Properties Characterization and Identification of Saponarin and Ribosnarin (apigenin-6-C-ribosyl -7-O-glucoside) Extracted Abundantly from the White-Color Moth Orchid Flowers (Phalaenopsis Hybrids)

In addition to ornamental purposes of the moth orchid flowers (Phalaelopsis hybrids), flower-bearing C-glycosylflavonoids and properties characterization deserve investigations.In this study, the petals and sepals of 9 different-colored moth orchid flowers were extracted with 60% methanol for HPLC analysis.Two noticed peaks were detected and varied with cultivar.Addressed on the flower components of white-color Phalaenopsis (Sogo Yukidian), the peak areas from lips were lower than those of petals or sepals.When the components were removed either from fresh or wilted flowers and dried at 60 o C prior to pulverization, extraction and HPLC analysis, both peak areas in each components varied limitedly.After purification of the flower extracts by medium-pressure liquid chromatography and semi-HPLC fractionation, and elucidation by NMR and ESI-MS analyses, apigenin-6-C-glucosyl-(saponarin) and -6-C-ribosyl-7-O-glucopyranoside (ribosnarin) were identified.Both are C-glycosylflavonids and used as authentic references in HPLC quantification of saponarin and ribosnarin in 11 collected white-color moth flowers, contents were 1.50.5 and 5.61.1% (dry basis).In ABTS scavenging and tyrosinase activities determination, both compounds exhibited ABTS scavenging activities with dose dependency and no obvious tyrosinase inhibitory activity in the test concentrations from 0 to 100 M.In substrate availability determination, both compounds were equally mixed with nitrophenyl--D-glucopyranoside (pNPG) or each one was alone mixed with pNPG and subjected to incubation with almond -glucosidase at 60 o C for 10 min, only pNPG was hydrolyzed, indicating that both are not -glucosidase hydrolysable.As generalized, the assessed activities were not differentiated by 6-C-gluco-and 6-C-ribo-molecularly different moiety.Since both exist abundantly in either fresh or wilted flowers, it is worthy to use the flowers as a potent source of C-glycosylflavonoids to explore their potencies for the known and unknown promising products development.