Structural characterization and screening of chemical markers of alkaloids in Aconiti lateralis radix Praeparata and its processed products by UHPLC/Q-TOF-MS/MS and GNPS combining multivariate statistical methods based on the clinic.

RATIONAL: Aconiti Lateralis Radix Praeparata (AC) is a traditional Chinese medicine with a long history of use. However, the current research on the material basis of AC and its processed products is still not comprehensive, especially the changes in lipo-diterpenoid alkaloids (LDAs) that can be hydrolyzed into diester-diterpenoid alkaloids in AC before and after processing. This study aimed to provide material basis guidance for the clinical use of AC and its processed products by comprehensively analyzing the changes in substances between AC and its processed products. METHODS: An ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS/MS) approach was optimized to chemical profiling. The MS data were processed using molecular networking combined with the in-house library database to fast characterize the compounds. Multivariate statistical methods were adopted to determine the dissimilarities of components in AC and its processed products. RESULTS: A total of 310 compounds were tentatively identified from AC, including 109 potential new alkaloids, of which 98 were potential novel LPAs. A metabolomics approach was applied to find the characteristic marker components. As a result, 52 potential chemical markers were selected to distinguish the AC samples of different extraction methods and 42 potential chemical markers for differentiating between AC and its processed products were selected. CONCLUSION: The results indicate that UHPLC/Q-TOF-MS/MS and Global Natural Products Social Molecular Networking coupled with multivariate analysis strategies was a powerful tool to rapidly identify and screen the chemical markers of alkaloids between the AC samples and its processed products. These results also indicate that the toxicity of water extracts of AC and its processed products were decreased. This research not only guides the clinical safe use of AC and its processed products, but also extends the application of the molecular networking strategy in traditional herbal medicine.

Nudifloside, a Secoiridoid Glucoside Derived from Callicarpa nudiflora, Inhibits Endothelial-to-Mesenchymal Transition and Angiogenesis in Endothelial Cells by Suppressing Ezrin Phosphorylation.

Callicarpa nudiflora is a traditional folk medicine in China used for eliminating stasis to subdue swelling. Several compounds from Callicarpa nudiflora have been proved to show anti-inflammatory, haemostasis, hepatitis, and anti-proliferative effects. Tumor endothelial cells play crucial roles in tumor-induced angiogenesis. Recently, it was demonstrated that ECs may be the important source of cancer associated fibroblasts (CAFs) through endothelial to mesenchymal transition (EndoMT). In this study, we evaluated the effects of nudifloside (NDF), a secoiridoid glucoside from Callicarpa Nudiflora, on TGF-ß1-induced EndoMT and VEGF-induced angiogenesis, and the underlying mechanisms were also involved. It was found that NDF significantly inhibited enhanced migration, invasion and F-actin assembly in endothelial cells (ECs) exposed in TGF-ß1. NDF obviously reversed expression of several biomarkers associated with EndoMT and recovered the morphological characteristics of ECs and tube-like structure induced by TGF-ß1. Furthermore, treatment of NDF resulted in a significant destruction of VEGF-induced angiogenesis in vitro and ex vivo. Data from co-immunoprecipitation assay provided the evidence that Ezrin phosphorylation and the interaction with binding protein can be inhibited by NDF, which can be confirmed by data from Ezrin silencing assay. Collectively, the application of NDF inhibited TGF-ß1-induced EndoMT and VEGF-induced angiogenesis in ECs by reducing Ezrin phosphorylation.

Preliminary investigation on the analysis of the whole components of Pogejiuxin decoction and its formulation pattern based on ultrahigh-performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

RATIONAL: Pogejiuxin decoction (PGJXD) is one of the most important formulas for the treatment of heart failure. However, there is a great lack of research on the material basis of this formula, especially research on its compatibility laws, which restricts its clinical use. Studying the complete ingredients and compatibility rules of PGJXD has great significance for guiding clinical medication. METHODS: The entire formula, the major single herbs, the drug pairs and the disassembled formula were analyzed by ultrahigh-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UHPLC/QTOFMS/MS), matching the chemical composition database and global natural product social molecular networking to explain the chemical composition as well as the combination pattern of PGJXD. RESULTS: A total of 1048 chemical constituents were fully analyzed from the major single herbs, the drug pairs and the disassembled formula and 188 chemical constituents, including 13 potential novel compounds, were firstly identified from the whole formula. We found that the chemical compositions were reduced after the single herbs were matched to the other herbs, especially the significant reduction of highly toxic diester alkaloids after compatibility, indicating that the medicines of PGJXD were interdependent and controlled by each other. CONCLUSION: This study innovatively researches and compares the compositional differences between the entire formula of PGJXD, the single, paired and separated formulas, greatly extending our understanding of the chemical substance basis of these compounds, and preliminarily explores the compatibility laws of PGJXD, providing some theoretical guidance for clinical medication.

