Summary of review of Manuscript # 637217

Summary of review of Manuscript # 637217 Submitted to
Advances in Cancer: Research & Treatment
Reviewer #1
Major Comments
The manuscript “Confluentic acid inhibits the growth of rat glioblastoma cells in vitro”
represents another attempt to test a biological product against GBM. The manuscript
contains several flaws:
a) The statement “Reinfection (sic) of tissue with cancer cells…” (P1,p2,L1-2) needs
to be modified.
b) Although the authors state that “we must turn to the secondary metabolites of
the lichens…” (P1,p2,L7-8) at no time they explain why the lichens might be antineoplastic; or why they studied them; or what antecedents were considered; or
why they think that lichens could be used for cancer research. The absence of
this information decreases the scientific value of the findings.
c) The whole paragraph 3 on page 1 is inexact in oncological terms.
d) What is the “social arrangement” of lichens? (P1,p3,L1-2).
e) Legend for fig. 2 says “Dose-dependent effects of confluentic acid on the growth
of the rat glioblastoma cell …” what is obvious in the figure is that it is NOT a
dose-dependent effect but a constant effect not related with the dose.
f) In contrast, the graphic on fig. 3 shows a dose-dependent effect which is not
g) The fact that the substance tested (confluentic acid) was diluted in ethanol
makes it very toxic for cultured cells. It is possible that the cytolytic effect
observed was due to this.
Reviewer #2
Major Comments
Several aspects of the manuscript should be improved, especially the quality of analysis
and evidence. For ex. in order to improve the paper, the authors should evaluate the
cell viability by a specific method such as MTT assay; the toxic effect of the extract
against a normal cell or tissue (for example, control astrocytes or organotypic culture)
should be also evaluated;
Some points are given below:
- Methods:
1) How the “pure extracts” were prepared? How pure is the extract? How is the
concentration of Confluentic acid in the extract? Which chemical class this
chemical substance belongs?
2) What is the final concentration of ethanol used? This should be indicated in the
3) Which cell line of glioma was used?
4) Why the authors used 5 days of treatment. Probably if they treat the cells for
48h, they could see if the effect was dose-dependent.
5) Although the authors present the statistical method used, they did not put the
significance in the figures.
1) The presentation of the figures should be improved. The numbers
presented in the axis should be bigger.
2) The title of Figure 2 should be correct because the presented results do
not demonstrate a “dose-dependent” effect.
3) In the Figure 1, what is the concentration of ethanol in the control?
The discussion should be improved. The points discussed are purely
speculative. Ex:
The sentence “We propose the biological activity of confluentic acid is related to
lichen ecology. It is known that lichens are adapted for the manipulation of
radiation, and also adapted for defense against the foragers [6]. Therefore, it is
not surprising that the secondary metabolites of the lichen can enhance the
effect of radiation and inhibit foreign cells” does not appear to be consistent,
since if the lichens produce some protective substances, such as Confluentic
acid, how this substance can increase the cytotoxic effect of radiation against
glioma cells?