Volatile Organic Compounds of the Glandular Trichomes of Ocimum basilicum and Artifacts during the Distillation of the Leaves

Round 1

Reviewer 1 Report

This work has been written with care. The results and discussion presented has been thoroughly prepared. The article is very interesting, both from a cognitive and practical point of view. It shows the differences in the chemical composition of the oils present in the plant tissues (with reference to their location in plant structures – various types of trichomes) and those already distilled. I have only one remark - avoid abbreviation in the title – VOC. This abbreviation should be explained when used for the first time in the text.

Author Response

Thank you for your consideration.

Reviewer 2 Report

The comments regarding the manuscript entitled “VOC of the Glandular Trichomes of Ocimum basilicum and Artifacts During the Distillation of the Leaves”

Authors: Bruno Tirillini, Filippo Maggi

The subject addressed in this article is interesting and could be useful for the researchers involved in this field of science. The manuscript presents the composition of the Ocimum basilicum essential oil obtain by hydrodistillation, respective the chemical composition of VOC presented in secretory trichomes of Ocimum basilicum leaves. The chemical composition was investigated by GC/FID and GC/MS.

Taking into consideration the observations below I recommend the publication of this manuscript after major revisions.

The abstract must be improved.

Row 163 idrodistilled leaf oils         -correct is  hydrodistilled

The experimental section must be improved with HPLC analysis of the VOC and LEO extract from Ocimum basilicum leaves to prove the composition and to identify all the artifacts formed during hydrodistillation and GC investigation. In addition, the GC/MS and GC/FID analysis are carried out at 220-300° C which can cause the oxidation and breakdown of the organic compounds presented in VOC and LEO which can generate artifacts.

Author Response

The HPLC technique is not used for volatile compounds (e.g. determination of the composition of essential oils) but for non-volatile fractions. The topic is well developed in the following review:

Dugo et al. (2005) Advanced and innovative chromatographic techniques for the study of citrus essential oils. Flavour and fragrance journal. 20: 249 - 264.

Chromatographic techniques can be used to fractionate essential oils whose fractions, however, are analyzed via GC/MS (the technique is little used because it leads to the significant loss of the most volatile compounds).The formation of artifacts during GC/MS analysis in principle is possible even if the analysis takes place in helium current and this limits the use of GC analysis to thermolabile or poorly stable compounds. The problem of artifacts during GC analysis is currently not considered for essential oils or VOC because the mass spectra of the libraries were made by injecting into a GC/MS under the conditions we followed a sample identified with NMR techniques and therefore even if some deterioration of the molecule could occur during the injection, the mass spectrum is correlated to that molecule.

I am sorry, but I cannot take that into consideration.

The abstract should be a total of about 200 words maximum

Reviewer 3 Report

The article of Tirillini and Maggi describes the determination of the chemical composition of volatile organic compounds (VOC) in secretory trichomes of Ocimum basilicum by GC/FID and GC/MS, then comparing this determination with that of 11 essential oil obtained by hydrodistillation of the leaves. In particular, for the purpose, the secretory content was sucked by using a microneedle. The manuscript is well written, and the data are clearly presented. On this basis, I recommend to accept the manuscript for publication in Applied Sciences after a minor revision.

Minor comments:

1) Please correct the manuscript for typos.

2) Introduction: I suggest that the authors insert some lines about importance a) of emission and function of VOC which are produced and released by plants, and b) of determination of VOC composition.

3) Figure 1: the Figure is too small and not clear. I suggest increasing size of the Figure and introducing the assignment for the main VOC identified in the analysed samples.

4) Please insert some recent references related to the field: a) Purushothaman, B. et al. A Comprehensive Review on Ocimum basilicum. Journal of Natural Remedies 2018, 18, 71-85. DOI: 10.18311/jnr/2018/21324; b) Shahrajabian, M. H. et al. Chemical components and pharmacological benefits of Basil (Ocimum basilicum): a review. International Journal of Food Properties 2020, 23, 1961-1970. DOI: 10.1080/10942912.2020.1828456; c) Dhama, K. et al. A Comprehensive Review on Chemical Profile and Pharmacological Activities of Ocimum basilicum. Food Reviews International 2021. DOI: 10.1080/87559129.2021.1900230

Author Response

The suggestions indicated were all taken into account and the manuscript shows in red the variations from the previous manuscript. In particular the figures have been magnified and report the numbers of the peaks.

The most common methods for the determination of the composition of Vocs and the main functions of the emission of Vocs by plants in the ecological field were briefly reported.

The suggested bibliographical references have been inserted and the text has been revised for possible typos.

The English revision I thought I’d do when the manuscript is finally accepted.

Thank you for helping to improve the manuscript.