Ten new resin glycosides, ipoalbins I-X, from Ipomoea alba seeds.

Abstract

Ipomoea alba L. (Convolvulaceae) is an annual vine native to tropical America that is cultivated primarily for ornamental purposes. Its seeds are used in traditional medicine as a laxative, and young shoots are consumed as food. In this study, ten new resin glycosides, ipoalbins I (1)-X (10), were isolated from I. alba seeds. The structures of 1-10 were determined based on spectroscopic data. All compounds had intramolecular cyclic ester structures (jalapins). The sugar moieties in 1-10 were partially acylated by organic acids, including isobutyric, (E)-2-methylbut-2-enoic, and 2S-methyl-3S-hydroxybutyric acids. Notably, one of these compounds has a rare jalapin structure characterized by an ester linkage between the carboxyl group of the aglycone moiety and the hydroxyl group of an organic acid attached to the sugar moiety. In contrast, other compounds exhibited typical macrolactone structures. Furthermore, the cytotoxic activity of 1-10 against HL-60 human promyelocytic leukemia cells and their antiviral activity against herpes simplex virus type 1 (HSV-1) were evaluated. All tested compounds, except 3, were comparable to or slightly less cytotoxic than cisplatin, the positive control. In addition, all the compounds showed anti-HSV-1 activity; notably, 5 showed an EC₅₀ value lower than that of acyclovir, the positive control. However, the selectivity indices of these compounds were lower than that of acyclovir.