Inhibitor Report for: Peganine

Vasicine (VAS) is a potential natural cholinesterase inhibitor for treatment of Alzheimer's disease. Due to one chiral centre (C-3) presenting in molecule, VAS has two enantiomers, d-vasicine (d-VAS) and l-vasicine (l-VAS). The study was undertaken to investigate the stereoselective glucuronidation metabolism, pharmacokinetics, anti-amnesic effect and acute toxicity of VAS enantiomers. In results, the glucuronidation metabolic rate of l-VAS was faster than d-VAS in human liver microsomes and isoenzymes tests, and it was proved that the UDP-glucuronosyltransferase (UGT) 1A9 and UGT2B15 were the major metabolic enzymes for glucuronidation of l-VAS, while only UGT1A9 for d-VAS, which take responsibility of the significantly less metabolic affinity of d-VAS than l-VAS in HLM and rhUGT1A9. The plasma exposure of d-VAS in rats was 1.3-fold and 1.6-fold higher than that of l-VAS after intravenous and oral administration of d-VAS and l-VAS, respectively. And the plasma exposure of the major glucuronidation metabolite d-VASG was one of tenth of l-VASG or more less, no matter by intravenous or oral administration. Both d-VAS and l-VAS were exhibited promising acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, and the BChE inhibitory activity of d-VAS with IC50 of 0.03+/-0.001muM was significantly stronger than that of l-VAS with IC50 of 0.98+/-0.19muM. The molecular docking results indicated that d-VAS and l-VAS could bind to the catalytic active site (CAS position) either of human AChE and BChE, and the BChE combing ability of d-VAS (the score of GBI/WAS dG -7.398) was stronger than that of l-VAS (the score of GBI/WAS dG -7.135). Both d-VAS and l-VAS could improving the learning and memory on scopolamine-induced memory deficits in mice. The content of acetylcholine (ACh) after oral administration d-VAS increased more than that of l-VAS in mice cortex, through inhibiting cholinesterase (ChE) and increasing choline acetyltransferase (ChAT). In addition, the LD50 value of d-VAS (282.51mg.kg(-1)) was slight lower than l-VAS (319.75mg.kg(-1)). These results indicated that VAS enantiomers displayed significantly stereoselective metabolic, pharmacokinetics, anti-amnesic effect and toxic properties in vitro and in vivo. The d-VAS might be the dominant configuration for treating Alzheimer's disease.

Vasicine (VAS), a potential natural cholinesterase inhibitor, exhibited promising anticholinesterase activity in preclinical models and has been in development for treatment of Alzheimer's disease. This study systematically investigated the in vitro and in vivo metabolism of VAS in rat using ultra performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry. A total of 72 metabolites were found based on a detailed analysis of their 1H- NMR and 13C NMR data. Six key metabolites were isolated from rat urine and elucidated as vasicinone, vasicinol, vasicinolone, 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, 9-oxo-1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, and 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-beta-D-glucuronide. The metabolic pathway of VAS in vivo and in vitro mainly involved monohydroxylation, dihydroxylation, trihydroxylation, oxidation, desaturation, sulfation, and glucuronidation. The main metabolic soft spots in the chemical structure of VAS were the 3-hydroxyl group and the C-9 site. All 72 metabolites were found in the urine sample, and 15, 25, 45, 18, and 11 metabolites were identified from rat feces, plasma, bile, rat liver microsomes, and rat primary hepatocyte incubations, respectively. Results indicated that renal clearance was the major excretion pathway of VAS. The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of VAS and its main metabolites were also evaluated. The results indicated that although most metabolites maintained potential inhibitory activity against AChE and BChE, but weaker than that of VAS. VAS undergoes metabolic inactivation process in vivo in respect to cholinesterase inhibitory activity.

Desoxypeganine hydrochloride isolated from Peganum harmala L. caused in animals a pronounced depression of cholinesterase activity. By anticholinesterase activity desoxypeganine was ten times superior peganine hydrochloride and 2 times galanthamine hydrochloride. In the experiments on anesthetized cats desoxypeganine hydrochloride eliminated blockade of neuromuscular conductivity induced by diplacine and on the contrary enhanced blockade induced by ditilin. It increases sensitivity to acetylcholine of the straight abdominal muscle of the frog and isolated segments of the small intestine. Desoxypeganine hydrochloride is used for treatment of patients with lesions of the peripheral nervous system.

