molecules Article Potential Pharmacokinetic Drug–Drug Interaction Between Harmine, a Cholinesterase Inhibitor, and Memantine, a Non-Competitive N-Methyl-D-Aspartate Receptor Antagonist Yunpeng Zhang 1, Shuping Li 1, Youxu Wang 1, Gang Deng 1, Ning Cao 1, Chao Wu 1, Wenzheng Ding 1, Yuwen Wang 1, Xuemei Cheng 1,2 and Changhong Wang 1,2,* 1 The MOE Key Laboratory for Standardization of Chinese Medicines and The SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicine, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Rood, Shanghai 201203, China; [email protected] (Y.Z.); [email protected] (S.L.); [email protected] (Y.W.); [email protected] (G.D.); [email protected] (N.C.); [email protected] (C.W.); [email protected] (W.D.); [email protected] (Y.W.); [email protected] (X.C.) 2 Shanghai R&D Centre for Standardization of Chinese Medicines, 1200 Cailun Rood, Shanghai 201203, China * Correspondence: [email protected] or [email protected]; Tel.: +86-021-5132-2511; Fax: +86-021-5132-2519 Received: 18 March 2019; Accepted: 10 April 2019; Published: 11 April 2019 Abstract: Harmine (HAR) is a beta-carboline alkaloid widely distributed in nature. It exhibits psychopharmacological effects of improving learning and memory. However, excessive dose of HAR can cause central tremor toxicity, which may be related to the glutamate system. Memantine (MEM) is a non-competitive N-methyl-D-aspartate receptor antagonist. It can be used for the treatment of Alzheimer’s disease and also can block the neurotoxicity caused by glutamate. Therefore, combination of HAR and MEM would be meaningful and the pharmacokinetics investigation of HAR and MEM in combination is necessary. A ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was established and validated for the simultaneous quantitative determination of MEM, HAR and harmol (HOL), a main metabolite of HAR, in rat plasma after oral administration of HAR and MEM in combination (5.0 mg/kg of MEM combined with 20.0, 40.0, 80.0 mg/kg of HAR). The contents of HAR and HOL were determined after oral administration of HAR (20.0, 40.0 and 80.0 mg/kg), and the content of MEM was determined after oral administration of MEM (5.0 mg/kg). Blood samples were collected from each rat at 0 (pre-dose), 0.08, 0.17, 0.25, 0.33, 0.50, 0.75, 1.0, 2.0, 4.0, 8.0, 12.0 and 24.0 h after administration. The maximum peak concentration (Cmax) of MEM was obviously decreased, and the area under the plasma concentration versus time curve from zero to time t (AUC(0-t)) and mean residence time (MRT) were significantly increased after combination with HAR. The Cmax and AUC(0-t) of HAR and its metabolite HOL were increased after combination with MEM. These findings suggested that co-administration of HAR and MEM could extend their residence time in rats, and then might increase the efficacy for treatment of Alzheimer’s disease. Therefore, this study will provide a basis for the rational combined application of HAR and MEM. Keywords: harmine; memantine; drug-drug interaction; pharmacokinetics; Alzheimer’s disease; liquid chromatography-mass spectrometry 1. Introduction Harmine (7-methoxy-1-methyl-9H-pyrido [3,4-β] indole, HAR, structure is shown in Figure1) is a tricyclic beta-carboline alkaloid originally isolated from seeds of Peganum harmala L. HAR is Molecules 2019, 24, 1430; doi:10.3390/molecules24071430 www.mdpi.com/journal/molecules Molecules 2018, 23, x FOR PEER REVIEW 2 of 17 Molecules 2019, 24, 1430 2 of 17 Harmine (7-methoxy-1-methyl-9H-pyrido [3,4-β] indole, HAR, structure is shown in Figure 1) is a tricyclic beta-carboline alkaloid originally isolated from seeds of Peganum harmala L. HAR is widely widelydistributed distributed in nature, in nature, such as such various as various plants, plants,insects, insects,marine creatures, marine creatures, mammalians, mammalians, human tissues human tissuesand andbody bodyfluids fluids [1]. HAR [1]. HARhas been has traditionally been traditionally used for used medicinal for medicinal preparations preparations and ritual and in the ritual in theMiddle Middle East, East,Central Central Asia, South Asia, America, South America, Africa, India Africa, and IndiaChina and[2,3]. China HAR exhibits [2,3]. HARa wide exhibits range a wideof biological range of biologicalactivities by activities inhibiting by acetylcholinesterase inhibiting acetylcholinesterase and monoamine and oxidase monoamine A (MAO oxidase-A) and A (MAO-A)combining and w combiningith benzodiazepine, with benzodiazepine, serotonin, imidazoline serotonin, and opiate imidazoline receptors and [4,5]. opiate HAR receptors possesses [a4 ,5]. HARvariety possesses of pharmacological a variety of pharmacological effects, particularly effects, in