Glycosides in African Dietary Leaves, Hibiscus sabdariffa

Seven glycosides were isolated from African dietary leaves, Hibiscus sabdariffa. Their structures were determined based on UV, MS, 1H-NMR and 13C-NMR spectroscopic data as kaempferol 3-O-rutinoside [1], kaempferol 3-O-glucopyranoside [2], quercetin 3-O-rutinoside [3], citrusin C [4], 2,3-dihydro-2-(4′-hydroxy-3′-methoxyphenyl)-3-β-D-glucopyranosylmethyl-7-hydroxy-5-benzofuranpropanol [5], corchoionoside C [6], and trans-carveol 6-O-β-glucopyranoside [7]. In the bioassay with superoxide scavenging activity, 1-BuOH extract, acidic components, neutral components, compound 3 and aglycone of 3 (3a) showed strong activity. And in the tyrosinase inhibitory activity, aglycone of 1 (1a) and aglycone of 3 (3a) showed good inhibition. As a result, we considered that Hibiscus sabdariffa may be related to the longevity, and their 1-BuOH extract was found promising as a cosmetic agent. The presence of compounds 4-7 in the leaves of Hibiscus sabdariffa is reported here for the first time.