Four new acylated glycosidic acid methyl esters and a new glycosidic acid from Ipomoea lacunosa seeds

Abstract

Resin glycosides, characteristic of plants of the Convolvulaceae family, are well-known purgative constituents found in traditional medicinal crude drugs, such as Rhizoma Jalapae, Rhizoma Jalapae Braziliensis, Orizaba Jalapa Tuber, and Pharbitidis Semen. The isolated compounds exhibited a wide range of biological activities, including antibacterial, ionophoric, anti-inflammatory, antiviral, and multidrug-resistance-modulating properties, as well as cytotoxicity against cancer cells. Ipomoea lacunosa L. (Convolvulaceae) is an herbaceous vine native to the United States. Four new acylated glycosidic acid methyl esters (1–4) and one new glycosidic acid (5) were isolated from the methanol extract of the plant seed. The structures of 1–5 were elucidated using spectroscopic data in conjunction with our previous studies on the components of the crude resin glycoside fraction from I. lacunosa seeds. Compounds 1 and 2 were identified as heptaglycosides, 3 as an octaglycoside, and 4 as a nonaglycoside, all sharing methyl 3S,11S-dihydroxytetradecanoate as a common aglycone. The saccharide moieties were partially acylated by glycosidic acid, 7S-hydroxydecanoic acid 7-O-β-d-quinovopyranoside, and organic acids, including (E)-2-methylbut-2-enoic, 2S-methylbutyric, and 2R-methyl-3R-hydroxybutyric acids. Compound 5 was identified as a triglycoside with a new aglycone, 4,11-dihydroxyhexadecanoic acid, which is the first glycosidic acid with a hydroxyl group at C-4 of the aglycone moiety.

Graphical abstract