particularlycentral nervous in central system. nervous According system. to previous According to previousreports, HAR reports, can enhance HAR can short enhance-term short-termmemory in memoryold rats [6], in oldand ratsalso [ca6],n andeffectively also can ameliorate effectively amelioratememory memoryimpairments impairments in a scopolamine in a scopolamine-induced-induced mouse, mouse,which can which be canused be in used the intreatment the treatment of of Alzheimer’sAlzheimer’s disease disease [7,8]. [7,8]. Figure 1. Chemical structures of harmine (HAR), memantine (MEM), harmol (HOL) and tacrine (IS). InFigure view 1. of Chemical the toxicity structures studies of harmine of (HAR) HAR,, memantine it is quite (MEM) similar, harmol to (HOL) 1-methyl-4-phenyl-1,2,3,6- and tacrine (IS). tetrahydropyridine (MPTP) in structure and has been used as model drug to produce one of the In view of the toxicity studies of HAR, it is quite similar to 1-methyl-4-phenyl-1,2,3,6- main toxin-induced animal models for Parkinson’s disease [9–11]. Studies have shown that HAR could tetrahydropyridine (MPTP) in structure and has been used as model drug to produce one of the main lead to central tremor in rats and mice at doses of 200 mg/kg and 38.0 mg/kg, respectively [12–14]. toxin-induced animal models for Parkinson’s disease [9–11]. Studies have shown that HAR could Moreover, it could produce rhythmic inferior olive firing, rhythmic purkinje cell complex spike lead to central tremor in rats and mice at doses of 200 mg/kg and 38.0 mg/kg, respectively [12–14]. dischargesMoreover, with it could suppression produce ofrhythmic simple inferior spikes, olive and rhythmicfiring, rhythmic discharges purkinje of fastigial,cell complex interpositus, spike reticulardischarges nucleus, with red suppression nucleus, nucleusof simple reticularis spikes, and tegmentipontis, rhythmic discharges lateral vestibularof fastigial, nucleus interpositus, neurons, spinalreticular motoneurons nucleus, red [15 nucleus,–17]. It nucleus is well reticularis known that tegmentipontis, the stimulation lateral signal vestibular is transmitted nucleus neuro throughns, glutamatespinal motoneurons climbing fibers, [15– raising17]. It is intracellular well known glutamate that the stimulation levels [18]. signal Additionally, is transmitted a large through amount of glutamateglutamate is releasedclimbing fibers, into the raising extracellular intracellular fluid, glutamate which haslevels toxic [18] effects. Additionally, on peripheral a large neuronsamount of and thenglutamate resulting is in released tremor into [19, 20the]. extracellular Therefore, it fluid, is speculated which has that toxic the effects combination on peripheral of glutamate neurons receptor and antagoniststhen resulting and HARin tremor would [19,20]. attenuate Therefore, the toxicityit is speculat of HAR.ed that the combination of glutamate receptor antagonistsGenerally and speaking, HAR would the attenuate over-activation the toxicity of non-competitiveof HAR. N-methyl-D-aspartate (NMDA) receptorsGenerally is thought speaking, to be involved the over in-activation Alzheimer’s of non disease-competitive [21,22], N and-methyl which-D- canaspartate increase (NMDA) synaptic noise,receptors weaken is thought the detection to be involved of related in Alzheimer’s signals such disease as [21,22 learning], and [ 23which]. Memantinecan increase (1-amino-3,synaptic 5-dimethyladamantane,noise, weaken the detection MEM, structureof related is signals shown insuch Figure as learning1) is an amantadine [23]. Memantine derivative, (1-amino a moderate-3, 5- NMDAdimethyladamantane, receptor antagonist MEM [24,,25 structure], which is is shown widely in used Figure in treatment1) is an amantadine of Parkinson’s derivative, disease, a moderate Alzheimer’s NMDA receptor antagonist [24,25], which is widely used in treatment of Parkinson’s disease, disease and neurogenic bladder dysfunction in spasticity, etc. [22,26]. It is reported that MEM is effective Alzheimer’s disease and neurogenic bladder dysfunction in spasticity, etc. [22,26]. It is reported that for symptomatic treatment of patients with moderate to severe Alzheimer’s disease [27]. Moreover, MEM is effective for symptomatic treatment of patients with moderate to severe Alzheimer’s disease the observations in monkeys indicate that glutamate is involved in the pathophysiological cascade [27]. Moreover, the observations in monkeys indicate that glutamate is involved in the of MPTP-inducedpathophysiological neuronal cascade cell of death,MPTP- andinduced the glutamateneuronal cell antagonists death, and such the asglutamate MEM may antagonists be able to retard the progression and to improve the