Formulation and Characterization of Niacinamide and Collagen Emulsion and Its Investigation as a Potential Cosmeceutical Product

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The topic of the study is in line with current scientific trends in the development of modern cosmetic products. The aim of the work was to produce cosmetic products in emulsion form (O/W), based on natural ingredients and containing hydrolysed collagen and niacinamide as active ingredients. The formulations were tested for stability, pH, saponification value, optical, superficia, rheological and textural properties as well as microbiological tests in order to investigate their potential as a cosmetic product. It is concluded that the presented research results have great practical potential. The manuscript, however, requires some refinements before publication:

1. (page 1, line 6) Please check the affiliation indicated as 4a;

2. (page 1, lines 18-29) The abstract lacks a summary of the main findings of the article;

3. (page 3) In Table 1, add a column with the nomenclature of raw materials according to INCI - International Nomenclature of Cosmetic Ingredients. This is the nomenclature for the composition of each cosmetic product. For example, Cosgard is INCI: Benzyl alcohol, Dehydroacetic acid. For vegetable raw materials, latin names are used, e.g. Almond Oil INCI: Prunus Amygdalus Dulcis (Sweet Almond) Oil.

4. (page 7) In section 3.1 Formulation of oil/water (O/W) emulsions, describe the different formulations: What are the differences? What is the variable? Can we compare them to each other or should they be interpreted separately?

5. (page 8, line 336) What does the statement 'moisturised appearance' mean?

6. (page 8, lines 337-339) In relation to the statement "Upon a first sensory analysis, all the emulsions are easily absorbed into the skin, do not irritate the skin and have a pleasant odour, which make them an alternative acceptable by the consumer", please provide the sensory testing methodology, number and characteristics of the probands.

7. (page 9, lines 366-368) It is stated that "It can be seen that emulsion blend no.4 does not contain almond oil, being characterised by high value of rHLB and emulsion no.2 is characterised by low value of rHLB which does not contain jojoba oil. This is justified by the low content of saturated fatty acids contained by the vegetable oils". What about the other formulations? Emulsion number 3 also did not contain almond oil. Please interpret.

8. (page 9) In section 3.3.2, the test results are presented in the form of a table. Are these averages? From how many samples were the presented test results obtained? Since the dry matter value can be estimated from the formulation of the cosmetic product, should Formulation 4 with approximately 50 % water not give comparable results to Formulation 1?

9. (page 10) Images obtained by optical microscopy for emulsion variants 1-4, magnification x 160 (figure 3) are barely legible. It is suggested that the images be enlarged so that the highlighted elements are visible to the Reader.

10. Standardise the abbreviations used for formulations throughout the paper (in tables, graphs, text). Currently, for example, E1 or 1 or Emulsion 1 or Emulsion no 1 was used.

Author Response

Please find in attachment the answers for your comments.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

I have read with interest the manuscript of Danila and cols developing oil in water (O/W) emulsions, based on natural ingredients (vegetable oils, floral waters and essential oils) and hydrolyzed collagen and niacinamide as active ingredients, and on evaluating the stability, pH, optical, superficial, rheological and textural properties and microbiological studies in order to investigate their potential as a cosmeceutical product. The study and the characterization of the formulations developed is well done and my suggestion is to publish this work after major revisions, see below.

1. 1. I suggest to the authors the inclusion of the word emulsion in the keywords
   2. The authors should describe more correctly all the equipment used in all manuscript. Please add: Commercial brand, model. And company, city and country in brackets. For example, pH meter, rheometer, microscope,,…
   3. During elaboration process. At what speed (rpm) did the authors stir? Did the authors carry out any ultra turrax and/or similar  type homogenization process?
   4. Are the stability studies carried out based on the ICH Guidelines? Explain it and cite references. Describe more in detail the equipment used for stability test.
   5. Describe more correctly raw materials of one's own creation (Characteristics, analysis,...)
   6. The particle size distribution has a significant influence on several fundamental properties of the final emulsion: viscosity, optical properties, mechanical strength. The globule size of the emulsion is an important factor that affects the physical stability and efficacy of the emulsions. Use DLS and/or other techniques to determine Particle size.
   7. Emulsions are thermodynamically unstable systems. Line. 370. How long were stable the studied emulsions?
   8. Conclusions: Line 708: “Optical microscopy analysis indicates that all emulsions have a “foam-like” aspect and are slightly aerated apperance”. How do the authors interpret these results? Could these results be due to the incorporation of air during the manufacturing process? Explain it.
   9. Incorporate a table with flow behavior and viscosity values ​​(Pa.s) at different temperatures to improve general understanding.
   10. Why do formulations 2,3,4 contain 5% emulsifier and formulation 1 contain 6%? Explain it.
   11. Skin irritation studies are commonly performed for topically applied products. Do the authors consider necessary to do it for the formulations developed? Explain it.
   12. Number of trials of pH measurements?
   13. Enlarge figure 3 (microscope images). It is impossible to clarify the particle sizes with the images in Figure 3.; Enlarge Fig.8; Center Fig. 1 and 2

