Ishizu E, Honda S, Vongsak B, Kumazawa S. Identification of plant origin of propolis from Thailand stingless bees by comparative analysis. Nat Prod Commun. 2018;13(8). doi: 10.1177/1934578X1801300813
In this article, the name and structure of 4 was incorrect. Compound 4 is cochinchinone T not garcinone D (Figure 1). When we re-analyzed the HMBC spectrum of 4, a cross peak between the methyl protons of a methoxyl group and the quaternary carbon at 18 position was observed as shown in a solid arrow of Figure 2. If 4 is garcinone D, this cross peak should not be observed. Therefore, we would like to correct the name and structure of 4 in the article and Supplementary data 1 and 2. The correct structure of 4, cochinchinone T is shown in Figure 1. Table 1 showed the assigned NMR data of 4. We apologize for any inconvenience caused by the error.
Structure of 4.
Key HMBC correlations of 4.
Chemical Shifts for 4 in CD3OD.
No.
δC
δH
1
160.2
C
2
109.8
C
3
162.0
C
4
91.5
CH
6.03 (1H, s)
4a
154.9
C
5
99.6
CH
6.47 (1H, s)
6
151.8
C
7
140.7
C
8
129.4
C
8a
110.9
C
9
182.2
C
9a
102.5
C
10a
152.7
C
11
20.8
CH2
3.10 (2H, masked by CD3OD singal)
12
122.5
CH
5.02 (1H, t, J = 2.6)
13
130.2
C
14
24.6
CH3
1.45 (3H, s)
15
16.5
CH3
1.57 (3H, m)
16
21.1
CH2
3.17 ~ 3.21 (2H, m)
17
38.2
CH2
1.57 (2H, m)
18
75.6
C
19
*24.3
CH3
1.09 (3H, s)
20
*24.3
CH3
1.09 (3H, s)
18-CH3-O
47.59
-OCH3
3.14 (3H, s)
1-OH
13.67 (1H, s)
Data were recorded at 400 MHz (1H-NMR) and 100 MHz (13C-NMR) in CD3OD.
J-values are given in Hz in parentheses. *Overlapping of the signals.
