Structures of anagallosaponins I-V and their companion substances from Anagallis arvensis L.

From the herb of Anagallis arvensis L., we have isolated five novel oleanane glycosides, anagallosaponins I-V and the artifact, methyl anagallosaponin I, besides anagallosides A, B, C, and desglucoanagallosides A and B. The structures of isolates were identified by the use of 2D-NMR techniques (1H-1H correlation spectroscopy (COSY), 1H-detected heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple quantum coherence (HMBC), rotating frame Overhauser enhancement spectroscopy (ROESY), total correlation spectroscopy (TOCSY). The structures of anagallosaponins I and II were characterized as anagallogenin A. 3-O-(beta-D-glucopyranosyl (1-->4)-[beta-D-xylopyranosyl (1-->2)-] beta-D-glucopyranosyl (1-->4)- [beta-D-glucopyranosyl (1-->2)]-alpha-L-arabinopyranoside) and anagallogein A 22-acetate 3-O-(beta-D-xylopyranosyl (1-->2)-O-beta-D- glucopyranosyl (1-->4)-[beta-D-glucopyranosyl (1-->2)]-alpha-L-arabinopyranoside), respectively. The structures of anagallosaponins III, IV and V were characterized as priverogenin B 22-acetate 3-O-beta-D-xylopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-alpha-L-arabinopyranoside, 3-O-(beta-D-xylopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-[beta-D-glucopyranosyl (1-->2)]-alpha-L-arabinopyranoside), 3-O-(beta-D-glucopyranosyl (1-->4)-[beta-D-xylopyranosyl (1-->2)]-beta-D-glucopyranosyl (1-->4)-alpha-L-arabinopyranoside), respectively. Methyl anagallosaponin I, the methylacetal of anagallosaponin I might be derived from anagallosaponin I during the isolation procedure.