Review Reports - Kinetics and Thermodynamics of Ultrasound-Assisted Extraction of Taxanes from <i>Taxus chinensis</i> by Natural Deep Eutectic Solvents

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In the abstract and results, increasing percentages in yield should be mentioned for all treatments.

In the introduction, the literature reviews regarding using different models in the extraction process and its thermodynamic properties are required.

In kinetic modelling, R² and RMSE are not enough to judge the models, so I recommend using other statistical parameters like PE % and AIC for precise results.

The equations used in the study should be removed from the section of results, as they were mentioned in methods.

Please try to use the Peleg model for modelling the data, as it can give more precise results.

Figure (2a) should be removed to be included in the graphical abstract.

In results, more discussions are required.

Author Response

Dear Editors,

We thank the editors and referees for the valuable review of our manuscript, entitled "Kinetics and Thermodynamics of Ultrasound-assisted Extraction of Taxanes from Taxus chinensis by Natural Deep Eutectic Solvents" (Manuscript Number: processes-3987721). According to the reviewer’s suggestions, we have made the necessary modifications and highlighted these sections with a yellow background in the revised version of the manuscript. Moreover, we have given the details of the changes carried out and answers to the comments raised by the reviewers below. Other minor errors in the previous version of the manuscript were also rectified in the revised version. We hope revisions over the comments have improved the manuscript's quality and made it acceptable for publishing in Processes.

With best regards for you,

Jiaxin Quan

Shiyan Key Laboratory of Biological Resources and Eco-environmental Protection, Department of Chemistry and Environmental Engineering;

Hanjiang Normal University, Shiyan, 442000, P.R. China;

E-mail: quanjiaxin@hjnu.edu.cn

Comments and Suggestions for Authors of the manuscript (ID processes-3987721) under the title "Kinetics and Thermodynamics of Ultrasound-assisted Extraction of Taxanes from Taxus chinensis by Natural Deep Eutectic Solvents"

by Ying Guo, Wenna Song, Lingyu Hu, Runbo Liu, Izni Atikah Abd Hamid, Jiaxin Quan

Review 1:

1. In the abstract and results, increasing percentages in yield should be mentioned for all treatments.
Response: Thank you for your valuable comments. In our previous work of “RSM-rCCD Optimizing for Paclitaxel Extraction from Taxus chinensis by Natural Deep Eutectic Solvents and Studying Antioxidant Activity”, this method achieves a significantly higher extraction rate compared to other methods. From both thermodynamic and kinetic perspectives, this paper examines the underlying process and mechanism of the extraction.
2. In the introduction, the literature reviews regarding using different models in the extraction process and its thermodynamic properties are required.
Response: Thank you for your valuable comments. In the Introduction section, we have added the different models in the extraction process and discussed its thermodynamic properties.
3. In kinetic modelling, R² and RMSE are not enough to judge the models, so I recommend using other statistical parameters like PE % and AIC for precise results.
Response: Thank you for your valuable comments. Regarding the statistical parameters for the kinetic models, the issue you highlighted is indeed crucial. Following your suggestion, we have incorporated additional statistical parameters for model evaluation, including the Percentage Error (PE%) and the Akaike Information Criterion (AIC), alongside R² and RMSE. This provides a more comprehensive and precise analysis of the model fitting quality.
Preliminary comparison based on these statistical parameters revealed that the second-order model exhibits lower values of RSS (Residual Sum of Squares), AIC, and PE% compared to the first-order model. These results confirm the reliability of the second-order model in this study.

4. The equations used in the study should be removed from the section of results, as they were mentioned in methods.
Response: Thank you for your valuable comments. We will remove equations that appear repeatedly in the Results section to ensure that all model equations are presented in a consolidated manner only within the Materials and Methods section, thereby maintaining a clear organizational flow of the article.
5. Please try to use the Peleg model for modelling the data, as it can give more precise results.
Response: Thank you for your recommending this model. We employed the Peleg model to fit the experimental data and compared its results with other traditional models to validate its accuracy and applicability within the framework of this study. Preliminary fitting revealed that the
fitting parameters of the Peleg model were not superior to those of the second-order model used in this study. This demonstrates that the second-order model exhibits higher applicability in the present context. A detailed comparative analysis between the two models have been elaborated.
6. Figure (2a) should be removed to be included in the graphical abstract.
Response: Thank you for your valuable comments. We have removed Figure (2a) while maintaining the conciseness of the figures in the manuscript.
7. In results, more discussions are required.
Response: Thank you for your valuable comments. We have conducted a more in-depth and comprehensive discussion of all sections of the results. In particular, detailed interpretations are provided regarding the comparative outcomes of different models, the implications of the thermodynamic parameters, and the comparison between the Peleg model and traditional models, so as to substantiate the research findings.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please see the attachment.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Dear Editors,

With best regards for you,

Jiaxin Quan

Shiyan Key Laboratory of Biological Resources and Eco-environmental Protection, Department of Chemistry and Environmental Engineering;

Hanjiang Normal University, Shiyan, 442000, P.R. China;

E-mail: quanjiaxin@hjnu.edu.cn

by Ying Guo, Wenna Song, Lingyu Hu, Runbo Liu, Izni Atikah Abd Hamid, Jiaxin Quan

There are several points to be addressed by the authors.

Many constants and variables have been calculated from the equations and (pseudo)linear curves in this work. How a knowledge on these quantities could aid the processes of the extraction of each taxane as separate target compound (not mixed with other 5 components in the accidental proportion in the given plant sample)? One should take into account that other Taxus chinensis raw material will be featured by other amounts and proportions of taxanes at least quantitatively. How important is solving a problem of deep theoretical knowledge about this 6-component mixture without progress in the isolation and purification of separate compounds, please discuss.

