Label-free target identification for natural products based on proteomics / 药学学报

Target identification and verification of natural products is an important and challenging work in the field of chemical biology. It is also an important job for researchers to apply chemical proteomics technology to biomedicine in order to identify target proteins of natural products. Target identification is critical to understanding its mechanisms and developing natural products as molecular probes and potential therapeutic drugs. Traditional approaches of small molecule target identification based on affinity have been shown to be successful, such as click-chemical probes, radioisotope labeling or photosensitized small-molecule probes. Nevertheless, these technologies require purified candidate target proteins, and modified small molecules with probes or linkers, such as adding agarose beads, biotin labels, fluorescent labeling or photo-affinity labeling. Many structure-activity relationship studies should be performed to ensure that the addition of small molecule labels undisturbed the original biological activity of the small molecules. Unfortunately, all these modifications are likely to alter their biological activity or binding specificity. To overcome the bottleneck of "target recognition", researchers have developed a series of new techniques for unmodified drug target identification. In this article, we reviewed the target identification techniques of natural product without structural modification in order to provide reference for the development of natural products.

The technologies of small molecule ligand-target protein interaction and high throughput ligand screening / 药学学报

The interaction of drug and target protein is a critical part of new drug discovery. It is the premise for drugs to exert therapeutic effects by targeting specific binding sites of target proteins and thereby affecting its pharmacological activity. Currently, a variety of techniques are exploited to detect the interaction between drug ligands and target proteins. For example, cellular thermal shift assay (CETSA) and differential scanning fluorimetry (DSF) based on thermodynamics, mass spectrometry and nuclear magnetic resonance technology, etc. In addition, high-throughput ligand screening technology provides technical convenience for the search of specific ligand, and is a powerful tool to efficiently identify the interaction between drug ligand and target protein. Here, we summarize the detection techniques of interaction between small molecules and target proteins, and discuss the application of high-throughput ligand screening technology in drug research.

Study on the mechanism of Wuzi-Yanzong-Wan-medicated serum interfering with the mitochondrial permeability transition pore in the GC-2 cell induced by atractyloside / 中国天然药物

Wuzi-Yanzong-Wan (WZYZW) is a classic prescription for male infertility. Our previous investigation has demonstrated that it can inhibit sperm apoptosis via affecting mitochondria, but the underlying mechanisms are unclear. The purpose of the present study was to explore the actions of WZYZW on mitochondrial permeability transition pore (mPTP) in mouse spermatocyte cell line (GC-2 cells) opened by atractyloside (ATR). At first, WZYZW-medicated serum was prepared from rats following oral administration of WZYZW for 7 days. GC-2 cells were divided into control group, model group, positive group, as well as 5%, 10%, 15% WZYZW-medicated serum group. Cyclosporine A (CsA) was used as a positive control. 50 μmol·L-1 ATR was added after drugs incubation. Cell viability was assessed using CCK-8. Apoptosis was detected using flow cytometry and TUNEL method. The opening of mPTP and mitochondrial membrane potential (MMP) were detected by Calcein AM and JC-1 fluorescent probe respectively. The mRNA and protein levels of voltage-dependent anion channel 1 (VDAC1), cyclophilin D (CypD), adenine nucleotide translocator (ANT), cytochrome C (Cyt C), caspase 3, 9 were detected by RT-PCR (real time quantity PCR) and Western blotting respectively. The results demonstrated that mPTP of GC-2 cells was opened after 24 hours of ATR treatment, resulting in decreased MMP and increased apoptosis. Pre-protection with WZYZ-medicated serum and CsA inhibited the opening of mPTP of GC-2 cells induced by ATR associated with increased MMP and decreased apoptosis. Moreover, the results of RT-qPCR and WB suggested that WZYZW-medicated serum could significantly reduce the mRNA and protein levels of VDAC1 and CypD, Caspase-3, 9 and CytC, as well as a increased ratio of Bcl/Bax. However, ANT was not significantly affected. Therefore, these findings indicated that WZYZW inhibited mitochondrial mediated apoptosis by attenuating the opening of mPTP in GC-2 cells. WZYZW-medicated serum inhibited the expressions of VDAC1 and CypD and increased the expression of Bcl-2, which affected the opening of mPTP and exerted protective and anti-apoptotic effects on GC-2 cell induced by ATR.

