O-Glucoside of natural cleomiscosin-A: An attenuator of pro-inflammatory cytokine production

The study was aimed to improve the hydrophilic property and pro-inflammatory cytokine inhibitory effect of cleomiscosin-A (CA), a naturally occurring coumarinolignan in plants. In view of this, O-, N- and S-glucosides of cleomiscosin-A was designed and docking studies were performed for TNF-alpha protein. All derivatives showed considerable docking scores in the range of -8.433 to -9.401 kcal/mol compared to a standard TNF-alpha inhibitor. The O-glucoside of cleomiscosin-A (CAG) was synthesized by reacting natural cleomiscosin-A (CA) with acetobromo-alpha-D-glucose and pyridine. The formed product was confirmed through APCI-MS and proton NMR analysis. Inhibition effect of CA and CAG against TNF-alpha, IL-6 and IL-1 beta secretions was determined on lipopolysaccharide-induced RAW 264.7 cells using ELISA kits. CAG was potentially inhibitory against IL-6 and IL-1 beta secretions exhibiting IC50 values of 7.94 and 45.76 mu M, respectively. Also, in-vivo (mouse endotoxemia model) performance of CAG (oral administration) in inhibiting TNF-alpha expression was significant (52.03% and 29.23% at 50 and 25 mg/kg body weight, respectively), demonstrating five-fold increase in activity compared to CA. In addition, CAG reduced LPS-induced NO levels and was found to be weakly cytotoxic (IC50 > 150 mu M). This is the first report of semi-synthesis and pro-inflammatory cytokine inhibition effect of a coumarinolignan glucoside.