Phytochemical Analysis and Antioxidant Activities of Prunus africana Bark, Leea indica and Paullinia pinnata Leaf Extracts
Round 1
Reviewer 1 Report
The study focused on the extraction of three plant leaves in order to obtain antioxidant compounds. For it, methanol was employed as solvent. The item is interesting. However, some aspects regarding the procedure and the basis of the study make it doubtful whether the manuscript can be accepted in a journal as the present one.
Abstract
It includes over 200 words, and ought to be shortened in agreement with the journal requirement.
Line 13: Methanol was used. A better choice would have been to employ a green solvent as ethanol.
Keywords
Include: methanol, flavonoid.
Replace medical plants with the names of the three plants.
Introduction
I have doubts about novelty of the study. The three plants have already been studied, their potential use already established. The authors need to prove that the study provides new aspects. Otherwise, I think it cannot be accepted in a journal as the present one.
Material and methods
Provide some justification for the use of methanol.
A 40 ºC/24 h extraction was carried out. Can this condition damage phenolic and flavonoid compounds ? The extraction procedure is not based on previous research.
Lines 105-147: This part is mentioned as if this document was an operating manual, instead of a scientific manuscript.
Lines 148-270: This part corresponds to the Material and methods section.
Line 266: Were there replicates carried out ?
Results
Table 2: A single value for yield ? Were there replicates carried out for TPC and TFC ?
Figure 2: Indicate the number of replicates. Also in Table 3 and Figure 3.
Table 5: …µg/g of extract.
General
The English language ought to be performed.
Author Response
Respected reviewer
Thank you very much for giving the time to review our manuscript. Please find the detailed responses below and the corresponding corrections highlighted in red color changes in the re-submitted files. We appreciate your valuable suggestions.
Yes
No
Does the introduction provide a comprehensive yet concise overview about the state of knowledge in the area of research?
Yes
No
Please, see comments to authors.
Is the research design appropriate and are the methods adequately described?
Yes
No
Please, see comments to authors.
Are the results presented clearly and in sufficient detail, are the conclusions supported by the results and are they put into context within the existing literature?
Yes
No
Please, see comments to authors.
Are all of the cited references relevant to the research?
Yes
No
Does this article provide a relevant contribution to the scientific discussion of this topic?
Yes
No
Please, see comments to authors.
Is it necessary to include study limitations in the discussion?
Yes
No
Is the quality and presentation of the figures satisfactory?
Yes
No
English language and style
The English could be improved to more clearly express the research.
The English is fine and does not require any improvement.
Comments for Authors
Major comments
The study focused on the extraction of three plant leaves in order to obtain antioxidant compounds. For it, methanol was employed as solvent. The item is interesting. However, some aspects regarding the procedure and the basis of the study make it doubtful whether the manuscript can be accepted in a journal as the present one.
Detail comments
Abstract
It includes over 200 words, and ought to be shortened in agreement with the journal requirement.
Response: Agree, we shortened the abstract in 200 words.
Line 13: Methanol was used. A better choice would have been to employ a green solvent as ethanol.
Response: Yes, ethanol would have been another choice for extraction. However, we used methanol for extraction and carried out all experiments in our study.
Keywords
Include: methanol, flavonoid.
Response: Agree, we included methanol and flavonoid in the list of keywords.
Replace medical plants with the names of the three plants.
Response: Agree, we replaced medical plants with the names of the three plants.
Introduction
I have doubts about novelty of the study. The three plants have already been studied, their potential use already established. The authors need to prove that the study provides new aspects. Otherwise, I think it cannot be accepted in a journal as the present one.
Response: The present study aimed to investigate the phytochemical constituents, antioxidant potentials, and explore new phenolic compounds of these plants. Discovery of even a single new compound is a novel work. Additionally, differences in methodologies, reference standard, extraction methods, sample-to-solvent ratios, harvesting time, geographical location, environmental conditions, and sample size of plant materials should also be novelty of the study. To the best of our knowledge, extraction, identification of phenolic compounds in this study and region of the plant materials are unique. We believe these are the novelty of our study.
Material and methods
Provide some justification for the use of methanol.
