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-β-D-glucosyl-(1≙6)-β-D-glucopyranoside] and scutellarein-6- O-α-L-rhamnopyranoside-8-C-β-D-glucopyranoside). The chemical structure of the isolated compounds was elucidated on the basis of chemical and spectral data.

Antibacterial activity of Hibiscus rosa-sinensis L. red flower against antibiotic-resistant strains of Helicobacter pylori and identification of the flower constituents

“…Nine compounds from the active EtOAc fraction were obtained and identified based on melting points and spectral data such as ESI-HRMS, 1 H-NMR, 13 C-NMR, 2D 1 H- 13 C HSQC, and 2D 1 H- 13 C HMBC. These nine compounds isolated and identified in this study can be found in several plant species, and three compounds (taraxerol acetate ( 20 ), p-hydroxybenzoic acid ( 21 ), and quercetin ( 21 )) were previously identified in H. rosa-sinensis . The remaining six compounds are being reported here for the first time in H. rosa-sinensis red flower.…”