The Paradigm Shift of Using Natural Molecules Extracted from Northern Canada to Combat Malaria

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The present review outlines the paradigm shift of the parasitic diseases transmission. It also covered historical background of antimalarial drug discovery and signifies the role of natural products as source of new antiparasitic hits. It explicitly highlighted the importance of investigating natural products from extreme environments and given the Canadian Boreal Forest as a valid example.

Here are some comments with regards to section 4 and 5, since they are of the most relevancy:

- The authors did not demonstrate enough the rationale on how the molecules obtained from those extreme environments could serve as better hits against parasitic diseases compared to molecules from other environments? (i.e, from points of chemical space, target affinity, biological evolution...etc).

- The referred sections lack enough examples and details of isolated molecules  from the Boreal forest that has been used traditionally to treat diseases/symptoms like those of parasitic diseases. Also, neither activity nor statistical data were shown to support the argument. This could be shown in table/figure format which enhance clarity and ease of data presentation.

- In section 5, paragraph L 375-378: the author mentioned "Also, extracts from Stereocaulon paschale, a lichen found in Nunavik, Canada showed some antimicrobial activity against oral pathogens such as Porphyromonas gingivalis and Streptococcus mutans [80]. While not tested against parasites, the unique lichen metabolites isolated could prove interesting in the development of new antimalarials". Question: Do Lichen compounds act on a common target that is available in both P. gingivalis and plasmodium? Could you elaborate, what is the rational of the assumption behind it can also be active on malaria?

Other comments:

- Reference redundancy (Try to avoid as much as possible in such reviews): For example, ref [3] in L72, ref. [2] L80, ref.[1] in L121 and L140, ref.[34] in L164, ref.[47] in L245&L248, ref. [54] L254, ref. [21] L303,L311, L320, L423, and L430, ref [20] L391, L393.

Author Response

The present review outlines the paradigm shift of the parasitic diseases transmission. It also covered historical background of antimalarial drug discovery and signifies the role of natural products as source of new antiparasitic hits. It explicitly highlighted the importance of investigating natural products from extreme environments and given the Canadian Boreal Forest as a valid example.

Here are some comments with regards to section 4 and 5, since they are of the most relevancy:

1- The authors did not demonstrate enough the rationale on how the molecules obtained from those extreme environments could serve as better hits against parasitic diseases compared to molecules from other environments? (i.e, from points of chemical space, target affinity, biological evolution...etc).

-Conventional screening strategies are more and more plagued by the high frequency of rediscovering already know molecules and natural product-based screening approaches have helped in finding new diversity. The rationale of our review is that not much work has been done on molecules obtained from northern environments to develop antimalarials so there is a lot of unexplored potential. Our goal was not to make any claims that better hits would be found, just that there might be new types of molecules because of how different these environments are. We then wanted to highlight some examples to show that indeed, molecules with activity against different types of diseases can be found in northern environments.

2- The referred sections lack enough examples and details of isolated molecules from the Boreal forest that has been used traditionally to treat diseases/symptoms like those of parasitic diseases. Also, neither activity nor statistical data were shown to support the argument. This could be shown in table/figure format which enhance clarity and ease of data presentation.

-We have now added Table 1 highlighting some examples of bioactive molecules originating from organisms living in polar environments. The table contains the name of the molecules, the source (organism and location), the properties (target species, activity etc…) and the references.

-We have also added a second table (Table 2) highlighting some examples of traditional plants used as medicines by the Native people of Canada. The table contains the plant species, the parts used, the type of preparation and the primary uses. We have also now specified that information on over 500 plant taxa used by indigenous people in the Canadian boreal forest to treat 28 diseases and disorders can be found in Additional Table 1 in reference Uprety et al, 2012.

-We have finally added Table 3 highlighting bioactive molecules with antimalarial activities from organisms isolated in Northern Canada. The table contains the species, its location, the name of the molecules and IC50s against a WT and a multidrug resistant strain of P. falciparum.

-We apologize but do not understand what the reviewer means with : “Also, neither activity nor statistical data were shown to support the argument.”

