Eight new resin glycosides, calyhedins XXIV–XXXI, from the rhizomes of Calystegia hederacea

Abstract

Eight new resin glycosides, named calyhedins XXIV (1)–XXXI (8), were isolated from the rhizomes of Calystegia hederacea Wall. (Convolvulaceae), along with six known calyhedins: calyhedins II (9), III (10), IV (11), V (12), VIII (13), and XII (14). Their structures were determined from the spectroscopic data. Compounds 1–7 were hexa- or hepta-glycosides with macrolactone structures (jalapins), and their sugar moieties were partially acylated by five organic acids, including 2S-methylbutyric, (E)-2-methylbut-2-enoic, and 2R-methyl-3R-hydroxybutyric acids. Compounds 1–7 were macrolactones with 22- (1, 7), 23- (2), 27- (3–5), or 28- (6) membered rings. Compound 8 was identified as an acylated glycosidic acid methyl ester, corresponding to the compound in which the lactone ring of 1 was cleaved and subsequently methylated. In addition, the cytotoxic activities of 1–8, 11, 12, and 14 against HL-60 human promyelocytic leukemia cells and the antiviral activities of 1–14 and 11 previously isolated calyhedins against herpes simplex virus type 1 (HSV-1) were evaluated. Except for 1, the other ten tested compounds exhibited cytotoxicity against HL-60 cells, with the IC₅₀ values of 3, 4, 6, 7, 11, and 12 being closer to or rather lower than that of the positive control cisplatin. Additionally, all tested compounds demonstrated anti-HSV-1 activity, with seven compounds, i.e., 3, 6, 9, 10, 22, 23, and 24, having EC₅₀ values lower than or comparable to that of the positive control acyclovir.