Betulinic acid induces apoptosis of HeLa cells via ROS-dependent ER stress and autophagy in vitro and in vivo.

Betulinic acid (BA), a naturally occurring lupane-type triterpenoid, possesses a wide range of potential activities against different types of cancer. However, the molecular mechanisms involved in anti-cervical cancer about BA were rarely investigated. Herein, the role of BA in cervical cancer suppression by ROS-mediated endoplasmic reticulum stress (ERS) and autophagy was deeply discussed. The findings revealed that BA activated Keap1/Nrf2 pathway and triggered mitochondria-dependent apoptosis due to ROS production. Furthermore, BA increased the intracellular Ca2+ levels, inhibited the expression of Beclin1 and promoted the expression of GRP78, LC3-II, and p62 associated with ERS and autophagy. Besides, BA initiated the formation of autophagosomes and inhibited autophagic flux by the co-administration of BA with 3-methyladenine (3-MA) and chloroquine (CQ), respectively. The in vivo experiment manifested that hydroxychloroquine (HCQ) enhanced the apoptosis induced by BA. For the first time, we demonstrated that BA could initiate early autophagy, inhibit autophagy flux, and induce protective autophagy in HeLa cells. Thus, BA could be a potential chemotherapy drug for cervical cancer, and inhibition of autophagy could enhance the anti-tumor effect of BA. However, the interactions of signaling factors between ERS-mediated and autophagy-mediated apoptosis deserve further attention.

A research on urban disaster resilience assessment system for rainstorm and flood disasters: A case study of Beijing.

Under the background of global climate change, rainstorm and flood disasters have become the most serious cataclysm. Under the circumstances of an increasingly severe risk situation, it is necessary to enhance urban disaster resilience. Based on the disaster resilience process of prevention, absorption, and enhancement, and considering the safety factors such as personnel, facility, environment and management, this paper forms a dual dimension of the urban disaster resilience assessment model covering the key elements of urban disaster response and the core capacity of urban disaster recovery. Furthermore, if taking into account the characteristics of rainstorm and flood disasters, the paper screens the key indicators to build up an assessment index system of an urban rainstorm and flood disaster. The practical application was implemented in Beijing to have an assessment of the ability to recover from rainstorm and flood disasters in all districts of Beijing. And then, some pertinent suggestions for enhancing the resilience of Beijing to rainstorm and flood disasters were proposed.

New chemical structures and liver-protective activity of the diterpenoids from Callicarpa rubella.

Callicarpa rubella is a characteristic folk herb in the genus Callicarpa, and has abundant ethnobotanical usage as indigenous medicine in Lingnan area of P. R. China. However, the phytochemical and pharmacological properties of C. rubella was rarely investigated. Now, three new diterpenoids, named rubellapene A-C (1-3), along with five known analogues (4-8), were isolated from C. rubella. Their structures were determined by spectroscopic methods, quantum chemical electronic circular dichroism calculations and single-crystal X-ray diffraction analysis. Notably, the norditerpenoids C18 of clerodane type (rubellapene B) was rarely found in the genus Callicarpa. The liver protective effects of all of the isolates (1-8) were evaluated by the changes of cell viability and transaminase content of AST and ALT in H2O2-induced BRL cells. Compound 1, 3-8 exhibited that potent liver protective effects at different levels.

Phenylethanoid Glycosides From Callicarpa kwangtungensis Chun Attenuate TNF-α-Induced Cell Damage by Inhibiting NF-κB Pathway and Enhancing Nrf2 Pathway in A549 Cells.

