Total Phenolic Content, Antioxidant Capacity and UV Radiation Protection Properties of Marigold (Calendula officinalis), Carrot (Daucus carota), Tomato (Solanum lycopersicum) and Hop (Humulus lupulus) Extracts
Round 1
Reviewer 1 Report
“Total phenolic content, antioxidant capacity and UV radiation protection properties of marigold (Calendula officinalis), carrot (Daucus carota), tomato (Solanum lycopersicum) and hop (Humulus lupulus) extracts”
The article has some interesting information, by comparing several plant extracts in their antioxidant and UV radiation protection properties. Though it needs some major revisions regarding the use of references. Overall, the article shows a poor use of references, in which many are missing or are not in agreement what is presented in the text. The introduction relies too much on just a few, not giving a robust support from literature. The discussion section is too descriptive, much alike the results section, also missing support from literature that could show how the obtained results are promising as claimed in the conclusion. If available, some data regarding the effect of sunflower oil alone for comparison with oil extracts should be provided as for the linear increase of the sun protection factor.
In my perspective, the article can be considered for publishing after addressing the following comments and suggestions.
1. Line 42-43 “New formulas, recipes, or forms of products and new sunscreen ingredients have been widely examined” Sentence missing references and I would also suggest a few examples at least from ingredients.
2. Line 70 “An important role play also enzymatic antiradical systems.” Sentence should be reviewed.
3. Line 83-84, examples of filters should be provided and the sentence should be referenced accordingly.
4. From line 85 until 100, only one reference is used, being the same identified several times. After that, in line 116, appears reference 11 while references 9 and 10 are missing. The text from line 100 to line 112 is missing references, which I would assume should be 9 and 10. I would advise the authors to review the section from line 85 until line 120, properly introducing references in agreement with the information present in the text.
5. From line 120 to line 146 proper references should be provided as the information does not agrees with the identified references. Review references from 12 to 16.
6. As in the abstract as in line 177, the ration 20 to 80 can be simplified as 1 to 4, otherwise authors can show it as a percentage.
7. Extraction procedure described from line 179 to 186 is not clear. As it is said the maceration process took 24h, I would assume it was a mechanical maceration. Though this is not clear, and the equipment was not identified. It should be described in the materials and methods sections.
8. The extraction procedure was performed at 25°C for water extracts and 30°C for water-glycol and oil extracts. Why not at the same temperature? The increase in temperature should promote a higher extraction yield so water extracts could not be directly compared with water-glycol and oil extracts.
9. All figures should be improved. Y and X-axis should be well defined and error bars should be introduced. Figures 3 and 6 image quality should also be improved.
10. Discussion needs to be improved. A better explanation is required when commenting results. Why is water-glycol solvent promoting such higher amount of extracted polyphenols from hops when compared with the other tested plants? Any mechanistic insight that could be referenced? It should also be shown if results are in agreement with literature, if it is expected that marigold and hops present similar amounts of polyphenols, which are higher than the amount present in carrot and tomato.
11. Antioxidant capacity seems to agree with TPC, which should be mentioned. However, antioxidant capacity discussion is too descriptive and seems a repetition from the results section.
12. Sentence from line 451 to 452 should be reviewed “Because of that not in all samples of extracts the increasing values of determined parameters were obtained with increasing concentration”.
13. In the discussion (lines 479 to 482), a reference to literature should be made on how it tis expected that sunflower oil alone also provides UVB protection. Did the authors performed experiments to assess the performance from sunflower oil in comparison with the oil extracts?
14. Sentence in lines 482 to 484 is missing a reference.
15. In line 488-489 it is mentioned that the sun protection factor increases linearly, though data is not shown to confirm this trend. Can the data be provided at least in a supplementary info file?
16. In conclusions, authors claim that the obtained extracts are very promising and can be applied in cosmetic formulations, though no comparison is made with literature in the discussion section, lacking support.
Author Response
Response to Reviewer 1
Thank you very much for your thorough review and very valuable comments. I hope that the answers below and the revised manuscript will meet your expectations.
- Line 42-43 “New formulas, recipes, or forms of products and new sunscreen ingredients have been widely examined” Sentence missing references and I would also suggest a few examples at least from ingredients.
Information on the compounds used in sunscreens is provided later in this paper. In my opinion, including a broader description will significantly increase the introduction part. References are added.
- Line 70 “An important role play also enzymatic antiradical systems.” Sentence should be reviewed.
This part of of manuscript was rearanged and new references was added.
- Line 83-84, examples of filters should be provided and the sentence should be referenced accordingly.
- From line 85 until 100, only one reference is used, being the same identified several times. After that, in line 116, appears reference 11 while references 9 and 10 are missing. The text from line 100 to line 112 is missing references, which I would assume should be 9 and 10. I would advise the authors to review the section from line 85 until line 120, properly introducing references in agreement with the information present in the text.
