Advances in Purple Tea Research: Chemical Compositions, Anthocyanin Synthesis and Regulation, Processing, and Health Benefits
, Juan Li 1,2,* and Kunbo Wang 1,2,3,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe review apparently very comprehensive on purple tea extracts is centered very much on the chemical composition and biosynthesis/regulation of anthocyanins/flavanols and results too long repetitive and only leading to better understanding by forwarding the reader to the original publication cited. Else it is too tedious to accept their sentence without further reading.
This is a common phenomenon in review synthesis where the expertise of the author has little synthetic capability ending up in copy/paste editing that might synthesize too much the main concept without the full exposure of the message.
Too many unexplained abbreviations and too much literature citation jumping is noticed all along the text with changing argument from sentence to sentence without unifying the concepts in maybe more paragraphs. Paragraphs names also became inappropriate at the end of the review.
For example, lane 502, 4. Biosynthesis and Regulation of Anthocyanins in Purple Tea and lane 588, 5. Biosynthesis and Regulation of Anthocyanins in Purple Tea does not focus on such headlines.
Recommended changes:
1) Shorten literature and aspects to anthocyanins biosynthesis.
2) Create a table with different tea cultivars and their main extracts
3) Lane 126: why advice for further transcriptomics analysis if later on you disclose in detail the RNAseq studies and genetics studies of the biosynthesis in detail? What more to know?
4) Lane 134-136: there is no instability on the metabolic pathways for the anthocyanin’s biosynthesis. The only variation is among cultivar a genetic variation of themechanism regulating the type of anthocyanins/flavanols.
5) lanes 243-246: the reaction that led to this transformation of polymeric catechins back to anthocyanins under acidic condition is not known in chemistry/biochemistry. Neither the reference you have taken it from explain that. REMOVE IT, unless you gie a proper citation where this phenomenon occurs.
6) Figure 1: there are dot arrows that point on the interchangeability between cyanidin and pelargonidin and delphinidin and pelargonidin as if they can change into each other. That is not true. Could you set a unidirectional arrow instead of bidirectional ones?
7) Lane 270 : “cornflowerin 3-O-galactoside”, what is that chemically? Can you rename it with more common names, else give a IUPAC name ?
8) lanes 292-296: the “anthocyanin accumulation” is put in relationship with “the strength of late modification” but bio/chemically it is does not equal to say that “ their glutathione conjugation and vacuole transport” represents the key of anthocyanins accumulations! Please rephrase it.
9) Figure 2: instead of a general regulatory figure this should contain a specific name of MYBs and bHLH that are involved in the activation and repression as mentioned in your review. Else as it is right now does not apply to your review. Besides, it might seem also that the GST is a membrane protein in your figure. Are you sure about it?
10) Lane 361: no info is given for “PAs” which is also misspelled in lane 364 and 367. Could you give as first the extended name and refer to it afterwards as “PAs”?
11) Lanes 425-432: too different abbreviations and citations. Try to simplify the concept without involving too many extra elements.
12) Lane 446-448: Needs more intro when shifting argument (this is often seen in your review). Here creating subparagraphs can let the reader know that you are changing slightly the argument. In the specific, the focus of the lanes 446 and 456 is “CsbZIP1”.
13) Lane 451: “higher” in the beginning of a new sentence should be in capital.
14) Lanes 457-464: jump from one topic (TF: CsAN1, CsCOP1, CsPIF3 and CSHY5) to another and forward the explanation of complex events to the literature…not good synthesis. Redo it.
15) Lanes 465-469: the concept of low temperature on the induction of increase of anthocyanins and Pas is explained very badly and forwarded to the reader to the reference [57]. However, the same concept is well explained in lanes 469-472 but with another reference [61].
16) Besides: the order of reference giving is not following an increase numbering: please check it.
17) Lanes 482-484: the “phosphorylation” of a protein, namely, the TFs CsMYBL2 and CsBES1 has a cascade effect that led to their proteolysis of CsBES1 but the stabilization of CsMYBL2! Since they are both negative regulators if CsMYBL2 is stabilized the final effect is still inhibition of anthocyanins and catechins production…Give Figure 3 as reference and explain in detail in Figure 3 the mechanism schematized (as now there is no text associated with Figure 3, only headline).
18) Lanes 486-494: you introduce here another concept: create a subparagraph with indentation. Give to MEJA abbreviation its full name. Here you have three topics: MEJA, 1-aminocyclopropane-1-carboxylic acid (ACC) and sucrose. It is very difficult for the reader to jump from topic to another one..
19) Lane 502: give a new name to this paragraph: i.e. processing methods to achieve different final tea preparation for the market.
20) Figure 4: it needs more description for the processes illustrated.
21) Lanes 524-525: trivial to say that “anthocyanins are a group of polyphenolic compounds”, but not trivial is the fact that few know that the “black tea” is produced by fermentation, which involve oxidation by Polyphenol-oxidases (PPO). Here PPOs are not mentioned!
