Anti-Inflammatory Effects of Nephelium lappaceum Peel Extract and Geraniin on External Skin Stimulation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled „Anti-inflammatory effects of Nephelium lappaceum peel extract and Geraniin on external skin stimulation” concerns evaluation of natural products as potential ingredient of cosmetic products. Authors performed appropriate in vitro and in vivo clinical studies in humans. The manuscript is interesting and provides valuable results in the field of cosmetology, however it needs major improvement before possible publication.  
Please find below my major comments:
1. The last part of Introduction section should be re-written to provide the aim of the study rather than results. Statements such as “We confirmed the anti-inflammatory effects of Nephelium lappaceum peel extract and its main active ingredient” should not be used in the Introduction section. In the last part of Introduction should be presented the aim of the study. 
2. Please modify “Skin samples” (page 3, line 130) – it sound like ex vivo study was conducted on skin samples collected from volunteers. 
3. Obligatory in “Materials and Methods” provide information about the source of the test material. How the extract was prepared? What was the composition of the test material? Etc.
4. Obligatory in “Materials and Methods” provide information about the kind of application of the test material – how was it applied? Study Design was not appropriately presented. 
5. Obligatory in “Materials and Methods” provide information about preparation of extract for in vitro experiments (solvent, storage and other information) as well as control probes, number of replicates, plates used, number of cells per well and other appropriate information. 
6. There is no information about tests performed for isolated geraniin, so the title does not correspond with the manuscript body. If geraniin was tested, all information about the source of the compound, purity, test samples preparation etc. must be provided. 

Author Response

I sincerely appreciate your time and effort in reviewing my manuscript. I have made revisions in accordance with the valuable comments you provided.

 

1. The last part of Introduction section should be re-written to provide the aim of the study rather than results. Statements such as “We confirmed the anti-inflammatory effects of Nephelium lappaceum peel extract and its main active ingredient” should not be used in the Introduction section. In the last part of Introduction should be presented the aim of the study.

=  The previous content at the end of the Introduction section has been deleted and substituted with a revised passage that more clearly outlines the objectives of the present study. ' Although Nephelium lappaceum peel is often discarded as waste, it is rich in ellagitannins, including Geraniin. Therefore, we considered that it could be a cost-effective ingredient for cosmetic formulations. To date, the anti-inflammatory potential of Nephelium lappaceum peel has not been well documented. Based on this, we hypothesized that Nephelium lappaceum peel may exert anti-inflammatory effects against various stimuli. We subsequently investigated the efficacy of Nephelium lappaceum peel extract and Geraniin as novel natural anti-inflammatory agents with skin-protective properties comparable to madecassoside through both in-vitro and clinical studies.' (page 3, line 89-97)

 

2. Please modify “Skin samples” (page 3, line 130) – it sound like ex vivo study was conducted on skin samples collected from volunteers.

=  The term "skin samples" referred to the extracts used in the clinical study. To clarify this point, an explanation has been added to Section 2.4.1. Study Design and Participants (page 5, line 196).

 

3. Obligatory in “Materials and Methods” provide information about the source of the test material. How the extract was prepared? What was the composition of the test material? Etc.

=  Details regarding the preparation of the extracts and the composition of the test materials have been included in Section ‘2.2. Preparation of extracts’. We kindly ask you to refer to this section for your review. (page 3 , line 111)

 

4. Obligatory in “Materials and Methods” provide information about the kind of application of the test material – how was it applied? Study Design was not appropriately presented.

=  The in-vitro experiments were conducted as follows. ‘HaCaT cells were seeded at a density of 2.5 × 10⁵ cells per well in 2 ml of 10% DMEM in 6-well plates. The cells were then washed with DPBS and incubated in serum-free (0%) DMEM for 24 hours (1 ml/ well) to induce starvation. Subsequently, each sample was serially diluted in 2% DMEM (2 ml/well) and applied to the cells in triplicate.For the control group, each solvent used to dilute the samples was added to 2% DMEM and applied to the cells.’ (page 4, line 170)
For the clinical study, the product was applied either once, for 3 days, or for 14 days depending on the treatment group, and results were assessed before and after exposure to each stimulus.

