Peer-Review Record
Verrucosidin Derivatives from the Deep Sea Cold-Seep-Derived Fungus Penicillium polonicum CS-252
Int. J. Mol. Sci. 2022, 23(10), 5567; https://doi.org/10.3390/ijms23105567
by
Yanhe Li 1,2,3, Xiaoming Li 1,2, Xin Li 1,2
, Suiqun Yang 1,2, Bingui Wang 1,2,3,4,* and Honglei Li 1,2,*
, Suiqun Yang 1,2, Bingui Wang 1,2,3,4,* and Honglei Li 1,2,*Reviewer 1:
Anonymous
Reviewer 2:
Anonymous
Int. J. Mol. Sci. 2022, 23(10), 5567; https://doi.org/10.3390/ijms23105567
Submission received: 9 April 2022
/
Revised: 1 May 2022
/
Accepted: 5 May 2022
/
Published: 16 May 2022
(This article belongs to the Special Issue Marine Natural Products Identified by Molecular Approaches and Human Disease)
Round 1
Reviewer 1 Report
This work is interesting and well presented.
Minor comments:
1-Comments: Missing of Experimental ECD spectrum figure for compound 5
2- Comments: Figure 9. 6 at BH&HLYP/TZVP level (red dashed line)> should be Figure 10.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This study has been well carried out and the results were found to be attracted and useful for the discovery of bioactivie natural products from marine fungi. I suggest the acceptance for publication of this work after the clarification of the questions which are as listed below.
- The title of this paper can be changed as compounds 4 and 6 do not possess the 2-pyrone ring which is one of the essential structure unit of verrucosidin-type compounds. Also, compounds 1-3 and 5 are new compounds, but it might be not suitable to describe these compounds as unusual because they are simply the deoxygenated compounds from those discovered previously.
- The absolute configuration of 3 was determined by experimental and calculated ECD spectra, however, both spectra shown in Figure 6 are not well matched, in particular between 200 to 250 nm.
- It was pointed that the TDDFT-ECD calculations suggested that both conformers 4a-(2R,10S,13R) and 4b-(2S,10S,13R) were recommended for 4 (Figure 8), which were further clarified by the DP4+ probability analysis. Both proton and carbon data of the two possible isomers were calculated based on the DP4+ protocol and the results were analyzed with the experimental values . The statistical analysis indicated that the isomer [4a-(2R,10S,13R)] was the equivalent structure with a probability of 99.91% (Figures 8 and
S42). The absolute configuration of 4 was thus assigned. However, in S42 it was found that the caululated proton and carbon data were not provided, and there should be provided. - It should be mentioned in the manuscript that compound 5 was isolated as a highly impured mixture, and also please discuss whether it is an artifact arisen from the photo-induced isomerization of compound 1.
- The structure of compound 6 is questionable. The NOESY spectrum was not well recorded so that I do not think that the NOE correlations mentioned in the manuscript which are important for accurate stereochemical assignment, such as between those olefinic methyls, could be found in the spectrum. Compound 6 might still be a compound with a pyron ring as the chemical shift of C-5 is quite close to C-5 shifts of compounds 1-3. The IR spectrum of 6 can solve the problem.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
