[Discovery, isolation and structural identification of alkaloid glycosides in six traditional Chinese medicine such as Coptis chinensis]

Alkaloids are important active ingredients occurring in many traditional Chinese medicines, and alkaloid glycosides are one of their existence forms. The introduction of saccharide units improves the water solubility of alkaloid glycosides thus presenting better biological activity.Because of the low content in plants, alkaloid glycosides have been not comprehensively studied. In this study, ultrahigh performance liquid chromatography-quadrupole time of flight-tandem mass spectrometry(UPLC-QTOF-MS/MS) was employed to identify and analyze the alkaloid glycosides in Coptis chinensis, Phellodendron chinense, Menispermum dauricum, Sinomenium acutum, Tinospora sagittata and Stephania tetrandra. The results showed that except Tinospora sagittata, the other five herbal medicines contained alkaloid glycosides. Furthermore, the alkaloid glycosides in each herbal medicine were identified based on UV absorption spectra, quasimolecular ion peaks in MS, fragment ions information in the MS/MS, and previous literature reports. A total of 42 alkaloid glycosides were identified. More alkaloid glycosides were identified in C. chinensis and Menispermum dauricum, and eleven in C. chinensis were potential new compounds. Furthermore, the alkaloid glycosides in the water extract of C. chinensis were coarsely se-parated by macroporous adsorption resin, purified by column chromatography with D151 cation exchange resin, ODS and MCI, combined with semi-preparative high performance liquid chromatography. Two new alkaloid glycosides were obtained, and their structures were identified by mass spectrometry and NMR data as(S)-7-hydroxy-1-(p-hydroxybenzyl)-2,2-N,N-dimethyl-1,2,3,4-tetrahydroisoquinoline-6-O-β-D-glucopyranoside and(S)-N-methyltetrahydropalmatubine-9-O-β-D-glucopyranoside, respectively. This study is of great significance for enriching the information about the chemical composition and the in-depth development of C. chinensis. Meanwhile, it can provide a reference for rapid identification and isolation of alkaloid glycosides from other Chinese herbal medicines.

A novel oxoisoaporphine-type alkaloid from the rhizome of Menispermum dauricum

A phytochemical investigation of Menispermum dauricum led to the isolation of five oxoisoaporphine-type alkaloids (1-5) and five aporphine-type alkaloids (6-10), including a novel oxoisoaporphine-type alkaloid: menispeimin A (1). Their structures were elucidated by spectroscopic studies including MS, 1 D and 2 D NMR, and confirmed by comparing with literature data. Among them, alkaloids 4-10 were obtained for the first time from Menispermum genus. Natural products 2, 4 and 6 exhibited significant cytotoxic activity against A549, Bel-7402 and MCF-7 cell lines.

Analgesic bisbenzylisoquinoline alkaloids from the rhizoma of Menispermum dauricum DC

Fifteen new bisbenzylisoquinoline alkaloids (1-15) were isolated from the rhizome of Menispermum dauricum DC. Compounds 1-9 were new N-oxides of dauricine-type alkaloids. Compounds 10-14 were rare tail-to-tail quaternary alkaloids. Their structures were characterized by comprehensive analysis of spectroscopic data, and absolute configurations were established from electronic circular dichroism (ECD) data and ECD calculations. Compounds were assayed on analgesic-related G-protein coupled receptors (GPCRs) including dopamine D1 and D2 receptors, opioid Mu receptor and muscarinic M3 receptor. Compound 1 showed high affinity and selective antagonistic activity on the M3 receptor with an IC₅₀ value of 2.2 ± 0.5 μM; compound 15 exhibited the highest antagonistic affinity among the evaluated compounds on Mu (IC₅₀ = 1.1 ± 0.6 μM) and it also acted as a D1 receptor antagonist (IC₅₀ = 8.8 ± 2.9 μM). These findings expanded the existing library of bisbenzylisoquinoline alkaloids and provided new structures for the related future drug design and synthesis.

