Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript reports the antioxidant effect of 11 plant species and C. sinensis, limited to in vitro methods. Many of the results described do not present new activities of the extracts studied. More elaborate assays of antioxidant activity, cosmetic application (as reported by the authors; line 327) and/or other biological properties would assist in a more in-depth study of the species analyzed.

i) Introduction: insert more information about the importance of consuming antioxidant molecules

ii) 2.2. Aromatic medicinal plants and tea samples preparation: inform the yield of each extract

iii) Several methods are used to investigate the antioxidant property of plant extracts. Antioxidant activity should not be investigated based on a single antioxidant assay for more complete/accurate results. To evaluate the antioxidant properties of bioactive  of 11 natural compounds the samples under study were evaluated using different in vitro anti-oxidant assays, such as: DPPH-FRSA, FRAP, and FIC activity: this phrase must be inserted in the results

iv) 2.3.1. Determination of DPPH-Free Radical Scavenging Activity (FRSA): To inform final concentration of DPPH

v) BHT would not be the most appropriate standard to be compared with extracts, in this case, it is important to compare with a molecule extracted from a natural product, such as curcumin, ascorbic acid, resveratrol or vitamin E

 

Author Response

The authors sincerely appreciate the reviewer’s comments

i)    Introduction: insert more information about the importance of consuming antioxidant molecules

 Response: The authors introduce in the text more information about the consuming of antioxidant molecules

ii)    2.2. Aromatic medicinal plants and tea samples preparation: inform the yield of each extract

Response: The authors introduce the new sections “2.3. and 3.1 Yield determination of Aromatic medicinal plants and C. sinensis green tea extracts” in the manuscript and the yield was presented in table 2.

iii) Several methods are used to investigate the antioxidant property of plant extracts. Antioxidant activity should not be investigated based on a single antioxidant assay for more complete/accurate results. To evaluate the antioxidant properties of bioactive of 11 natural compounds the samples under study were evaluated using different in vitro anti-oxidant assays, such as: DPPH-FRSA, FRAP, and FIC activity: this phrase must be inserted in the results

Response: The authors introduce this sentence in the results.

iv) 2.3.1. Determination of DPPH-Free Radical Scavenging Activity (FRSA): To inform final concentration of DPPH

Response: The final concentration of DPPH was 100 µM and was described in the text.

v) BHT would not be the most appropriate standard to be compared with extracts, in this case, it is important to compare with a molecule extracted from a natural product, such as curcumin, ascorbic acid, resveratrol or vitamin E

Response: The authors sincerely appreciate the reviewer comments. For antioxidant capacity the authors changed the BHT for ascorbic acid as reference and the values were reported in table 2.  

Reviewer 2 Report

Comments and Suggestions for Authors

 

Dear authors,

         After reviewing the following manuscript entitled " Nutraceutical value of eleven aromatic medicinal plants and 2 Azorean Camellia sinensis: Comparison of antioxidant properties, phenolic and flavonoid contents” (Processes-3062073), I am sending you the following comments and observations that should be tended to before its publication in this journal.

 I appreciate the work of the authors, but please resolve the following data:

 1.  Abstract: The Abstract should contain some of the values obtained from the research.

2. Keywords: The chosen keywords are very vague. I recommend the use of terms more specific to the performed study, e.g., Camellia sinensis, etc.

3. Introduction: The Introduction is too long. I suggest that it be reduced to a maximum of a page.

4. Throughout the body of the text, the binomial names of the plant spcies must be written completely and in italics, e.g., Camellia sinensis Kuntze, etc.

5. Lines 141-142: An explanation for the reason which water (or other aqueous solutions) was used as an extraction solvent and not another substance is required. So as to provide a stronger extraction capacity and selectivity for polyphenols, respectively. Also, the concentration of extractive solution that resulted is not mentioned, in order for the use of the rotary evaporator to be justified. The obtained sampled could have been directly frozen and lyophilized.

6. Point 2.3.1. Determination of DPPH-Free Radical Scavenging Activity (FRSA): The DPPH reagent name should be correctly written: DPPH (2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl.

7.  Line 158: What is the concentration of the extracts?

8. Figure 1: I recommend that the results shown in Figure 1 should be presented in table form.

9.   Figure 2: Same recommendation.

10. Very different substances were used as references for result interpretation, e.g., rutin for TFC, gallic acid for TPC, and for the antioxidant capacity – 2 different means of expressing antioxidant activity. This leads to a difficult and uncertain comparison of the results. especially since the title of the article contains the phrase “Comparison of antioxidant properties, phenolic and flavonoid contents”.