Response: Thank you for your valuable comments. Recent studies have indicated that taxane compounds found in Taxus chinensis possess certain medicinal value. Therefore, the thorough extraction of taxanes is conducive to the subsequent separation of each component. Although the content of taxanes may vary in Taxus chinensis from different regions, the underlying extraction mechanism for these compounds remains consistent. Thus, exploring the optimal extraction conditions and the inherent extraction mechanisms for taxanes in local Taxus chinensis can be applied to optimize extraction conditions for taxanes in Taxus chinensis from different regions.

The results of HPLC for real plant sample are poor being not

Response: Thank you for your valuable comments. We have tested and optimized the results of HPLC for real plant sample as following.

The role played by a type of solvent, deep eutectic one, has been entirely hidden in the

Response: Thank you for your valuable comments. In our previous work of “RSM-rCCD Optimizing for Paclitaxel Extraction from Taxus chinensis by Natural Deep Eutectic Solvents and Studying Antioxidant Activity”, we specifically compared the advantages of NADES with traditional solvents. NADES demonstrate higher extraction yields compared to conventional solvents. NADES are widely used as greener alternatives to traditional solvents for the following reasons: (1) Their components are structurally simple, readily available in bulk chemical markets, and low-cost; (2) They are non-volatile during the extraction process, making NADES usable and recyclable; (3) They can be synthesized with low energy consumption; (4) They have low toxicity; (5) They are biodegradable and do not produce environmentally toxic products; (6) NADES possess extraction capabilities comparable to conventional volatile organic solvents; (7) NADES are stable at high temperatures; (8) They are non-flammable; (9) Their preparation is straightforward.

Materials and Methods, Line 92 "These samples were extracted …": by all appearances, the case in point is the samples mentioned a paragraph above, at Line 80. That is why "These samples were extracted" would be better to be replaced by " chinensis powder samples were extracted".

Response: Thank you for your noteworthy mention. We have revised this section in the manuscript.

Section 3.1 "HPLC Analysis": "The developed HPLC method demonstrated excellent reliability and achieved baseline separation of all six taxanes" seems to be an Even in Figure 1(a), the more so in real-sample-picture (Figure 1(b)), the peak 3 (10-deacetyltaxol) is virtually absent; and the resolution of peaks 5-6 is far from a baseline separation. To confirm a technique's suitability for accurate taxanes quantification, the authors should particularly underline the near-coincidence of retention time values for each compound taken in reference mixture and in real sample.

Response: Thank you for your valuable comments. We have tested the results of HPLC for six standard taxanes, respectively. The retention times of the six taxanes were determined individually. Furthermore, the relationship between the concentration of taxanes and their corresponding peak areas were analyzed by HPLC, establishing a standard curve (Fig. 1c). Based on this, we analyzed the retention times and peak areas of different taxanes in the actual extraction samples. These retention times of the actual samples were generally consistent with those of the standard substances.

In the Figure 1(d), the linear fit equations for taxanes present a full duplication of the left part of Table 2. By the way, what the concentrations within a very right column of Table 2 correspond to: a real-sample mixture or standards? To avoid duplication and simultaneously to attract attention to the retention time variables, three right columns may be extracted from Table 2, complemented with a column with lacking concentration values (I suppose, of standards), and all four columns inserted in Figure 1 to replace a content of its part (d).

Response: Thank you for your valuable comments. We have revised this section in Fig. 1 as following.

Order	Compounds	Time (min) Standard Sample		Content (μg/mL) Standard Sample
1	10-DAB Ⅲ	2.572	2.744	170	4.19
2	Baccatin Ⅲ	2.908	2.929	170	6.37
3	10-DAT	5.157	5.263	170	8.29
4	DXT	6.021	6.261	170	4.31
5	Cephalomannine	6.756	6.879	170	0.22
6	Paclitaxel	7.024	7.211	170	0.85

Table 2 should undergo modifications by taking into account point 6 The proposed amendments could be a replacement of taxanes content in sample by the taxanes concentrations in standards (which correspond to Figure 1(a)), and deletion of the retention time values for taxanes in sample.

Response: Thank you for your valuable comments. We have revised this section in Table 2 as following.

Order	Compounds	Regression Equation	R²	Linear Range (μg/mL)	Formula	M.W. (g/mol)
Order	Compounds	Regression Equation	R²	Linear Range (μg/mL)	Formula	M.W. (g/mol)
1	10-DAB Ⅲ	y=18530x-21993	R²=0.9998	1.25-125	C₂₉H₃₆O₁₀	544.590
2	Baccatin Ⅲ	y=11274x+101571	R²=0.9992	1.25-125	C₃₁H₃₈O₁₁	586.627
3	10-DAT	y=7285x+2697	R²=0.9998	1.25-125	C₄₅H₄₉NO₁₃	811.870
4	DXT	y=16326x+27972	R²=0.9998	1.25-125	C₅₀H₅₇NO₁₇	943.984
5	Cephalomannine	y=15990x+4008	R²=0.9996	1.25-125	C₄₅H₅₃NO₁₄	831.901
6	Paclitaxel	y=27486x+17276	R²=0.9998	1.25-125	C₄₇H₅₁NO₁₄	853.906

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript has been modified, and it can be accepted for publication as is.

Reviewer 2 Report

Comments and Suggestions for Authors

I have checked the revised version. The manuscript has been extensively revised for clarity and consistency. The authors have answered the questions asked by reviewers and performed an additional improvement of their work.

Comments on the Quality of English Language

The English could be improved to more clearly express the research.