Imidazole-Based AT₁ Receptor Ligands: Design, Synthesis and Pharmacological Evaluation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. In the introduction, the development of current inhibitors and representative drugs can be introduced.
2. In the second and third paragraphs of the introduction, the author introduces the design of losartan-based compounds, such as the binding status between losartan and proteins. If a protein interaction diagram and the design scheme are added to the main text, it will be easier for readers to understand, for instance, why the author chose this parent nucleus.
3. Does the R1 and R2 mentioned by the author in line 75 of the main text correspond to those in Scheme 1?
4. What is the design basis of the compounds in Scheme 1 proposed by the author? Why are the structural formulas of 4a-b and 4c completely different? In 4a-b: methoxy substitution is adopted, and the R1 position is substituted with biphenyl; in 4c, methyl ether substitution is used, and the biphenyl group at the R1 position has structural changes.
5. The superscript notations for Ki and IC50 in Table 1 should be a and b.
6. The text first discusses the structure-activity relationship (Table 1), followed by the molecular docking results (Figure 1). Please reverse the order of these two sections.
7. Line 194 shows the docking result of 4b, but it is not displayed in the main text. Please provide it.

Author Response

Answers to reviewers’ comments

We thanks both reviewers for all the comments that helped us to improve this manuscript. We’ve corrected the manuscript following the several points mentioned here, and answered point by point to your questions to provide as much context as possible.

 

Reviewer 1

Comments and Suggestions for Authors

1. In the introduction, the development of current inhibitors and representative drugs can be introduced.

We have added a small up-to-date point about current state of AT1 inhibitors and representative molecules in a new figure 1.

1. In the second and third paragraphs of the introduction, the author introduces the design of losartan-based compounds, such as the binding status between losartan and proteins. If a protein interaction diagram and the design scheme are added to the main text, it will be easier for readers to understand, for instance, why the author chose this parent nucleus.

It was indeed not so easy to follow without models, so we have added a map of main residues involved with the binding of sartan, from the RX of losartan.

1. Does the R1 and R2 mentioned by the author in line 75 of the main text correspond to those in Scheme 1?

They are the same indeed, with R1 being on the biphenyl and R2 in the scheme 1 being either the methoxy or the MOM moiety.

1. What is the design basis of the compounds in Scheme 1 proposed by the author? Why are the structural formulas of 4a-b and 4c completely different? In 4a-b: methoxy substitution is adopted, and the R1 position is substituted with biphenyl; in 4c, methyl ether substitution is used, and the biphenyl group at the R1 position has structural changes.

The structural diversity observed between compounds 4a-b and 4c mainly reflects the synthetic pathway rather than a deliberate break in the medicinal chemistry design. Series 3 compounds were first generated from aldehyde intermediates, and series 4 compounds were subsequently obtained through Grignard reactions on these precursors. Therefore, the differences in methoxy/methyl ether substitution patterns and in the biphenyl moiety originate from the specific synthetic intermediates and transformations used in each case.

1. The superscript notations for Ki and IC50 in Table 1 should be a and b.

It was corrected.

1. The text first discusses the structure-activity relationship (Table 1), followed by the molecular docking results (Figure 1). Please reverse the order of these two sections.

While we understand the rationale for reversing these two sections, in the present study molecular docking was not used as a predictive tool, but rather as a structural interpretation of the SAR derived from the binding assay results. For this reason, we believe that presenting the SAR first and the docking analysis afterwards provides a more logical progression, as the docking data are intended to rationalize and deepen the experimentally observed SAR.

1. Line 194 shows the docking result of 4b, but it is not displayed in the main text. Please provide it.

We have added 4b to the now figure 2, as well as reference it in the text.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

A manuscript by F. Descamps et al. describes the synthesis and in vitro and in silico studies of a series of compounds with a structure similar to that of the known drug losartan. The structure of the new compounds was rationally designed with the hope of achieving biological activity similar to or better than that of the reference compound. This was not entirely successful, although the synthesis of many new substances with confirmed purity and structure is valuable.

It’s a pity that the m/z values in the LRMS are expressed to the nearest whole number; it would be helpful to know at least one decimal place. However, it’s good that HRMS was performed for the new compounds and the number of decimal places (four) is correct. In the first LRMS spectrum shown in the Supplementary Materials, the accuracy is to one decimal place; for all others, it is rounded to whole numbers. Therefore, this may be due to the instrument’s settings rather than its low resolution. Please check whether the instrument allows for accuracy to one decimal place. If so, please enter the corrected values into the characteristics.

The word “novel” has a much stronger connotation than the word “new”. I do not agree that the substances obtained deserve such a strong term. They are not particularly unexpected or “exotic”, so please use the word “new” instead in the body of the manuscript. Furthermore, in article titles, it is recommended to use strong words sparingly and only when justified. In my opinion, the use of either “new” or “novel” in the title is not justified. Please remove the word ‘novel’ from the title and do not even include “new”.

As soon as a figure, table, scheme, etc., is first mentioned in the text, it should appear as close as possible to that reference. In line 72 (page 2), there is a reference to Table 1, whereas Table 1 does not appear until page 7. In addition, other figures and schemes appear before Table 1. 

In papers, when there are many compounds or they have complicated names, they are designated by numbers or alphanumeric symbols, both of which are written in bold. Since these abbreviations identify the substances on their own, it is unnecessary to precede them with the word “compound”. Instead of using, for example, the term “compound 6”, it is sufficient to use only “6”; this is truly sufficient, as it is clearer and less tiresome to read. Furthermore, in the experimental section, before the synthesis, although the systematic names were provided, the authors failed to write these abbreviations in bold. 

