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

Abstract

ObjectiveTo study the effects of extracts from Honghua (Flos Carthami) on lipopolysaccharide induced nitric oxide (NO) production in RAW 264.7 cells and the influence of the extracts on yeast α-glucosidase activity. The total flavonoid content of the extracts was also determined. MethodsCytotoxicity of the extracts to RAW 264.7 cells was evaluated by the ATPlite™ 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 potential α-glucosidase inhibitors was done by a fluorometric assay. The assay was based on the hydrolysis of 4-methylumbelliferyl-a-D-glucopyranoside to form the fluorescent product, 4-methylumbellifer-one. Acarbose was used as a positive control. The total flavonoid content was tested using kaempferol as the standard. ResultsThere 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 α-glucosidase activity at the concentrations of 15.6-125 μg/mL with a half maximal (50%) inhibitory concentration (IC50) of (32.8 ± 5.7) μg/mL, compared with the IC50 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 flavonoids per gram of dried herb was 1.14 mg. ConclusionHonghua (Flos Carthami) showed inhibitory effects on NO production in activated RAW 264.7 macrophage cells and an inhibitory effect on yeast α-glucosidase. There might be a relationship between these pharmacological effects and its flavonoid content.