Quality control and discrimination of pericarpium citri reticulatae and pericarpium citri reticulatae viride based on high-performance liquid chromatographic fingerprints and multivariate statistical analysis

High-performance liquid chromatographic (HPLC) fingerprints of Pericarpium Citri Reticulatae (PCR) and Pericarpium Citri Reticulatae Viride (PCRV) were firstly measured for deliberately collected 39 authentic samples and 21 commercial samples. Both correlation coefficients of similarity for chromatograms and absolute peak areas of characteristic compounds were calculated for quantitative expression of the HPLC fingerprints. After principal component analysis (PCA) successfully distinguished the ‘mixed peels’ samples from authentic samples, partial least squares-linear discrimination analysis (PLS-LDA) was then effectively applied to class separation between authentic PCR and PCRV. Furthermore, the unequivocally determined compounds, hesperidin, nobiletin and tangeretin, were screened out by loadings plots of PCA and PLS-LDA. The results indicated that they could be used as chemical markers for discrimination among different groups of samples. The proposed method shows an efficient strategy for quality control of PCR and PCRV, which cannot only distinguish the ‘mixed peels’ but also discriminate authentic PCR and PCRV. This method has potential perspective for quality control of traditional Chinese medicine (TCM).     

Comparative analysis of volatile constituents in Citrus Reticulata Blanco using GC–MS and alternative moving window factor analysis

The similarities and differences of essential oil components in Album Citri Reticulatae (ACR), Cylindricae Citri Reticulatae (CCR), Folium Citri Reticulatae (FCR), Exocarpium Citri Grandis (ECG), Pericarpium Citri Reticulatae Viride (PCRV) and Pericarpium Citri Reticulatae (PCR) were investigated by GC–MS combined with a chemometric method named alternative moving window factor analysis (AMWFA). And temperature‐programmed retention indices (PTRIs) were used together with mass spectra for identification of the essential oil components. In essential oils of ACR, CCR, FCR, ECG, PCRV and PCR, 28, 26, 61, 62, 52 and 48 components were determined representing 93.13, 94.44, 93.53, 87.67, 99.03 and 98.03% of the total relative content, respectively. Also, the essential oils significantly differed both qualitatively and quantitatively. There were 14 common components among ACR, CCR, FCR, ECG, PCRV and PCR, their abundance varied in the ranges from 32.39% in FCR to 94.66% in PCRV. The results obtained may be helpful to the further study of pharmacological activity for their potential utilization as therapeutical agents.     

Identification of lipophilic components in Citri Reticulatae Pericarpium cultivars by supercritical CO2 fluid extraction with ultra‐high‐performance liquid chromatography–Q Exactive Orbitrap tandem mass spectrometry

To systematically identify the lipophilic constituents of Citri Reticulatae Pericarpium from different cultivars, supercritical CO₂ fluid extraction and ultra‐high‐performance liquid chromatography–Q Exactive Orbitrap tandem mass spectrometry were integrated for the component analysis of 18 batches of Citri Reticulatae Pericarpium from 12 cultivars for the first time. A total of 57 components from the supercritical CO₂ fluid extracts were demonstrably or tentatively identified by the obtained parent peaks, fragment peaks, and retention times. In total, two flavonoids, six organic acids, nine coumarins, three aldehydes, seven esters, three terpenes, one limonoid, and five other compounds were detected for the first time; notably, coumarin components have not yet been reported in Citri Reticulatae Pericarpium. Furthermore, the extract constituents differed between cultivars. In particular, organic acids were more abundant in Citrus reticulata “Chachi” than in other cultivars, and pterostilbene was exclusively found in Citrus reticulata “Yichangju”. The results showed that a greater variety of compounds in Citri Reticulatae Pericarpium could be extracted by supercritical CO₂ fluid extraction and detected by ultra‐high‐performance liquid chromatography–Q Exactive Orbitrap tandem mass spectrometry. This study provides a more scientific basis for further analysis of the pharmacological activity and quality of Citri Reticulatae Pericarpium components from different cultivars.     