 

Author Response

Please find in attachment the answers for your comments.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

This is an interesting article regarding the development and physico-chemical characterization, together with the microbiological evaluation of O/W emulsions incorporating hydrolyzed collagen and niacinamide.

I suggest some aspects, which could enhance the quality of the manuscript:

Please rewrite the title to be more clear and more informative.

For e.g., what do the authors mean by “investigation as a cosmeceutical product”? Eventually efficacy assessment of cosmetic ingredients/formulations could be a confirmation, but evaluations were not performed and described in the manuscript.

Please consider this aspect also in the Abstract and Introduction sections (Lines 29 and 86-87) - “in order to investigate their potential as a cosmeceutical product”.

Please make Keywords more specific!

Abstract:

Lines 19-20: „Cosmeceuticals are cosmetic products with medicinal or drug-like benefits ...” - Indeed, cosmeceuticals are classified as „hybrid” products between cosmetics and pharmaceutics, but please consider that according to current EU legislation, namely Regulation 1223/2009 cosmetics/cosmeceuticals can ammeliorate skin conditions, but do not possess any pharmacological effect. A various number of literature data gives a clear and correct classificaction of cosmeceuticals/dermatocosmetics.

Lines 24-25: regarding niacinamide „it has not been thoroughly studied as a topical agent until recently ...” – nicotinamide was and still is explored for the management of skin disorders, skin ageing, akne, hyperpigmentation, etc. and a pretty clear evidence of it’s effect is evidenced in literature data (for e.g. PubMed reflects more than 7000 articles in the last 10 years).

Introduction:

Lines 33-34, 38: Please do not use terms like „medical:, „medicinal”, „therapeutic”, „healing” etc. regarding cosmeceuticals/dermatocosmetics/cosmetics according to current EU legislation.

Line 81: „... dark spots, red blotchiness” – do you mean hyperpigmentation and skin redness?

Materials and Methods:

Lines 90-91: “Collagen hydrolysate was obtained by acid hydrolysis of fresh bovine dermis at 125°C during 8 h according to the technology previously described [16].” – is it not clear if hydrolyzed collagen was obtained in this study or from an ingredient manufacturer/distributor. Is a general preparation method indicated according to the mentioned reference?

Please provide detailed information of cosmetic ingredients according to mentioned INCI names, and manufacturer (name, city (state abbreviation if USA or Canada), country) (NOT distributor) – for e.g. „Cosgard”- Geogard® ECT, Arxada AG, Basel, Switzerland?, “Emulsifinat Bella” - Cutina® GMS-SE, BASF Personal Care and Nutrition GmbH, Monheim, Germany?

Table 1: Please indicate ingredients under INCI (International Nomenclature of Cosmetic Ingredients) denomination – for e.g. “Avocado oil” the correct denomination in a cosmetic formula is Persea Gratissima (Avocado) Oil, etc. I would suggest that authors introduce a column indicating cosmetic ingredients function.

Line 109: regarding manufacturing procedure of the emulsions, personally I would recommend the incorporation of active ingredients (e.g. hydrolyzed collagen and niacinamide) when the emulsion obtained from the aqueous phase and emollients/emulsifier phase reaches 30°C.

Please indicate all details regarding used apparatus, for e.g. “FagronLab™PRO” Fagron Hellas, Trikala, Greece? Could you please mention the dispersing tool, and also rpm.?

Line 130: regarding organoleptic properties – do you mean odor („smell”)?

Lines 132-134: regarding stability testing of the emulsions- is this an in house protocol or an adapted one? Please indicate references!

Line 210 and Line 240: regarding microbial contamination control and antibacterial activity please add References.