- From line 120 to line 146 proper references should be provided as the information does not agrees with the identified references. Review references from 12 to 16.
The manuscript from verse 83 to 171 has been rearranged and references have been correctly assigned as was suggested by reviewer 1 and 2.
- As in the abstract as in line 177, the ration 20 to 80 can be simplified as 1 to 4, otherwise authors can show it as a percentage.
The expression 20:80 has been corrected in the abstract and in the text of the manuscript.
- Extraction procedure described from line 179 to 186 is not clear. As it is said the maceration process took 24h, I would assume it was a mechanical maceration. Though this is not clear, and the equipment was not identified. It should be described in the materials and methods sections.
In the Materials and Methods section, information on the device used in the maceration process has been added.
- The extraction procedure was performed at 25°C for water extracts and 30°C for water-glycol and oil extracts. Why not at the same temperature? The increase in temperature should promote a higher extraction yield so water extracts could not be directly compared with water-glycol and oil extracts.
I agree with the reviewer that the increase in temperature increases the efficiency of the extraction process. This is a well-known fact. Perhaps it was unfortunate that we proposed different temperatures for the process, wanting to obtain a higher concentration of less hydrophilic antioxidants. In addition, the use of different extractants and different extraction temperatures allows obtaining information on the sun protection of the extracts used in various cosmetic formulations, e.g. creams, sunscreens, lipsticks, etc.
- All figures should be improved. Y and X-axis should be well defined and error bars should be introduced. Figures 3 and 6 image quality should also be improved.
I did not fully understand what a better definition of the X and Y axes would consist in. I kindly ask for additional explanations. Also, it's not clear to me what the errors are. If that's not a problem, please be more specific. Thank you very much.
- Discussion needs to be improved. A better explanation is required when commenting results. Why is water-glycol solvent promoting such higher amount of extracted polyphenols from hops when compared with the other tested plants? Any mechanistic insight that could be referenced? It should also be shown if results are in agreement with literature, if it is expected that marigold and hops present similar amounts of polyphenols, which are higher than the amount present in carrot and tomato.
This part of manuscript was corrected.
- Antioxidant capacity seems to agree with TPC, which should be mentioned. However, antioxidant capacity discussion is too descriptive and seems a repetition from the results section.
This part of manuscript was corrected.
- Sentence from line 451 to 452 should be reviewed “Because of that not in all samples of extracts the increasing values of determined parameters were obtained with increasing concentration”.
This part of manuscript was corrected and adequate references were added.
- In the discussion (lines 479 to 482), a reference to literature should be made on how it tis expected that sunflower oil alone also provides UVB protection. Did the authors performed experiments to assess the performance from sunflower oil in comparison with the oil extracts?
The authors did not conduct experiments to evaluate the effects of sunflower oil in terms of protection against sun radiation. In this part of manuscript two references were added.
- Sentence in lines 482 to 484 is missing a reference.
The reference was added.
- In line 488-489 it is mentioned that the sun protection factor increases linearly, though data is not shown to confirm this trend. Can the data be provided at least in a supplementary info file?
The graphs of the dependence of the sun protection factor on the concentration of the tomato extracts are placed in supplementary.
Fig.1 The dependence of the protection factor on the concentration of the tomato water extracts
Fig.2 The dependence of the protection factor on the concentration of the tomato water-glycol extracts
Fig.3 The dependence of the protection factor on the concentration of the tomato oil extracts
- In conclusions, authors claim that the obtained extracts are very promising and can be applied in cosmetic formulations, though no comparison is made with literature in the discussion section, lacking support.
This part of manuscript was corrected.
Reviewer 2 Report
In the manuscript entitled “Total Phenolic Content, Antioxidant Capacity and UV Radiation Protection Properties of Marigold (Calendula officinalis), Carrot (Daucus carota), Tomato (Solanum lycopersicum) and Hop (Humulus lupulus) Extracts” authors have reported Total phenolic content using Folin Ciocalteau method, antioxidant capacity by CUPRAC method and sun protection properties were measured for four different extracts of selected plants: marigold petals, carrot roots, tomato fruits and hop cones. The study is backed up with high class experimental data and evidences, which are currently followed for similar types of work worldwide. In totality, the conceptualization, designing of experiments and the overall write up is good and quite clear.
However, it needs some corrections and there are some queries which the authors should kindly respond to make it good.
Major review:
Results:
The main aspect for improvement is statistic. There is no statistical analysis that would make it possible to compare the samples with each other and with the control. Statistical methods should be added especially for content of phenolic compounds and antioxidant activity in different extracts.