高速逆流色谱分离制备陈皮中的黄酮类化合物

应用高速逆流色谱法分离制备了陈皮中3种黄酮类化合物。以石油醚-乙酸乙酯-甲醇-水(体积比为2∶4∶3∶3)为两相溶剂系统,在主机转速850 r/min、流动相流速1.7 mL/min、检测波长280 nm条件下进行分离制备,6 h内从4.0 g陈皮粗提物中一步分离制备得到橙皮苷10.1 mg、桔皮素49.8 mg和5-羟基-6,7,8,3′,4′-五甲氧基黄酮50.6 mg,纯度均达97.0%以上,各化合物结构经质谱和核磁共振氢谱、碳谱鉴定。利用该方法可以对陈皮中的黄酮类化合物进行快速的分离和纯化。     

在线提取-高效液相色谱-二极管阵列检测-四极杆飞行时间质谱法快速鉴定陈皮中黄酮类化合物

建立了简便、高效的在线提取-高效液相色谱-二极管阵列-四极杆飞行时间质谱法（OLE-HPLC-DAD-QTOF-MS）快速提取和分离鉴定陈皮中黄酮类化合物。在线提取体系中,将填有陈皮粉末样品（2.0 mg）的固相萃取小柱取代样品环连接在手动进样阀上,样品直接被流动相提取并进入HPLC-DAD-QTOF-MS系统分析,无需额外的样品前处理步骤。与传统的溶剂回流提取法相比,在线提取法具有较高的提取率。通过分析化合物的紫外谱图、色谱保留时间和质谱信息,共鉴定出24种黄酮类化合物,其中新圣草次苷、柠檬黄素-3-O-（3-羟基-3-甲基戊二酸）-葡萄糖苷及其异构体首次在陈皮中报道。建立的方法为中药复杂体系中活性成分的快速分离鉴定提供了新的研究思路。     

Rapid Discrimination of Citrus reticulata ‘Chachi’ by Electrospray Ionization–Ion Mobility–High-Resolution Mass Spectrometry

A common idea is that some dishonest businessmen often disguise Citrus reticulata Blanco varieties as Citrus reticulata ‘Chachi’, which places consumers at risk of economic losses. In this work, we combined high-resolution ion mobility (U-shaped mobility analyzer) with high-resolution mass spectrometry to rapidly distinguish Citrus reticulata ‘Chachi’ from other Citrus species. The samples were analyzed directly through simple extraction and the analytes were separated in one second. It only took about 1 min to perform a cycle of sample analysis and data acquisition. The results showed that polymethoxylated flavones and their isomers were separated easily by the ion mobility analyzer and preliminarily identified according to the accurate mass. Moreover, the collision cross-section values of all analytes, which could be used as auxiliary parameters to characterize and identify the compounds in the samples, were measured. Twenty-four samples were grouped as two clusters by multivariate analysis, which meant that Citrus reticulata ‘Chachi’ could be effectively differentiated. It was confirmed that the developed method had the potential to rapidly separate polymethoxylated flavones and distinguish between Citrus reticulata ‘Chachi’ and other Citrus reticulata Blanco varieties.     

陈皮挥发油的气相色谱/质谱分析

用ＧＣ／ＭＳ分析复方制剂平胃散中的一种单味药材陈皮的挥发油化学成分及其相对含量,对色质联用仪产生的二维数据借助直观推导式演进特征投影法来分辨以得到组分的纯色谱和质谱,根据组分的色谱保留时间和质谱对组分进行定性,继而用总体积积分法定量。本文分离出５３个组分,其中鉴定了３４个组分,约占其挥发油总量的９６．０８％。     

Isolation, structural elucidation and synthesis of a novel antioxidative pseudo-di-peptide, Hanasanagin, and its biogenetic precursor from the Isaria japonica mushroom

The entomogenous ‘Hanasanagitake’ mushroom, Isaria japonica, is used as a folk medicine and as a traditional health food choice in Japan. A search for naturally occurring antioxidative compounds from the mushroom led to the isolation of a novel pseudo-di-peptide, named Hanasanagin, and a possible biogenetic precursor. The structures of the pseudo-di-peptides were determined as (R)-3,4-diguanidinobutanoyl-(S)-DOPA and (R)-3,4-diguanidinobutanoyl-(S)-tyrosine by spectral analysis, chemical synthesis and enzymatic conversion.     

Efficient production of raspberry ketone via ‘green’ biocatalytic oxidation

For the development of a ‘green’ oxidation method, the transformation of 4-(p-hydroxyphenyl)butan-2-ol (rhododendrol) into 4-(p-hydroxyphenyl)butan-2-one (raspberry ketone) was used as a model reaction. Different lyophilized cells of Rhodococcus spp. have been screened for their ability to perform the desired oxidation. Rhodococcus equi IFO 3730 and R. ruber DSM 44541 were able to use acetone as a hydrogen acceptor in a hydrogen transfer-like process. The oxidation can be performed at substrate concentrations up to 500 g/L.     

