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

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.