1998/10/01 by Peter Luger, M. Weber, Setsuo Kashino +5 · 2 citations
Biochemistry, Genetics and Molecular Biology · Pharmacology, Toxicology and Pharmaceutics · #Natural product bioactivities and synthesis #Pharmacological Effects of Natural Compounds #Plant biochemistry and biosynthesis
paper · doi:10.1107/s0108768198000081
openalex publication_date 1998/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
Geraniin, C 41 H 28 O 27 .7H 2 O, is the main tannin from Geranium thunbergii Sieb. et Zucc., which is one of the most popular folk medicines and also an official antidiarrheic drug in Japan. Conventional X-ray diffractometer data at 295 K and synchrotron data at 293 and 120 K (at EMBL/DESY Hamburg with a MARRESEARCH imaging plate) were measured. The structure could not be determined with any of the currently distributed direct-methods programs, but was easily solved with DIRDIF using several conformers of the hexahydroxydiphenoyl group as input fragments into a vector-search procedure. A molecular structure was established where a cyclohexenetrione moiety attached to O4 of a central glucose unit was in a hydrated six-membered hemiacetal ring structure, as expected from the NMR study of crystalline geraniin. Owing to the high oligocyclic substitution the glucopyranosyl ring is in the unusual 1 C 4 conformation. Refinement of the low-temperature synchrotron data allowed identification of almost all the H atoms, even within the seven water molecules, so that a rather complex system of approximately 30 different hydrogen bonds can be studied in some detail.