Substituents are denoted by the symbol R. If there are several such substituents, we add the numbers 1, 2, and so on. It is better to write the numbers next to the R symbol as superscripts rather than subscripts. A subscript could be confused with the number of such substituents. Furthermore, labeling a tetrazole derivative (in terms of a substituent) as CN₄ (Scheme 1) or CN₄H (Table 1) is not ideal; it is probably better to represent it with a structural formula rather than a molecular formula, as this is ambiguous and may cause confusion regarding the nature of the substituent. 

It is recommended to use consistent abbreviations or symbols throughout a single article. In the body of the article, the authors refer to methylene chloride as DCM, while in Scheme 3 they use the molecular formula, CH₂Cl₂. 

The common names of drugs are written with a lowercase letter. Brand names of drugs, on the other hand, are written with an uppercase letter. Generally, the name “losartan” is written with a lowercase letter, although it is sometimes written with an uppercase letter (Table 1 and line 242). 

In the experimental section, line 280 reads “NH4OH”. This is incorrect. Ammonium hydroxide does not exist. It is better to write “NH₃(aq)”. 

Although 9 was crystallized from ethanol, the formula for acetonitrile was incorrectly listed after the melting point. 

At Publishing House MDPI, we use the term Supplementary Materials rather than Supporting Information. 

Author Response

Answers to reviewers’ comments

We thanks both reviewers for all the comments that helped us to improve this manuscript. We’ve corrected the manuscript following the several points mentioned here, and answered point by point to your questions to provide as much context as possible.

Reviewer 2

Comments and Suggestions for Authors

A manuscript by F. Descamps et al. describes the synthesis and in vitro and in silico studies of a series of compounds with a structure similar to that of the known drug losartan. The structure of the new compounds was rationally designed with the hope of achieving biological activity similar to or better than that of the reference compound. This was not entirely successful, although the synthesis of many new substances with confirmed purity and structure is valuable.

It’s a pity that the m/z values in the LRMS are expressed to the nearest whole number; it would be helpful to know at least one decimal place. However, it’s good that HRMS was performed for the new compounds and the number of decimal places (four) is correct. In the first LRMS spectrum shown in the Supplementary Materials, the accuracy is to one decimal place; for all others, it is rounded to whole numbers. Therefore, this may be due to the instrument’s settings rather than its low resolution. Please check whether the instrument allows for accuracy to one decimal place. If so, please enter the corrected values into the characteristics.

Unfortunately, our device for LRMS only allow us to provide unit values while final compounds were systematically analyzed in HRMS to have proper number of decimal values.

The word “novel” has a much stronger connotation than the word “new”. I do not agree that the substances obtained deserve such a strong term. They are not particularly unexpected or “exotic”, so please use the word “new” instead in the body of the manuscript. Furthermore, in article titles, it is recommended to use strong words sparingly and only when justified. In my opinion, the use of either “new” or “novel” in the title is not justified. Please remove the word ‘novel’ from the title and do not even include “new”.

We understand that such a nuance may exist in english, so we modified the title and text accordingly.

As soon as a figure, table, scheme, etc., is first mentioned in the text, it should appear as close as possible to that reference. In line 72 (page 2), there is a reference to Table 1, whereas Table 1 does not appear until page 7. In addition, other figures and schemes appear before Table 1. 

We moved the table 1 accordingly, while it may be moved again during the editorial process.

In papers, when there are many compounds or they have complicated names, they are designated by numbers or alphanumeric symbols, both of which are written in bold. Since these abbreviations identify the substances on their own, it is unnecessary to precede them with the word “compound”. Instead of using, for example, the term “compound 6”, it is sufficient to use only “6”; this is truly sufficient, as it is clearer and less tiresome to read. Furthermore, in the experimental section, before the synthesis, although the systematic names were provided, the authors failed to write these abbreviations in bold. 

We tried to removing the many occurrences of “compound” and add the bold into the experimental section.

Substituents are denoted by the symbol R. If there are several such substituents, we add the numbers 1, 2, and so on. It is better to write the numbers next to the R symbol as superscripts rather than subscripts. A subscript could be confused with the number of such substituents. Furthermore, labeling a tetrazole derivative (in terms of a substituent) as CN₄ (Scheme 1) or CN₄H (Table 1) is not ideal; it is probably better to represent it with a structural formula rather than a molecular formula, as this is ambiguous and may cause confusion regarding the nature of the substituent. 

We modified the CN₄ with full letter tetrazole as it was indeed quite confusing.

It is recommended to use consistent abbreviations or symbols throughout a single article. In the body of the article, the authors refer to methylene chloride as DCM, while in Scheme 3 they use the molecular formula, CH₂Cl₂. 

The notations were harmonized here and corrected in the text.

The common names of drugs are written with a lowercase letter. Brand names of drugs, on the other hand, are written with an uppercase letter. Generally, the name “losartan” is written with a lowercase letter, although it is sometimes written with an uppercase letter (Table 1 and line 242). 

Lower case was harmonized in the text.

In the experimental section, line 280 reads “NH4OH”. This is incorrect. Ammonium hydroxide does not exist. It is better to write “NH₃(aq)”. 

It is now corrected

Although 9 was crystallized from ethanol, the formula for acetonitrile was incorrectly listed after the melting point. 

We corrected the typo here.

At Publishing House MDPI, we use the term Supplementary Materials rather than Supporting Information. 

We changed it for supplementary Materials.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised content has been improved and meets the requirements of the article. It is recommended to accept it.