Antioxidant Properties and Kidney Cell Protection by the Extracts of Curcuma longa, Artemisia princeps, Salicornia herbacea, and Schisandra chinesis
Round 1
Reviewer 1 Report
In this manuscript, antioxidant properties and kidney cell protection of extracts from four medical plant, tumeric (TM), Gangwha mugwort (GM), glasswort (GW), and omija (OM), were investigated. The changes between unfermented and fermented extracts using hot water and ethanol as solvent were analyzed. The research is meaningful and the methods are correct. However, there are also some deficiencies and confusions in the article. According to the current status, I think it cannot be accepted by this journal.
Major concerns:
1. The antioxidant activities of these plants have been reported by previous studies. What is the difference between this study and previous studies? The innovation point and the problem to be solved are not clearly stated in the background.
2. What is the purpose of monitoring pH during fermentation? What are the effects of pH changes on microbial proliferation and metabolite accumulation? It’s more necessary to monitor changes in product accumulation during fermentation, including polyphenols and flavonoids.
3. Abbreviations of the four plants have been used in the preceding text, so it is suggested to use abbreviations in the following text and figures.
4. Why the yields of polyphenols and flavonoids in fermented extracts were reduced? Is it related to fermentation conditions? If the changes in these products during the fermentation process are continuously examined, are there different optimal times for higher product concentration in four plants?
5. In Fig. 2, the significance mark is not very clear. It is suggested that the significance mark could be placed across the horizontal line between the two groups of comparison. The same problem exists in Fig. 6.
6. In Fig. 4, the antioxidant activities of unfermented and fermented extracts were compared. The results showed that the activity of polyphenols and flavonoids was not correlated linearly with their concentrations. Then the authors should supplement the ingredient variation of extracts before and after fermentation.
Minor concerns:
7. Formula (1) is wrong.
8. There are some spelling mistakes in this manuscript. The authors should check carefully.
eg. In Fig. 4 and 5, the spelling of the word “concentration” was wrong.
Author Response
- The purpose of monitoring pH during fermentation is to control the growth and activity of microorganism. During the fermentation, more LAB decrease pH, and then other microorganisms cannot be alive and function. Hence pH is important factor on increasing enzyme activities, microbial proliferation and the metabolites accumulation.
- Corrected in text and figures
- The reasons of decreasing yields of polyphenols and flavonoids in fermented extracts were that because of the accumulating complex of phenolic compounds and other metabolic substrates during the fermentation period decreased concentration of free phenolic compounds.
- Corrected in figure 2 and 6
- Antioxidant activity is attributed to the presence of not only several phenolic compounds, but also degradation metabolite such as maillard products, peptides, amino acid, tocopherol, and carotenoids.
- corrected spellings
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The topic falls in the scope of this journal. I found this article complete, detailed and well written. The design is reasonable and the authors have given a good number of citations about the subject. Therefore, I consider the manuscript suitable for publication.
I recommend making some minor revisions before publishing the manuscript:
1) lines 12, 199, 300, 319, 325, 357 - correct the word “tumeric” with “turmeric”
2) lines 103, 104, 220, etc. – standardize the text by writing liters with capital letter (L, mL, etc.), also in the figures
3) lines 87, 91, 121, 216, etc. - write v/v, w/v, etc. in italics
4) lines 159, 161 and 164 - standardize the text by writing “h” instead of “hrs”
5) line 202 – correct the word “remain”
6) line 220 - delete the brackets in (~ 107 CFU/ml)
7) line 284 – correct the word “marginally”
8) Figures 4 and 5 – correct the word “concentration”.
Author Response
1~8. It was corrected in the text.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors didn't respond to some comments or respond incompletely. According to the current status, it needs major revision before acceptance for publication in this journal.
1. The antioxidant activities of these plants have been reported by previous studies. What is the difference between this study and previous studies? The innovation point and the problem to be solved are not clearly stated in the background.
The authors didn’t respond to this comment. The difference of antioxidant activities of these plants in this study and previous studies is still obscure and insufficient. The authors should explain for this.
2. In Fig. 4, the antioxidant activities of unfermented and fermented extracts were compared. The results showed that the activity of polyphenols and flavonoids was not correlated linearly with their concentrations. The authors explained that " Antioxidant activity is attributed to the presence of not only several phenolic compounds, but also degradation metabolite such as maillard products, peptides, amino acid, tocopherol, and carotenoids." If so, what are the main components in the two extract “HWE” and “EE”? How about the contents and proportion of these components? And Which are the most important roles in displaying antioxidant activity? It’s necessary to supplement the ingredient variation of extracts before and after fermentation.
3. The significance mark in Fig. 6 is still unclear, and it’s not helpful for reading.
Author Response
- The previous study was about only antioxidant effect of fermented medicinal plant, in contrast this research was determined not only antioxidant activity, but also protection effect of kidney cell of these plants.
- Hot water extract of wormwood were phenolic compounds such as catecuic acid, benzoic acid, syringic acid, and cinamic acid group containing caffeic acid, courmaric acid, ferulic acid, and also flavonoid group including hesperidin, myricetin, naringenin, rhamnetin etc. The more ethanol concentration, the more extraction of phenolic acids. After fermentation increased the concentration of salicylic acid, protocateuic acid, caffeic, coumaric and ferulic acid, in contrast decreased quinic acid, chlorogenic, and caffeoyl acid. Fig 4 displayed no cytotoxicity of these fermented plants except turmeric, therefore it was declared that these medicinal plants had good protection effects on kidney cell without toxicity.
- Fig. 6 was corrected in the text.
Round 3
Reviewer 1 Report
According to the current status, it could be accepted by this journal.
