Cinnamon (Cinnamomum cassia (L.) J.Presl) barks has been a regularly consumed dietary additive due to its rich flavor. Cinnamon extracts of varying polarity, trans-cinnamaldehyde and trans-cinnamic acid were specifically evaluated for HDAC 1 inhibitory activity. Essential oil (IC50: 51.11 μg/ml) and 70% ethanol extract (IC50: 107.90 μg/ml) exhibited most potent HDAC 1 inhibitory activity. Individually, cinnamaldehyde and cinnamic acid were determined to have an IC50 of 7.58 μg/ml and 9.15 μg/ml, respectively. Essential oil and 70% ethanol extracts of Cinnamomum cassia barks can be further evaluated to be used in products against HDAC 1 related diseases in future studies.
Compared with existing reports, the present topic is very interesting, the method used in the research is novel and reliable, and the results are supported by the experimental evidence supplied, so the conclusion was solid. This study has significantly contributed to food research, especially to the function research on cinnamon, a dietary additive. This manuscript can be accepted after minor revision. The reviewer would like to review the revision again. Apart from grammar editing, several suggestions were given on this manuscript.
1, The significance of this study needs to be strengthened, so the background of anti-HDAC 1 activity research and the research progress of natural products with anti-HDAC 1 activity, needs to be systematically summarized in the instruction section.
2, UPLC-DAD and ESI-MS/MS were used to analysis the extracts obtained from Cinnamomum cassia, and they are important techniques for the analysis of active ingredients of natural products. So, the application of UPLC-DAD and ESI-MS/MS in the field of natural products should be summarized in the introduction and discussion section, such as doi: 10.1002/dta.2123; doi: 10.1186/1471-2091-15-19; DOI: 10.1016/j.jep.2014.03.031.
3, The extracts obtained from Cinnamomum cassia were analyzed with HPLC analysis using UV-visible detector for cinnamaldehyde content. High-performance liquid chromatography (HPLC) is a very powerful and versatile chromatographic technique for the separation of natural products (NPs) in complex matrices, So, the application of HPLC in the field of natural products should be summarized in the introduction and discussion section, such as doi: 10.1039/c5ay02941d; doi: 10.1002/pca.993; doi: 10.1039/c5ay02941d.
3, The resolution of the figures should be improved, and the format of the reference list needs to be checked again.
4, There are some grammatical errors in the text, so the English express needs to be polished by a native speaker.