Bioassay-Guided Isolation of Triterpenoids as α-Glucosidase Inhibitors from Cirsium setosum
, Xiangjian Zhong 2,†, Xin Wang 2, Jinjie Li 2, Jiachen Liu 2, Kaiqi Wang 2, Jianyu Yue 2, Ximiao Yang 2, Xiaoya Shang 2,* and Sheng Lin 3,*
Round 1
Reviewer 1 Report
REVIEW
"Bioassay-guided isolation of triterpenoids as α-glucosidase inhibitors from Cirsium setosu"
By Xiuting LI et al.
The authors have shown the α-glucosidase inhibitory activity of some compounds from Cirsium setosum. Thus, according to the experimental procedure, fractions from apolar solvent were obtained and there were isolated 3 triterpenoids with high α-glucosidase inhibition, wherein compounds 1-3 were mentioned as new triterpenoids. The manuscript is well-written, easy to read and with complete experimental data (spectroscopy data for new compounds among other). My suggestion to the authors to improve it is to complete the discussion with the differences between triterpenoid derivatives 1-3 because some chemical moieties at the position 20, 22 and 30 for 1 could be important in the biological activity respect to the triterpenoid framework .
When the authors can carry out these improvements, this article can be considered to publish in Molecules.
Author Response
This result indicated the presence of methyl at C-20 is essential for α-glucosidase inhibitory activity in taraxastane-type triterpenoids. Compounds 1 with oxygenation methyl group at the C-30 exhibited the highest level of bioactivity, followed by methyl group compound 2. The none methyl group compound 3 showed the lowest level of bioactivity. The activity of compound 7 was slightly weaker than that of 4, the only difference was that the hydroxyl group at the C-22 was oxidized to a carbonyl group. However, the activities of compounds 5 and 6 even disappeared when compared with compound 4. It was found that the hydroxyl group at the C-3 was oxidized to a carbonyl group or acylation, suggesting that the presence of a hydroxyl group at the C-3 may have played an essential role when it comes to activity.
Reviewer 2 Report
This manuscript describes the alpha-glucosidase screening of several bioactive triterpenoids found in Cirsium setosum as potential antihyperglycemic molecules. The structure of 3 new compounds and five known taraxastanes has been determined by detailed analysis, spectroscopic 1D and 2D NMR and spectrometric data. The manuscript is clear, well organized and fit within the scopes of Molecules. However there are several points that the authors should address before to be published:
-Instead of figure 4, the discussion can be done by ranking the compounds by their IC50 (4=1>7>2>3>6>>>8). Also the authors must calculate the relative potency to refer to the ability of a test sample to produce the desired response compared to acarbose, using the following formula:
Relative Potency =[ IC50 of Standard sample (acarbose)]/ [IC50 Test sample (1-8)]
-Table 2. There is a typo in “Acarbose”
-Could the authors propose a Plausible biogenetic pathway for the hydroperoxy-20-taraxastene?
Through a careful reading of the manuscript, I found this paper acceptable for publication, pending these minor corrections
.
Author Response
Reviewer 2：1. -Instead of figure 4, the discussion can be done by ranking the compounds by their IC50 (4=1>7>2>3>6>>>8). Also the authors must calculate the relative potency to refer to the ability of a test sample to produce the desired response compared to acarbose, using the following formula:
Relative Potency =[ IC50 of Standard sample (acarbose)]/ [IC50 Test sample (1-8)]Thank you for your valuable suggestion. We have ranked the compounds by their IC50 (4=1>7>2>3>6>>>8) instead of figure 4, and completed the calculation of the relative potency (please see lines 279-281).
The relative potency of compounds 4, 1, 7, 2, 3, 6, 5 and 8 were 2.43, 2.32, 1.87, 1.57, 0.95, 0.78, 0.62 and 0.53 respectively, when compared with acarbose at the IC50 level.2. -Table 2. There is a typo in “Acarbose”Thank you for your suggestion. We have corrected the typo in “Acarbose”.
3. -Could the authors propose a Plausible biogenetic pathway for the hydroperoxy- 20-taraxastene?Thank you for your suggestion. But the plausible biogenetic pathway for the hydroperoxy-20-taraxastene is simple, it is not worth the drawing.
Plausible biogenetic pathway of compound 1
Reviewer 3 Report
This paper is good quality research I recommend accepting after minor revision
1. kindly revise the language
2. arrange the references according to journal style
Author Response
Reviewer 3：1. kindly revise the languageThank you for your suggestion. We have corrected the errors in the manuscript with the change points highlighted in yellow.2. arrange the references according to journal styleThank you for your suggestion. We have arranged the references according to journal style