Response: Some justifications for using methanol as extracting solvent.
- Methanol has a broad range of polarities for bioactive compounds, including phenolics and flavonoids. It can penetrate plant cell walls effectively, aiding in maximum compound release.
- Methanol often yields higher extraction efficiency compared to other solvents, especially for low molecular weight phenolics.
- Methanol tends to preserve the antioxidant activity of phenolics and flavonoids comparatively better than other solvents.
Comments: A 40 ºC/24 h extraction was carried out. Can this condition damage phenolic and flavonoid compounds? The extraction procedure is not based on previous research.
Response: Agree, in fact we set only 40ºc at rotary evaporator at the time of drying the extract. However, the extraction was carried out at room temperature for 24 h. We corrected it accordingly in the edited manuscript.
Comments: Can 40 ºC/24 h methanolic extraction condition damage phenolic and flavonoid compounds?
Response: Agree, 40 ºC/24 h methanolic extraction conditions might damage phenolic and flavonoid compounds to some extent.
Comments: Lines 105-147: This part is mentioned as if this document was an operating manual, instead of a scientific manuscript.
Response: These experiments are typically carried out following the manuals that we just followed as well.
Comments: Lines 148-270: This part corresponds to the Material and methods section.
Response: Agree, we corrected these parts, incorporated them into the material and method section and put new numbering accordingly.
Comments: Line 266: Were there replicates carried out?
Response: Yes, replicates were carried out.
Results
Comments: Table 2: A single value for yield? Were there replicates carried out for TPC and TFC?
Response: Yes, single value for yield. Yes, three replicates were carried out for TPC and TFC.
Comments: Figure 2: Indicate the number of replicates. Also in Table 3 and Figure 3.
Response: Agree, number of replicates are indicated in figure 2 and figure 3.
Comments: Table 5: …µg/g of extract.
Response: Yes, it was µg/g of extract.
General
The English language ought to be performed.
Reviewer 2 Report
The Materials and methods section is not well organized. There is a mess in the numbering of the headings.
The discussion of the results against literature is superficial, being mostly base on simply comparisons with previous results reported in the literature.
The results from tables are duplicated in figures.
The paper of Karim et al. presents original results on the antioxidant properties and phytochemical profile of the extracts from Prunus africana bark, Leea indica and Paullinia pinnata leaves
The novelty of the study is not clearly presented in the Introduction section. The authors failed to make clear to the readers which is the identified gap in the literature and how their study contribute to solving the problem.
The authors are advised to avoid starting the sentences with a number. There are many examples in the Materials and methods section. Please revise.
The Materials and methods section is not well organized. There is a mess in the numbering of the headings.
Line 152: The formula is not clear. With is the meaning of gm? What was the dry weight of the extract?
Line 181: The authors should avoid stating that the methods use din the study “these are more reliable …” There is a complex and profound discussion to be made on this subject.
The repeated definitions of the abbreviations should be voided. The abbreviations must be defined when first use din the manuscript body, and should be consequently used afterwards.
Lines 183-189: How was the reaction mixture accommodated in a well? What was the volume of a well in the 96-well plate?
The discussion of the results against literature is superficial, being mostly base on simply comparisons with previous results reported in the literature.
The scientific level of the information provided in the section 4.1. Phytochemical Screening is not compatible to the journal reputation. The statement “were mostly consistent with those reported in previous studies in P. africana 278 [50], L. indica [51-52] and P. pinnata leaves [31]. “ is questionable. The authors might consider removing this part of the study.
Lines 293-295: Repetition (“… expressed in forms of mg gallic acid …”) should be avoided. Moreover, the equation of the standard curve should not be presented in the paper.
The results from table 2 are duplicated in figure 2. This practice is not recommended.
The same observation for the results presented in Table 3, which are duplicate din Figure 3. In addition, almost all values are explicitly mention in the body of the paper.
The authors failed to present in a concise manner the main findings of their study in the Conclusions section. No references should be cited in the Conclusions section.
Author Response
Respected reviewer
Thank you very much for giving the time to review our manuscript. Please find the detailed responses below and the corresponding corrections highlighted in red color changes in the re-submitted files. We appreciate your valuable suggestions.