 

5. Obligatory in “Materials and Methods” provide information about preparation of extract for in vitro experiments (solvent, storage and other information) as well as control probes, number of replicates, plates used, number of cells per well and other appropriate information.

=  All pertinent details have been included in Sections 2.1 Materials, 2.2. Preparation of extracts and 2.3 In-vitro for clarity and completeness.

 

6. There is no information about tests performed for isolated geraniin, so the title does not correspond with the manuscript body. If geraniin was tested, all information about the source of the compound, purity, test samples preparation etc. must be provided.

=  We first analyzed Nephelium lappaceum peel extract using HPLC. The analysis revealed that Geraniin was the most abundant compound, and based on this result, Geraniin was selected for the in-vitro experiments. Geraniin was purchased from Cayman Chemical, dissolved in DMSO at a concentration of 30 mg/mL, and stored at –20 °C until use. For further details, please refer to Sections 2.1 Materials, 2.2 Preparation of Extracts, 2.3.1 Preparation and Storage of Reagents, and 3.1 Quantification of Geraniin, Corilagin, Gallic Acid, and Ellagic Acid in Nephelium lappaceum Peel Extracts Using NADES .

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript demonstrates a coherent structure and presents substantial results. Minor revisions are recommended, and the following suggestions are provided:
In the introduction, the authors inform the reader that the anti-inflammatory activity of these active ingredients has already been reported in the extant literature. Therefore, the novelty of this study should be more clearly explained in the Introduction.

The origin and characteristics of the extract utilized must be thoroughly delineated in the Materials and Methods section. This encompasses its composition and the methodology by which it was obtained. In addition, in vitro tests must include the concentrations of the treatment, the method by which the extract was prepared for addition to the cells, and the controls utilized.

Author Response

I sincerely appreciate your time and effort in reviewing my manuscript. I have made revisions in accordance with the valuable comments you provided.

 

1. In the introduction, the authors inform the reader that the anti-inflammatory activity of these active ingredients has already been reported in the extant literature. Therefore, the novelty of this study should be more clearly explained in the Introduction.

=  Apologies for the oversight. The constituents of Nephelium lappaceum peel have been more extensively reported for their antioxidant, antipyretic, and antidiabetic activities, while evidence regarding its anti-inflammatory effects remains limited. In particular, studies exploring its potential as a cosmetic ingredient are scarce. Accordingly, the relevant part in the Introduction section has been revised to: 'Nephelium lappaceum peel extract, rich in polyphenolic compounds such as ellagitannins, has been shown to possess strong antioxidant, antipyretic, and antidiabetic activities. (page 3, line 85)

In addition, this study examined the anti-inflammatory effects of Nephelium lappaceum peel extract using a range of stimuli (including LPS, UV, SDS, and RA) on HaCaT cells, and these findings were further supported by a clinical trial. We consider this integrated approach to be a key aspect of novelty that distinguishes our work from existing literature.

 

2. The origin and characteristics of the extract utilized must be thoroughly delineated in the Materials and Methods section. This encompasses its composition and the methodology by which it was obtained. In addition, in vitro tests must include the concentrations of the treatment, the method by which the extract was prepared for addition to the cells, and the controls utilized.

=  Information on the composition, extraction procedure, and properties of the extract used can be found in Section 2.2 Preparation of extracts (page 3, line 111). Moreover, the identical extract was utilized in the in-vitro experiments. Information concerning the stimulatory samples, Geraniin, and the control groups is provided in Section 2.3 In-vitro for your reference. (page 4, line 149)

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Authors implemented all recommended changes, the manuscript can be published in current form. This is a valuable contribution.