Antioxidant Activity and Chemical Characteristics of Sambucus nigra L. Blossom from Different Regions in Bulgaria

Round 1

Reviewer 1 Report

Horticulturae Review Report

General comments: -

The topic is very interesting and has a great impact for the field. The manuscript is fairly written and suitable to be published in the Horticulturae Journal after taking care of some MINOR comments.

Detailed comments: -

In general, please REWRITE some sections (as they will be mentioned later) in the manuscript according to the journal style.

Keywords:

The keywords list is carefully chosen.

Abstract:

This section is poorly written and missing the structure of the abstract. The aim is not clearly stated in this section. Please state the aim or the objectives clear and specific. Also add some significant findings.

The author is advised to rewrite this section according to the journal style.

Introduction:

This section is ok

Materials and Methods:

The experimental design is adequate and suitable to the current study But phenolic contents, polyphenols and the flavonoids should be determined using the HPLC.

Results and Discussion:

The results are interesting But the results presentation could be improved

• The data in Figure 2 Amino acid composition is better presented in a table with numerical values and suitable statistical analysis.

Conclusion:

This section is poorly written, and it is too short. Please improve the conclusion section and rewrite it according to the journal style. This section should provide a good conclusion for the study and include the significant findings. This section must be supported by the results.

References:

The authors provided enough citations. It is also UPTODATE

 

 

Author Response

Dear reviewer,

I attach the answers in the file.

 

Author Response File: Author Response.docx

Reviewer 2 Report

The paper adds to a body of work on Elder but does need some clarity before it can be accepted. Please state the in the introduction that Sambucus nigra is Elder. This may be obvious to you but not necessarily to the reader. You talk about elderflower tea but have made no connection to your species.

In line 54 extragent is not a word commonly used in English please change to extraction solvent. Overall I found the introduction a little hard to read. The English needs some improvement but you need to make clear the difference in applications between leaves, blossoms etc as this was not easy to follow. The final sentences states the aim but nowhere does it mention amino acids which you then go on to measure. Please make sure the aims match the study.

Materials and methods - no mention is made of replication this is very important particularly as you have calculated errors. Please state number of biological and/or technical reps and how error calculations were performed. Please clarify and expand the drying procedure - it was not clear what you meant from the text. Some of the methods contain no clear details on weight of sample used and volume of solvent used. Please include these details.

Section 2.2.2 I assume this is a comparison of methods. This is not stated that you will compare methods. This should be in your introduction and/or aims but also there should be an introduction as to why you need to do this. You have described how the methods work but not why you might use one over the other. It seems this is not relevant to the paper or it's aims.

Line 151 what is a hydromodule?

Section 2.2.6 SI and TSI measurements are not described anywhere please expand.

2.2.7 As mentioned above amino acid measurement is not stated as an aim anywhere in the paper.

2.2.8 As above no mention of replication please amend

Figure 1 Please add a scale bar

Line 222 Measurement of sorbitol - this has not been mentioned at all neither in the aims, introduction or methods. Please remove this or include sorbitol as in your aims, introduction and methods and state it's importance.

Figure 2 line 261 average of how many samples?? The figure is not highly useful as it just shows a distribution of amino acids. Is this normal for Elder is it different?? Maybe better to show the different distributions from the different areas as that is the aim of the study. I would remove the figure otherwise as it does not add to the story.

The discussion and conclusions need more work. The aim of the article was to compare different regions of Bulgaria. Some more detail about why there are differences would give this article more impact. The conclusions need to be expanded to include this information too.

 

Author Response

Dear reviewer,

 

I give the answers in the attached file below.

 

 

Author Response File: Author Response.docx

Reviewer 3 Report

The submitted manuscript describes some chemical and antioxidant activity study of Sambucus nigra flowers and leaves collected in different regions in Bulgaria. The paper is concise, written clearly and the methodology used seems correct.

My main concerns are as follows:

• the applied methods are rather simple and do not introduce much novelty into the topic. The phytochemistry of nigra have been already recognized in much more details using LC-MS techniques (see e.g. Biomolecules 2021, 11, 1222. https://doi.org/ 10.3390/biom11081222). Adding LC-MS comparison of the investigated samples would definitely add more relevance to the study.
• it seems that there was only one sample collected in each region (at least there is no information that there were more of them). In that case the conclusion about the advantage of the samples from the Rhodopes region might only be consider as preliminary. This fact should be acknowledged by the Authors in the conclusions.
• there is no statistical analysis for the results. For the conclusions to be valid, the differences between samples should be evaluated for statistical significance.
• the introduction section needs to be re-checked and if necessary re-written. There are some inconsistencies. E.g. lines 43-44 – free fatty acids are not volatile constituents, thus they should not be major constituents of an essential oil (please compare with some more recent publications concerning essential oil in S. nigra, e.g. https://doi.org/10.1080/11263504.2020.1779841); lines 46-49 – considering that the phenolics and their antioxidant activity are one of the main focus of the work, a more detailed information should be provided in the introduction about that group of constituents (compiled from more than one source); lines 53-58 – anthocyanins are present only in the fruits of S. nigra, I do not see the connection between their content in different extracts with the studies described in the manuscript; line 67-70 – ref 14 seems to consider the berries of the S. nigra, thus again not much relevance; bioactivities of the flowers or leaves should be mentioned here instead. Ref. 16 is about antibacterial activity not anticancer. More over caffeic acid is not a typical anticancer constituent.

Author Response

Dear reviewer,

 

I give the answers in the attached file below.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Much improved document with methods now more accurately described and a clearer conclusion.

Author Response

Dear reviewer,

Thank you for your revision.

Reviewer 3 Report

The manuscript has been improved. I see still some minor issues to correct:

• introduction, lines 50-52 – this sentence is still incorrect. Oxygenated monoterpenes constitute 71% of the volatile fraction of the flower, not 71% of the flower themselves. Thus, they cannot be considered as main constituents. Kaempferol is a flavonoid thus it is included in the second sentence. Besides, the flower contains mainly kaempferol glycosides, not kaempferol itself. Thus again, it might not be considered as a main constituent. Please rewrite the fragment. I would suggest a consultation with an expert in phytochemistry.
• lines 333-334 – This sentence should be in the caption under Table 6 (please use the appropriate font for a table caption). Similar captions should be under Tables 5, 4 and 3. Also, please pay attention, in which case in it should be ‘means in the column’ and in which ‘means in the row’
• Table 3-6 – the superscripts for statistic are usually given after the SD (they are more legible this way)
• Table 4 – please add SDs for the means. If they are too small, all results may be recalculated to mg/100 g. Also, all results should be given with the same accuracy (number of digits after the comma)
• lines 337-338 – The last sentence in the paragraph is not fully understandable. Please re-check the language.
• conclusions, line 353 – should be glutamine, leucine, aspartic acid?

Author Response

Dear reviewer,

I will give the answer to your questions in the attached file.

Author Response File: Author Response.docx