Antioxidant Potentials of Different Genotypes of Cowpea (Vigna unguiculata L. Walp.) Cultivated in Bulgaria, Southern Europe

Round 1

Reviewer 1 Report

Dear Authors,

I read the manuscript "Antioxidant Potential of Different Genotypes of Vigna (Vigna 2 unguiculata L. Walp.) Cultivated in Bulgaria, South Europe”

This work is interesting, well written, and the experiments well explained.

I just have a few comments on the presentation of the data.

1)      When the value of an analysis is reported, the accepted convention is that only one uncertain digit is to be used in the error. So, if the calculated error is 118.05 it should be approximated as 100 and to write the measure 291.01 ± 118.05 you should write 300 ± 100. Analogously, 50.43 ± 8.99 should be reported as 50 ± 9. This problem is present in all the data reported. However, the robustness of the data you presented is not questioned, it’s only required for a correct presentation of the results. The fact that in many publications this error is accepted doesn’t make it less wrong.

2)      I do not understand why in Table 3 you calculate Pearson correlation matrix also between data that are logically not correlated as the TPC or TFC of seeds with the RSC of leaves or vice versa.

Below are reported some other small errors and some unclear sentences of the manuscript that deserve your attention:

●       In line 33 and 34 you wrote twice globuline even if once is “highly present” and in the second phrase is ”less represented”. Please check the phrase.

●       In line 46 you wrote about antinutrients as good products. This is a bit strange. Could you explain better the concept.

●       In line 189 I do not understand which unit is mgE/g DW. What is E? you talked about tannic acid, but it is not clear.

●       In line 255 is written: “colored ones??.” Is it a typing error?

●       Il line 261-263 the phrase is not clear maybe you could divide in two.

●       In Figure 2 and 3, is it not better to put the numbers of the genotype instead of the color of seeds to indicate each point?

●       Figures 4 and 5 are not very clear, considering that all the samples have been represented as seeds or leaves. Maybe you can specify which leaves or seeds with genotype number?

●       In line 318, the “was” verb needs a subject.

●       In line 334 I do not understand the phrase may be something is missing

●       The literature does not follow the rules of the journal. Please correct it.

 

I believe this manuscript could be published in Agronomy after minor revisions.

Best regards

Comments for author File: Comments.pdf

The quality of english is generally good. A few mistakes were reported in the letter to authors

Author Response

Dear Reviewer,

Thank You for your comments and constructive suggestions! Here are our responses to your questions and proposals.

1. “When the value of an analysis is reported, the accepted convention is that only one uncertain digit is to be used in the error. So, if the calculated error is 118.05 it should be approximated as 100 and to write the measure 291.01 ± 118.05 you should write 300 ± 100. Analogously, 50.43 ± 8.99 should be reported as 50 ± 9. This problem is present in all the data reported. However, the robustness of the data you presented is not questioned, it’s only required for a correct presentation of the results. The fact that in many publications this error is accepted doesn’t make it less wrong.”

• Response: We have rounded the values to the first decimal place, because there are smaller and larger values.

2. “I do not understand why in Table 3 you calculate Pearson correlation matrix also between data that are logically not correlated as the TPC or TFC of seeds with the RSC of leaves or vice versa.”

Response: At the beginning, we made a table of Pearson matrix for leaves and a second one for seeds. After that, we decide to combine them in one total table to perform total Pearson correlation matrix. We were surprised by the values of R between leave and some seed studied parameters. We couldn’t find similar analysis between leaves and seeds, specifically for the biochemical parameters investigated in our project and decided to be presented here. The results are interesting and with much more samples could confirmed or rejected. In that reason, we comment that fact vary carefully. We think it is worth leaving the table in the manuscript in this way.

3. „In line 33 and 34 you wrote twice globuline even if once is “highly present” and in the second phrase is ”less represented”. Please check the phrase.“

• Response: We have corrected the sentence.

4. “In line 46 you wrote about antinutrients as good products. This is a bit strange. Could you explain better the concept.”

• Response: “Antinutrients” was replaced by “byproducts”.

5. “In line 189 I do not understand which unit is mgE/g DW. What is E? you talked about tannic acid, but it is not clear.”

• Response: The cited authors used this dimension. E is for E We have correct it.

6. “In line 255 is written: “colored ones??.” Is it a typing error?”

• Response: Yes, it is. We have correct it.

7. “In line 261-263 the phrase is not clear maybe you could divide in two.”

• Response: It’s done.

8. “In Figure 2 and 3, is it not better to put the numbers of the genotype instead of the color of seeds to indicate each point?”

• Response: It’s done.

9. “Figures 4 and 5 are not very clear, considering that all the samples have been represented as seeds or leaves. Maybe you can specify which leaves or seeds with genotype number?”

