Corrigendum to Identification of Plant Origin of Propolis From Thailand Stingless Bees by Comparative Analysis

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.

Figure 1

Structure of 4.

Figure 2

Key HMBC correlations of 4.

Table 1

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.