Collagenase and Tyrosinase Inhibitory Activities and Stability of Facial Cream Formulation Containing Cashew Leaf Extract

Round 1

Reviewer 1 Report

Dear Authors

Your paper is an interesting preliminary screening study towards antioxidant activity, along with collagenase /tyrosinase inhibitory effects of Anacardium occidentale various extracts.

Nevertheless, although there is sufficient bibliography regarding this sp, I dont see, in your experimental part any content chemical identification of extracts  eg. phenolics, flavonoids etc. constituents obviously responsible for the activities detected

Furthermore, there are also additional important points lacking in your text:

1. Collegenase inhibition is not statistically supported

2. There is not official (e.g University lab) plant botanical identification

3. The amount (weight) of the leaves you extracted is not stated in the Materials 

4. the facial cream formulation and tests need more be more detailed 

Author Response

Dear Editor and reviewer,

Thank you very much for your suggestions that are valuable to improve the quality of our manuscript. We have revised and made our responses according to your suggestions, as follows:

1. The chemical identification of extracts eg. phenolics, flavonoids etc. constituents obviously responsible for the activities detected.

For this study, we focused on screening effective crude extracts for use as active ingredients in cosmetics. We will plan our future work on the chemical identification of extracts.

2. Collagenase inhibition is not statistically supported.

Thank you for the comment. We rechecked and revised the statistical analysis in Figures 2 and 3 (line 249-252 and 264-267).

3. There is not official (e.g University lab) plant botanical identification.

Thank you, we added plant botanical identification.

Line 89-91: The voucher specimens of the plant samples were authenticated by a botanist and deposited at the School of Pharmaceutical Sciences, University of Phayao, Thailand.

4. The amount (weight) of the leaves you extracted is not stated in the Materials.

Thank you for your suggestion. We added the amount 200 g of leaves for extraction in line 92.

5. The facial cream formulation and tests need more be more detailed.

Thank you for the comment. We added in the revised version the detail of cream formulation in line 152.

 

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript entitled “Collagenase and Tyrosinase Inhibitory Activities and Stability of Facial Cream Formulation Containing Cashew Leaf Extract” presents the research topic that may be of value for Cosmetics readers. However, in my opinion some points should be further addressed.

· There is a little known about the extracts chemical composition. Although, in the introduction section there is a mention about some potential chemicals found in the Anacardium occidentale leaves that were previously found by different authors, but it is not said that the same compound may be found in the extracts tested in this study. First, there is matter of plants origin, and secondly the dependence of the composition on the type of extract – in this case three tested extracts may have different composition both quantitative (what the authors were trying to show) but also qualitative, and so in same type of extracts a given ingredient may not be present even it is present in the plant material used for extract preparation. So although the chemical composition of the  Anacardium occidentale leaf extract is not the basic topic of the study, since the biological activity depends on the composition of plants products, it is important to actually know the activity of what product we investigate (what components may be responsible for the activity under study).  And to achieve it the proper investigative methods should be used. In case of flavonoids composition the authors tested the total flavonoid content using aluminum chloride colorimetric assay, but this method have same serious limitations. Above all, due to the variations in absorbance values at quantitation wavelengths between different flavonoids, the assay produced huge false-positive or false-negative results when the concentration of one flavonoid is express as equivalents of another flavonoid (you may read more for example in the study https://doi.org/10.1016/j.lwt.2021.111932). So when it is used as a way to test the same extracts (e.g. as a part of quality control), results can be considered comparable, but when testing different extracts (that may be rich in different flavonoids, although the same plant was used for production), the results can be misleading. It may partly explain the low total flavonoids content for ethyl acetate in comparison to other extracts, because from my experience this solvent is rather good extractant for flavonoids (better then e.g. water). Ethyl acetate, water and methanol were also investigated previously as solvent for Anacardium occidentale leaf and bark extraction, and the results for ethyl acetate were methanol > ethyl acetate > water, which is more what I would think (doi: 10.11648/j.jdmp.20200603.13, not cited in the present manuscript). Similarly, the total phenolic content measured using the Folin-Ciocalteu test it gives only a hasty results. In this case I would advise the authors to perform the quantitative analysis by using standard calibration curves of appropriate compounds using HPLC analysis and report the total content of phenolics/flavonoids/other groups as a sum of each compound. When using the appropriate standards and the methodology of HPLC analysis, it may also give some information about qualitative aspect of chemical composition in the absence of the MS analysis.   

· Lines 223-224: The authors said that “Sampathkumar and Rammkrishnam [46] reported that the main flavonoids found in Naringi crenulata were important inhibitors of tyrosinase” – what are these main flavonoids?

· Figures 2 and 3: lack of statistical analysis - standard deviation and significant differences

Author Response

Dear Editor and reviewer,

Thank you very much for your suggestions that are valuable to improve the quality of our manuscript. We have revised and made our responses according to your suggestions, as follows:

1. 1. In this case I would advise the authors to perform the quantitative analysis by using standard calibration curves of appropriate compounds using HPLC analysis and report the total content of phenolics/flavonoids/other groups as a sum of each compound

Thank you for your suggestion, for this study, we focused on screening effective the crude extracts for use as active ingredients in cosmetics. We plan for the future work on the chemical identification of these extracts.

2. 2. Lines 227-228: The authors said that “Sampathkumar and Rammkrishnam [46] reported that the main flavonoids found in Naringi crenulata were important inhibitors of tyrosinase” – what are these main flavonoids?

We rechecked about the type of flavonoids from the original article, we found an error from the reference. So, we revised the new reference in line 227-231: Kishore et al. [46] described twelve flavonoid glycosides from methanol extract of Myrsine africana (Myrsinaceae). Among the list of these compounds, rutin and myricetin-3-O-α-L-rhamnopyranoside showed singnificant tyrosinase inhibitory effects with IC₅₀ values of 0.13 ± 0.003 and 0.12 ± 0.002 mM, respectively, compared to kojic acid (0.01 ± 0.001 mM).

3. 3. Figures 2 and 3: lack of statistical analysis - standard deviation and significant differences

Thank you for your comment. We rechecked and revised the statistical analysis in Figures 2 and 3 (line 249-252 and 264-267).

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Authors having almost responded to main comments suggested, represents a preliminary in terms of phytochemical profile study. More analytical work is desperatelly needed.

Nevertheless, present revised edition that contain valuable data towards a potential candidate cosmetic formulation can be now accepted for publication.

Reviewer 2 Report

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