Andrographolide Attenuates Inflammation by Inhibition of NF-κB Activation through Covalent Modification of Reduced Cysteine 62 of p50

Abstract

NF-κB is a central transcriptional factor and a pleiotropic regulator of many genes involved in immunological responses. During the screening of a plant extract library of traditional Chinese herbal medicines, we found that NF-κB activity was potently inhibited by andrographolide (Andro), an abundant component of the plant Andrographis that has been commonly used as a folk remedy for alleviation of inflammatory disorders in Asia for millennia. Mechanistically, it formed a covalent adduct with reduced cysteine (62) of p50, thus blocking the binding of NF-κB oligonucleotide to nuclear proteins. Andro suppressed the activation of NF-κB in stimulated endothelial cells, which reduced the expression of cell adhesion molecule E-selectin and prevented E-selectin-mediated leukocyte adhesion under flow. It also abrogated the cytokine- and endotoxin-induced peritoneal deposition of neutrophils, attenuated septic shock, and prevented allergic lung inflammation in vivo. Notably, it had no suppressive effect on IκBα degradation, p50 and p65 nuclear translocation, or cell growth rates. Our results thus reveal a unique pharmacological mechanism of Andro’s protective anti-inflammatory actions.

Anti-angiogenic effects of dietary isothiocyanates: Mechanisms of action and implications for human health

“…Interestingly, a number of reactive chemical compounds have been shown to inhibit NF-B activity via direct covalent modification of NF-B signalling pathway components. For example, the DNA binding domains of the p50 and p65 NF-B subunits contain redox-regulated cysteine residues (Cys 62 and Cys 38 , respectively) that have been shown to be covalently modified by andrographolide and picroliv, respectively, thereby preventing DNA binding [50,51]. Also, IKK contains a redox regulated cysteine residue (Cys 179 ) that is essential for activity [52], and is modulated by other agents such as curcumin and butein (3,4,2,4-tetrahydroxychalcone) [53,54].…”

Andrographolide inhibits NF-κB activation and attenuates neointimal hyperplasia in arterial restenosis

“…Leukocytes on the endothelium and within the intima were counted double-blindly under a CX31 microscope (Olympus, Tokyo, Japan) at ×1 000 magnification. The percentage of leukocytes was calculated by dividing the number of counted leukocytes by the total number of cells within the adventitia [9].…”

“…4-Hydro-andrographolide (4H-Andro) was prepared via the palladium on activated carboncatalyzed hydrogenation [9], to serve as the inactive structural analog of Andro as the negative control.…”

“…All incubations were followed by washing three times in TBS over 15 min. Tissue sections were counterstained with hematoxylin and slides were mounted with coverslips [9,16].…”

“…In addition to the long history of using Andro as a remedy for inflammatory disorders, we have recently reported that andrographolide (Andro) covalently conjugates the reduced cysteine 62 of p50, thus blocking NF-κB DNA binding and preventing NF-κB-activated inflammation in the murine models of acute peritonitis, septic shock and allergic lung inflammation [9]. In this study, we sought to examine whether NF-κB activation has a critical role in the pathogenesis of arterial restenosis and whether Andro, by inhibition of NF-κB activation, suppresses neointimal hyperplasia in experimental arterial restenosis.…”