O=C(/C=C/c1ccc(O)c(O)c1)O[C@@H]1C[C@@](O)(C(=O)O)C[C@H](O)[C@@H]1O
Hydrogen bond acceptor: The atom, ion, or molecule component of a hydrogen bond which does not supply the bridging (shared) hydrogen atom. How many hydrogen bond acceptors does the molecule have?