• Response: We have corrected figures 4 & 5 and specified with genotype nombers.

10. “In line 318, the “was” verb needs a subject”.

• Response: We have corrected the sentence.

11. “In line 334 I do not understand the phrase may be something is missing”

• Response: We have corrected the sentence.

12. „The literature does not follow the rules of the journal. Please correct it.“

• Response: We have corrected the reference list according to the journal requirements. Please, see References.

Reviewer 2 Report

The authors studied the antioxidant potential of 15 genotypes of cowpea (Vigna 

unguiculata L. Walp.)  cultivated in Bulgaria. However, they did not provide details of these genotypes. Particularly, their genetic background, hybrid or inbred, sources, yield potential, major uses, specific stress tolerance and disease resistance, etc. are missing.

Vigna is a genus name, it should be italicized. The common name of Vigna  unguiculata L. Walp. Is cowpea, not Vigna. The authors should justify why they used Vigna as a synonym/alternative name for cowpea.

How could potentially these locally cultivated cowpea genotypes have global significance since it is intended to be considered for publication in an international journal, not a domestic journal?

The current study neither analyzes any agronomic techniques nor agronomic traits. Rather focuses on food/feed quality issues. How the article falls within the scope of the journal “Agronomy” remains a question.

 

In the first line of the manuscript (line 27), the scientific name of cowpea has been abbreviated (V. unguiculata L. Walp), however, in the latter occurrence (line 53), the full form of Vigna unguiculata L. Walp. Has been used. The full form should be used at the first occurrence and the abbreviation in the rest occurrences

 

The authors concluded that Vigna genotypes with dark-colored seed coats showed greater antioxidant potential and this statement appeared only in the abstract (Line 18) and conclusion (Line 328), without exploration and discussion of underlying reasons. Anthocyanins are a kind of flavonoid with strong antioxidant potential, which provide pigmentation (red, purple, etc.) to different plant tissue. The authors should analyze the anthocyanin content to support the conclusion. At present, the study is limited to the analysis of a few biochemical parameters. There are many other reliable indexes of antioxidant capacity, such as antioxidant enzymes, glutathione, ascorbate, carotenoids, etc., and analysis of these indexes would provide a broader scenario of the antioxidant potential of these cowpea genotypes.

 

There are many grammatical issues that need to be addressed by proofreading by English expert colleagues or native speakers. Line 47: “evidences”?! always “evidence”, you should not add ‘s’ to express plural cases for ‘evidence. 

 

 

The authors studied the antioxidant potential of 15 genotypes of cowpea (Vigna 

unguiculata L. Walp.)  cultivated in Bulgaria. However, they did not provide details of these genotypes. Particularly, their genetic background, hybrid or inbred, sources, yield potential, major uses, specific stress tolerance and disease resistance, etc. are missing.

Vigna is a genus name, it should be italicized. The common name of Vigna  unguiculata L. Walp. Is cowpea, not Vigna. The authors should justify why they used Vigna as a synonym/alternative name for cowpea.

How could potentially these locally cultivated cowpea genotypes have global significance since it is intended to be considered for publication in an international journal, not a domestic journal?

The current study neither analyzes any agronomic techniques nor agronomic traits. Rather focuses on food/feed quality issues. How the article falls within the scope of the journal “Agronomy” remains a question.

 

In the first line of the manuscript (line 27), the scientific name of cowpea has been abbreviated (V. unguiculata L. Walp), however, in the latter occurrence (line 53), the full form of Vigna unguiculata L. Walp. Has been used. The full form should be used at the first occurrence and the abbreviation in the rest occurrences

 

The authors concluded that Vigna genotypes with dark-colored seed coats showed greater antioxidant potential and this statement appeared only in the abstract (Line 18) and conclusion (Line 328), without exploration and discussion of underlying reasons. Anthocyanins are a kind of flavonoid with strong antioxidant potential, which provide pigmentation (red, purple, etc.) to different plant tissue. The authors should analyze the anthocyanin content to support the conclusion. At present, the study is limited to the analysis of a few biochemical parameters. There are many other reliable indexes of antioxidant capacity, such as antioxidant enzymes, glutathione, ascorbate, carotenoids, etc., and analysis of these indexes would provide a broader scenario of the antioxidant potential of these cowpea genotypes.

 

There are many grammatical issues that need to be addressed by proofreading by English expert colleagues or native speakers. Line 47: “evidences”?! always “evidence”, you should not add ‘s’ to express plural cases for ‘evidence. 

 

Author Response

Dear Reviewer,

Thank You for your comments and constructive suggestions! Here are our responses to your questions and proposals.

1. “Vigna is a genus name, it should be italicized. The common name of Vigna  unguiculata L. Walp. Is cowpea, not Vigna. The authors should justify why they used Vigna as a synonym/alternative name for cowpea.”

