Cosmetopoeia of African Plants in Hair Treatment and Care: Topical Nutrition and the Antidiabetic Connection?

Round 1

Reviewer 1 Report

The review by Ajao and Sadgrave focuses on a survey of African plants to treat conditions such as alopecia, scalp dermis, and distinguishing between topical nutrition and sterilization. The review is well written and presents an interesting topic of high relevance in today's society. 

I would suggest adding some chemical structures of the most important metabolites recognized in the current review and map of the geographic distribution of the plants illustrating hotspots of interest in plant-based hair treatment and care. This would also highlight if the chemistry of the plants is correlated to their evolutionary history and geographic distribution, similar to the approach followed by doi.org/10.1093/botlinnean/box078 and doi.org/10.1016/j.plaphy.2019.05.020. 

Author Response

Response: Thank you for your suggestion. We have added some chemical structures of the important metabolites from the reported plants. Furthermore, all three of the reveiwers were concerned about geography, so we have written a brief section addressing this concept.

Reviewer 2 Report

With the title of the manuscript, the authors give an expectation of an interesting review article. The study area is a reservoir of preserved traditional knowledge including natural cosmetics. An undeniably current topic of interest to a wide range of researchers and users.

The manuscript presents information on 68 species of medicinal plants noted mainly in ethnobotanical studies in Africa. For some of them, their research on the mechanism of action is discussed.

Regardless of the good points of the manuscript, in my opinion it lacks focus, which is a result of the lack of a specific goal set in the introduction. It's said there: „This study provides a comprehensive summary of the indigenous knowledge on African plants that are being used for haircare.“ The information in Table 1 is important and valuable, but not sufficient. It is not clear what are the interesting finds that are unique to the area - plants, method of preparation and application, combinations used, etc. I would recommend the authors to provide data on the degree of study of the different regions of the continent (Introduction). How many and what type of articles were analyzed in the review, period of publication, research methods used (Materials and methods). My manuscript looks like it was assembled mechanically from two parts (focused around the two tables).

Fig.1 and Fig. 2 are not informative, repeat the text and are not necessary in this form. Grouping by habit - climbers/creepers/trailers, alongside trees, grasses and shrubs is botanically incorrect.

Table 1 has some inaccuracies and needs to be carefully clarified for taxonomic and botanical accuracy. For example:

-        Acorus calamus (Aceraceae change to  Acoraceae); Elaeis guineensis (Palmaceae change to Arecaceae)

-        Dicerocaryum senecioides is  synonym of Sesamum senecioides (Klotzsch) Byng & Christenh.

-        Ocimum Sanctum change to Ocimum sanctum

-        Acorus calamus (root change to  rhizome) and for other plants

-        flower for Asteraceae change to inflorescence (corymb) for botanical accuracy

Author Response

Response: Thank you for the comments and suggestions; much appreciated. Information on the number of articles analyzed, the period of publication, research methods, and criteria for selecting articles for the review have been added to the methods section.

Furthermore, we have decided to analyze the data further and we realized that most of the species in Table 1 have potential as antidiabetic therapies, demonstrated through in vitro and in vivo assays, as well as traditional use reports. Thus, the title was tweaked slightly, the introduction expanded and Table 1 revised significantly.

Comment: Fig.1 and Fig. 2 are not informative, repeat the text and are not necessary in this form. Grouping by habit - climbers/creepers/trailers, alongside trees, grasses and shrubs is botanically incorrect.

Response: Based on growth habit, plants are generally grouped into trees, herbs, shrubs, and climbers/creepers/trailers. Regarding grasses, only one plant is grass in the table, Cymbopogon citratus, which is grouped as an herb based on its growth habit.

Response: All the inaccuracies have been clarified, and the corrections have been made. Thank you so much.

Reviewer 3 Report

General comment

If the authors plan to obtain a highly-cited work, they need to improve this work.

Section 1

The objective of this review is not clear. Who might read this information? Who might be interested in this topic? Why is it essential to publish a review on this topic? Is this the first review manuscript of its kind?

Section 2.

Are there any inclusion/exclusion criteria? Did authors consider all languages spoken in Africa? or was there a restriction on looking for information in any language? What was the range date of searching? It is not clear if the authors report only native plants from Africa. Were the plant names checked in a database?

Section 3.

In my point of view, 68 plants reported for hair conditions in a huge continent such as Africa seem a little. Did they consider all countries in Africa? Otherwise, the title should be changed to plants from North Africa, for instance.

What do the authors mean by the term "country" in Table 1? Is it the native country of the plant species?

Table 2. No quantitative information is shown. 

Are there any clinical trials with these plant extracts? 

Mechanisms of action of current drugs used for hair treatment. Do authors want to focus the review on hair growth or dandruff? This is not clear.

The authors need to show the chemical structures of the compounds isolated from the medicinal plants. Do any of these compounds have reports regarding hair treatment?

There is no discussion, this work is more a description of the data they gathered.

Are there any perspectives on this work?

The conclusion section must be improved.

no comments

Author Response

General comment

If the authors plan to obtain a highly-cited work, they need to improve this work.

Response: Thank you for the comments and suggestions. Much appreciated.

Section 1

The objective of this review is not clear. Who might read this information? Who might be interested in this topic? Why is it essential to publish a review on this topic? Is this the first review manuscript of its kind?

