The effect of dextromethorphan use in Parkinson's disease: A 6-hydroxydopamine rat model and population-based study.

This study investigated the effect of dextromethorphan (DXM) against Parkinson's disease (PD) in rats and explored the association between DXM dose and PD risk in elderly patients 65 years and older using a population-based database. The PD rat model (Sprague Dawley rats) was induced by injecting 6-hydroxydopamine (6-OHDA) into the unilateral medial forebrain bundle of the rat brain. DXM (20 mg/kg) was administered intraperitoneally twice daily from 7 days before the appearance of a 6-OHDA lesion to 28 days after the lesion appeared. The availability of dopamine transporter (DAT) and serotonin transporter (SERT) in the striatum of the rat brain was measured using positron emission tomography. The apomorphine-induced rotation test was performed to study the hypersensitivity of the brain regions with lesions. This animal study demonstrated that DXM significantly attenuated 6-OHDA-induced DAT and SERT loss, correlating to rotational behaviors. The population-based human study analyzed the data from the Taiwan Longitudinal Health Insurance Database 2005 between January 2005 and December 2013 and then used the DXM dose-response curve to investigate the trend of its protective effect against PD. In the human study, low cumulative doses of DXM may potentially achieve a protective effect for PD; however, high cumulative doses seem to be a risk for PD.

Evaluation of brain SERT with 4-[18F]-ADAM/micro-PET and hearing protective effects of dextromethorphan in hearing loss rat model.

This study investigated the protective effects of dextromethorphan (DXM) on noise-induced hearing loss (NIHL) in rats. This study aimed to improve the auditory threshold and to understand the protective effects of DXM against N-methyl-d-aspartate (NMDA)-induced neurite degeneration of serotonergic neurons. The animals were exposed to 8-kHz narrowband noise at a 118-dB sound pressure level for 3.5 h. The hearing thresholds were determined by measuring the auditory brainstem response to click stimuli. Serotonin transporter (SERT) expression was determined through micro-positron emission tomography (PET) using N,N-dimethyl-2-(2-amino-4-18F-fluorophenylthio)benzylamine (4-[18F]-ADAM). We also investigated the effects of DXM on NMDA-induced morphological changes in the primary cultures of rat serotonergic neurons. NIHL significantly improved after prophylactic treatment with DXM (p < .05). SERT density in DXM-treated rats was significantly higher than that in non-DXM-treated rats. Because prophylactic medication restored the NMDA-inhibited neurite length of serotonergic neurons and presented SERT density, DXM could be a potential agent in alleviating NIHL.

Synthetic chalcones as potential anti-inflammatory and cancer chemopreventive agents.

In an effort to develop potent anti-inflammatory and cancer chemopreventive agents, a series of chalcones were prepared by Claisen-Schmidt condensation of appropriate acetophenones with suitable aromatic aldehyde or prepared with appropriate dihydrochalcone reacted with appropriate alkyl bromide or prepared in one-pot procedure involving acetophenone and convenient aromatic aldehyde using ultrasonic agitation on basic alumina. The synthesized products were tested for their inhibitory effects on the activation of mast cells, neutrophils, macrophages, and microglial cells. The potent inhibitors of NO production in macrophages and microglial cells were further evaluated for their in vitro cytotoxic effects against several human cancer cell lines. 2'-Hydroxychalcones 1-3, and 2',5'-dihydroxychalcone 7 exhibited potent inhibitory effects on the release of beta-glucuronidase or lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP)/cytochalasin B (CB). Two 2'-hydroxychalcones (1 and 3) showed potent inhibitory effects on superoxide anion generation in rat neutrophils in response to fMLP/CB. The previously reported chalcone, 5, 6, and 12, exhibited potent inhibitory effect on NO production in lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma)-activated N9 microglial cells or in LPS-activated RAW 264.7 macrophage-like cells. The potent inhibitors 5, 6, and 12 of NO production in macrophages or microglial cells revealed significant or marginal cytotoxic effects against several human cancer lines. Compound 12 manifested potent selective cytotoxicity against human MCF-7 cells and caused cell death by apoptosis. The present results demonstrated that 1-3, and 7 have anti-inflammatory effects and 5, 6, and 12 are potential anti-inflammatory and cancer chemopreventive agents.

Structure-activity relationship studies on chalcone derivatives: potent inhibition of platelet aggregation.

In an effort to develop potent antiplatelet agents with anti-inflammatory action, a novel series of anti-inflammatory chalcones was screened to evaluate their antiplatelet effects. Structure-activity relationships and mode of action were investigated and characterized. The antiplatelet effects of the chalcones on washed rabbit platelets and human platelet-rich plasma were evaluated. Arachidonic acid-induced platelet aggregation was potently inhibited by almost all the chalcone derivatives. Collagen-induced platelet aggregation was potently inhibited by all the chalcone derivatives at 300 microM, except for compound 4 at 100 microM. Compounds 6, 7 and 9 significantly inhibited the aggregation of washed rabbit platelets induced by platelet-activating factor at 300 microM. Of the compounds tested in human platelet-rich plasma, compounds 2, 8 and 9 showed significant inhibition of secondary aggregation induced by adrenaline. It is concluded that the antiplatelet effect of 2, 8 and 9 is mainly owing to an inhibitory effect on thromboxane formation. The inhibitory effect of 6, 7 and 9 on platelet aggregation induced by platelet-activating factor could be owing to a calcium antagonizing effect or inhibition of intracellular calcium mobilization.

Structure-activity relationship studies on chalcone derivatives. the potent inhibition of chemical mediators release.

Some chalcones exert potent anti-inflammatory activities. 2',5'-Dialkoxychalcones and 2',5'-dihydroxy-4-chloro-dihydrochalcone inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma)-activated N9 microglial cells and in LPS-activated RAW 264.7 macrophage-like cells have been demonstrated in our previous reports. These compounds also suppressed the inducible NO synthase (iNOS) expression and cyclooxygenase-2 (COX-2) activity in RAW 264.7 cells. In an effort to continually develop potent anti-inflammatory agent, a series of chalcones were prepared by Claisen-Schmidt condensation of appropriate acetophenones with appropriate aromatic aldehyde and then evaluated their inhibitory effects on the activation of mast cells, neutrophils, macrophages, and microglial cells. Most of the 2',5'-dihydroxychaclone derivatives exhibited potent inhibitory effects on the release of beta-glucuronidase and lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP)/cytochalasin B (CB). Some chalcones showed potent inhibitory effects on superoxide anion generation in rat neutrophils in response to fMLP/CB. Compounds 1 and 5 exhibited potent inhibitory effects on NO production in macrophages and microglial cells. Compound 11 showed inhibitory effect on NO production and iNOS protein expression in RAW 264.7 cells. The present results demonstrated that most of the 2',5'-dihydroxychaclones have anti-inflammatory effects. The potent inhibitory effect of 2',5'-dihydroxy-dihydrochaclones on NO production in LPS-activated macrophage, probably through the suppression of iNOS protein expression, is proposed to be useful for the relief of septic shock.