Results contain general descriptions and references, which is not necessary. Original results should only be described in this section (for e.g. Lines 279-287).

Line 336: „moisturized appearance” – eventually moisturizing effect/properties which have to be demonstrated via instrumental evaluation, for e.g. corneometry.

Line 337: „sensory analysis” – was such kind of analysis performed, please describe in detail!

Line 338: „... do not irritate” – was safety assessment performed that could sustain skin compatibility, for e.g. single or repeated patch test?

Line 339: „... make them an alternative acceptable by the consumers” – what kind of alternative, to what? Please reformulate!

Line 562-563: „... (Figure ) and force vs. distance traces (Figure ).”- please indicate Figure numbers!

Conclusions:

Line 726: “… are safe for the skin” – like mentioned before, safety of cosmetic ingredients/formulations is mandatory according to current legislation- skin tolerance/compatibility studies and for e.g. eventually in silico evaluation.

Lines 727-728: “… therefore they can be used as a cosmeceutical product”- physico-chemical and microbiological evaluation cannot confirm this aspect!

Please verify and adapt References according to Cosmetics Instructions for authors.

Kindly, could you recheck the English grammar and the syntax?

Kind regards!

Comments on the Quality of English Language

Extensive editing of English language required.

Author Response

Please find in attachment the answers for your comments.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Some of the suggestions proposed for the authors have not been corrected. Please correct them.

1.       I suggest to the authors the inclusion of the word emulsion in the keywords.

2.       The authors should describe more correctly all the equipment used in all manuscript. Please add: Commercial brand, model. And company, city and country in brackets. Response: pH was determined using inoLab pH meter

3.       Conclusions: Line 708: “Optical microscopy analysis indicates that all emulsions have a “foam-like” aspect and are slightly aerated apperance”. How do the authors interpret these results? Could these results be due to the incorporation of air during the manufacturing process? Explain it.

Author’s response:  The foam-like apperance is due to the incorporation of air during the manufacturing process. During displacement, oil is increasingly solubilized and transported in a phase with a foam-like texture that develops from a droplet traffic flow. The extent and stability of these emulsion phases depend on the salinity and surfactant efficiency. The similarity with textures of classic foam phases is used to hypothesize the mechanisms that stabilize such macroemulsions in porous media. The observed microscopic displacement mechanisms can be traced back to foam formation, quality and transport. The resulting phases are of particular interest for mobility control during surfactant flooding, which, however, requires further investigation.

Reviewer response: If the emulsion obtained has the appearance of foam-like, the authors should change some aspect in the elaboration process. In no case does an emulsion prepared for these purposes have to have the appearance of foam-like.

Author Response

Please find the answers of your comments as attachment.

Thanks and regards

Authors

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for providing the revised version of your manuscript!

I still have some observations regarding following aspects:

Line 41: Keywords- “cosmeceutical emulsion”- eventually cosmetic emulsion, cosmeceutical, emulsion, …

Lines 70-71: According to author response, cosmeceuticals are not at all “a very controversial subject.”. Even the term cosmeceutical and/or dermatocosmetic is widely used nowadays, as a legal classification they are “general” cosmetics, and as mentioned before they can not possess a pharmacological/therapeutical effect.  

Line 135-…: Please provide detailed information of cosmetic ingredients - manufacturer (name, city (state abbreviation if USA or Canada), country) as suggested in the previous review!

Line 144: Please use the correct denomination for INCI- International Nomenclature of Cosmetic Ingredients, not “International Nomenclature Cosmetic Ingredient”.

Line 388: According to author response “the moisturized appearance was demonstrated only visual ...”, please avoid this aspect, like mentioned before, a biophysical parameter characterizing the status of the skin barrier cannot be “visually” performed!

Safety (e.g. skin compatibility/tolerance, specifically “not irritating”) cannot be argued by simple observation. Indeed, authors mention in the manuscript the performance of further clinical studies regarding safety and efficacy assessment, but this aspect cannot sustain the skin compatibility and/or cosmetic/cosmeceutical properties of the developed formulations.   

For a correct approach, please consider that physico-chemical and microbiological evaluation cannot confirm the safety and efficacy of a cosmetic/cosmeceutical/dermatocosmetic formulation!

Comments on the Quality of English Language

Moderate editing of English language is required.

Author Response

Please find the answers of your comments as attachment.

Thanks and regards

Authors

Author Response File: Author Response.pdf