*2.1. Isolation of Polyprenylated Benzophenones from Symphonia globulifera and BRP*

Samples of both BRP and *S. globulifera* resin were extracted with aqueous ethanol 70% and submitted to partition with solvents of increasing polarities. The hexane fractions were separately submitted to chromatographic procedures that resulted in the isolation of two polyprenylated benzophenones (**8** and **9**) and two pentacyclic triterpenoids (**10** and **11**) from both fractions. The structures of the isolated compounds were established based on 1D and 2D-NMR spectroscopy, high-resolution MS, and comparison with the literature data for the polyprenylated benzophenones guttiferone E (**8**) [10], in a mixture with its double bond position isomer xanthochymol [11], oblongifolin B (**9**) [12], and the triterpenoids β-amyrin (**10**) [13] and glutinol (**11**) [14]. The NMR spectra of **8** and **9** in CDCl3 displayed abnormalities that disappeared when spectra were recorded in CD3OD + 0.1% trifluoroacetic acid (TFA). The chemical structure of those isolated constituents (**8**–**11**), as well as other phenolic compounds (**1**–**7**) identified in BRP are displayed in Figure 1.

**Figure 1.** Chemical constituents of Brazilian red propolis.

The oblongifolins were first isolated from *Garcinia oblongifolia* by Hamed et al. (2006) [12]. The occurrence of oblongifolin A in samples of BRP was initially reported by Piccinelli et al. (2011), while further publications replicated this finding by LC-MS analyses. However, mass spectrometry of oblongifolins is not enough to identify them, since they bear the same molecular weight, while none of those previous reports have provided NMR data to confirm the occurrence of oblongifolin A in BRP [4,6–8]. Therefore, the NMR spectroscopic data of the isolated compound **9** in comparison with published data of oblongifolins A and B is presented in Table S1 (Supplementary Material). The 1H and 13C NMR chemical shifts of these two stereoisomers are almost identical. Nonetheless, significant differences are found in the 13C NMR spectra of these two oblongifolins at δC-6 (47.8 for A and 44.2 for B), δC-7 (40.8 for A and 43.3 for B), and δC-8 (61.8 for A and 64.3 for B). Similarly, the 1H NMR spectra of oblongifolin B displays a characteristic axial coupling constant for H-7 of 13.0 Hz. Therefore, the isolated compound **9** corresponds to oblongifolin B and its isolation from BRP is here reported for the first time.
