4-methoxyphenyl)piperazin-1-yl)-1-methylquinolin-1-ium iodide, as well as preliminary results from biological assays against coronavirus, and cytotoxicity profile against HCT-8 cells. Thus, despite the synthetic route is short and simple, the synthesized compound is a hybrid because it contains the piperazine pharmacophore along with the quinolinium one. The overall yield (i.e. 80%) is good considering the relatively complex structure of the synthesized bis-heterocycle. Cytotoxicity value is lower in comparison to CQ and HCQ. IC50 value against OC-43 of SARS-CoV-2 shows the potential of the synthesized compound for further in vitro and in silico assays. NMR, MS, and IR spectra are Okay. For these positive reasons, I consider this manuscript is suitable to be published by MDPI in the Molbank journal, practically in its present form, as well.
Response: The authors of the manuscript are grateful for the positive opinion of the Reviewer.
