The Synthesis and Pharmacokinetics of a Novel Liver-Targeting Cholic Acid-Conjugated Carboplatin in Rats

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled: ” Pharmacokinetics and tissue distribution in rats of a novel cholic acid-conjugated carboplatin.” presents interesting work in terms of chemical synthesis, in vitro and in vivo studies. A very valuable element of the manuscript is at this early stage to establish pharmacokinetic and tissue distribution parameters for the newly synthesized compound. Both the introduction and the results and discussion sections are very carefully prepared and are of high merit. Only my comments relate to the experimental part and after addressing them the manuscript is suitable for publication.

 

Detailed comments:

1.      Figure 5 – on the graph on x-asis there are numbers from 1-6, as I understand they correspond to type of tissues as presented in Figure 4, but it should be better explained either in the caption or on the graph.

2.      Please indicate the source of 3-cholylamide-1,1-cyclobutanedicarboxylic acid if it was purchased if not include the synthetic procedure.

3.      Please include in the supplementary data elemental analysis, HRESI+-MS, infrared spectrum (IR), and HNMR for CP-CA.

4.      The preparation of samples for ICP-MS measurements is given for plasma samples and tissue samples, please also include the information on sample preparation for the other experiments: cell uptake and PPBR.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript titled “Pharmacokinetics and Tissue Distribution in Rats of a Novel Cholic Acid-Conjugated Carboplatin” by Yinyin Lan et al. presents the synthesis of the complex CP-CA and its distribution in liver tumor cells. While the manuscript contains significant results for the readers of Inorganics, it falls short in a crucial area: the characterization of the synthesized CP-CA. The experimental section provides minimal information, and the characterization of Cp-CA is very poor. Techniques such as NMR, X-ray crystallography, and mass spectrometry are necessary to confirm the structure of the compound. Without this scientific evidence, the manuscript's value is significantly reduced. Although the authors claim to have identified the structure of CP-CA using various spectroscopic techniques, neither the supplementary materials (not provided), nor in the main text of the article contains such data. The authors should provide detailed synthesis and characterization of CP-CA, similar to their work on the oxaliplatin conjugated complex published in JIB. (https://doi.org/10.1016/j.jinorgbio.2023.112200).

At present, the manuscript cannot be published in its current form.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The results presented in this manuscript show the incorporation of cholic acid and carboplatin, obtaining the new compound CP-CA. This strategy has already been used by the group and the synthesis and biological characterization results were published in JIB 2023, reference 31. The compound LLC-202 should be similar to the unpublished Cp-CA, but there is no comparison between the results, and this should be carried out by the authors.

In general, the manuscript is well written, the results and original and relevant. The experimental part was well described, in details. In general, the manuscript is organized.

1- In the third paragraph of the introduction, references 25-30, the reason for the greater antitumor activity of compounds containing bile acids should be informed. Is there a synergistic effect? Has this been proven? To improve it, please.

2- Comparison of experimental results with the compound LLC-202, cite the reference for this as soon as it is mentioned. Perhaps a figure together, LLC-202, ree carboplatin and the new compound  CP-CA would be interesting for the reader.

3- Figure 2 is very clear, showing the direct comparison between normal and tumor cells, with greater uptake for CP-CA, in a time of 4.5h. The question that arises is whether this time is adequate, whether there are MTT data that indicate that these compounds are not toxic? The uptake does not report anything about toxicity. Do you have any idea of ​​the mechanism of death, whether apostosis or necrosis? Are there annexin data to support the low toxicity of these compounds?

4- The authors state on page 3 that the greater uptake for the CP-CA compound indicates its selectivity for cancer cells. It is known that these cells have an accelerated metabolism and will therefore capture it, but the question is to explain the reason, from a chemical point of view. What does the CP-CA compound have in relation to CP that increases its uptake? This answer was not answered by the authors.

5- It would be interesting to include images of treated and untreated tissues in the manuscript to assess the toxicity issue.

6- Present MTT data within 12 hours, to be able to compare with the other results.

7- Carry out stability studies of the CP-CA compound in the medium/DMSO solvent system (0.5%). I thought this value was 0.5% high, wouldn't it be a maximum of 0.1% DMSO in the medium?

8- Caption of Figure 7: explain the value of 2.28mk/Kg, please.

9- Explain the AUC and MRT values ​​more completely, do not just mention that they are higher, justify these values.

10- Item 2.3, mention all the tissues investigated in the first paragraph.

11- Page 5, last line. The authors report a higher logP for CP-CA compared to CP. Cite a reference and values, to be clear. This information is very useful but is incomplete. Justification with the inclusion of CA increases the lipophilicity of CP-CA in relation to the compound CP.

12- Figures 4 and 5- The authors must mention that numbers 1-6 refer to tissues. Relate to the images of each tissue, to inform whether there is tissue damage. Improve the captions for both figures, including the numbering 1-6 and the type of fabric.

13- There is no information on the LD50 of the new compound and this information could invalidate the entire study, as if it is very toxic it could be causing necrosis. Without access to images of the tissues, before and after treatment, we have no way of knowing.

14- Page 7. Review the method of synthesis of the CP-CA compound. Where is the carboplatin CP?

15- Page 8. Justify the first paragraph of the PK study.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have made a significant effort to characterize the compound CP-CA, and it is now suitable for publication.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors answered all questions completely, justifying the absence of some experimental results. Considering the focus of the article, and the changes made, I approve the revised version.