• Response: Thanks for the remark! We have considered and used as common name “cowpea” instead of “Vigna”. Please, see the text body.

2. “How could potentially these locally cultivated cowpea genotypes have global significance since it is intended to be considered for publication in an international journal, not a domestic journal?”

• Response: Cowpea is grown in tropical and subtropical geographical regions. In Europe in South part of the continent, in countries like Italy, Greece, Portugal, Spain, etc. Local genotypes of cowpea are grown in many countries for production. There are many articles which object were local genotypes.

For example, please see the References section: Sombié, P.A.E.D.; Compaoré, M.; Coulibaly, A.Y.; Ouédraogo, J.T.; Tignégré, J.-B.D.L.S.; Kiendrébéogo, M. Antioxidant and Phytochemical Studies of 31 Cowpeas (Vigna unguiculata (L. Walp.)) Genotypes from Burkina Faso. Foods 2018, 7, 143. https://doi.org/10.3390/foods7090143;

Liyanage, R.; Perera, O.S.; Weththasinghe, P.; Jayawardana, B.C.; Vidanaarachchi, J.K.; Sivakanesan, R. Nutritional proper-ties and antioxidant content of commonly consumed cowpea cultivars in Sri Lanka. J Food Legum. 2014, 27(3), 215-217., etc.

So, our study contribute to the global data about Vigna unguiculata L. Walp. We hope to arouse readers' interest in this useful and neglected crop at a time when the need for protein-rich foods is increasing worldwide.

3. “The current study neither analyzes any agronomic techniques nor agronomic traits. Rather focuses on food/feed quality issues. How the article falls within the scope of the journal “Agronomy” remains a question.”

• Response: Thanks for the question! Our research is focused on seeds of the cowpea used as an "ancient" traditional crop in many countries. Cowpea ( unguiculata L. Walp.) is a legume crop with high content of protein, fibre, antioxidants, etc. It is major source of protein for human populations in developing countries, as well as fodder for animals. Today, looking for functional foods, cowpea could become “new - old” food not only due to its high protein content, but also with its potential for functional foods with high antioxidant potential. In our opinion, it is worth every study with this plant food, to get more knowledge and to reinvent “old” foods, as cowpea. This is one of the reason to work with V. unguiculata, recently.  The section “Plant-Crop Biology and Biochemistry” of the journal “Agronomy” is suitable for our manuscript, we think.

 

4. “In the first line of the manuscript (line 27), the scientific name of cowpea has been abbreviated (V. unguiculata L. Walp), however, in the latter occurrence (line 53), the full form of Vigna unguiculata L. Walp. Has been used. The full form should be used at the first occurrence and the abbreviation in the rest occurrences”

• Response: Thanks for the remark! We have considered and used the full form of the species at the begin, and the abbreviation in the rest occurrences. Please, see the text body.

 

5. “The authors concluded that Vigna genotypes with dark-colored seed coats showed greater antioxidant potential and this statement appeared only in the abstract (Line 18) and conclusion (Line 328), without exploration and discussion of underlying reasons. Anthocyanins are a kind of flavonoid with strong antioxidant potential, which provide pigmentation (red, purple, etc.) to different plant tissue. The authors should analyze the anthocyanin content to support the conclusion. At present, the study is limited to the analysis of a few biochemical parameters. There are many other reliable indexes of antioxidant capacity, such as antioxidant enzymes, glutathione, ascorbate, carotenoids, etc., and analysis of these indexes would provide a broader scenario of the antioxidant potential of these cowpea genotypes.”

• Response: Color is not only a function of one group of substances like antocyanins. In nature, color is often only an indication, and biological activity is not always a function of the chromophore For example, red grapes and red wine have very good antioxidant qualities, mainly due to "non-colored" substances such as trans-resveratrol and quercetin (Tzanova M. & Peeva P., 2018. Rapid HPLC Method for Simultaneous Quantification of trans-Resveratrol and Quercetin in the Skin of Red Grapes, Food Analytical Methods, 11 (2): 514- 521. https://doi.org/10.1007/s12161-017-1022-z; Tzanova M, Atanasov, V., Ivanov, M., Iliev, A., Atanassova, S. & Peeva, P., Grozeva, N., Gerdzhikova, M. & Dinev, T, 2019. Antioxidant Constituents and Antioxidant Activity of Some Red Wine and Red Table Grape Varieties, Cultivated in Different Regions of Bulgaria, Bulgarian Journal of Agricultural Sciences, 25 (3): 3-12; Novelle MG, Wahl D, Diéguez C, Bernier M, de Cabo R (2015) Resveratrol supplementation: Where are we now and where should we go? Ageing Research Reviews, 21: 1 – 15.)