On the α relaxation of the constrained amorphous phase in poly(ethylene)

The idea of coexistence of two different amorphous fractions in semi-crystalline poly(ethylene) (PE) is taken into consideration. Differential scanning calorimetry, dynamic mechanical thermal analysis and positron annihilation were used to study the effect of supermolecular structure on the glass transition associated with ‘semi-ordered’ amorphous phase. The arrangement of chains, located in this phase, is forced internally by the presence of crystalline domains. Influence of drawing, irradiation and annealing on thermodynamic and structural parameters was investigated. In a series of experiments the correlation between the glass transition, the α relaxation and the free volume of a semi-crystalline system was found. In order to better describe the relaxation, existence of two types of amorphous fractions was assumed. The relaxations are treated as a long-scale motion of macromolecule segments located into the ‘semi-ordered’ amorphous regions, or into the ‘real’ amorphous regions, and are labelled as α_c and α_g, respectively. The magnitudes of the loss peaks were quite sensitive to the free volume, which was found to increase by drawing and decrease by irradiation. Two different DSC traces were recorded for both glass transitions.     

Comparative studies of chemically synthesized polyaniline and poly(o-toluidine) doped with p-toluene sulphonic acid

Polyaniline and poly(o-toluidine) doped with p-toluene sulphonic acid (p-TSA) were synthesized by in situ chemical polymerization method using ammonium per sulphate as an oxidizing agent. This is a novel polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The polymers were characterized by using UV-Vis and FT-IR spectroscopy, SEM, elemental analyzer, TGA/DSC and conductivity measurements. Thermal analysis shows that poly(o-toluidine) is less thermally stable compared to polyaniline. The less conductivity in poly(o-toluidine) is due to the cumulative steric as well as electronic effect of the bulky methyl substituent present on the benzene ring. High temperature conductivity measurements show ‘thermal activated behavior’.     

‘Total fluorine’ analysis of seed of Australian Gastrolobium spp. showing temporal, spatial and morphological variation

Alkali-fusion in conjunction with a fluoride selective electrode were used to quantify ‘total fluorine’, being organic fluorine + inorganic fluoride, for the seed of 13 species of Gastrolobium from south-west Western Australia. Intact seed covering spatial and temporal distributions, as well as G. bilobum, G. calycinum and G. parviflorum seed dissected into cotyledons and testa + aril, were analysed. Analysis found significant intra-and inter-species variation, both temporally and spatially, with intact seed concentrations ranging from 1.6 ± 0.3 mg kg⁻¹ in G. spinosum from Mundaring to 1063.9 ± 77.8 mg kg⁻¹ for G. cuneatum from Torbay. Approximately 87% of the ‘total fluorine’ was found to be in the seed cotyledons. Additional analysis detected little inorganic fluoride, indicating the majority of fluorine in the seed is organically bound. Parent compound(s) of the fluorine, seed toxicity and the implications of the results for seed chemical defense are discussed.     

Platypodiol a novel clerodane diterpene from Baccharis platypoda

There is an urgent need for effective leishmanicidal drugs to replace or supplement those in current use. Our group has been bioprospecting many Brazilian plants looking for potential new ‘hits’ to combat leishmaniasis. We found that Baccharis platypoda was one of the Asteraceae species that displayed leishmanicidal activity. We now describe the isolation of the new clerodane diterpene (1), named platypodiol after its ethanolic leaf extract. Its structure was determined by detailed NMR and ESI-TOF/MS/MS experiments. Considering the few publications about this species, this result has increased the phytochemical knowledge about B. platypoda.     

‘O-Acyl isopeptide method’ for the efficient synthesis of difficult sequence-containing peptides: use of ‘O-acyl isodipeptide unit’

A novel ‘O-acyl isodipeptide unit’, Boc-Thr(Fmoc-Val)-OH 5 has been successfully used for the efficient synthesis of a difficult sequence-containing pentapeptide based on the ‘O-acyl isopeptide method’, in which racemization-inducible esterification could be omitted, suggesting that the use of O-acyl isodipeptide units allows the application of this method to fully automated protocols for the synthesis of long peptides or proteins.     