Response: Yes, it is the first review of its kind on African plants. During the first revision of this manuscript we realized that we had an opportunity to test a hypothesis proposed in 2018 by the 2^nd author. We realized that newer information of plants used in therapy for hair can be tested the same was as the 2018 review by the 2^nd author, to see if the observation still holds weight. The manuscript has now been revised accordingly.

Section 2.

Are there any inclusion/exclusion criteria? Did authors consider all languages spoken in Africa? or was there a restriction on looking for information in any language? What was the range date of searching? It is not clear if the authors report only native plants from Africa. Were the plant names checked in a database?

Response: Yes, there are inclusion/exclusion criteria that have been added to the methodology. Yes. Papers written in English or translated to English were used in the review. The range of searching is between 1991 to 2023. We did not report only native plants; there are also domesticated plants on the list. The plant names were checked and verified on Plant List website and WorldFloraOnline. All the information has now been added to the methodology and appropriate section of the manuscript.

Section 3.

In my point of view, 68 plants reported for hair conditions in a huge continent such as Africa seem a little. Did they consider all countries in Africa? Otherwise, the title should be changed to plants from North Africa, for instance.

Response: Yes, we consider all countries in Africa. Plants' usage for hair conditions is generally not common. This is explained now in section 3.3

What do the authors mean by the term "country" in Table 1? Is it the native country of the plant species?

 Response: The country where a specific plant is used.

Table 2. No quantitative information is shown. 

Response: Our intention with this table is to report the plants' findings or mechanism of action. Please let us know if there is specific quantitative information you want us to add to the table. Thank you.

Are there any clinical trials with these plant extracts? 

Response: There are clinical trials, and some of the results are listed into Table 2

Mechanisms of action of current drugs used for hair treatment. Do authors want to focus the review on hair growth or dandruff? This is not clear.

Response: The paper is on general hair care, such as alopecia, scalp dermis infection, dandruff, and hair tinea. In our discussion we have commented that the mechanism of action is not well addressed in the published literature. Although we have listed some of this information in Table 2, we argue that mechanisms are better explained as nutritional rather than as drugs with single targets and highly selective mechanisms.

The authors need to show the chemical structures of the compounds isolated from the medicinal plants. Do any of these compounds have reports regarding hair treatment?

Response:  Yes. The structures have been added.

There is no discussion, this work is more a description of the data they gathered.

Response:  The discussion has been improved.

Are there any perspectives on this work?

Response: Yes, we believe that our findings provide a strong argument for the newer and emerging theories of alopecia, which are hypothesized to have an etiological component involving dysregulated glucose metabolism.

The conclusion section must be improved.

Response: The conclusion has been rewritten.

Round 2

Reviewer 3 Report

Section 2

Exclusion criteria should be indicated.

It should be indicated if the plant names were corroborated in a scientific database.

Table 2 must contain quantitative information. For instance, Promote hair growth by __%, __% increase in follicular density, etc.

Table 2 should be split. Preclinical and clinical information should be presented in different tables.

Section 3

Discussion of the findings should be improved. The hair growth activity of the identified compounds should be mentioned. Discussion in depth of the mechanisms of action of plant extracts and active compounds, among other topics such as state of conservation, etc.

A perspective section should be included in the manuscript. What can the readers obtain from this review?  

no comments

Author Response

Exclusion criteria should be indicated.

Response: Exclusion criteria have now been added. See methodology section, line 15 'Articles exempted from this review are (1) studies that use chemical agents or non-plant-based agents for the treatment of hair; (2) studies on hair care that were not peer-reviewed; (3) studies that mentioned that a plant is used for hair care in Africa without information on how and where it is used ; (4) duplicated studies similar to already reviewed articles."

It should be indicated if the plant names were corroborated in a scientific database.

Response: This is already included in the previous draft of the manuscript. See methodology section line 8" The plant names were verified on the Plant List website and WorldFloraOnline."

Table 2 must contain quantitative information. For instance, Promote hair growth by __%, __% increase in follicular density, etc.

Response. Where quantitative information was available, it has been added to the table. See Table 2.

Table 2 should be split. Preclinical and clinical information should be presented in different tables.

Response: We see no need to split the table as it will make the paper unnecessarily long. However,  we have added information on the type of studies ( Preclinical and clinical) to the results column in Table 2. See line 146.

Section 3

Discussion of the findings should be improved. The hair growth activity of the identified compounds should be mentioned. Discussion in depth of the mechanisms of action of plant extracts and active compounds, among other topics such as state of conservation, etc.

Response:   The mechanistic activity has been mentioned, and we have improved the discussion and mechanism of action of the extract and compounds. See line 126, line 153, line 172. Having said this, the discussion included in the review, and the point of view expressed, is that much of the published data does not adequately explain mechanisms. For this reason, we keep this section light and maintain emphasis on a nutritional aspect.

A perspective section should be included in the manuscript. What can the readers obtain from this review?  

Response: This was already added in the last revision of the manuscript, although with a different sub-heading; however,  we have now changed the sub-heading to 'Perspectives on the culture of hair care in Africa". The reviewer should please read from line 43 of the manuscript.

Round 3

Reviewer 3 Report

The authors improved the manuscript. This work can be accepted for publication

no comments