Loureirin B, a flavonoid extracted from Dracaena cochinchinensis, is an inhibitor of plasminogen activator inhibitor-1 (PAI-1), with an IC50 of 26.10 μM. Loureirin B (1, 0.1, and 0.01 µM) increases insulin secretion in Ins-1 cells. Loureirin B (0.01 µM) almost causes no toxicity on cells. Loureirin B improves the level of expressions of MafA and Pdx-1 and ATP level. Loureirin B inhibits the KATP current but increases the [Ca2+]i level in Ins-1 cells[1]. Loureirin B directly inhibited STIM1/Orai1 channel in a dose-dependent manner. Loureirin B inhibits Ca2+ influx and IL-2 secretion in Jurkat T cells by inhibiting both KV1.3 and STIM1/Orai1 channels[2]. Loureirin B inhibits the expression of Col1 and FN, as well as the TGF-β1-mediated up regulation of p-JNK. Loureirin B also inhibits the up regulation of p-ERK that is induced by TGF-β1. Moreover, Loureirin B inhibits the contraction of TGF-β1-stimulated fibroblasts through the down regulation of p-ERK and p-JNK. However, Loureirin B does not suppress the up regulation of p-p38 that is induced by TGF-β1[3]. LrB (Loureirin B) represses osteoclastogenesis, bone resorption, F-actin belts formation, osteoclast specific gene expressions, ROS activity and calcium oscillations through preventing NFATc1 translocation and expression as well as affecting MAPK-NFAT signaling pathways in vitro. In vivo, LrB prevents OVX-induced osteoporosis and preserves bone volume by repressing osteoclast activity and function[4].
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