Background: Acute lung injury (ALI) is a complicated and severe lung disease, which is often characterized by acute inflammation. Poliumoside (POL), acteoside (ACT) and forsythiaside B (FTB) are phenylethanoid glycosides (PGs) with strong antioxidant, anti-inflammatory, and anti-apoptotic properties, which are extracted from Callicarpa kwangtungensis Chun (CK). The aim of this study was to investigate the protective effects of POL, ACT, and FTB against TNF-α-induced damage using an ALI cell model and explore their potential mechanisms. Methods and Results: MTT method was used to measure cell viability. Flow cytometry was used for detecting the apoptosis rate. Reactive oxygen species (ROS) activity was determined using fluorescence microscope. The expression of mRNA in apoptosis-related genes (Caspase 3, Caspase 8, and Caspase 9) were tested by qPCR. The effects of POL, ACT, FTB on the activities of nuclear factor erythroid-2 related factor 2 (Nrf2), nuclear factor kappa-B (NF-κB) and the expression of their downstream genes were assessed by western blotting and RT-PCR in A549 cells. In the current study, POL, ACT, and FTB dose-dependently attenuated TNF-α-induced IL-1ß, IL-6 and IL-8 production, cell apoptosis, the expression of apoptosis-related genes (Caspase 3, Caspase 8, and Caspase 9) and ROS activity. POL, ACT, and FTB not only increased in the mRNA levels of antioxidative enzymes NADPH quinone oxidoreductase (NQO1), glutamate cysteine ligase catalytic subunit (GCLC), heme oxygenase (HO-1), but also decreased the mRNA levels of IL-1ß, IL-6 and IL-8. Furthermore, they upregulated the expression of Keap1 and enhanced the activation of Nrf2, while decreased the expression of phosphor-IκBα (p-IκBα) and nuclear p65. In addition, no significant changes were observed in anti-inflammatory and antioxidant effects of POL, ACT, FTB following Nrf2 and NF-κB p65 knockdown. Conclusion: Our study revealed that POL, ACT, and FTB alleviated oxidative damage and lung inflammation of TNF-α-induced ALI cell model through regulating the Nrf2 and NF-κB pathways.

Natural phenylethanoid glycosides isolated from Callicarpa kwangtungensis suppressed lipopolysaccharide-mediated inflammatory response via activating Keap1/Nrf2/HO-1 pathway in RAW 264.7 macrophages cell.

ETHNOPHARMACOLOGICAL RELEVANCE: Callicarpa kwangtungensis, as a characteristic traditional herb in China, has been widely used as indigenous medicine for thousands of years in the treatment of upper respiratory tract infection, tonsillitis, pneumonia and traumatic bleeding in China. Phenylethanoid glycosides (PhGs), as natural polyphenols, are especially abundant in this herb and can be regarded as the representative active ingredients in C. kwangtungensis. AIM OF THIS STUDY: This study was performed to investigate the anti-inflammatory pharmacodynamic basis of six PhGs (acteoside, forsythoside B, poliumoside, alyssonoside, parvifloroside A, and syringalide A 3'-α-L-rhanmnopyranoside) isolated from C. kwangtungensis from the perspective of antioxidation. MATERIALS AND METHODS: Six PhGs were isolated from the anti-inflammatory extracts of C. kwangtungensis by various chromatographic techniques and their anti-inflammatory activity on RAW 264.7 murine macrophages induced by LPS was investigated by measuring the release of tumor necrosis factor (TNF-α), the colonic interleukin-6 (IL-6), nitric oxide (NO) and reactive oxygen species (ROS). Further, the underlying anti-inflammatory mechanism of two PhGs (forsythoside B and alyssonoside) was explored by determining the expression of Kelch-like ECH-association protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (OH-1) and quinone oxidoreductase 1 (NQO1). Besides, molecular simulation was also employed to evaluate the binding capacity of two PhGs with Keap1. RESULTS: Compared with the model group, six PhGs revealed obviously inhibitory effects on TNF-α, IL-6, NO and the generation of ROS in RAW 264.7 macrophages. Moreover, forsythoside B and alyssonoside could act as the inhibitors of Keap1-Nrf2 interaction, then activated the nuclear translocation of Nrf2 and promoted the upregulated protein expression of HO-1 and NQO1, finally suppressed LPS-induced inflammatory response in RAW 264.7 macrophages. Molecular modeling exhibited hydrogen bonds played a crucial role for the binding of PhGs with the Nrf2 binding site in Keap1 protein. CONCLUSIONS: Natural PhGs-induced protection against LPS-induced inflammatory response via activating Keap1/Nrf2/HO-1 signaling pathway in RAW 264.7 macrophages were confirmed, which provided experimental and theoretical basis for the deeper use of C. Kwangtungensis in the treatment and prevention of diseases related to inflammation and oxidative stress.

