In vitro and in vivo anti-inflammatory, antibacterial and pharmacokinetic properties of baicalein

Abstract

Baicalein is a bioactive flavone originally isolated from the roots of Scutellaria baicalensis, Scutellariala teriflora and Oroxylum indicum. The in vitro and in vivo anti-inflammatory and antibacterial properties of baicalein and pharmacokinetics after its single intramuscular administration were studied in Wistar rats. The in vitro anti-inflammatory activity of baicalein (10, 50 and 100 µM) was tested for its ability to inhibit the COX-2 enzyme by measuring PGE2 levels and determination of nitric oxide (NO) production in lipopolysaccharide (LPS) treated RAW 264.7 macrophage cells, in which baicalein was found to have significant inhibition of NO and PGE2 production in RAW 264.7 macrophage cells as compared with the LPS control group. The in vivo anti-inflammatory activity of baicalein (200 mg/kg) was assessed using the carrageenan-induced rat paw oedema model, following intramuscular injection. A significant percentage of inhibition of oedema volume was observed when compared with the carrageenan control group. In vitro and in vivo antibacterial activities of baicalein were determined by the micro broth dilution technique and neutropenic rat thigh infection model, wherein baicalein did not show any antibacterial property. Concentrations of baicalein were determined in rat plasma by high performance liquid chromatography (HPLC) after a single intramuscular administration at a dose of 200 mg/kg body weight, in which the mean peak plasma drug concentration (Cmax) of 0.77 ± 0.02 μg/mL was achieved at 0.08 h. The mean elimination half-life (t½β), the apparent volume of distribution (Vd(area)), total body clearance (Cl(B)) and mean residence time (MRT) were observed as 0.63 ± 0.06 h, 601.03 ± 28.18 L/kg, 677.39 ± 35.36 L/h/kg and 0.76 ± 0.06 h, respectively. Conclusively, in the present study, baicalein did not show in vitro or in vivo antibacterial property, but proved to have good anti-inflammatory activity. The available anti-inflammatory drugs have proved to have side effects in veterinary and human therapeutics. In this situation, baicalein may become an effective alternative to non-steroidal anti-inflammatory drugs and should also be studied in target animal species. Further research should be carried out to improve the solubility and bioavailability of baicalein through injectable routes.