title: Polyphenolic compounds from flowers of Hibiscus rosa-sinensis Linn. and their inhibitory effect on alkaline phosphatase enzyme activity in vitro.
abstract: Graded concentrations (0.1-100 mg/mL reaction mixture) of the methanolic extract of the flowers of Hibiscus rosa-sinensis Linn., its water-soluble fraction as well as compounds isolated from this fraction were tested for their inhibitory effect on alkaline phosphatase enzyme activity in vitro. Both the methanolic extract and its water-soluble fraction showed significant inhibitory effects on the enzyme activity in vitro. On screening the activity of the compounds isolated from the water-soluble fraction, its high inhibitory activity was attributed to the presence of quercetin-7-O-galactoside which showed a high potent inhibition of the enzyme activity reaching 100% at 100 mg/mL reaction mixture. Phytochemical investigations of the water-soluble fraction were also carried out and afforded ten polyphenolic compounds including two new natural compounds, namely kaempferol-7-O-[6'''-O-p-hydroxybenzoyl-beta-D-glucosyl-(1-->6)-beta-D-glucopyranoside] and scutellarein-6-O-alpha-L-rhamnopyranoside-8-C-beta-D-glucopyranoside). The chemical structure of the isolated compounds was elucidated on the basis of chemical and spectral data.
authors.affiliation: Chemistry of Tanning Materials, National Research Centre, Dokki, Cairo, Egypt. joslineysalib@gmail.com
authors.forename: Josline Y
authors.initials: JY
authors.lastname: Salib
authors.forename: Enas N
authors.initials: EN
authors.lastname: Daniel
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Hifnawy
authors.forename: Shadia M
authors.initials: SM
authors.lastname: Azzam
authors.forename: Iman B
authors.initials: IB
authors.lastname: Shaheed
authors.forename: Sally M
authors.initials: SM
authors.lastname: Abdel-Latif
mesh_terms: D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D035264:Flowers / Q000737:chemistry*; D031584:Hibiscus / Q000737:chemistry*; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D010936:Plant Extracts / Q000494:pharmacology*; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D004791:Enzyme Inhibitors; D010936:Plant Extracts; D059808:Polyphenols; D000469:Alkaline Phosphatase