Figure 1 and 2: standard deviation are missing
Discussion:
Discussions need to be improved. In this form Discussion is an extended description of the Results and should be transferred to the Results section, so in manuscript Discussion is missing. The discussion should be extended to the analysis of the obtained results based on available literature data, for example, if authors find the presence of phenolic compounds in extract, they should additionally describe what properties this compound has from an practical point of view and the possibility of its application to cosmetics - because this is the aim of the study. Moreover, it is necessary to discuss, based on the literature, the influence of solvents on the composition of plant extracts, compare solvents of different polarity.
Author Response
Response to Reviewer 2
Thank you very much for your thorough review and very valuable comments. I hope that the answers below and the revised manuscript will meet your expectations.
- The main aspect for improvement is statistic. There is no statistical analysis that would make it possible to compare the samples with each other and with the control. Statistical methods should be added especially for content of phenolic compounds and antioxidant activity in different extracts.
ANOVA statistical analysis was performed to compare the results obtained for the Folin and Cuprac methods.
- Figure 1 and 2: standard deviation are missing
Figures 1 and 2 have been graphically corrected and the values of standard deviations have been added.
- Discussions need to be improved. In this form Discussion is an extended description of the Results and should be transferred to the Results section, so in manuscript Discussion is missing.
- The discussion should be extended to the analysis of the obtained results based on available literature data, for example, if authors find the presence of phenolic compounds in extract, they should additionally describe what properties this compound has from an practical point of view and the possibility of its application to cosmetics - because this is the aim of the study.
This part of the manuscript has been rearranged as suggested by reviewers 1 and 2.
- Moreover, it is necessary to discuss, based on the literature, the influence of solvents on the composition of plant extracts, compare solvents of different polarity.
The following sentence has been added and the relevant citations included:
Our results confirm the well-known fact that the use of different extractants affects the amount of isolated compounds and the chemical composition of the extract.
Conde E, Moure A, Domínguez H, Parajó J.C., Extraction of natural antioxidants from plant foods, Separation, extraction and concentration processes. Woodhead Publishing Series in Food Science, Technology and Nutrition, 2013.
Cannell R.J.P., Natural Products Isolation. Humana Press lnc., New Jersey, 1998.
Round 2
Reviewer 1 Report
“Total phenolic content, antioxidant capacity and UV radiation protection properties of marigold (Calendula officinalis), carrot (Daucus carota), tomato (Solanum lycopersicum) and hop (Humulus lupulus) extracts”
The authors clearly made a good effort to improve the manuscript. Showing data in tables 1 and 2 was a good improvement. The present manuscript has much better support from the literature and seems more robust than the previous version. I would suggest the authors review figures 3 and 6 quality and address the following as answers from the request in point 9.
- All figures should be improved. Y and X-axis should be well defined and error bars should be introduced. Figures 3 and 6 image quality should also be improved.
"I did not fully understand what a better definition of the X and Y axes would consist in. I kindly ask for additional explanations. Also, it's not clear to me what the errors are. If that's not a problem, please be more specific. Thank you very much."
In reply to the author's request, the X and Y axis are the plot's horizontal and vertical axis. It was a simple presentation suggestion to eliminate the horizontal lines and better define the axis to improve the data viewing and comprehension. The error bars would be at least the standard deviation calculated from the obtained data, or the results from statistical analysis.
I would consider that after following the reviewer's suggestions, improving the quality of the figure, uniformizing the plots and checking for a few typos and small English corrections, the article could be published.
Author Response
Answer for Reviewer 1
Dear Reviewer,
Thank you very much for re-reading the paper and valuable comments. Below are responses to your comments.
All figures should be improved. Y and X-axis should be well defined and error bars should be introduced. Figures 3 and 6 image quality should also be improved.
All figures have been corrected according to your suggestion.
All changes are highlighted in red (first round) or green (second round) color.
Yours faithfully
M. Kurzawa
Reviewer 2 Report
Authors corrected manuscript by my sugessted, but duscussion part still should be improved:
Line 47-42: Please discuss more detailed first and second paragraph of discussion. In literature data are a lot of information described phytochemical composition and antioxidants activity of plant extracts
Line 536: bacteria name should be italic
Author Response
Answer to Reviewer 2
Dear Reviewer,
Thank you very much for re-reading the paper and valuable comments. Below are responses to your comments.
Line 47-42: Please discuss more detailed first and second paragraph of discussion. In literature data are a lot of information described phytochemical composition and antioxidants activity of plant extracts.
This part of Discussion has been extended according to your suggestion.
Line 536: bacteria name should be italic
This part was corrected. The names have been changed to italic.
All changes are highlighted in red (first round) or green (second round) color.
Yours faithfully
M. Kurzawa
