Calysolins V–IX, Resin Glycosides from <i>Calystegia soldanella</i> and Their Antiviral Activity toward Herpes

Abstract

Five new resin glycosides having macrolactone structures (jalapins), named calysolins V-IX (1-5), were isolated from the leaves, stems, and roots of Calystegia soldanella ROEM. et SCHULT. (Convolvulaceae). Their structures were determined on the basis of spectroscopic data as well as chemical evidence. The isolated compounds could be classified into two macrolactone types-one having a 22-membered ring (1-4) and the other with a 27-membered ring (5). The sugar moieties of 1-5 were found to exist in partially acylated forms comprising 2S-methylbutyric acid and tiglic acid. Compounds 4 and 5 are the first representatives of the calysolic acid C as the component glycosidic acid. Additionally, the antiviral activity of 1-5, together with calysolins I-IV and soldanelline B, which are previously isolated jalapins from this plant, toward herpes simplex virus type 1 was evaluated. All the compounds showed antiviral activity.Key words resin glycoside; jalapin; Calystegia soldanella; Convolvulaceae; calysolin; anti-herpes activityis widely distributed on the sandy beaches of seas and lakes in temperate regions of the world. The roots of this plant are used for the treatment of arthritis.1) In our previous investigations, we reported the isolation and structural elucidation of four new glycosidic acids, calysolic acids A-D, which were obtained along with the known glycosidic acid, soldanellic acid B, and three organic acids, 2S-methylbutyric, tiglic, and 2S,3S-nilic acids, upon alkaline hydrolysis of the crude resin glycoside fraction of the leaves, stems, and roots of C. soldanella.2) Further, we isolated four genuine resin glycosides named calysolins I-IV, all of which were found to possess characteristic macrolactone structures, as in already known jalapins, 3) along with one known jalapin, soldanelline B. 4) As part of an ongoing study of the resin glycosides from this plant, the present report deals with the isolation and structural elucidation of five new resin glycosides named calysolins V-IX. Additionally, the antiviral activity of calysolins I-IX and soldanelline B toward herpes simplex virus type 1 (HSV-1) 5) is described.The fresh leaves, stems, and roots of C. soldanella were extracted with methanol. The obtained extract was suspended in H 2 O and then extracted successively with ethyl acetate and n-butanol. The ethyl acetate-soluble fraction was subjected to silica gel column chromatography and HPLC on octadecyl silica (ODS) and naphthylethyl group bonded silica to yield five resin glycosides (1-5).Compound 1

Macrolide Core Synthesis of Calysolin IX Using an Intramolecular Glycosylation Approach

“…To prove this hypothesis we present herein such approach for the synthesis of the most complex resin glycosides isolated to date – Calysolin IX ( 2 , Figure ). This new resin glycoside having 27‐membered ring macrolactone structure (jalapins) was isolated from the leaves, stems, and roots of Calystegia soldanella ( Convolvulaceae ) . The sugar moiety of 2 was found to exist in partially acylated forms comprising (2 S )‐methylbutyric acid and tiglic acid.…”

Novel Types of Hypermodified Fluorescent Phyllobilins from Breakdown of Chlorophyll in Senescent Leaves of Grapevine (Vitis vinifera)

“…A range of natural, and semisynthetic non‐pyrrolic organic compounds exhibit the exceptional 1,6‐glycopyranosyl‐bridged macrocyclic bicyclo‐[ n .3.1]‐structure and are the target of considerable interest from biological and pharmaceutical points of view . Indeed, among such 1,6‐glycopyranose‐bridged organic compounds, also classified as ansaglycosides, figure inhibitors of cell growth, as well as compounds with antifungal, antibacterial and antiviral effects . The exceptional bc PBs in grapevine leaves may be surmised to play crucial (however, still elusive) physiological roles, both in plants and in humans.…”

Acylated Glycosidic Acid Methyl Esters Generated from the Convolvulin Fraction of Rhizoma Jalapae Braziliensis by Treatment with Indium(III) Chloride in Methanol

“…The instruments and materials used were as cited in the preceding report 16) unless otherwise specified. ESI-TOF-MS data was collected using a Q-Exactive Plus (Thermo Fisher Scientific K.K., Kanagawa, Japan) mass spectrometer.…”