Structural characterization and discrimination of Paris polyphylla var. yunnanensis by a molecular networking strategy coupled with ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

RATIONALE: Paris polyphylla var. yunnanensis (Franch) Hand Mazz (PPY) is a traditional Chinese medicine with antitumor, antibacterial, hemostatic, and anthelmintic activities. Identification of the chemical composition in PPY is helpful to discover its active ingredients and can be used to establish its quality control protocols. METHODS: The composition of PPY was identified using ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS/MS) coupled with a molecular networking strategy. First, the UHPLC/QTOF-MS/MS approach was optimized for chemical compound profiling. Then, the MS data were processed using PeakView™ combined with an in-house database to quickly characterize the secondary metabolites. Finally, molecular networking excavated new molecular weights to discover unknown or trace natural products based on the characteristics of each cluster. RESULTS: A total of 222 compounds, including 77 isospirostanols, 2 spirostanols, 19 furostanols, 10 pseudospirostanols, 6 cholesterols, 10 C21 steroids, 5 insect metamorphosis hormones, 3 plant sterols, 6 five-ring triterpenoids, 4 flavonoids, 8 fatty acids, 2 phenylpropanoids, and 8 other compounds, were characterized in PPY by comparing their main fragmentation characteristics and pathways with the literature data, and 62 of them, 54 steroidals and 8 phenylpropanoids, were discovered or tentatively identified for the first time. CONCLUSIONS: This study extended the application of a molecular networking strategy to traditional herbal medicines and developed a molecular networking based screening approach with a significant increase in efficiency for the discovery and identification of trace novel natural products.

New glycosylsphingolipids from Psychotria serpens L.

In clinical, Psychotria serpens L. was often substitute for Caulis trachelospermi to treat cancer in China. Meanwhile, EtOAc and n-BuOH fractions of MeOH extract of P. serpens L. show power activity against H460, HepG2, Hela, and PC9/GR cell lines, and no toxic effects against normal 16HBE cell lines. In our ongoing search for bioactive novel compounds from Chinese material medica, one new type of glycosylsphingolipids Psychotramide (1a-1c) were isolated from P. serpens L., and their structures were identified through spectroscopic techniques including NMR (1D and 2D) and MS (LC-MS, and GC-MS).

Synthesis and Antitumor Evaluation in Vitro of NO-Donating Ursolic Acid-Benzylidene Derivatives.

Antitumor activity of triterpenoid and its derivatives has attracted great attention recently. Our previous efforts led to the discovery of a series of NO-donor betulin derivatives with potent antitumor activity. Herein, we prepared eight compounds derived from ursolic acid (UA). All the compounds were evaluated for their in vitro cytotoxicity against four human cancer cell lines (HepG-2, MCF-7, HT-29 and A549). Among the compounds tested, compound 4a was found to be most active against HT-29 (IC50 =4.28 µm). Further biological assays demonstrated that compound 4a could induce cell cycle arrest at G1 phase and apoptosis in a dose-dependent manner. In addition, compound 4a was found to upregulate pro-apoptotic Bax, p53 and downregulate anti-apoptotic Bcl-2. All these results suggested that compound 4a is a potential candidate drug for the therapy of colon cancer.

Antioxidation and Cytoprotection of Acteoside and Its Derivatives: Comparison and Mechanistic Chemistry.

The study tried to explore the role of sugar-residues and mechanisms of phenolic phenylpropanoid antioxidants. Acteoside, along with its apioside forsythoside B and rhamnoside poliumoside, were comparatively investigated using various antioxidant assays. In three electron-transfer (ET)-based assays (FRAP, CUPRAC, PTIO•-scavenging at pH 4.5), the relative antioxidant levels roughly ruled as: acteoside >forsythoside B > poliumoside. Such order was also observed in H⁺-transfer-involved PTIO•-scavenging assay at pH 7.4, and in three multiple-pathway-involved radical-scavenging assays, i.e., ABTS⁺•-scavenging, DPPH•-scavenging, and •O2--scavenging. In UV-vis spectra, each of them displayed a red-shift at 335→364 nm and two weak peaks (480 and 719 nm), when mixed with Fe2+; however, acteoside gave the weakest absorption. In Ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) analysis, no radical-adduct-formation (RAF) peak was found. MTT assay revealed that poliumoside exhibited the highest viability of oxidative-stressed bone marrow-derived mesenchymal stem cells. In conclusion, acteoside, forsythoside B, and poliumoside may be involved in multiple-pathways to exert the antioxidant action, including ET, H⁺-transfer, or Fe2+-chelating, but not RAF. The ET and H⁺-transfer may be hindered by rhamnosyl and apiosyl moieties; however, the Fe2+-chelating potential can be enhanced by two sugar-residues (especially rhamnosyl moiety). The general effect of rhamnosyl and apiosyl moieties is to improve the antioxidant or cytoprotective effects.

