Absolute configuration of strictosidinic acid

The absolute configuration of strictosidinic acid, (2S,3R,4S)-3-ethenyl-2-(β-D-glucopyranos­yloxy)-4-{[(1S)-2,3,4,9-tetra­hy­dro-1H-pyrido[3,4-b]indol-1-yl]meth­yl}-3,4-dihydro-2H-py­ran-5-carboxyl­ate, was determined from its sodium chloride trihydrate, poly[[diaqua­((2S,3R,4S)-3-ethenyl-2-(β-D-gluco­pyranos­yloxy)-4-{[(1S)-2,3,4,9-tetra­hydro-1H-pyrido[3,4-b]in­dol-2-ium-1-yl]meth­yl}-3,4-dihydro-2H-pyran-5-carboxyl­ate)sodium] chloride monohydrate], {[Na(C₂₆H₃₂N₂O₉)(H₂O)₂]Cl·H₂O}_n. The strictosidinic acid molecule participates in inter­molecular hydrogen bonds of the O—H...O and O—H...Cl types. The solid-state conformation was observed as a zwitterion, based on a charged pyridine N atom and a carboxyl­ate group, the latter mediating the packing through coordination with the sodium cation.