Aquilarinenside E (5) [18] showed the molecular formula of
C21H22O10 by analysis of its HRESIMS spectrum (m/z 435.1247
[M+H], calcd. for C21H23O10: 435.1227) (Fig. S42 in Supporting
information). Comparison of the NMR spectroscopic data (Table 1)
revealed a similar structure to 1. Compound 5 incorporated an
acetyl group instead of the outer rhamnopyranosyl found in 1,
which was further confirmed by 2D NMR spectra. The key HMBC
correlation between H-400 (dH 4.79) and C-1000 (dC 172.7) indicated
the acetyl group was located at C-400 position of the rhamnopyranosyl.
Thus, aquilarinenside E (5) was determined as iriflophenone
2-O-a-L-(400-acetyl)-rhamnopyranoside.