Vasicine (VAS) is a potential natural cholinesterase inhibitor for treatment of Alzheimer's disease. Due to one chiral centre (C-3) presenting in molecule, VAS has two enantiomers, d-vasicine (d-VAS) and l-vasicine (l-VAS). The study was undertaken to investigate the stereoselective glucuronidation metabolism, pharmacokinetics, anti-amnesic effect and acute toxicity of VAS enantiomers. In results, the glucuronidation metabolic rate of l-VAS was faster than d-VAS in human liver microsomes and isoenzymes tests, and it was proved that the UDP-glucuronosyltransferase (UGT) 1A9 and UGT2B15 were the major metabolic enzymes for glucuronidation of l-VAS, while only UGT1A9 for d-VAS, which take responsibility of the significantly less metabolic affinity of d-VAS than l-VAS in HLM and rhUGT1A9. The plasma exposure of d-VAS in rats was 1.3-fold and 1.6-fold higher than that of l-VAS after intravenous and oral administration of d-VAS and l-VAS, respectively. And the plasma exposure of the major glucuronidation metabolite d-VASG was one of tenth of l-VASG or more less, no matter by intravenous or oral administration. Both d-VAS and l-VAS were exhibited promising acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, and the BChE inhibitory activity of d-VAS with IC50 of 0.03+/-0.001muM was significantly stronger than that of l-VAS with IC50 of 0.98+/-0.19muM. The molecular docking results indicated that d-VAS and l-VAS could bind to the catalytic active site (CAS position) either of human AChE and BChE, and the BChE combing ability of d-VAS (the score of GBI/WAS dG -7.398) was stronger than that of l-VAS (the score of GBI/WAS dG -7.135). Both d-VAS and l-VAS could improving the learning and memory on scopolamine-induced memory deficits in mice. The content of acetylcholine (ACh) after oral administration d-VAS increased more than that of l-VAS in mice cortex, through inhibiting cholinesterase (ChE) and increasing choline acetyltransferase (ChAT). In addition, the LD50 value of d-VAS (282.51mg.kg(-1)) was slight lower than l-VAS (319.75mg.kg(-1)). These results indicated that VAS enantiomers displayed significantly stereoselective metabolic, pharmacokinetics, anti-amnesic effect and toxic properties in vitro and in vivo. The d-VAS might be the dominant configuration for treating Alzheimer's disease.

Vasicine (VAS), a potential natural cholinesterase inhibitor, exhibited promising anticholinesterase activity in preclinical models and has been in development for treatment of Alzheimer's disease. This study systematically investigated the in vitro and in vivo metabolism of VAS in rat using ultra performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry. A total of 72 metabolites were found based on a detailed analysis of their 1H- NMR and 13C NMR data. Six key metabolites were isolated from rat urine and elucidated as vasicinone, vasicinol, vasicinolone, 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, 9-oxo-1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, and 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-beta-D-glucuronide. The metabolic pathway of VAS in vivo and in vitro mainly involved monohydroxylation, dihydroxylation, trihydroxylation, oxidation, desaturation, sulfation, and glucuronidation. The main metabolic soft spots in the chemical structure of VAS were the 3-hydroxyl group and the C-9 site. All 72 metabolites were found in the urine sample, and 15, 25, 45, 18, and 11 metabolites were identified from rat feces, plasma, bile, rat liver microsomes, and rat primary hepatocyte incubations, respectively. Results indicated that renal clearance was the major excretion pathway of VAS. The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of VAS and its main metabolites were also evaluated. The results indicated that although most metabolites maintained potential inhibitory activity against AChE and BChE, but weaker than that of VAS. VAS undergoes metabolic inactivation process in vivo in respect to cholinesterase inhibitory activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Seeds of Peganum harmala Linn are traditionally used as folk medical herb in Uighur medicine in China to treat disorders of hemiplegia and amnesia. Previously studies have proved that dominating alkaloids in P. harmala show significant inhibitory activities on the cholinesterase. AIM OF THE STUDY: The aim of the present study is to isolate trace ingredients from seeds of P. harmala and evaluate its inhibitory activities on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). MATERIALS AND
METHODS: For sake of screening effective cholinesterase inhibitors, trace compounds were isolated from seeds of P. harmala through a bioassay-guided fractionation and their structures were determined via detailed spectral analysis. The inhibitory activities on AChE and BChE were assessed using an improved Ellman method by UPLC-ESI-MS/MS to determine the common final product choline.
RESULTS: The activity-guided fractionation led to the isolation of two new alkaloids 2-aldehyde-tetrahydroharmine (10), 2-carboxyl-3,4-dihydroquinazoline (19), one syringin structure analog 1-O-beta-D-xylopyranose sinapyl alcohol (22), and along with 19 known compounds. Compounds acetylnorharmine (6), harmic acid methy ester (7), harmine N-oxide (13), 6-methoxyindoline (14), syringin (21) were first found from genus Peganum and compounds 3-hydroxylated harmine (4), 1-hydroxy-7-methoxy-beta-carboline (5) were new natural products. The results showed that the 2-aldehyde-tetrahydroharmine (10) has a potential inbibitive effect on both AChE and BChE with IC50 values of 12.35+/-0.24 and 5.51+/-0.33microM, respectively. Deoxyvasicine (15) and vasicine (16) showed the strongest BChE inhibitory activity with IC50 values of 0.04+/-0.01 and 0.1+/-0.01microM. The analysis of the structure-activity relationship indicated that the saturation of pyridine ring and the presence of substitution at indole ring, C-1, C-3, C-7 and N-2, for beta-carbolines, were essential for effective inhibition of both AChE and BChE and the five-membered ring between C-2 and N-3 as well as the substituent groups sited at C-4 and C-9, for quinazolines, were important to both the AChE/BChE-inhibitory activity.
CONCLUSIONS: Bioassay-guided fractionation has led to the isolation of AChE and BChE inhibitors from the seeds of P. harmala. These results are in agreement with the traditional uses of the seeds of P. harmala.

Desoxypeganine hydrochloride isolated from Peganum harmala L. caused in animals a pronounced depression of cholinesterase activity. By anticholinesterase activity desoxypeganine was ten times superior peganine hydrochloride and 2 times galanthamine hydrochloride. In the experiments on anesthetized cats desoxypeganine hydrochloride eliminated blockade of neuromuscular conductivity induced by diplacine and on the contrary enhanced blockade induced by ditilin. It increases sensitivity to acetylcholine of the straight abdominal muscle of the frog and isolated segments of the small intestine. Desoxypeganine hydrochloride is used for treatment of patients with lesions of the peripheral nervous system.