Effect of Honghua (Flos Carthami) on nitric oxide production in RAW 264.7 cells and α-glucosidase activity

OBJECTIVE： To study the effects of extracts from Honghua （Flos Carthaml~ on lipopolysaccharide in- duced nitric oxide （NO） production in RAW 264.7 cells and the influence of the extracts on yeast a-glucosidase activity. The total flavonoid content of the extracts was also determined. METHODS： Cytotoxicity of the extracts to RAW 264.7 cells was evaluated by the ATPliteTM method. Inhibitory effects of the extracts on NO production were evaluated by Griess assay. Curcumin was used as a positive control. Screening of extracts for po- tential a-glucosidase inhibitors was done by a fiuo- rometric assay. The assay was based on the hydroly- sis of 4-methylumbelliferyl-a-D-glucopyranoside toform the fluorescent product, 4-methylumbellifer- one. Acarbose was used as a positive control. The total t3avonoid content was tested using kaempfer- ol as the standard. RESULTS： There were significant inhibitory effects on NO production when the extracts were 25-100 μg/ mL （P〈0.05） and curcumin was 2-4 μg/mL （P〈 0.001）. The extracts showed an inhibitory effect on a-glucosidase activity at the concentrations of 15.6-125 μg/mL with a half maximal （50%）inhibito- ry concentration （ICs0） of （32.8± 5.7） μg/mL, com- pared with the ICs0 of acarbose at （1.8±0.4） μg/mL. There was a significant difference between the two IC50 values （P〈0.001）. The total content of flavo- noids per gram of dried herb was 1.14 mg. CONCLUSION： Honghua （Flos Carthami） showed in- hibitory effects on NO production in activated RAW 264.7 macrophage cells and an inhibitory effect on yeast a-glucosidase. There might be a relationship between these pharmacological effects and its fla- vonoid content.