Sesquiterpenoids from the leaves of Sarcandra glabra / 中国天然药物

Sarglanoids A-F, six new sesquiterpenoids belonging to eudesmane (1-5) and eremophilane (6) types, were isolated from the leaves of Sarcandra glabra, a famous traditional Chinese medicine (TCM). Their structures including absolute configurations were elucidated through extensive spectroscopic analysis and electronic circular dichroism (ECD) calculations. Compounds 1-2 were rare N-containing eudesmane-type sesquiterpenoids. Compound 3 exhibited inhibitory activity against nitric oxide (NO) production in lipopolysaccharides (LPS)-induced RAW 264.7 cells with IC50 values at 20.00 ± 1.30 μmol·L-1. These findings provide scientific evidence for sesquiterpenoids as the material foundation of S. glabra.

Lignans with (N, N-diethyl)methyl amino group from Buxus rugulosa / 中国天然药物

Buxrugulosides A-E, four lignan glycosides (1-4) and a protocatechuate derivative (5) featuring a rare (N, N-diethyl)methyl amino group at aromatic rings, were obtained from the aerial parts of Buxus rugulosa, which is famous for treating coronary heart disease. Their structures including absolute configurations were elucidated by HRMS, 1D and 2D NMR, and by comparing their CD data with previous reports. Compound 1 was a rare sesquilignan, and all of these compounds were the first example of lignans with (N, N-diethyl)methyl amino group.

New oligomeric neolignans from the leaves of Magnolia officinalis var. biloba / 中国天然药物

Six new oligomeric neolignans including two trimeric neolignans (1 and 2) and four dimeric neolignans (3-6) were isolated from the leaves of Magnolia officinalis var. biloba. Their structures were determined based on HR-ESIMS and NMR data, as well as electronic circular dichroism (ECD) calculations. Compound 1 is formed from two obovatol moieties directly linked to an aromatic ring of the remaining obovatol moiety, which is an unprecedented type of linkage between monomers. All isolates were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 1 and 3 showed significantly inhibitory activities with IC

Type B polycyclic polyprenylated acylphloroglucinols from the roots of Hypericum beanii / 中国天然药物

Two new type B polycyclic polyprenylated acylphloroglucinols (PPAPs) (1 and 2) and a known biogenetic precursor hyperbeanol Q (3) were isolated from the root extract of Hypericum beanii, a medicinal plant widespread in southwest China. Their chemical structures were elucidated by 1D/2D NMR and HRESIMS data analysis, and absolute configurations were determined through detailed electric circular dichroism (ECD) analysis including ECD exciton chirality, Mo

Polyphyllin I promotes cell death via suppressing UPR-mediated CHOP ubiquitination and degradation in non-small cell lung cancer / 中国天然药物

Polyphyllin I (PPI) purified from Polyphyllarhizomes displays puissant cytotoxicity in many kinds of cancers. Several researches investigated its anti-cancer activity. But novel mechanisms are still worth investigation. This study aimed to explore PPI-induced endoplasmic reticulum (ER) stress as well as the underlying mechanism in non-small cell lung cancer (NSCLC). Cell viability or colony-forming was detected by MTT or crystal violet respectively. Cell cycle, apoptosis, reactive oxygen species (ROS) and mitochondrial membrane potential were assessed by flow cytometry. Gene and protein levels were evaluated by qRT-PCR and immunoblotting respectively. Protein interaction was determined by immunoprecipitation or immunofluorescence assay. Gene overexpression or silencing was carried out by transient transfection with plasmids or small interfering RNAs. The Cancer Genome Atlas (TCGA) database was used for Gene Set Enrichment Analysis (GSEA), survival analysis, gene expression statistics or pathway enrichment assay. PPI inhibited the propagation of NSCLC cells, increased non-viable apoptotic cells, arrested cell cycle at G2/M phase, induced ROS levels but failed to decrease mitochondrial membrane potential. High levels of GRP78 indicates poor prognosis in NSCLC patients. PPI selectively suppressed unfolded protein response (UPR)-induced GRP78 expression, subsequently protected CHOP from GRP78-mediated ubiquitination and degradation. We demonstrated that the natural product PPI, obtained from traditional herbal medicine, deserves for further study as a valuable candidate for lead compound in the chemotherapy of NSCLC.

Trichilin-type limonoids isolated from the fruits of Trichilia connaroides / 药学学报

Two new trichilin-type limonoids were isolated from the fruits of Trichilia connaroides along with two known limonoids, 3α-deacetylamoorastatin (3) and mesendanins K (4). Their planar structure and relative configuration were elucidated by comprehensive analyses of HR-ESI-MS, 1H NMR, 13C NMR, HSQC, HMBC and ROESY data. An antitumor activity assay showed that compounds 1, 2 and known compound 4 had weak cytotoxicity against a human cervical cancer cell line (HeLa).

