Valencene, Nootkatone and Their Liposomal Nanoformulations as Potential Inhibitors of NorA, Tet(K), MsrA, and MepA Efflux Pumps in Staphylococcus aureus Strains
, Jorge Ederson Gonçalves Santana 2, Gabriel Gonçalves Alencar 1, Gustavo Miguel Siqueira 1, Sheila Alves Gonçalves 1, Saulo Relison Tintino 1, Irwin Rose Alencar de Menezes 1, João Pedro Viana Rodrigues 3, Vanessa Barbosa Pinheiro Gonçalves 3, Roberto Nicolete 3, Jaime Ribeiro-Filho 3,*, Teresinha Gonçalves da Silva 2 and Henrique Douglas Melo Coutinho 1,*
Round 1
Reviewer 1 Report
The manuscript titled “Valencene, nootkatone, and their liposomal nanoformulations inhibit NorA, Tet(K), MsrA, and MepA efflux pumps in S. aureus strains” written by Cícera Datiane de Morais Oliveira-Tintino focuses on the potentiating effects of the natural sesquiterpenes Valencene and nootkatone in association with Norfloxacin, Tetracyclin and Erythromycin in the treatment of S. aureus infections. Despite the manuscript reported valuable results, major revisions are required before its acceptance for the publication in Pharmaceutics.
Details:
- The title should be modified since the results suggest a “possible” mechanism of action involving the inhibition of the efflux pumps, but no experimental evidence or specific assays confirmed this hypothesis. Moreover the liposomal nanoformulations showed no activit.
- Introduction: The names of the bacterial strains must be in italics (e.g. lines 38, 40, 43…). The bibliography related to the antibiotic resistance in S. aureus needs an update, add the recent references Future Medicinal Chemistry, 2021, 13(6), pp. 529–531; Front. Cell. Infect. Microbiol., Sec. Clinical Microbiology, 10 – 2020, https://doi.org/10.3389/fcimb.2020.00107; Future Medicinal Chemistry, 2020, 12(5), pp. 357–359
- Line 78: insert a figure with the chemical structures of Valencene and nootkatone
- It is not clear why the authors decided to investigate the activity of Valencene and nootkatone against the efflux pumps. Clarify.
- Pages 10, 11: check µg in fig 3
Author Response
Dear Reviewer, we appreciate your contribution. All the considerations have been acknowledged, and the corrections have been applied in order to improve our manuscript
Details:
Comment 1. The title should be modified since the results suggest a “possible” mechanism of action involving the inhibition of the efflux pumps, but no experimental evidence or specific assays confirmed this hypothesis. Moreover the liposomal nanoformulations showed no activit.
R1. Thank you for the suggestion. The new title is: Valencene, Nootkatone and their liposomal nanoformulations as potential inhibitors of NorA, Tet(K), MsrA, and MepA efflux pumps in Staphylococcus aureus strains
Comment 2-Introduction: The names of the bacterial strains must be in italics (e.g. lines 38, 40, 43…). The bibliography related to the antibiotic resistance in S. aureus needs an update, add the recent references Future Medicinal Chemistry, 2021, 13(6), pp. 529–531; Front. Cell. Infect. Microbiol., Sec. Clinical Microbiology, 10 – 2020, https://doi.org/10.3389/fcimb.2020.00107; Future Medicinal Chemistry, 2020, 12(5), pp. 357–359
R2: Corrected
Comment 3-Line 78: insert a figure with the chemical structures of Valencene and nootkatone.
R3: Done
Comment 4-It is not clear why the authors decided to investigate the activity of Valencene and nootkatone against the efflux pumps. Clarify.
R4: This is now clarified in the introduction.
Comment 5-Pages 10, 11: check µg in fig 3
R: Done
Reviewer 2 Report
Check the attached comments
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 2
Dear Reviewer, thank you for your contribution. All the considerations have been acknowledged, and the corrections have been applied.
