Shading of Medical Plants Affects the Phytochemical Quality of Herbal Extracts

Round 1

Reviewer 1 Report

Dear Authors,

I am sorry but this revised version of the MS still lacks novelty, scientific quality and the MS needs to be majorly improved before being considered for publication.

Best regards,

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

 

The manuscript entitled “Shading of medical plants affects the phytochemical 2 quality of herbal liqueurs” from Nadica Tmušić and Co-Workers describes the effect of two different growth conditions on the total phenols, flavonoids, and antioxidant activity. The interest in medicinal plants is still rising as they provide an alternative source of potentially bioactive compounds.
The results are of general interest to the readers of Horticulturae as well as the broad scientific community. The overall impression of the manuscript is good and therefore I recommend the publication after a minor revision. Please find additional details below:

 

General points:

Some of the data may be visualized not presented as a table e.g. as a bar chart (Table 2-5).

 

Introduction:

The introduction covers major points regarding the topic. However, I wonder why the authors have not cited a recent study by Montero et al. (Montero et al. J Chromatogr A. 2020 Sep 8;1631:461560. DOI: 10.1016/j.chroma.2020.461560) describing the detailed composition of herbal liqueurs commonly drunken in Europa. It would be of benefit for the reader to also get some information on the complexity of the final composition of herbal liqueurs.

Are there any reports of how the individual compounds do change when the plants were grown under shade nets?

 

Materials and Methods:

L147 – 150 The authors say that they modified the method but not how.

 

Results:

L175 Check the layout of this line.

 

Discussion:

L300 – 315 and l331 - 332 Light is generally leading to the production of more polyphenols, pigments, or other bioactive compounds. However, in Lemon balm and Oregano higher levels of TPC were found. Is there any further biological explanation for this observation? It is an interesting measurement as all other values such as total flavonoids levels are going down when the plants were grown under shades.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript entitle “Shading of medical plants affects the phytochemical quality of herbal liqueurs” includes the study and comparison of different medicinal herbs submitted to different light intensity (50% shade index with pearl nets or un-shading) during the growth of the plant to obtain a response in the production of secondary metabolites. To evaluate the influence of this factor, different parameters were evaluated such as total extractive substances, total phenolic and flavonoid contents, and antioxidant activity by DPPH method. The results are focused on the production of herb macerates with a greater medicinal (healthy) character. Although the study is interesting, below I write a series of questions/suggestions to try to improve the scientific quality of the paper.

 

General comments/questions: carefully review all the text for typographical errors and word breaks.

Origanum and thymus are among the mint plants?

 

Introduction section

 

Line 51. “…due to the presence of polyphenols and flavonoids…”. Flavonoids are a family of polyphenol compounds, therefore, authors must correct this sentence.

 

Paragraph of lines 52-54. In the previous paragraph authors are talking about polyphenols and then they mentioned that these compounds are what provide the aroma and flavor of strong alcoholic drinks. This statement is not entirely correct. Regarding the aromatic part, it is the volatile compounds of medicinal and aromatic plants those that mainly provide the aroma to the corresponding alcoholic macerates.

 

Paragraph 82-90. These lines belong more to the results and discussion section than to the introductory. If authors want to keep them, they have to write them with a more introductory approach.

 

Materials and methods section

 

Include a section of reagents to know its commercial brand and purity, in order to carry out the experiments in the most reproducible way in future works.

 

Line 126. Why have the authors chosen to macerate the plants in fresh? Normally, both in the production of liqueurs and in the laboratory extractions, they are usually used dry to improve the extraction of the components.

 

Line 127. What kind of ethanol did the authors use for the experiments? Ethyl alcohol of agricultural origin or spirit? In the event that the authors have chosen laboratory ethanol not suitable for food use, they should change the focus of the entire publication…

 

Lines 128-130. Include the bibliographic citation of this statement.

 

Line 134. The temperature used (105ºC) to eliminate the solvent and leave the solid extract, is not a very high temperature that can damage the analyzed phenolic composition?

 

Lines 143 and 150. What modifications have been made to these methods?

 

Lines 147-150. What units does this method have?

 

Line 151. Why have the authors chosen this method of antioxidant capacity?

 

Line 163. What is the blank of this method?

 

Results section

 

Line 243. “In addition to phenolics, herbs also contain antioxidants”. With this statement it appears that phenolics are not antioxidants and this is not correct.

 

Table 6. Write the title of the table outside the table as in the rest of the cases. Unify in tables and text, or authors speak of plant extracts or they speak of plant macerates for the preparation of liqueurs (this depends on whether they have used laboratory ethyl alcohol or one for food purposes). To be able to talk about liqueurs, the authors would have to have added sugar in the elaboration.

