Effects of CYP2D6 activity on the efficacy and safety of mirtazapine in patients with depressive disorders and comorbid alcohol use disorder.

The objective of the study was to investigate the effects of CYP2D6 activity on the efficacy and safety of mirtazapine in patients with depressive disorders and comorbid alcohol use disorder who received mirtazapine. The study included 109 Russian patients who received mirtazapine at a dose of 30.0 [15.0; 45.0] mg per day. Genotyping of CYP2D6*4 (1846G > A, rs3892097) was performed using real-time polymerase chain reaction with allele-specific hybridization. The activity of CYP2D6 was evaluated by determining the concentration of endogenous substrate of the enzyme and its urinary metabolite - pinoline to 6-hydroxy-1,2,3,4-tetrahydro-beta-carboline ratio, using high-performance liquid chromatography - mass spectrometry. The statistically significant differences between the scores on the Hamilton Depression Rating Scale (HAMD) in patients with different genotypes were revealed by day 16: (GG) 5.0 [3.0; 6.0], (GA) 1.5 [1.0; 3.2] (p < 0.001), and for the The UKU Side Effects Rating Scale (UKU): (GG) 6.0 [6.0; 7.0], (GA) 8.5 [8.0; 10.0] (p < 0.001). The calculation of correlation coefficients between the differences in scale scores and metabolic rate showed the presence of statistically significant weak inverse correlation with the efficacy indicator evaluated by HAMD (r = -0.278, p < 0.05), but not by UKU (r = 0.274, p > 0.05). This study demonstrated that an increased CYP2D6 activity reduces the efficacy of treatment with mirtazapine.

Morphing of Ibogaine: A Successful Attempt into the Search for Sigma-2 Receptor Ligands.

Ibogaine is a psychoactive indole alkaloid with high affinity for several targets including the σ2 receptor. Indeed, extensive data support the involvement of the σ2 receptor in neurological disorders, including Alzheimer's disease, schizophrenia, alcohol abuse and pain. Due to its serious side effects which prevent ibogaine from potential clinical applications, novel ibogaine derivatives endowed with improved σ2 receptor affinity may be particularly beneficial. With the purpose to facilitate the investigation of iboga alkaloid derivatives which may serve as templates for the design of selective σ2 receptor ligands, here we report a deconstruction study on the ibogaine tricyclic moiety and a successive scaffold-hopping of the indole counterpart. A 3D-QSAR model has been applied to predict the σ2 pKi values of the new compounds, whereas a molecular docking study conducted upon the σ2 receptor built by homology modeling was used to further validate the best-scored molecules. We eventually evaluated pinoline, a carboline derivative, for σ2 receptor affinity through radioligand binding assay and the results confirmed the predicted high µM range of affinity and good selectivity. The obtained results could be helpful in the drug design process of new ibogaine simplified analogs with improved σ2 receptor binding capabilities.

Melatonin and structurally-related compounds protect synaptosomal membranes from free radical damage.

Since biological membranes are composed of lipids and proteins we tested the in vitro antioxidant properties of several indoleamines from the tryptophan metabolic pathway in the pineal gland against oxidative damage to lipids and proteins of synaptosomes isolated from the rat brain. Free radicals were generated by incubation with 0.1 mM FeCl(3), and 0.1 mM ascorbic acid. Levels of malondialdehyde (MDA) plus 4-hydroxyalkenal (4-HDA), and carbonyl content in the proteins were measured as indices of oxidative damage to lipids and proteins, respectively. Pinoline was the most powerful antioxidant evaluated, with melatonin, N-acetylserotonin, 5-hydroxytryptophan, 5-methoxytryptamine, 5-methoxytryptophol, and tryptoline also acting as antioxidants.

Neurogenic Potential Assessment and Pharmacological Characterization of 6-Methoxy-1,2,3,4-tetrahydro-ß-carboline (Pinoline) and Melatonin-Pinoline Hybrids.

6-Methoxy-1,2,3,4-tetrahydro-ß-carboline (pinoline) and N-acetyl-5-methoxytryptamine (melatonin) are both structurally related to 5-hydroxytryptamine (serotonin). Here we describe the design, synthesis, and characterization of a series of melatonin rigid analogues resulting from the hybridization of both pinoline and melatonin structures. The pharmacological evaluation of melatonin-pinoline hybrids comprises serotonergic and melatonergic receptors, metabolic enzymes (monoamine oxidases), antioxidant potential, the in vitro blood-brain barrier permeability, and neurogenic studies. Pinoline at trace concentrations and 2-acetyl-6-methoxy-1,2,3,4-tetrahydro-ß-carboline (2) were able to stimulate early neurogenesis and neuronal maturation in an in vitro model of neural stem cells isolated from the adult rat subventricular zone. Such effects are presumably mediated via serotonergic and melatonergic stimulation, respectively.

Hydroxyl radical reactions and the radical scavenging activity of ß-carboline alkaloids.

ß-Carbolines are bioactive pyridoindole alkaloids occurring in foods, plants and the human body. Their activity as hydroxyl radical (OH) scavengers is reported here by using three different methods: deoxyribose degradation, hydroxylation of benzoate and hydroxylation of 2'-deoxyguanosine to give 8-hydroxy-2'-deoxyguanosine (8-OHdG) as assessed by RP-HPLC (MS). Fenton reactions (Fe(2+)/Fe(3+) plus H2O2) were used for OH generation, and the radical increased in the presence of ascorbic acid or 6-hydroxydopamine as pro-oxidants. ß-Carbolines were scavengers of OH in the three assays and in the presence of pro-oxidants. Tetrahydro-ß-carboline-3-carboxylic acids were active against the hydroxylation of 2'-deoxyguanosine. ß-Carbolines reacted with hydroxyl radicals (OH) affording hydroxy-ß-carbolines, whereas tetrahydro-ß-carbolines gave oxidative and degradation products. On the basis of IC50 and reaction rates (k), ß-carbolines (norharman and harman), and tetrahydro-ß-carbolines (tetrahydro-ß-carboline, 1-methyltetrahydro-ß-carboline and pinoline) were good OH radical scavengers and their activity was comparable to that of the indole, melatonin, which is an effective hydroxyl radical scavenger and antioxidant.