Isofraxidin attenuates IL-1β-induced inflammatory response in human nucleus pulposus cells

Inflammation has been demonstrated to be the key factor for intervertebral disc degeneration (IVD), which remains a major public health problem. Isofraxidin is a coumarin compound that possesses strong anti-inflammatory activity. However, the role of isofraxidin in IVD remains unclear. The aim of this study was to evaluate the effects of isofraxidin on inflammatory response in human nucleus pulposus cells (NPCs) exposed to interleukin-1β (IL-1β). The results proved that isofraxidin attenuated the IL-1β-induced significant increases in inflammatory mediators and cytokines including nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), and IL-6. Besides, isofraxidin also inhibited the induction effect of IL-1β on matrix metalloproteinases (MMP)-3 and MMP-13. Moreover, the NF-κB activation caused by IL-1β was significantly inhibited by isofraxidin treatment. These findings suggested that isofraxidin alleviates IL-1β-induced inflammation in NPCs. Our work provided an idea that isofraxidin might act as a novel preventive role in IVD.     

Binding of isofraxidin to bovine serum albumin

The binding of isofraxidin to bovine serum albumin (BSA) was studied under physiological conditions with BSA concentration of 1.5 x 10(-6) mol x L(-1) and drug concentration in the range of 1.67 x 10(-6) mol x L(-1) to 2.0 x 10(-5) mol x L(-1). Fluorescence quenching spectra in combination with uv absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and CD spectroscopy was used to determine the drug-binding mode, binding constant, and the protein structure changes in the presence of isofraxidin in aqueous solution. The linearity of Scatchard plot indicates that isofraxidin binds to a single class of binding sites on BSA and the values given for the binding constants agree very closely with those obtained by the modified Stern-Volmer equation. The thermodynamic parameters, enthalpy change (DeltaH) and entropy change (DeltaS), were calculated to be -17.63 kJ x mol(-1) and 51.38 J x mol(-1) x K(-1) according to the van't Hoff equation, which indicated that hydrophobic interaction played a main role in the binding of isofraxidin to BSA.     

高效液相色谱法测定刺五加超临界提取物中异嗪皮啶的含量

用高效液相色谱法在线检测刺五加超临界提取物中异嗪皮啶的含量, 采用ODS 色谱柱, 检测波长为345 nm, 流动相为乙腈/超纯水(v/v)=2/8, 异嗪皮啶加样回收率100.8%, RSD 为2.0%, 该方法简便, 结果准确可靠。