[Interaction of phenylethanoid glycosides and calf thymus DNA].

In physiological condition, the interaction of acteoside and forsythoside B with calf thymus DNA using neutral red (NR) as a fluorescence probe were investigated by fluorescence, UV-visible spectrophotometry, viscosity, DNA melting techniques, and molecular docking. It is observed that acteoside and forsythoside B can react with DNA. The major mode of recognition between drug and DNA is groove binding by hydrogen bonds, and the interaction of acteoside with DNA is stronger than that of forsythoside B.

Diterpenoid alkaloids and flavonoids from Delphinium trichophorum.

Five hetisane-type C20-diterpenoid alkaloids, trichodelphinines A-E, one delnudine-type C20-diterpenoid alkaloid, trichodelphinine F and three known flavonoids, quercetin, quercetin 3-O-ß-D-glucopyranoside, and quercetin 3-O-ß-D-glucopyranoside-7-O-α-L-arabinopyranoside, were isolated from whole plants of Delphinium trichophorum Franch. Their structures were elucidated on the basis of extensive spectroscopic analysis, including HSQC, HMBC, (1)H-(1)H COSY, NOESY and X-ray crystallographic analysis, and from chemical evidence. The cytotoxic activities of the diterpenoid alkaloids were evaluated using the MTT method, and the IC50 values of their cytotoxicity against A549 cancer cells ranged from 12.03 to 52.79 µM.

Structure-activity relationships of antioxidant activity in vitro about flavonoids isolated from Pyrethrum tatsienense.

AIM: Antioxidant activity is one of the important indexes for estimating medicinal value for the traditional Chinese medicine. The aim of this study is to investigate the antioxidant activity of 11 flavonoids mainly revealing luteolin as mother nucleus isolated from Pyrethrum tatsienense. MATERIALS AND METHODS: The antioxidant activity of 11 flavonoids was measured in vitro using the classical 1,1-diphenyl-2-picrylhydrazyl removal method. The percentages of scavenging activity of 11 flavonoids were analyzed by taking the choice of a-tocopherol as positive drugs, and the scavenging activity was plotted against the sample concentration to obtain the IC50 values. RESULTS: Ten flavonoids containing phenolic hydroxyl groups have different levels of antioxidant activity. Antioxidant activity mainly depends on the numbers and the substitutional positions of phenolic hydroxyls in B ring. When C-3', 4' positions in B ring of flavonoids are replaced by hydroxyl groups, the antioxidant activity improved remarkably. Phenolic hydroxyl groups in A ring contribute some to antioxidant activity because of the electrophilic effect of C ring, and the numbers and substitutional positions of methoxyl and glycosyl have a little effect on the antioxidant activity. CONCLUSION: Structure-activity relationships of antioxidant activity about flavonoids isolated from P. tatsienense are concluded, which will be beneficial to deep understanding the pharmacological functions of this Tibetan medicine in vivo from the point of antioxidation.

Investigation on the differences of four flavonoids with similar structure binding to human serum albumin.

Flavonoids are structurally diverse and the most ubiquitous groups of polyphenols distributed in the various plants, which possess intensive biological activities. In this study, the interaction mechanisms between four flavonoids containing one glucose unit with similar molecular weight isolated from the Tibetan medicinal herb Pyrethrum tatsienense, namely, apigenin-7-O-ß-D-glucoside(1), luteolin-7-O-ß-D-glucoside(2), quercetin-7-O-ß-D-glucoside(3), quercetin-3-O-ß-D-glycoside(4), and human serum albumin(HSA), were investigated by fluorescence, UV-vis absorbance, circular dichroism, and molecular modeling. The effects of biological metal ions Mg2+, Zn2+, and Cu2+ on the binding affinity between flavonoids and HSA were further examined. Structure-activity relationships of four flavonoids binding to HSA were discussed in depth and some meaningful conclusions have been drawn by the experiment data and theoretical simulation. In addition, an interesting phenomenon was observed that the microenvironment of the binding site I in HSA has hardly changed in the presence of 4 differentiating from the other three flavonoids on the basis of conformation investigations.

[Study on chemical constituents of Callicarpa peii].