Open Review
I would not like to sign my review report
I would like to sign my review report
Does the title describe the article's topic with sufficient precision?
Yes
No
Does the introduction provide a comprehensive yet concise overview about the state of knowledge in the area of research?
Yes
No
The novelty of the study is not clearly presented in the Introduction section. The authors failed to make clear to the readers which is the identified gap in the literature and how their study contribute to solving the problem.
Is the research design appropriate and are the methods adequately described?
Yes
No
The Materials and methods section is not well organized. There is a mess in the numbering of the headings. Line 152: The formula is not clear. With is the meaning of gm? What was the dry weight of the extract? Line 181: The authors should avoid stating that the methods use din the study “these are more reliable …” There is a complex and profound discussion to be made on this subject. Too many details are provided for well known methods, in addition to quoting the correct reference.
Are the results presented clearly and in sufficient detail, are the conclusions supported by the results and are they put into context within the existing literature?
Yes
No
The discussion of the results against literature is superficial, being mostly base on simply comparisons with previous results reported in the literature. The authors failed to present in a concise manner the main findings of their study in the Conclusions section. No references should be cited in the Conclusions section.
Are all of the cited references relevant to the research?
Yes
No
Does this article provide a relevant contribution to the scientific discussion of this topic?
Yes
No
The manuscript needs to be reconsidered in order to be suitable for publication.
Is it necessary to include study limitations in the discussion?
Yes
No
No suggestion
Is the quality and presentation of the figures satisfactory?
Yes
No
English language and style
The English could be improved to more clearly express the research.
The English is fine and does not require any improvement.
Comments for Authors
Advice for completing your review can be found at: https://www.mdpi.com/reviewers#Review_Report
Major comments
The Materials and methods section is not well organized. There is a mess in the numbering of the headings.
The discussion of the results against literature is superficial, being mostly base on simply comparisons with previous results reported in the literature.
The results from tables are duplicated in figures.
Detail comments
The paper of Karim et al. presents original results on the antioxidant properties and phytochemical profile of the extracts from Prunus africana bark, Leea indica and Paullinia pinnata leaves
The novelty of the study is not clearly presented in the Introduction section. The authors failed to make clear to the readers which is the identified gap in the literature and how their study contribute to solving the problem.
Response: Novelty and aim of the study have been provided in the introduction section in the edited manuscript.
Comments: The authors are advised to avoid starting the sentences with a number. There are many examples in the Materials and methods section. Please revise.
Response: Actually, there are many examples of published articles even in “Antioxidant” journal, where the authors used numbering on the starting sentences that we just followed.
Comments: The Materials and methods section is not well organized. There is a mess in the numbering of the headings.
Response: Agree, we corrected the numbering of the headings in the Materials and Methods section. We believe this section is now well organized.
Comments: Line 152: The formula is not clear. With is the meaning of gm? What was the dry weight of the extract?
Response: We corrected the formula as follows
% of yield = (Weight of dry extract obtained in g/ Weight of powder sample in g) ×100
Gm means gram.
Line 181: The authors should avoid stating that the methods used in the study “these are more reliable …” There is a complex and profound discussion to be made on this subject.
Comments: The repeated definitions of the abbreviations should be voided. The abbreviations must be defined when first used in the manuscript body, and should be consequently used afterwards.
Response: Agree, we avoided these repetitions as per advice.
Comments: Lines 183-189: How was the reaction mixture accommodated in a well? What was the volume of a well in the 96-well plate?
Response: Mixture of 3 ml methanol + 1 ml test solution was just a procedure, but actually we used it as 150µl+50 µl. We corrected it accordingly, like 150µl and 50 µl in place of 3ml and 1 ml, respectively in the edited manuscript.
Comments: The discussion of the results against literature is superficial, being mostly base on simply comparisons with previous results reported in the literature.
Response: We edited the discussion section.
Comments: The scientific level of the information provided in the section 4.1. Phytochemical Screening is not compatible to the journal reputation. The statement “were mostly consistent with those reported in previous studies in P. africana 278 [50], L. indica [51-52] and P. pinnata leaves [31]. “ is questionable. The authors might consider removing this part of the study.