11. The scientific interest of this study is reduced, given that aqueous extracts were realized.

12. Conclusions: require reformulation so as the novelty of the study to be brought to the attention of the reader.

13. References not older than 10 years should be chosen, given the fact that the studied plant species are highly researched.

 

Author Response

The authors sincerely appreciate the reviewer’s comments

I appreciate the work of the authors, but please resolve the following data:

1. Abstract: The Abstract should contain some of the values obtained from the research.

Response: The authors described some of the values obtained in the Abstract.

2. Keywords: The chosen keywords are very vague. I recommend the use of terms more specific to the performed study, e.g., Camellia sinensis, etc.

Response: The authors added some new specific Keywords.

3. Introduction: The Introduction is too long. I suggest that it be reduced to a maximum of a page.

Response: The authors reduced the section Introduction and added a table for the desciption of aromatic medicial plants.

4. Throughout the body of the text, the binomial names of the plant species must be written completely and in italics, e.g., Camellia sinensis Kuntze, etc.

Response: The authors revised all text and correct the names of the aromatic medicinal plants and Camellia sinensis.

5. Lines 141-142: An explanation for the reason which water (or other aqueous solutions) was used as an extraction solvent and not another substance is required. So as to provide a stronger extraction capacity and selectivity for polyphenols, respectively. Also, the concentration of extractive solution that resulted is not mentioned, in order for the use of the rotary evaporator to be justified. The obtained sampled could have been directly frozen and lyophilized.

Response: We sincerely appreciate the reviewer’s comments. The authors introduce the below setence in the text.
Knowing the impact of sample preparation conditions (e.g., solvent type, temperature of extraction, contact time, particle size, and solute:solvent ratio) on the preservation of antioxidant activity, the tea extraction yield was performed using an aqueous solution, to mimic the tea infusions used by general population. The tea extraction procedure was carried out using the following conditions:…
We used the rotary evaporator to reduce the volume of solution, because we have a small freeze dryer in our laboratory.

6. Point 2.3.1. Determination of DPPH-Free Radical Scavenging Activity (FRSA): The DPPH reagent name should be correctly written: DPPH (2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl.

Response: The authors rewritten the reagent name.

7.  Line 158: What is the concentration of the extracts?

Response: The information was added to the text (mg/mL).

 

8. Figure 1: I recommend that the results shown in Figure 1 should be presented in table form.

Response: The authors changed the Figure 1 to table 3.

9.   Figure 2: Same recommendation.

Response: The authors changed the Figure 2 to a table 3.

10. Very different substances were used as references for result interpretation, e.g., rutin for TFC, gallic acid for TPC, and for the antioxidant capacity – 2 different means of expressing antioxidant activity. This leads to a difficult and uncertain comparison of the results. especially since the title of the article contains the phrase “Comparison of antioxidant properties, phenolic and flavonoid contents”.

Response: The authors used the rutin for TFC and acid gallic for TPC in order to compare our results with some studies already published allowing a better discussion of our results. For antioxidant capacity the authors changed the BHT, for ascorbic acid as reference in FRSA and FRAP assays. For FIC activity, after several experiments using the ascorbic acid whithout stable results, the authors decide to keep the EDTA, as a reference.
According to some authors described in the publication of Kontoghiorghes et al. (2020), the interaction of ascorbic acid and iron is unstable. “The metal coordination chemistry of ascorbic acid has been thoroughly studied in connection with its high redox activity and participation in various biologically important redox processes. In contrast to strong chelators, like the chelating drugs, which are used in iron overloading conditions for removing excess iron, ascorbic acid is generally considered as a weak chelating agent and cannot form strong iron complexes or be used effectively in iron removal.”

11. The scientific interest of this study is reduced, given that aqueous extracts were realized.

Response: We appreciate the reviewer’s comments. The autors introduce the explaination in the section “2.2. Aromatic medicinal plants and tea samples preparation”. The authors received samples from the tea factory and the objetive was to mimic the tea infusions used by general population. The authors added this explanaition in the text.

12. Conclusions: require reformulation so as the novelty of the study to be brought to the attention of the reader.

Response: Thank you for your suggestion. In accordance with the comments, the authors revised the "Conclusion".

13. References not older than 10 years should be chosen, given the fact that the studied plant species are highly researched. 

Response: The authors improve the reference section according to the reviewer guideline.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors adequately informed the questions about the manuscript

Author Response

We would like to express our deepest appreciation to the reviewer for their helpful comments and suggestions about the manuscript. 

Reviewer 2 Report

Comments and Suggestions for Authors

The selected extraction method, as well as the solvent were not the most suitable. I recommend that, for future attempts, scientifically relevant extraction methods be selected. 

Author Response

We would like to express our deepest appreciation to the reviewer for their helpful comments and suggestions about the manuscript.