Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated from Hibiscus sabdariffa (Malvaceae)

The biologically active title compounds have been isolated from Hibiscus sabdariffa plants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2S,3R)-3-hy­droxy-5-oxo-2,3,4,5-tetra­hydro­furan-2,3-di­carb­oxy­lic acid dimethyl sulfoxide monosolvate], C(6)H(6)O(7)·C(2)H(6)OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2S,3R)-3-hy­droxy-5-oxo-2,3,4,5-tetra­hydro­furan-2,3-di­carboxyl­ate], C(8)H(10)O(7), (II). Compound (I) forms a layered structure with alternating layers of lactone and solvent mol­ecules, that include a two-dimensional hydrogen-bonding construct. Compound (II) has two crystallographically independent and conformationally similar mol­ecules per asymmetric unit and forms a one-dimensional hydrogen-bonding construct. The known absolute configuration for both compounds has been confirmed.