The pharmaceutical applications of total flavonoids extract from Isatis tinctoria L. leaves

Abstract

Isatis tinctoria L. leaves (Folium isatidis), as dried leave of the isatis indigotica in the cruciferous family, has a variety of pharmacological effects, including regulation of immune function, anti-inflammatory, bacteriostasis, antipyretic effect. In this study, total flavonoids extract from Folium isatidis was systematically studied about extractive process, main components, antibacterial, antioxidant and anti-inflammatory activities. The total flavonoids extract yield was (7.65±0.07)% under the optimal extraction parameters of ethanol concentration 54.37%, ratio of solvent volume to material weight 40:1 ml/g, and ultrasonic extraction time 20 min. Nineteen chemical components were inferred and identified by UPLC-QTOF-MS method. Although the extract showed mild antibacterial and antioxidant effects with MIC values 31.25, 62.5, 125 and 125 mg/ml against Streptococcus, Salmonella, Staphylococcus aureus and Escherichia coli, and IC50 DPPH 12.64 µg/ml, IC50 ABTS 16.72 µg/ml and FRAP value at 0.11 mmol Fe2+/100 µg/ml compared with the positive control butylated hydroxytoluene with IC50 DPPH 8.13 µg/ml, IC50 ABTS 2.22 µg/ml and FRAP value at 0.16 mmol Fe2+/100 µg/ml. It exhibited better anti-inflammatory effects in LPS induced RAW 264.7 cell (50, 100 and 200 µg/ml of TFE) and ALI mice (100, 250, or 500 mg/kg•b•w of TFE), which was demonstrated by reducing cell phagocytic activity, decreasing the content of pro-inflammatory cytokine and inflammatory mediator, and improving lung tissue injury. Furthermore, the mechanism of anti-inflammatory action was further revealed to be related to the regulation of TLR4-TRIF-NF-κB signaling pathway. These studies revealed that total flavonoids extract could be used as a natural and green candidate for anti-inflammatory drugs and enrich the variety of clinical anti-inflammatory drugs.