OBJECTIVE: To study the chemical constituents of Callicarpa peii. METHODS: The chemical constituents were isolated and purified by chromatographic methods and elucidated by spectral analysis, including UV, IR, MS, 1H-NMR and 13C-NMR. RESULTS: Ten compounds were obtained and identified as oleanolic acid (1), 2beta, 3beta,19alpha-trihydroxy-12-en-28-ursolic acid (2), luteolin -7,4'-dimethylether (3), luteolin -3', 4', 7, -trimethylether (4), luteolin -4'-methylether (5), hydnocarpin (6), luteolin (7), lyoniresinol 3alpha-O-beta-D-glucopyranoside (8), kelampayoside A (9), kaempferol -3-O-glucuronide (10). CONCLUSION: All these compounds are isolated from Callicarpa peii for the first time and compounds 3, 4, 6, 8 and 10 are isolated from this genus for the first time.

Investigation of the interaction between two phenylethanoid glycosides and bovine serum albumin by spectroscopic methods.

Two phenylethanoid glycosides, acteoside and forsythoside B, were first isolated from the traditional Chinese herb Callicarpa peii H.T. Chang. The interaction between the two phenylethanoid glycosides and bovine serum albumin (BSA) was investigated by fluorescence, UV-vis absorbance and circular dichroism (CD). The results showed that the quenching mechanism in the drug-BSA binary systems was a combination of static quenching and non-radiative energy transfer. Displacement experiments confirmed that the drug bound to the site I of BSA. UV-vis and CD measurements indicated that the binding of the drug to BSA induced conformational changes in BSA.

Phenylethanoid glycosides from the stems of Callicarpa peii (hemostatic drug).

Two new trisaccharide intermediates of phenylethanoid glycosides, peiioside A(1)/A(2) (1a/1b) and peiioside B (2), were isolated from the n-BuOH fraction of MeOH extract of the stems of Callicarpa peii H.T. Chang, together with five biogenetic relevant known compounds 3-7. The structures of compounds 1 and 2 were elucidated by extensive spectroscopic methods (especially 2D-NMR techniques) and acid-catalyzed hydrolysis as O-α-l-rhamnopyranosyl-(1″→3')-O-[ß-d-apiofuranosyl-(1‴→6')] -4'-O-[(E)-caffeoyl]-d-glucopyranoside] (1a/1b), 3,4-dihydroxy-ß-phenylethoxy-O-[ß-d-apiofuranosyl-(1‴→6')-α-l-rhamnopyranosyl-(1″→3')-O-ß-d-glucopyranoside] (2), respectively. On the basis of the isolated compounds, a presumable biogenetic pathway of the biologically interesting phenylethanoid glycosides about forsythoside B (3) and acteoside (4) isolated from this species was proposed. Isolation of five related intermediates (1-2, 5-7) provided further support for the biogenetic path. This is the first report about phytochemical research on C. peii and the biogenetic hypothesis of forsythoside B and acteoside.

[Spectroscopic study on interaction between cistanoside F and bovine serum albumin].

OBJECTIVE: To study the conjugation reaction characteristics of caffeic acid micromolecule cistanoside F and bovine serum albumin. METHOD: The interaction between bovine serum albumin (BSA) and cistanoside F that was separated from Callicarpa plant for the first time and abbreviated CF was detected by fluorescence (FS), UV-vis absorbance and circular dichroism (CD) under simulative physiological conditions. RESULT: CF-BSA's static apparent binding constant (K(a)), number of binding sites (n), efficiency of energy transfer (E), spatial distance (r), thermodynamic parameters deltaG, deltaH and deltaS and changes in alpha-helical structure content in BSA before and after CF's effect were calculated to define the binding site of CF in BSA and analyze the impact of several common metal ions on the interaction of CF and BSA. CONCLUSION: Ground state compounds formed by CF and BSA could cause intrinsic fluorescence quenching. Their binding constant K(a) of cistanoside F with BSA was 4.36 x 10(4) L x mol at 25 degrees C, the number of binding site n was 1, and the spatial distance r was 3.09 nm. The results indicated that the hydrogen bond played a major role in cistanoside F-BSA association. The displacement experiments confirmed that cistanoside F can bind to site I of BSA. In addition, the binding constant of cistanoside F with BSA was enhanced after the addition of some common metal ions Mg2+, Fe3+, Cu2+ and Zn2+. The intrinsic fluorescence of BSA was quenched by cistanoside F via forming cistanoside F-BSA complex and non-radiation energy transfer. CD spectra showed that the binding of cistanoside F with BSA induced conformational changes in BSA.