The First Cyclic Phenolic Acid Glycoside Dimer and New .ALPHA.-Tetralone and Triterpenoid Glucosides from Gentiana loureirii

Abstract

NotesGentiana loureirii GRISEB. (Gentianaceae), a perennial herb widely distributed in South China, 1) is a Chinese folk medicine used for the treatment of various disorders related to inflammation and infections.2) We previously reported the isolation of iridoids, flavonoids, and oleanolic acid as its predominant constituents.3) In further investigation on the minor constituents of this plant, a novel phenolic acid glycoside, cyclic 4-O-b-D-glucopyranosylcaffeic acid dimer (1), a new a-tetralone, 4-hydroxy-6-methyl-a-tetralone 4-O-b-D-glucopyranoside (2), and a new triterpenoid saponin, 3b,30-dihydroxy-12-ursen-28-oic acid 28-O-b-D-glucopyranosyl ester (3), were isolated along with five known compounds, rotundic acid, tormentic acid, 2a,3a,23-trihydroxy-12,20(30)-ursadien-28-oic acid, 1a,2a,3a,24-tetrahydroxy-12-oleanen-28-oic acid, and 1-O-feruloylglucose. Herein, we report the isolation and structure elucidation of these new compounds. Results and DiscussionThe EtOH extract of the whole plants of Gentiana loureirii was fractionated with petroleum ether, CHCl 3 , EtOAc, and nBuOH. Separation by a combination of silica gel, octadecyl silica (ODS) column chromatography, and preparative HPLC afforded three new compounds, 1-3, and five known compounds, rotundic acid, 4) tormentic acid, 5) 2a,3a,23-trihydroxy-12,20(30)-ursadien-28-oic acid, 6) 1a,2a,3a,24-tetrahydroxy-12-oleanen-28-oic acid, 7) and 1-O-feruloylglucose.8) The structures of the known compounds were determined by interpretation of their spectroscopic data as well as by comparison with reported data. and the carbonyl carbon at d C 166.7 (C-9) were observed, indicating attachments of the glucose moiety to C-4 of the caffeic acid residue via a glycosidic linkage and the caffeoyl group to C-6Ј of the glucose moiety via an ester linkage. These findings in the NMR spectra in combination with the molecular formula suggested a symmetrical structure composed of two 4-O-b-D-glucopyranosylcaffeic acid units which were connected with each other by ester linkages between each C-6Ј in one unit and the carbonyl carbon (C-9) in the other unit to form a 26-membered macrolide ring. The large coupling constant (Jϭ10.3 Hz) observed between H-5Ј and H-6Јb in the 1 H-NMR spectrum was in accord with the energy-minimized structure (Fig. 1) obtained by MOPAC in CS Chem3D, which showed a dihedral angle of near 180°between H-5Ј and H-6Јb bonds. Therefore compound 1, tentatively named cyclic 4-O-b-Dglucopyranosylcaffeic acid dimer, was established to have the

Triterpenoids

“…270 2,3-Secofriedel-1-en-3-oic acid 462, 3b-hydroxyfriedelan-23oic acid 463 and 1b-hydroxyfriedelan-3-one 464 have been isolated from Garcia parviflora. 287 Ursane saponins with known genins include 23-O-acetylmadecassoside from Centella asiatica, 206 and saponins from Actinidia chinensis, 55 Centella erecta, 288 Commiphora gladulosa, 289 Gentiana loureirii 290 and Schefflera actinophylla. An unusual oxetane ring is present in 3b,23-epoxyfriedelan-28-oic acid 465, from Calophyllum inophyllum.…”

“…286 Reticulataursenoside is an ursane saponin, from fruit peel of Citrus reticulata, with the new genin 508 34 and ilexpublesnins A and B, from Ilex pubescens, have the new genin 509. 287 Ursane saponins with known genins include 23-O-acetylmadecassoside from Centella asiatica, 206 and saponins from Actinidia chinensis, 55 Centella erecta, 288 Commiphora gladulosa, 289 Gentiana loureirii 290 and Schefflera actinophylla. 170 Taraxast-20-ene-3b,12b,16b-triol 510 and the related ester 511 have been found in fruit of Cicuta virosa var.…”

Phytochemistry and Pharmacological Activities of the Genus Gentiana (Gentianaceae)

“…Immunomodulatory Activity. TheBuOH fraction of G. olivieri extracts showed the maximum effect in mice by acting via the models of immunomodulation consistingo f cell-mediated immune response (in vivo carbon clearance Roots,r hizomes [87] 2016 Verlag HelveticaChimica Acta AG,Z ürich www.cb.wiley.com [104] 2016 Verlag HelveticaChimica Acta AG,Z ürich www.cb.wiley.com [127] 2016 Verlag HelveticaChimica Acta AG,Z ürich www.cb.wiley.com [136] or phagocytosis and delayed-type hypersensitivity)a nd humoral antibody response( hemoglutination antibody titres)a tadose of 200 mg kg À1 [168]. Nikolaeva et al [185]s howedt he immunostimulant activity of 20 as determined by formation of cytolytic Tkiller cells in mixed lymphocyte cultures obtained from allegoric mice and from the peripheral blood of patients with rectalc ancer.…”