Highly oxygenous trichilin-type limonoids from Trichilia sinensis / 中国天然药物

Six new trichilin-type limonoids (1-6) with C-19/29 lactol or acetal bridge and a new ring intact limonoid (7) were isolated from the desiccative ripe fruits of Trichilia sinensis. Their structures were determined by extensive spectroscopic methods including H NMR, C NMR, HSQC, HMBC, ROESY experiments as well as HRESI-MS data. All isolated compounds were evaluated for toxicities against human pulmonary carcinoma A549 and Hela cell lines by sulforhodamine B (SRB) method. Compound 7 showed weak inhibitory activity in Hela cell line at 40 μmol·L.

Withaminimas A-F, six withanolides with potential anti-inflammatory activity from Physalis minima / 中国天然药物

Withaminimas A-F (1-6), six new withaphysalin-type withanolides were isolated from the aerial parts of Physalis minima L.. The structures of these compounds were elucidated through a variety of spectroscopic techniques including HR-MS, NMR, and ECD. Compound 1 belongs to rare 18-norwithanolides, and 2-3 were 13/14-secowithanolides. According to the traditional usage of P. minima, inhibitory effects on nitric oxide (NO) production in lipopolysaccaride-activated RAW264.7 macrophages were evaluated, and compounds 1-4 exhibited significant inhibitory effects with IC values among 3.91-18.46 μmol·L.

Reversal of multidrug resistance by icaritin in doxorubicin-resistant human osteosarcoma cells / 中国天然药物

Multidrug resistance (MDR) is one of the major obstacles in cancer chemotherapy. Our previous study has shown that icariin could reverse MDR in MG-63 doxorubicin-resistant (MG-63/DOX) cells. It is reported that icariin is usually metabolized to icariside II and icaritin. Herein, we investigated the effects of icariin, icariside II, and icaritin (ICT) on reversing MDR in MG-63/DOX cells. Among these compounds, ICT exhibited strongest effect and showed no obvious cytotoxicity effect on both MG-63 and MG-63/DOX cells ranging from 1 to 10 μmol·L. Furthermore, ICT increased accumulation of rhodamine 123 and 6-carboxyfluorescein diacetate and enhanced DOX-induced apoptosis in MG-63/DOX cells in a dose-dependent manner. Further studies demonstrated that ICT decreased the mRNA and protein levels of multidrug resistance protein 1 (MDR1) and multidrug resistance-associated protein 1 (MRP1). We also verified that blockade of STAT3 phosphorylation was involved in the reversal effect of multidrug resistance in MG-63/DOX cells. Taken together, these results indicated that ICT may be a potential candidate in chemotherapy for osteosarcoma.

Two new phenolic glycosides isolated from Ginkgo seeds / 中国天然药物

Two new phenolic glycosides, 7S, 8R-urolignoside-9'-O-β-D-glucoside (1) and scrophenoside G (2), were isolated and identified from the seeds of Ginkgo biloba L., a famous traditional medicine and functional food around the world. Their structures were elucidated by spectroscopic methods (1D and 2D NMR, HR-ESI-MS, and CD), and the comparisons of spectroscopic data with the reported values in the literature.

Reversal of multidrug resistance by icaritin in doxorubicin-resistant human osteosarcoma cells / 中国天然药物

Multidrug resistance (MDR) is one of the major obstacles in cancer chemotherapy. Our previous study has shown that icariin could reverse MDR in MG-63 doxorubicin-resistant (MG-63/DOX) cells. It is reported that icariin is usually metabolized to icariside II and icaritin. Herein, we investigated the effects of icariin, icariside II, and icaritin (ICT) on reversing MDR in MG-63/DOX cells. Among these compounds, ICT exhibited strongest effect and showed no obvious cytotoxicity effect on both MG-63 and MG-63/DOX cells ranging from 1 to 10 μmol·L. Furthermore, ICT increased accumulation of rhodamine 123 and 6-carboxyfluorescein diacetate and enhanced DOX-induced apoptosis in MG-63/DOX cells in a dose-dependent manner. Further studies demonstrated that ICT decreased the mRNA and protein levels of multidrug resistance protein 1 (MDR1) and multidrug resistance-associated protein 1 (MRP1). We also verified that blockade of STAT3 phosphorylation was involved in the reversal effect of multidrug resistance in MG-63/DOX cells. Taken together, these results indicated that ICT may be a potential candidate in chemotherapy for osteosarcoma.

Two new phenolic glycosides isolated from Ginkgo seeds / 中国天然药物

Two new phenolic glycosides, 7S, 8R-urolignoside-9'-O-β-D-glucoside (1) and scrophenoside G (2), were isolated and identified from the seeds of Ginkgo biloba L., a famous traditional medicine and functional food around the world. Their structures were elucidated by spectroscopic methods (1D and 2D NMR, HR-ESI-MS, and CD), and the comparisons of spectroscopic data with the reported values in the literature.