Comment 1: Line 17: in liposomal formulations against strains of Staphylococcus aureus “here” after that add the (S. aureus) and used in remaining parts of manuscript instead complete name and italic them
R1. Done
Comment 2: Line 40: S. aureus primarily causes skin infections “here” S. aureus should be italic
R2: Thank you. Corrected
Line 43: S. aureus is an opportunistic pathogen in humans and mammals “here” S. aureus should be italic
R3. Thank you. Corrected
Comment 4. Lines 50: The mechanisms of antibiotic resistance in S. aureus “here” S. aureus should be italic
R4. Thank you. Corrected
Comment 5. Line 74-77: Rephrase the sentence “In the search for clinically promising efflux pump inhibitors, natural product research has identified aromatic compounds, such as sesquiterpenes, as new weapons in combating antibiotic resistance”
R5. The sentence has been rephrased: “Natural product research has demonstrated the effectiveness of natural products against resistant bacteria. Importantly, sesquiterpenes have been highlighted as efflux pump inhibitors and, therefore, are promising candidates in drug discovery”
Comment 6. Lines 173: PBS at a concentration of 1.5 x 108 colony-forming units (CFU) is it correct?
R6. A correction has been made.
Comment 7. Line 322-323: Studies have shown that essential oils containing valencene as a principal constituent have significant antimicrobial activity “here” add the reference
R7: Thank you for your observation. Done.
Comment 8. Line 332: interaction with S. aureus, with binding affinity ranging “here” S. aureus should be italic.
R8. Thank you. Corrected
Comment 9. Line 348: possible inhibitor of efflux pumps in S. aureus “here” S. aureus should be italic
R9. Thank you. Corrected
Comment 10. Line 384-537: Check the references following the reference's journal style
R10. Thank you. The reference style was corrected.
Reviewer 3 Report
It can be accepted in the current format.
Author Response
Thank you so much for your positive evaluation of our work.
Reviewer 4 Report
The research work evaluates the activity of Valencene and nootkatone in their isolated state as well as in liposomal formulations against strains of Staphylococcus aureus carrying efflux pumps. The results indicate positive action of antibiotics and efflux inhibitors in strains carrying NorA, Tet(K), and MsrA proteins. The comments are as follows,
1. 2. Materials and Methods: Please add materials as separate part.
2. 2.2. Drugs and reagents, please cite the materials selected, based on reagent or from standard protocols.
To study the activity of Valencene and nootkatone in their isolated state or in liposomal formulations against strains of Staphylococcus aureus carrying efflux pumps.
Research is original and relevant to the delivery of bioactive. Liposomal formulation act most suitable to delivery this bioactive. It may required further study for commercialization.
The study concluded that liposome are did not improve the effectiveness of these 364 compounds as antibiotic resistance modulators,
There no direct relicense of this work with published work. Few work on valencene and nootkatone are there with lipid based formulation, however this is totally novel concept and can be consider as proof new concept.
The methodology are well explained and can be reproducible.
More study should be done with other lipid, to conclude that, liposomes did not improve the effectiveness of these 364 compounds as antibiotic resistance modulators,
Author Response
Response to Reviewer 4
Dear Reviewer, we appreciate your contribution. All the considerations have been acknowledged, and the corrections have been applied.
Comment 1. 2. Materials and Methods: Please add materials as separate part.
R1: Done
Comment 2. 2.2. Drugs and reagents, please cite the materials selected, based on reagent or from standard protocols.
R2: Thank You. The changes were performed
Comments “To study the activity of Valencene and nootkatone in their isolated state or in liposomal formulations against strains of Staphylococcus aureus carrying efflux pumps.
Research is original and relevant to the delivery of bioactive. Liposomal formulation act most suitable to delivery this bioactive. It may required further study for commercialization.
The study concluded that liposome are did not improve the effectiveness of these 364 compounds as antibiotic resistance modulators,
There no direct relicense of this work with published work. Few work on valencene and nootkatone are there with lipid based formulation, however this is totally novel concept and can be consider as proof new concept.
The methodology are well explained and can be reproducible.
More study should be done with other lipid, to conclude that, liposomes did not improve the effectiveness of these 364 compounds as antibiotic resistance modulators,
R3.: Thank you for your comments. All suggestions were applied to the manuscript.
Round 2
Reviewer 1 Report
The manuscript in the revised form can be accepted for the publication in the journal.