 

Lines 243 and 252. “Extracts of lemon…” and “Herbal drinks from lemon…”. Unify nomenclature, I find this confusing.

 

Line 265. Significant correlations between the studied parameters…” what parameters the authors talk about?

 

Line 267. TF = total flavonoids?

 

Lines 267-269. Please better explain this sentence and cite reference.

 

Discussion section

Line 277. The most appropriate bibliographic citation for this part would be 12, although it can also include 13.

 

Line 278. I do not understand this phrase. Authors have macerated for 3 and 4 weeks and that is why it is concluded that 4 weeks is the best option? if so, why are there no tables with both results? It is understood then that all the results of the tables that authors expose in the work are for 4 weeks, right? this should also be clarified in the materials and methods section.

 

Lines 317-324. This paragraph is a bit empty because authors do not conclude or link the benefit of the present investigation in relation to this theory.

 

Lines 331-334. The content of this paragraph is not contradicted?

 

Lines 333-338. Justify this with correlations. Clarify this sentence because flavonoids are phenolic compounds ...

 

Lines 345-351. I don't understand why the authors are comparing solvents that are not used in this research and extractive techniques that are not used here either. Please improve this section considerably by comparing with literature related to macerations made in ethanol of these plants, if possible with plants (even if they are other Lamiaceae) that have also been grown in the shade and of course also with herb liqueurs!

Discuss and cite works like:

Rodríguez‐Solana, R., Esteves, E., Mansinhos, I., Gonçalves, S., Pérez‐Santín, E., Galego, L., & Romano, A. (2021). Influence of elaboration process on chemical, biological, and sensory characteristics of E uropean pennyroyal liqueurs. Journal of the Science of Food and Agriculture.

Vázquez-Araújo, L., Rodríguez-Solana, R., Cortés-Diéguez, S. M., & Domínguez, J. M. (2013). Study of the suitability of two hop cultivars for making herb liqueurs: volatile composition, sensory analysis, and consumer study. European Food Research and Technology, 237(5), 775-786.

 

Lines 357-359. This paragraph has already been cited before in line 340.

Author Response

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Author Response File: Author Response.doc

Round 2

Reviewer 3 Report

The authors have considerably improved the manuscript taking into account the reviewer's considerations. However, below I write some small revisions to improve the manuscript

Line 119. The authors cannot say herbs liqueurs, because authors have not produced liqueurs (authors have not used ethyl alcohols of agricultural origin or spirit, and sugar), but hydroalcoholic extracts of mint plants.

Line 135. Semi-dry. Describe in the manuscript how the semi-drying of plants was done.

Line 139. Approx. 40% v/v ethyl alcohol instead of Approx. 40%. The authors still do not specify the origin of the alcohol used. Based on what authors have written, I understand that it is ethyl alcohol of non-food use (laboratory), therefore specify the commercial company and purity in reagents section. In the same way, authors have to modify (which they have already done in most of the cases) where they say that authors have made a liqueur, put that authors have made a macerate or hydroalcoholic extract and that the results could be conclusive for the preparation of liqueurs, although future research will be done to expand and verify its final effect in those beverages.

Lines 400-403. Modify the phrase so that it is intuited that due to the analysis in essential oils of the mentioned plants in previous works, the results obtained in the current macerations or plant extracts may suggest that certain terpenes present in these plants may be those, among others, that provide bioactive properties .

Author Response

Answer to reviewer comments:

Line 119. The authors cannot say herbs liqueurs, because authors have not produced liqueurs (authors have not used ethyl alcohols of agricultural origin or spirit, and sugar), but hydroalcoholic extracts of mint plants.

As you suggest, we accept and include… in body text …..hydroalcoholic extracts of mint plants.

 

Line 135. Semi-dry. Describe in the manuscript how the semi-drying of plants was done.

We try to explained stage of plant material for maceration ....

Chopped and homogenized plant material harvested a few days before maceration,.....

Line 139. Approx. 40% v/v ethyl alcohol instead of Approx. 40%. The authors still do not specify the origin of the alcohol used. Based on what authors have written, I understand that it is ethyl alcohol of non-food use (laboratory), therefore specify the commercial company and purity in reagents section. In the same way, authors have to modify (which they have already done in most of the cases) where they say that authors have made a liqueur, put that authors have made a macerate or hydroalcoholic extract and that the results could be conclusive for the preparation of liqueurs, although future research will be done to expand and verify its final effect in those beverages.