-We now present IC50 or MIC values for some of our examples (Table 1 and 3) but do not know where the statistical data would come from. As discussed above, we are not making the argument that molecules from northern/more extreme environments will be better, just that there is potentially great diversity that has not been explored.

3- In section 5, paragraph L 375-378: the author mentioned "Also, extracts from Stereocaulon paschale, a lichen found in Nunavik, Canada showed some antimicrobial activity against oral pathogens such as Porphyromonas gingivalis and Streptococcus mutans [80]. While not tested against parasites, the unique lichen metabolites isolated could prove interesting in the development of new antimalarials". Question: Do Lichen compounds act on a common target that is available in both P. gingivalis and plasmodium? Could you elaborate, what is the rational of the assumption behind it can also be active on malaria?

-There is no evidence that lichen compounds would first of all be effective against malaria and much less acting on a common target between P. gingivalis and Plasmodium. However, as we wrote above, the northern flora and in this case lichens, have not been extensively explored in terms of their potential antimalarial activity so represent an interesting new avenue to investigate.

Other comments:

- Reference redundancy (Try to avoid as much as possible in such reviews): For example, ref [3] in L72, ref. [2] L80, ref.[1] in L121 and L140, ref.[34] in L164, ref.[47] in L245&L248, ref. [54] L254, ref. [21] L303,L311, L320, L423, and L430, ref [20] L391, L393.

-We tried as much as possible to provide more references however due to the lack of a high number of studies, it is expected that some would be cited more than once.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors show very well the historical facts related to the development of the first antimalarials and introduce well the topic, but they lack depth on data and mechanism of antimalarial function.

 

I would suggest to the authors to comment on specific data on the antimalarial properties of the plants and compounds that they talk about. Could you be more specific on how much is the growth inhibition? Is it known which stage of the parasite growth or which part of the Plasmodium biology is affected?

Could they mention with type of research it is needed to be able to use or test these plants are derivative of antimalarials? I believe that this is useful knowledge but it needs to be described in more details if possible, in particular the scientific part.

Minor corrections: add space 187 and remove space 198.

 

 

Author Response

The authors show very well the historical facts related to the development of the first antimalarials and introduce well the topic, but they lack depth on data and mechanism of antimalarial function.

 

1-I would suggest to the authors to comment on specific data on the antimalarial properties of the plants and compounds that they talk about. Could you be more specific on how much is the growth inhibition? Is it known which stage of the parasite growth or which part of the Plasmodium biology is affected?

-We have added Table 3 highlighting bioactive molecules with antimalarial activities from organism isolated in Northern Canada. The table contains the species, its location, the name of the molecules and IC50s against a WT and a multidrug resistant strain of P. falciparum. The assays were done on in vitro asexual stage parasites. We do not know what other parts of the Plasmodium biology is affected nor what the specific mechanisms would be.

2-Could they mention with type of research it is needed to be able to use or test these plants are derivative of antimalarials? I believe that this is useful knowledge but it needs to be described in more details if possible, in particular the scientific part.

-We thank the reviewer for this great suggestion. We have now added a paragraph in the Conclusion about the challenges associated with exploiting compounds from polar/remote/extreme environments.

-Minor corrections: add space 187 and remove space 198.

-Done

Reviewer 3 Report

Comments and Suggestions for Authors

In this review article, the authors highlight the utilization of extracts derived from plants and microbes residing in the unexplored North Canadian Boreal forest as potential treatments for malaria. While the authors have made a good effort to compile an article exploring new treatment options for malaria, this article has significant shortcomings. Its content lacks clarity and organization, making it quite confusing to navigate. Please refer to my comments below for further details.

1. Title: I found the title and content mismatched. The term "northern molecules" in the title is a little misleading and could be clarified by suggesting a change to " natural molecules extracted from Northern Canada." Furthermore, while the title mentions 'tropical diseases,' the article focuses primarily on malaria, resulting in another inconsistency. The authors may want to consider replacing 'tropical diseases' with 'malaria' in the title or expanding the scope of the article to include other tropical diseases.

