Resin Glycosides from the Leaves and Stems of Ipomoea lacunosa

Abstract

Alkaline hydrolysis of the crude resin glycoside fraction from the leaves and stems of Ipomoea lacunosa L. (Convolvulaceae) yielded organic acid and glycosidic acid fractions. The organic acid fraction included n-decanoic and n-dodecanoic acids. Acidic hydrolysis of the glycosidic acid fraction yielded 3 monosaccharides (d-glucose, d-fucose, and l-rhamnose) and 2 known hydroxyl fatty acids (11S-hydroxytetradecanoic and 11S-hydroxyhexadecanoic acids). Treatment of the glycosidic acid fraction with trimethylsilyldiazomethane (in hexane) afforded 1 new glycosidic acid methyl ester (lacunosinic acid J methyl ester) and 6 known glycosidic acid methyl esters. Eight new resin glycosides (lacunosins V–XII) were isolated from the leaves and stems, along with 2 known resin glycosides. Their structures were determined using spectroscopic and chemical analyses. Three types of resin glycosides were identified: those with 18-membered macrolactone, those with 19-membered macrolactone, and those with non-macrolactone structures. All these compounds contained n-decanoic and n-dodecanoic acids as the organic acid components. Nine of the isolated resin glycosides were tested for cytotoxic activity against HL-60 human promyelocytic leukemia cells. One compound exhibited activity with an IC₅₀ value of 44.5 μM, while 3 compounds demonstrated moderate activity, with inhibition rates ranging from 53.5 to 68.7% at a concentration of 200 μM. In contrast, the remaining 5 compounds showed negligible effects even at 200 μM.