Seeds of genotypes we tested have been collected from farmers and are not available in large quantities. These genotypes have just been described, and their potential has yet to be realized. We expect a better yield from our research fields this year, and select favorites for further experiments.

 

6. “There are many grammatical issues that need to be addressed by proofreading by English expert colleagues or native speakers. Line 47: “evidences”?! always “evidence”, you should not add ‘s’ to express plural cases for ‘evidence.”

• Response: Thanks for the remark! We have considered it and corrected. A professional translator proofreads our article. Please see the text body.

Reviewer 3 Report

 

The article Antioxidant Potential of Different Genotypes of Vigna (Vigna 2 unguiculata L. Walp.) Cultivated in Bulgaria, South Europe presented by Tzanova and cols., present for the first time the evaluation of different genoytypes of Vigna unguiculata from Bulgaria.

The experimental procedure has been well conducted and the results consistent. However, there are some aspects that need to be improved.

Introduction and abstract.

In these section authors mention the characteristic of high drought resistance, but don’t include more information about it, would be valuable for the reader to include a little bit more information of this fact, including the reason why this is so important. I think, some of the recent references of the topic are not including in the manuscript, some of these references are:

·         Sombié, P.A.E.D.; Compaoré, M.; Coulibaly, A.Y.; Ouédraogo, J.T.; Tignégré, J.-B.D.L.S.; Kiendrébéogo, M. Antioxidant and Phytochemical Studies of 31 Cowpeas (Vigna unguiculata (L. Walp.)) Genotypes from Burkina Faso. Foods 2018, 7, 143. https://doi.org/10.3390/foods7090143

·         Moloto, M.R.; Phan, A.D.T.; Shai, J.L.; Sultanbawa, Y.; Sivakumar, D. Comparison of Phenolic Compounds, Carotenoids, Amino Acid Composition, In Vitro Antioxidant and Anti-Diabetic Activities in the Leaves of Seven Cowpea (Vigna unguiculata) Cultivars. Foods 2020, 9, 1285. https://doi.org/10.3390/foods9091285

·         Thumbrain, D., Dwarka, D., Gerrano, A. S., & Mellem, J. J. (2020). Antioxidant and apoptotic potential of protein isolates derived from Vigna unguiculata (L.) Walp. International Journal of Food Science & Technology, 55(7), 2813-2823.

Results and discusión:

Would be valuable to include on this sections the information of the previous articles and a up-to-date search about the topic, since information is constantly updated.

Some issues in tables and figures are indicated in the manuscript

References

References don’t match with the format from MDPI, please edit each one

Comments for author File: Comments.pdf

Moderate english revision is required

Author Response

Dear Reviewer,

Thank You for your comments and constructive suggestions! Here are our responses to your questions and proposals.

1. Introduction and abstract.

“In these section authors mention the characteristic of high drought resistance, but don’t include more information about it, would be valuable for the reader to include a little bit more information of this fact, including the reason why this is so important. I think, some of the recent references of the topic are not including in the manuscript, some of these references are:

Sombié, P.A.E.D.; Compaoré, M.; Coulibaly, A.Y.; Ouédraogo, J.T.; Tignégré, J.-B.D.L.S.; Kiendrébéogo, M. Antioxidant and Phytochemical Studies of 31 Cowpeas (Vigna unguiculata (L. Walp.)) Genotypes from Burkina Faso. Foods 2018, 7, 143. https://doi.org/10.3390/foods7090143

Moloto, M.R.; Phan, A.D.T.; Shai, J.L.; Sultanbawa, Y.; Sivakumar, D. Comparison of Phenolic Compounds, Carotenoids, Amino Acid Composition, In Vitro Antioxidant and Anti-Diabetic Activities in the Leaves of Seven Cowpea (Vigna unguiculata) Cultivars. Foods 2020, 9, 1285. https://doi.org/10.3390/foods9091285

Thumbrain, D., Dwarka, D., Gerrano, A. S., & Mellem, J. J. (2020). Antioxidant and apoptotic potential of protein isolates derived from Vigna unguiculata (L.) Walp. International Journal of Food Science & Technology, 55(7), 2813-2823.”

• Response: We have included more info about the drought, and added some references to this characteristic. Please, see Introduction and

2. Results and discusión:

“Would be valuable to include on this sections the information of the previous articles and a up-to-date search about the topic, since information is constantly updated.”

• Response: We have cited the proposed articles and used in the discussion to make it up-to-date. Please, see Results and Discussion section.

Some issues in tables and figures are indicated in the manuscript

• Response: We have corrected the tables and figure according to the suggestions made by the reviewer. Some clarification is needed: Line 176: “feed’ is correct. We are meaning, the green mass of leaves are suitable fodder, and functional feed.

3. References

“References don’t match with the format from MDPI, please edit each one”

• Response: We have corrected the reference list according to the journal requirements. Please, see References.