Animal experiment:

C57BL/6 mice receive each morphinan (dextromethorphan, dextrorphan or dimemorfan) compound (20 or 40 mg/kg, i.p. per day) or PCP (2.5 or 5 mg/kg, i.p. per day) once a day for 7 days. Ten minutes after the last treatment with each drug, locomotor activity is measured for 30 min using an automated video-tracking system. Eight test boxes (40 cm×40 cm×30 cm high) are operated simultaneously by an IBM computer. Animals are studied individually during locomotion in each test box, where they are adapted for 10 min before starting the experiment. A printout for each session showed the pattern of the ambulatory movements of the test box. The distance traveled in cm by the animals in horizontal locomotor activity is analyzed. Data are collected and analyzed between 09:00 and 17:00 h.

Dimemorfan phosphate is a sigma 1 receptor agonist, used as a potent antitussive.

Dimemorfan (5-20 μM) inhibits both fMLP- and PMA-induced ROS production in a concentration-dependent manner and is relatively more potent in inhibiting fMLP-induced ROS production with an IC50 value of 7.0 μM. Dimemorfan (10-50 μM) does not display significant activity in scavenging free radicals by xanthine/xanthine oxidase system. Dimemorfan significantly suppressed Mac-1 upregulation both in PMA- and fMLP-activated groups. Dimemorfan (10-20 μM) significantly suppresses LPS-induced ROS and NO production, and suppresses LPS-induced iNOS protein expression, and both the percentage of the positively stained population and the MCF intensities of MCP-1 and TNF-α in BV2 cytosol. Dimemorfan (20 μM) significantly blocks the degradation of cytosolic Iκ-Bα and nuclear translocation of NF-κB p65, as well as the transcriptional activity of NF-κB[2].

Dimemorfan (6.25 or 12.5 mg/kg, s.c.) significantly attenuates the BAY k-8644-induced convulsive behaviors, in a dose-related manner (6.25 mg/kg dimemorfan+BAY k-8644 or 12.5 mg/kg dimemorfan+BAY k-8644 versus Saline+BAY k-8644, P<0.05 and P<0.01, respectively). Dimemorfan significantly attenuates BAY k-8644-induced increases in the c-fos and c-jun protein expression in a dose-dependent manner. Dimemorfan does not significantly affect locomotor activity or produce significant circling behavior in any locomotor pattern in mice[1]. Dimemorfan (1 and 5 mg/kg, i.p.) surpresses the incarease of the plasma levels of TNF-α in mice. The infiltration of neutrophils into lung and liver as well as the production of oxidative stress (EB staining) in these tissues induced by LPS is markedly inhibited by the treatment with dimemorfan[2].

[1]. Shin EJ, et al. Dimemorfan prevents seizures induced by the L-type calcium channel activator BAY k-8644 in mice. Behav Brain Res. 2004 May 5;151(1-2):267-76. [2]. Wang YH, et al. Anti-inflammatory effects of dimemorfan on inflammatory cells and LPS-induced endotoxin shock in mice. Br J Pharmacol. 2008 Jul;154(6):1327-38.