22) Lanes 542-554: try to simplify for the reader that for each different processing method arise a commercial tea type with different antioxidant capabilities…
23) Lane 588: give to this paragraph a right title…
24) Figure 5: need to be added a rich legend with the explanation of the different mechanisms of antioxidant action and abbreviations.
25) Lane 610: give a full name of COX-2;
26) Lane 615: give a full name of iNOS, TNF-α, IL-1β, IL-6, and CINC-1.
27) Lane 620: it is mentioned the “IHBT 269 clone”. Which clone refers it to? Try to put it in the text without forwarding the reader to the citation.
28) Lane 630: give full name to the abbreviations: Green or black teas (PG and PB) and TTES No. 12 teas (TG and TB). I.e. purple shoot black (PB); purple shoot green tea (PG); Taiwan Tea Experiment Station (TTES); Taiwan Tea Experiment Station No.12 (TTES No. 12) green tea (TG); Taiwan Tea Experiment Station No.12 (TTES No. 12) black tea (TB).
29) Lane 668: “purple” has to be in capital.
30) Lane 710: give a full name for “LHE”.
31) Conclusions and prospect: from such huge review on tea anthocyanins and catechins I was expecting more focused to what you mentioned as elucidating mechanism of producing anthocyanins in purple tea cultivars and how these compounds as compared catechins in green leaf tea extracts can be more health beneficial. Therefore, I will expect you re-made the conclusions accordantly to the main paragraphers and findings of the purple tea, besides the processing procedures.
Author Response
Dear Ms.Nichakarn Thuenprom, Dear reviewers,
Thank you for your letter dated December 01 2023 regarding your decision on our manuscript (horticulturae-2739109; Advances in Purple Tea Research: Chemical Compositions, Anthocyanin Synthesis and Regulation, Processing, and Health Benefits). We thank the reviewers for the time and effort that they have put into reviewing the previous version of the manuscript. Your suggestions have enabled us to improve our work. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Accordingly, we have uploaded a copy of the original manuscript with all the changes. Appended to this letter is our point-by-point response to the comments raised by the reviewers. The comments are reproduced and our responses are given directly afterward in a different color (red). Please see the attachment.
We would like also to thank you for allowing us to resubmit a revised copy of the manuscript. The content we revised this time is marked in red font in the the manuscript.
We hope that the revised manuscript is accepted for publication in the Horticulturae.
Sincerely,
Meihong Yan
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University,
Changsha, Hunan, 410128, People’s Republic of China.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors of the review “Advances in Purple Tea Research: Chemical Composition, Anthocyanin Synthesis and Regulation, Processing, and Health Benefits” did a fine job. Reading this article provides one with lots of insight, and reading is smooth because of good structuring, eloquent English and impressive figures.
However, I want to make a number of suggestions in the order of the text:
Line 27: “to much less well-known and consumption of purple tea”. Rephrasing would help that sentence, the stylistic principle is parallelism.
Line 88: “Purple tea exists numerous varieties…..! Correct this sentence.
Line 194 “ 3. Biosynthesis and Regulation of Anthocyanins in Purple Tea” is the title in this line but also in line 502 and in line 588. This oversight has to be corrected by inserting the correct titles.
Figure 1: As a chemist/biochemist I consider this figure to be of high importance. However, when I read the print-out I can hardly decipher the names of the metabolites. My idea is always that letters in a figure should rarely be smaller than letters in the main text (comparable font size). The authors might consider to give that first figure some more space. They could also consider to add chemical structures to the phenylpropanoid pathway to increase coherence.
Line 721: “The above results clearly show that purple tea plays a significant role in inhibiting the value-added of cancer cells…”
Please correct.
All in all, this is a very satisfying review!
Comments for author File: Comments.pdf
Author Response
Dear Ms.Nichakarn Thuenprom, Dear reviewers,
Thank you for your letter dated December 01 2023 regarding your decision on our manuscript (horticulturae-2739109; Advances in Purple Tea Research: Chemical Compositions, Anthocyanin Synthesis and Regulation, Processing, and Health Benefits). We thank the reviewers for the time and effort that they have put into reviewing the previous version of the manuscript. Your suggestions have enabled us to improve our work. Based on the instructions provided in your letter, we uploaded the file of the revised manuscript. Accordingly, we have uploaded a copy of the original manuscript with all the changes. Appended to this letter is our point-by-point response to the comments raised by the reviewers. The comments are reproduced and our responses are given directly afterward in a different color (red). Please see the attachment.
We would like also to thank you for allowing us to resubmit a revised copy of the manuscript. The content we revised this time is marked in red font in the the manuscript.
We hope that the revised manuscript is accepted for publication in the Horticulturae.
Sincerely,
Meihong Yan
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University,
Changsha, Hunan, 410128, People’s Republic of China.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAll the necessary changes have been incorporated.
