Magnolol Inhibits Leukotriene Synthesis in Rat Basophilic Leukemia-2H3 Cells

Abstract

We have observed an inhibitory action of magnolol on the production of leukotriene (LT) C4 and LTB4, important lipid mediators in allergy and inflammation. IgE- and A23187-stimulated production of LTC4 and LTB4 was measured by radio-immunoassay (RIA) in the absence or presence of various concentrations of magnolol in intact rat basophilic leukemia (RBL)-2H3 cells. Magnolol dose-dependently inhibited synthesis of LTC4 and LTB4. Magnolol inhibited the IgE-mediated increase of intracellular calcium ion concentration, resulting in the inhibition of cytosolic phospholipase A2 (cPLA2) and possibly 5-lipoxygenase (5-LO), both calcium ion-dependent enzymes. In cell-free studies magnolol inhibited LTC4 synthase activity. LTA4 hydrolase activity was only inhibited at the higher concentration (2.5 x 10(-5)M). These results indicate that magnolol inhibits production of LTs by inhibiting PLA2, 5-LO, LTC4 synthase and LTA4 hydrolase which are essential for LT-synthesis. Magnolol may have anti-allergic effect by blocking LT-synthesis.

Magnolol and Honokiol: Inhibitors against Mouse Passive Cutaneous Anaphylaxis Reaction and Scratching Behaviors

“…These constituents also repressed the activation of NF-kB, which is the transcription factor of proinflammatory cytokines. In the previous study, Hamasaki et al 9) reported that magnolol inhibits leukotriene synthesis in RBL-2H3 cells. Lee et al 15) also reported that magnolol and honokiol exhibit anti-inflammatory effect through the inhibition of NF-kB activation.…”

Anti-diarrhea and anti-oxidant properties of Magnolol

“…Wang et al observed that magnolol inhibited mouse hindpaw oedema induced by carrageenan and polymyxin B, and reversed passive Arthus reaction, and it was proposed that the antiinflammatory and analgesic action of magnolol is dependent on reducing the level of eicosanoid mediators [15]. An inhibitory action of magnolol on the production of leukotriene (LT) C4 and LTB4, important lipid mediators in allergy and inflammation was observed in basophilic leukemia (RBL)-2H3 cells of intact rat [16]. It was also found that magnolol inhibits TNF-α-induced nuclear translocation of NF-κB p65 and thereby suppresses expression of VCAM-1, resulting in reduced adhesion of leukocytes [17].…”

Inhibitory effect of magnolol on tumour metastasis in mice

“…Therefore, it was considered that the antimetastatic effect of magnolol in vivo may be related to other mechanisms. Magnolol has been shown to have many biological activities such as an antiplatelet aggregation (Teng et al, 1988), hydroxyl radical scavenging (Fujita and Taira, 1994), Ca 2+ -channel blocking (Teng et al, 1990) and antiinflammation action (Hamasaki et al, 1999;Wang et al, 1995), and some of these findings play a role in the inhibition of metastasis. Tsuruo et al demonstrated that verapamil, a calcium channel antagonist, inhibits B16 melanoma liver metastasis model.…”