2. Please consider adding a figure showing the life cycle of the malarial parasite for lines 53-68.

3. For lines 112-119, where authors talk about "natural remedies to synthetic molecules and back again," please present this section in a tabular format for enhanced clarity and comprehension for the journal's audience. Including columns with details such as the natural compound/plant, its source (literature reference), plant species, chemical nature of the compound, toxicity test results, mechanism of action, and efficacy against bacterial species would be beneficial.

3. In the section "Extreme Environment and...." (lines 200-286), I am confused as to why the authors have included a significant long section within this category that does not relate to tropical diseases or malaria. While I understand the authors' intention to highlight the potential of microbes from extreme environments in treating diseases such as HIV and cancer, these conditions are not caused by malarial parasites or other protozoan species, making it confusing. I think there is no necessity for such a long paragraph that diverges from the main topic. However, discussing any literature linking these compounds extracted from extremophiles to treating malaria or diseases by other protozoan spp could be helpful.

4. For lines 303, 311, and 320, although the authors mention these compounds are used against a 'wide range of diseases', please specify whether these diseases are caused by bacteria, viruses, or protozoans or are non-infectious diseases, including cancers.

5. 365-378: well summarized!

6. 379-394: It might be helpful to present this paragraph in a tabular format for enhanced clarity and comprehension (as mentioned in point 3 above).

7. In the conclusion section, please provide future directions, including the challenges associated with harvesting these compounds from forests and/or extremophiles.

 

Author Response

In this review article, the authors highlight the utilization of extracts derived from plants and microbes residing in the unexplored North Canadian Boreal forest as potential treatments for malaria. While the authors have made a good effort to compile an article exploring new treatment options for malaria, this article has significant shortcomings. Its content lacks clarity and organization, making it quite confusing to navigate. Please refer to my comments below for further details.

1. Title: I found the title and content mismatched. The term "northern molecules" in the title is a little misleading and could be clarified by suggesting a change to " natural molecules extracted from Northern Canada." Furthermore, while the title mentions 'tropical diseases,' the article focuses primarily on malaria, resulting in another inconsistency. The authors may want to consider replacing 'tropical diseases' with 'malaria' in the title or expanding the scope of the article to include other tropical diseases.

-We agree with the reviewer and have thus changed the title to: The Paradigm Shift of Using Natural Molecules Extracted from Northern Canada to Combat Malaria. We have also changed to title of section 5 from The Paradigm of Using Northern Molecules to Treat Tropical Diseases to: The Paradigm of Using Natural Molecules Extracted from Northern Canada to Treat Malaria

2. Please consider adding a figure showing the life cycle of the malarial parasite for lines 53-68.

-As per the reviewer’ suggestion, we have now added a figure showing the life cycle (Figure 1).

3. For lines 112-119, where authors talk about "natural remedies to synthetic molecules and back again," please present this section in a tabular format for enhanced clarity and comprehension for the journal's audience. Including columns with details such as the natural compound/plant, its source (literature reference), plant species, chemical nature of the compound, toxicity test results, mechanism of action, and efficacy against bacterial species would be beneficial.

-We have now added Table 1 highlighting some examples of bioactive molecules originating from organisms living in polar environments. The table contains the name of the molecules, the source (organism and location), the properties (target species, activity etc…) and the references.

-We have also added a second table (Table 2) highlighting some examples of traditional plants used as medicines by the Native people of Canada. The table contains the plant species, the parts used, the type of preparation and the primary uses and the references.

-We have finally added Table 3 highlighting bioactive molecules with antimalarial activities from organisms isolated in Northern Canada. The table contains the species, its location, the name of the molecules and IC50s against a WT and a multidrug resistant strain of P. falciparum and the references.

 

3. In the section "Extreme Environment and...." (lines 200-286), I am confused as to why the authors have included a significant long section within this category that does not relate to tropical diseases or malaria. While I understand the authors' intention to highlight the potential of microbes from extreme environments in treating diseases such as HIV and cancer, these conditions are not caused by malarial parasites or other protozoan species, making it confusing. I think there is no necessity for such a long paragraph that diverges from the main topic. However, discussing any literature linking these compounds extracted from extremophiles to treating malaria or diseases by other protozoan spp could be helpful.