De novo Transcriptome Assembly, Gene Annotation and SSR Marker Development in the Moon Seed Genus Menispermum (Menispermaceae)

The moonseed genus Menispermum L. (Menispermaceae) is disjunctly distributed in East Asia and eastern North America. Although Menispermum has important medicinal value, genetic and genomic information is scarce, with very few available molecular markers. In the current study, we used Illumina transcriptome sequencing and de novo assembly of the two Menispermum species to obtain in-depth genetic knowledge. From de novo assembly, 53,712 and 78,921 unigenes were generated for M. canadense and M. dauricum, with 37,527 (69.87%) and 55,211 (69.96%) showing significant similarities against the six functional databases, respectively. Moreover, 521 polymorphic EST-SSRs were identified. Of them, 23 polymorphic EST-SSR markers were selected to investigate the population genetic diversity within the genus. The newly developed EST-SSR markers also revealed high transferability among the three examined Menispermaceae species. Overall, we provide the very first transcriptomic analyses of this important medicinal genus. In addition, the novel microsatellite markers developed here will aid future studies on the population genetics and phylogeographic patterns of Menispermum at the intercontinental geographical scale.

[Chemical constituents from rhizome of Menispermum dauricum and their anti-hypoxic activities]

To study the chemical constituents from the rhizome of Menispermum dauricum,fifteen compounds,N-methylcorydaldine( 1),thalifoline( 2),stepholidine( 3),acutumine( 4),daurisoline( 5),acutumidine( 6),dauricicoline( 7),bianfugecine( 8),6-O-demethylmenisporphine( 9),bianfugedine( 10),dauricoside( 11),eleutheroside D( 12),aristolactone( 13),aristoloterpenateⅠ( 14) and aristolochic acid( 15) were isolated from 75% ethanol extract of Menispermi Rhizoma by using thin layer chromatography and column chromatography methods. Their structures were identified based on their physicochemical properties and spectral data. Among them,compounds 12-15 were obtained from the genus Menispermum for the first time. Six alkaloids with higher contents were subjected to evaluate the anti-hypoxic activities by using MTT method. As a result,six alkaloids exhibited significant anti-hypoxia activities.

The complete chloroplast genome of Menispermum dauricum (Menispermaceae, Ranunculales)

Menispermum dauricum is a woody liana with great medicinal value. In the current study, we assembled the first chloroplast (cp) genome of M. dauricum. The whole chloroplast genome is 158,623 bp in length, with one large copy region (LSC: 88,879 bp), a small single copy region (SSC: 20,644 bp), and two inverted repeats (IR: 24,550 bp). The cp genome contains 114 unique genes with 80 protein-coding genes, 30 tRNA genes, and four rRNA genes. In our phylogeny of Ranunculales, Papaveraceae is found to be the basal group of Ranunculales and M. dauricum is sister to Stephania japonica.

A Strategy for Quality Control of Menispermum dauricum DC Based on Cytotoxic Activity and HPLC Fingerprint Analysis

The rhizome of Menispermum dauricum DC known as a traditional Chinese medicine, with high content of alkaloids, has been found to possess antitumor activity. In this research, an attempt to correlate fingerprinting with bioactivity was made for quality control of M. dauricum. Firstly, the cytotoxicity of extracts from ten batches of samples against human breast MCF-7 cancer cells was estimated by [3-(4, 5-dimethylthiazole-2-yl)-2, 5-diphenyltetrazoliumbromide] assay. Then, cytotoxic activity-integrated fingerprints were established by high performance liquid chromatography. Eight peaks were selected as the common peaks to evaluate the similarities of samples and hierarchical clustering analysis was used to identify and classify different samples into groups. Assays for determinations of total alkaloids and dauricine contents enabled cytotoxicity coefficient of each extract. The potential usefulness of employing cytotoxicity coefficient was investigated by a combination of Pearson correlation coefficients and multiple linear regression analysis as being the reliable parameter to evaluate the herbal extracts. The results indicated that the level of dauricine (peak 8 in the fingerprint) correlated closely with cytotoxicity and played a significant role in the cytotoxicity of Bei Dou-Gen and could be related to its antitumor properties. It is proposed that the cytotoxicity coefficient value with a cytotoxic activity-integrated fingerprint of key biomarkers (dauricine) may be useful indicators to adopt for the quality control of M. dauricum. The analysis of cytotoxic-activity-integrated fingerprint could correlate fingerprinting with bioactivities and would provide a reasonable strategy for quality control of complex mixture of herbal medicines.