Nontargeted urine metabolomics analysis of the protective and therapeutic effects of Citri Reticulatae Chachiensis Pericarpium on high-fat feed-induced hyperlipidemia in rats

In this study, we focused on studying the changes in urine metabolites in hyperlipidemic rats using ultra-performance liquid chromatography coupled with quadrupole time-of-fight mass spectrometry (UPLC–Q-TOF/MS) and metabolomics, as well as the effect of Citri Reticulatae Chachiensis Pericarpium (CRCP) on hyperlipidemia. These urine samples were examined by UPLC–Q-TOF/MS to obtain MS data. The MS data were analyzed by principal component analysis and partial least squares-discriminant analysis to identify the differential metabolites. CRCP reduced the body weight and levels of triglycerides, total cholesterol and low-density lipoprotein cholesterol and abnormally decreased high-density lipoprotein cholesterol in hyperlipidemic rats, which were significantly raised by a high-fat diet. Twenty-seven potential biomarkers were identified within the complex sample matrix of urine. Fourteen biomarkers increased in the hyperlipidemia rats compared with normal rats. Meanwhile, 13 biomarkers decreased. CRCP reversed abnormal changes in biomarkers, including 5-l -glutamyl-taurine, 5-aminopentanoic acid, cis-4-octenedioic acid and 2-octenedioic acid. These biomarkers show that hyperlipidemia is related to the metabolic pathways of taurine and hypotaurine metabolism, fatty acid biosynthesis , and arginine and proline metabolism . CRCP mainly prevents hyperlipidemia by intervening in these metabolic pathways.     

Molecular solvent effect on the acidity constant of protic ionic liquids

In this work how the microscopic properties of a molecular solvent affect the chemical environment of the protic ionic liquids (PILs) was analyzed. Using Reichardt’s dye as indicator of acidity, new acidity constant values for eight PILs (pK_a^PILs) were determined by spectrophotometric titration. Modifying the character hydrogen bonding donor of the molecular solvent it is possible to handle the PIL acid strength. Thus, we can turn basic PILs into acidic ones thereby the molecular solvent could be used as ‘additive’ for PILs, which allowed us to tune PILs design.     

X-ray and neutron powder diffraction studies of Ba(NdxY2−x)CuO5

Ba(R,R′)₂CuO₅ (R,R′=lanthanides and Y) plays an important role as a flux-pinning agent in enhancing the superconducting properties of the Ba₂(R,R′)Cu₃O_6+x (R,R′=lanthanides and Y) coated conductors. Using X-ray diffraction and neutron diffraction, we found that the Ba(Nd_xY_2−x)CuO₅ solid solution adopts two structure types. In the Nd-rich region (1.8?x?2.0), the materials are of brown color (commonly referred to as the ‘brown phase’), and the structure is tetragonal with space group I4/mbm (no. 127). In the Y-rich region (0.0?x?1.4), the materials are green (commonly referred to as the ‘green phase’) and the structure is orthorhombic with space group Pnma (no. 62). A two-phase region (1.4<x<1.8) exists between the orthorhombic and tetragonal phases. The crystal chemistry and crystallography of the orthorhombic ‘green phase’ series, Ba(Nd_xY_2−x)CuO₅ (isostructural to BaY₂CuO₅), are discussed in this paper.     

The structure of manganese dioxide and position of proton studied by neutron diffraction with isotopic substitution

The position of proton inside manganese dioxide, γ-MnO₂, was studied by the total neutron-scattering technique using H/D isotopic substitution. The first-order difference was obtained by subtracting the results for the two different isotopic compositions and obtaining the weighted sum of partial structure factors and radial distribution functions related to the structure around hydrogens. The deuterium-substituted γ-MnO₂ was prepared by de-intercalation of the proton via an oxidative treatment prior to re-intercalation with deuterium. The proton occupied two different positions with the H-O length of 1.0 and 1.9 Å, which corresponds to the ‘Ruetschi’ and ‘Coleman’ protons, respectively. The former protons situated in the Mn⁴⁺ vacant site and the latter in the tunnel centered in an oxygen octahedron. The isotopic substitution technique and the structure around protons are discussed in details.     

Pseudoasymmetry, stereogenicity, and the RS-nomenclature comprehended by the concepts of holantimers and stereoisograms

The concepts of holantimer and stereoisogram are applied to comprehensive discussions on the term ‘pseudoasymmetry’, where the concept of RS-stereogenicity is used as a more definite concept than usual stereogenicity. Thereby, three relationships contained in each stereoisogram can be definitely specified: an enantiomeric relationship is related to chiral/achiral, an RS-diastereomeric relationship is related to RS-stereogenic/RS-astereogenic, and a holantimeric relationship is related to scleral/ascleral, which is coined to keep the terminology in a balanced fashion. Such stereoisograms are classified into five types (Types I-V) by virtue of the three relationships. Among them, Type I, III, and V are selected as a set of RS-stereogenic units: chiral/ascleral RS-stereogenic unit (or Type I unit), chiral/scleral RS-stereogenic unit (or Type III unit), and achiral/scleral RS-stereogenic unit (or Type V unit). Thereby, the term ‘pseudoasymmetric stereogenic units’ should be replaced by the term ‘achiral/scleral RS-stereogenic units’ (or ‘Type V units’).