-Our goal with this section was first to highlight the challenges associated with sampling more extreme environments and second how the adaptations of the organisms living under these harsh conditions can potentially provide diverse molecules not found anywhere else. Third, we wanted to provide examples showing that some molecules coming from these environments have shown promising activities against diverse ailments such as HIV1 and cancers and use this as our validation to propose that perhaps the same could be true for malaria.

4. For lines 303, 311, and 320, although the authors mention these compounds are used against a 'wide range of diseases', please specify whether these diseases are caused by bacteria, viruses, or protozoans or are non-infectious diseases, including cancers.

-As stated above, we have now added Table 2 highlighting some examples of traditional plants used as medicines by the Native people of Canada. The table contains the plant species, the parts used, the type of preparation and the primary uses and the references.

5. 365-378: well summarized!

-We thank the reviewer for this comment

6. 379-394: It might be helpful to present this paragraph in a tabular format for enhanced clarity and comprehension (as mentioned in point 3 above).

            - As stated above, we have added Table 3 highlighting bioactive molecules with antimalarial activities from organism isolated in Northern Canada. The table contains the species, its location, the name of the molecules and IC50s against a WT and a multidrug resistant strain of P. falciparum and the references.

7. In the conclusion section, please provide future directions, including the challenges associated with harvesting these compounds from forests and/or extremophiles.

-We thank the reviewer for this great suggestion. We have now added a paragraph in the Conclusion about the challenges associated with exploiting compounds from polar/remote/extreme environments.

 

Reviewer 4 Report

Comments and Suggestions for Authors

Goode evening.-

1.-In the section 2  (line 113): Write more about history of discovering of the natural products against Malaria. Focus more about  history  of discovering of Cinchona for curing malaria  ( use the cite and references for supporting your historical information).

2.- In the paragraf (line 312 to 320) you mentioned M. tuberculosis but you did not the plants that are using for threatment that disease (Mention of the most important plants). Similarly in the Canadian plants (line 317) and disease (Mention the most important plants and diseases)

Comments for author File: Comments.pdf

Author Response

Goode evening.-

1.-In the section 2  (line 113): Write more about history of discovering of the natural products against Malaria. Focus more about  history  of discovering of Cinchona for curing malaria  ( use the cite and references for supporting your historical information).

-We appreciate the reviewer’s suggestion and have added some more details however the review is not about cinchona but about how molecules from northern environments are an untapped source of potential antimalaria molecules. Therefore, we do not think it is appropriate to outline the complete history of cinchona discovery.

2.- In the paragraf (line 312 to 320) you mentioned M. tuberculosis but you did not the plants that are using for threatment that disease (Mention of the most important plants). Similarly in the Canadian plants (line 317) and disease (Mention the most important plants and diseases)

-We have now added Table 1 highlighting some examples of bioactive molecules originating from organisms living in polar environments. The table contains the name of the molecules, the source (organism and location), the properties (target species, activity etc…) and the references.

-We have also added a second table (Table 2) highlighting some examples of traditional plants used as medicines by the Native people of Canada. The table contains the plant species, the parts used, the type of preparation and the primary uses and the references.

-We have finally added Table 3 highlighting bioactive molecules with antimalarial activities from organisms isolated in Northern Canada. The table contains the species, its location, the name of the molecules and IC50s against a WT and a multidrug resistant strain of P. falciparum and the references.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed all my suggestions and concerns. The revisions have significantly improved the manuscript.

Author Response

-The authors have addressed all my suggestions and concerns. The revisions have significantly improved the manuscript.

We thank the reviewer for their initial constructive comments and for their support of our revised manuscript.

Reviewer 4 Report

Comments and Suggestions for Authors

Correct:

a0rtemisinin: 169

Delete "0" in the word "artemesinin"

Author Response

-Correct:

a0rtemisinin: 169

Delete "0" in the word "artemesinin"

-Fixed