Response: Agree, we removed this part as per advice.
Comments: Lines 293-295: Repetition (“… expressed in forms of mg gallic acid …”) should be avoided. Moreover, the equation of the standard curve should not be presented in the paper.
Response: Agree, repetition and equation have been avoided.
Comments: The results from table 2 are duplicated in figure 2. This practice is not recommended.
Response: Agree, we removed table 2 and kept only figure 2.
Comments: The same observation for the results presented in Table 3, which are duplicated in Figure 3. In addition, almost all values are explicitly mention in the body of the paper.
Response: Agree, we removed table 3 and kept only figure 3.
Comments: The authors failed to present in a concise manner the main findings of their study in the Conclusions section. No references should be cited in the Conclusions section.
Response: We edited the conclusion section that reflects the main findings of the study. We also avoided the citation in the conclusion section.
Round 2
Reviewer 1 Report
The manuscript has been performed according to some of the previous comments. However, I think others have not been addressed adequately.
Keywords
“three plants” is mentioned. Instead, the Latin name of each of the plants would be a better indication for the reader.
Material and methods
The use of methanol is not justified. Most authors have employed ethanol, which is recognized as a green solvent and would provide a very similar extraction capacity. Contrary, methanol is recognized as relatively harmful. Please, justify the choice.
Lines 102, 114, 119, 124, 130, and 136: Such groups were not identified, just their presence in the extract was detected. The sub-section titles ought to be modified to something like “Detection of flavonoid presence”, and something similar for the remaining groups.
Line 260: “Three determinants” are mentioned. I still have doubts whether three analyses were carried out on a single sample, or if three independent trials (i.e., three replicates) were carried out. I think it would be very important to clarify this.
Results
Tables/Figures
In all cases, n=3 is mentioned. However, I still have the same doubt as previously mentioned in the experimental section. Please, clarify in all cases.
Author Response
Dear Reviewer
Thank you very much for taking the time to review this manuscript. Please find the detailed
responses below and the corresponding revisions/corrections highlighted in red ink in
the resubmitted files.
Major comments
The manuscript has been performed according to some of the previous comments. However, I think others have not been addressed adequately.
Detailed comments
Keywords
“three plants” is mentioned. Instead, the Latin name of each of the plants would be a better indication for the reader.
Response: Agree, “three plants” has been avoided and the Latin name of each of the plants has been indicated.
Material and methods
The use of methanol is not justified. Most authors have employed ethanol, which is recognized as a green solvent and would provide a very similar extraction capacity. Contrary, methanol is recognized as relatively harmful. Please, justify the choice.
Response: There are a lot of articles in almost all journals where researchers used pure methanol for extraction. Yes, other solvents might be used, no problem. But we used pure methanol. Why we used methanol, we explained it in the previous response. Again, we described it as follows.
- Methanol has a broad range of polarities for bioactive compounds, including phenolics and flavonoids. It can penetrate plant cell walls effectively, aiding in maximum compound release.
- Methanol often yields higher extraction efficiency compared to other solvents, especially for low molecular weight phenolics.
- Methanol tends to preserve the antioxidant activity of phenolics and flavonoids comparatively better than other solvents.
Lines 102, 114, 119, 124, 130, and 136: Such groups were not identified, just their presence in the extract was detected. The sub-section titles ought to be modified to something like “Detection of flavonoid presence”, and something similar for the remaining groups.
Response: Agree, the sub-section titles have been replaced in the name of “Detection of alkaloid, phenolics, flavonoids, terpenoids, tannins and saponins.
Line 260: “Three determinants” are mentioned. I still have doubts whether three analyses were carried out on a single sample, or if three independent trials (i.e., three replicates) were carried out. I think it would be very important to clarify this.
Response: Three determinants were carried out.
Results
Tables/Figures
In all cases, n=3 is mentioned. However, I still have the same doubt as previously mentioned in the experimental section. Please, clarify in all cases.
Response: Three determinants were carried out.
Reviewer 2 Report
The manuscript was improved.
The manuscript was improved.
Author Response
Respected Reviewer
Thank you very much for taking the time to review this manuscript. We appreciate you.