We accept this suggestion….and now stay….40% v/v ethyl alcohol

Lines 400-403. Modify the phrase so that it is intuited that due to the analysis in essential oils of the mentioned plants in previous works, the results obtained in the current macerations or plant extracts may suggest that certain terpenes present in these plants may be those, among others, that provide bioactive properties .

We are make modification of these sentence……

It can be intuited that due to the analysis in essential oils of the mentioned plants in previous works (such as terpinen-4-ol in marjoram; thymol in thyme; geranial (E-Citral) in lemon balm; caryophyllene oxide in oregano and piperitenone oxide in mint) the results obtained in the current macerations or plant extracts may suggest that certain terpenes present in these plants may be those, among others, that provide bioactive properties.

 

 

We would like to thank the Editor and Reviewer for their comments and suggestions to improve our manuscript. We hope that in current form our manuscript will meet high standards for publishing in your journal Horticulturae MDPI

 

Sincerely Yours

Prof dr Zoran Ilic

Author Response File: Author Response.doc

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The article deals with the investigation on the effect of shading by pearl nets on the content of bioactive compounds in five different plants belonging to mint family. In my opinion, the writing is clear and concise but the conclusions are poorly supported by the content, So, I encourage authors to try a major revision and a second peer review

 

In particular:

The article title are not appropriate

The content of phytochemical compounds in plants depends on many parameters including growing and storage conditions. It would be interesting if the authors reported the effects of shading on yield.

The extraction technique must be optimized to obtain the maximal yield of extraction. This is different from plant to plant. I suggest the authors include this part in the discussion

A chemical characterization of extracts is desirable to consider the phytochemical quality of herb liqueurs

Fig 1 can be improved by using summary graphs

Author Response

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Reviewer 2 Report

This manuscript, entitled "Total phenolic, flavonoid contents and antioxidant activity of selected medicinal plants and respective herb liqueurs", provides quantitative and biochemical data about the effects of shading nets on the antioxidant profile and activity of different medicinal plants, commonly used to prepare alcoholic beverages. Although the paper is well-planned and follows a standard organization, some aspects need to be revised before it is suitable for publication. Attached to these comments, a PDF with revision can be found.

Suggestions include, but are not limited to:

1) The Introduction can be improved, by adding some sentences/paragraphs about the importance of shading nets and how these structures affect agricultural productivity, in terms of pros and cons.

2) The statistical analyses employed can be certainly improved - if authors want to compare species and the effects of nets, a 2-way anova must be performed. 

3) Some details concerning methods are missing.

4) Results are generally well described, but sometimes the info appears in a very confusing way. Please double-check.

5) The discussion and conclusion need to be majorly revised. This is the main flaw of the MS. Please see my suggestions in the PDF file.

Lastly, the English speech must be improved. There are a lot of errors that are not acceptable.

Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

The research "Total phenolic, flavonoid contents and antioxidant activity of selected medical plants and respective herb liqueurs" is a simple elaboration confirming the reaction of some Lamiaceae species to shading. In general, the manuscript is written correctly, which means it follows the main principles of scientific elaboration. My objection refers mainly methodology. The comparison of the different species' reactions to any experimental factor, especially the agrotechnical one, is not in line with methods of modern research because it’s obvious that species are different concerning all biological aspects, so they respond in a different way to experimental treatments. So, the manuscript doesn't present novel aspects, what was is reflected in the Discussion is a simple comparison with the referenced research. The authors haven't explained the mechanisms of how shading affects the physiology of investigated species. I haven't detailed comments on how to improve the scientific soundness of the paper because of the simple experimental design but in my opinion, it represents the too low substantive level to be published in such a reputable journal as Horticulturae. A deeper introduction confirming the novelty and significance of the study, broadening of the results with analysis of fresh plant material chemical composition as affected by shade nets (Authors include in the discussion chapter some links to the fresh herb biochemistry L259-260, without supporting results) and wider discussion focusing on possible mechanisms of the effects are necessary to resubmit the paper for publication.

Author Response

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Round 2

Reviewer 1 Report

The authors did not respond fully to the suggestions given by the reviewer, in some cases they even ignored them. The manuscript in its current form lacks sufficient data to support the conclusions. 

Reviewer 2 Report

Dear Authors,

I am deeply sorry to see that most of the suggestions I gave were not followed. The effort made by reviewers to improve the MS should not be ignored and the comments must be taken into account. When not in accordance, a justification needs to be given.

Also, the response to the reviewer is full of errors and denotes an enormous lack of care.