When the isomers associated with the peak at 4.40 min were treated with a methanolic solution of 0.5 M NaOH for 5 min followed by neutralization with HOAc and separated using HPLC (NH2), a single peak (tR = 9.1 min) was observed.
An accurate mass (negative ESI) gave a molar mass of 1039.3229 corresponding to a molecular formula of C43H59O29 (calculated 1039.3142). When the peak at 4.70 min was treated under the same conditions, a single peak (tR = 8.00) was obtained.
Accurate mass of that peak gave an m/z of 1039.3218, which corresponds to C43H59O29. The loss of 146 amu from the native compounds upon hydrolysis was inconsistent with our initial hypothesis that these native compounds were mixtures of regioisomeric monoacetates (i.e., anticipating a loss of 42 amu).
However, a decrease of 146 amu is consistent with the loss of an O-acetyl group with H-transfer (42 amu) and the loss of a benzoyl group with H-transfer (104 amu).
The 1H NMR spectrum of the hydrolysis product(s) now lacked the signals