Two new phragmalin-type limonoids orthoesters from Entandrophragma candollei / 中国天然药物

Two new phragmalin-type limonoids orthoesters, encandollens A and B (1 and 2), were isolated from the stem barks of Entandrophragma candollei collected in Ghana. The structures of these compounds were elucidated on the basis of HR-ESI-MS, H and C NMR, HSQC, HMBC, and ROESY data. Compound 1 was a rare C-15 enolic acyl phragmalin-type limonoid orthoester. Compounds 1 and 2 exhibited weak inhibitory effects on NO production in lipopolysaccharide (LPS)-induced RAW 264.7 cells.

A new biflavone from needles of Taxus canadensis / 中国中药杂志

The presentstudy is to investigate the chemical constituents of needles of Taxus canadensis. The constituent was isolated by various chromatographic methods, and the chemical structure was elucidated on the basis of spectral analysis. A new biflavone was isolated and identified as 3"'-hydroxy-4"', 7-dimethylamentoflavone.

Determination of α-glucosidase inhibitors from Scutellaria baicalensis using liquid chromatography with quadrupole time of flight tandem mass spectrometry coupled with centrifugal ultrafiltration / 中国天然药物

The present study aimed at identifying potential lead compounds for diabetes mellitus drug discovery. We developed a novel method involving centrifugal ultrafiltration separation subsequent liquid chromatography with quadrupole time of flight tandem mass spectrometry (LC-Q/TOF-MS/MS) determination to screen α-glucosidase inhibitors in complex Scutellaria baicalensis Georgi (SBG) extract. By adding a second filter to the screening process, the level of non-specific binding of Compounds 1, 3, 10 and 11 was significantly decreased, and the level of non-specific binding of Compounds 5 and 15 also was reduced. As a result, five flavonoids identified as baicalein, baicalein, wogonin, chrysin, and oroxylin A, were rapidly found to interact with α-glucosidase and possess potent anti-α-glucosidase activity in vitro. Specific binding of ligands to α-glucosidase was demonstrated though the proposed method and the ligands could be ranked in order of affinity for α-glucosidase, which were corresponded to the order of inhibitory activity in vitro. In conclusion, our results indicated that the developed method is a rapid and effective screening method for rat intestinal α-glucosidase inhibitors from complex herbal medicines such as SBG.

A new Lycopodium alkaloid from Phlegmariurus fargesii / 中国天然药物

AIM@#To investigate the chemical constituents from the whole plants of Phlegmariurus fargesii.@*METHOD@#Compounds were isolated by repeated silica gel column chromatography. Their structures were elucidated by spectroscopic methods and chemical correlation. The acetylcholinesterase (AChE) inhibitory activity of the isolated compounds was evaluated.@*RESULTS@#A new Lycopodium alkaloid, lycopodine N-oxide (1), along with lycopodine (2), 8,15-dehydrolycopodine (3), 6α-hydroxylycopodine (4), deacetyllycoclavine (5), N-methylhuperzine B (6), lycodine (7), and phlegmarine (8), was isolated.@*CONCLUSION@#Compound 1 is a new Lycopodium alkaloid, and compound 3 was obtained from nature for the first time. Other alkaloids are isolated from this plant for the first time.

Triterpenes from the stem bark of Mitragyna diversifolia and their cytotoxic activity / 中国天然药物

AIM@#To study the chemical constituents and bioactivity of the stem bark of Mitragyna diversifolia.@*METHOD@#Compounds were isolated by various chromatographic methods. Their structures were elucidated on the basis of spectroscopic techniques (IR, UV, MS, and NMR), and they were evaluated for their cytotoxic activities by the MTT method.@*RESULTS@#Eight triterpenes were isolated and identified as 3α, 6β, 19α-trihydroxy-urs-12-en-28-oic acid (1), 3β, 6β, 19α-trihydroxy-urs-12-en-28-oic acid (2), 3-oxo-6β-19α-dihydroxy-urs-12-en-28-oic acid (3), 3β, 6β, 19α-trihydroxy-urs-12-en-24, 28-dioic acid 24-methyl ester (4), 3β, 6β, 19α, 24-tetrahydroxy-urs-12-en-28-oic acid (5), rotundic acid (6), 23-nor-24-exomethylene- 3β, 6β, 19α-trihydroxy-urs-12-en-28-oic acid (7), and pololic acid (8), respectively. All of the isolates were tested against two human tumor cell lines, MCF-7 (breast) and HT-29 (colon).@*CONCLUSION@#Compound 1 was a new triterpene. Compounds 5 - 7 exhibited potent inhibitory effects on the growth of MCF-7 and HT-29 cells, and the others showed no cytotoxicity.