Isorhamnetin-3-O-glucoside

Isorhamnetin (3'-methyl quercetin) and its glucoside form exhibit anti-inflammatory, antiasthmatic, and bronchospasmolytic properties. Isorhamnetin inhibits 5-lipoxygenase (5-LOX), reducing leukotriene B4 and cysteinyl leukotriene synthesis — a mechanism directly relevant to bronchospasm and pleural inflammation where leukotriene signaling is prominent. It stabilizes mast cells by inhibiting IgE-mediated calcium influx and histamine secretion. Phosphodiesterase IV (PDE4) inhibition elevates intracellular cAMP in bronchial smooth muscle, producing relaxation analogous to theophylline. Additionally, isorhamnetin scavenges reactive oxygen species at inflamed serosal surfaces, reducing oxidative damage to pleural mesothelial cells.