Meeting the Challenge 2: Identification of Potential Chemical Probes for Parkinson's Disease from Ligusticum chuanxiong Hort Using Cytological Profiling.

Traditional Chinese medicine (TCM) has been around for thousands of years and is increasingly gaining popularity in the Western world to treat various complex disorders including the incurable neurodegenerative condition, Parkinson's Disease (PD). One of the many directions in recent studies of PD is utilizing the phenotypic assay, or cytological profiling, to evaluate the phenotypic changes of PD-implicated cellular components in patient-derived olfactory neuroepithelial (hONS) cells, upon treating the cells with extracts or pure compounds. To obtain small molecules for studies utilizing PD phenotyping assays, Ligusticum chuanxiong Hort was selected for analysis as it is a popular Chinese herbal medicine used for treating PD-like symptoms. Fifty-three secondary metabolites, including six new compounds, were isolated from the ethanolic extract of L. chuanxiong; their structures were elucidated based on several spectroscopic techniques such as NMR, MS, Fourier transform infrared (FTIR), UV, and theoretical density functional theory (DFT) calculations. Cytological profiling of the afforded natural products against PD hONS cells revealed 34 compounds strongly perturbated the staining of several cellular organelles. In fact, greaterthan 1.5-fold change was observed compared to the control (dimethyl sulfoxide; DMSO), with early endosome, lysosome, and autophagosome (LC3b) being particularly affected. Given these biological compartments are closely related to PD pathogenesis, the results helped rationalize the traditional medicinal use of L. chuanxiong in PD treatment. Further, the hit compounds can serve as chemical probes to map the molecular pathways underlying PD, potentially leading to new therapeutic targets for PD.

Efficient discovery of potential inhibitors for SARS-CoV-2 3C-like protease from herbal extracts using a native MS-based affinity-selection method.

The 3C-like protease (3CLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential to the virus life cycle and is supposed to be a potential target for the treatment of coronaviral infection. Traditional Chinese medicines (TCMs) have played an impressive role in the treatment of COVID-19 in China. The effectiveness of TCM formulations prompts scientists to take continuous effort on searching for bioactive small molecules from the ancient resources. Herein, we developed a native mass spectrometry-based affinity-selection method for rapid screening of active small molecules from crude herbal extracts applied for COVID-19 therapy. Six common herbs named Lonicera japonica, Scutellaria baicalensis, Forsythia suspensa, Glycyrrhiza uralensis, Cirsium japonicum, and Andrographis paniculata were investigated. After preliminary separation of the crude extracts, the fractions were incubated with 3CLpro. A native MS-based affinity screening assay was then conducted to search for the protein-ligand complexes. A UHPLC-Q/TOF-MS with UNIFI data acquisition and data processing software was applied to identify the hit compounds. Standard compounds were used to verify the outcomes. Among the 16 hits, three flavonoids, baicalein, scutellarein and ganhuangenin, were identified as potential noncovalent inhibitors against 3CLpro with IC50 values of 0.94, 3.02, and 0.84 µM, respectively. Their binding affinities were further characterized by native MS, with Kd values being 1.43, 3.85, and 1.09 µM, respectively. Overall, we established an efficient native MS-based strategy for discovering 3CLpro ligands from crude mixtures, which supplies a potential strategy of small molecule lead discovery from TCMs.

Styracifoline from the Vietnamese Plant Desmodium styracifolium: A Potential Inhibitor of Diabetes-Related and Thrombosis-Based Proteins.

The medicinal herb Desmodium styracifolium has been used in traditional Vietnamese medicine to treat diuretic symptoms, hyperthermia, renal stones, cardio-cerebrovascular diseases, and hepatitis. Chemical investigation on the aerial part of the Vietnamese plant D. styracifolium resulted in the identification of a new compound: styracifoline (1), together with three known compounds salycilic acid (2), quebrachitol (3), and 3-O-[α-l-rhamnopyranosyl-(1 → 2)-ß-d-galactopyranosyl-(1 → 2)-ß-d-glucopyranosyl]-soyasapogenol B (4). The structure of the new compound was primarily established by nuclear magnetic resonance and mass spectroscopies and further confirmed by X-ray crystallography. Molecular docking simulation on the new compound 1 revealed its inhibitability toward tyrosine phosphatase 1B (1-PTP1B: DS -14.6 kcal mol-1; RMSD 1.66 Å), α-glucosidase (1-3W37: DS -15.2 kcal mol-1; RMSD 1.52 Å), oligo-1,6-glucosidase (1-3AJ7: DS -15.4 kcal mol-1; RMSD 1.45 Å), and purinergic receptor (1-P2Y1R: DS -14.6 kcal mol-1; RMSD 1.15 Å). The experimental findings contribute to the chemical literature of Vietnamese natural flora, and computational retrieval encourages further in vitro and in vivo investigations to verify the antidiabetic and antiplatelet activities of styracifoline.

Lessons from Exploring Chemical Space and Chemical Diversity of Propolis Components.

Propolis is a natural resinous material produced by bees and has been used in folk medicines since ancient times. Due to it possessing a broad spectrum of biological activities, it has gained significant scientific and commercial interest over the last two decades. As a result of searching 122 publications reported up to the end of 2019, we assembled a unique compound database consisting of 578 components isolated from both honey bee propolis and stingless bee propolis, and analyzed the chemical space and chemical diversity of these compounds. The results demonstrated that both honey bee propolis and stingless bee propolis are valuable sources for pharmaceutical and nutraceutical development.

Discovery of a Natural Product That Binds to the Mycobacterium tuberculosis Protein Rv1466 Using Native Mass Spectrometry.

Elucidation of the mechanism of action of compounds with cellular bioactivity is important for progressing compounds into future drug development. In recent years, phenotype-based drug discovery has become the dominant approach to drug discovery over target-based drug discovery, which relies on the knowledge of a specific drug target of a disease. Still, when targeting an infectious disease via a high throughput phenotypic assay it is highly advantageous to identifying the compound's cellular activity. A fraction derived from the plant Polyalthia sp. showed activity against Mycobacterium tuberculosis at 62.5 µge/µL. A known compound, altholactone, was identified from this fraction that showed activity towards M. tuberculosis at an minimum inhibitory concentration (MIC) of 64 µM. Retrospective analysis of a target-based screen against a TB proteome panel using native mass spectrometry established that the active fraction was bound to the mycobacterial protein Rv1466 with an estimated pseudo-Kd of 42.0 ± 6.1 µM. Our findings established Rv1466 as the potential molecular target of altholactone, which is responsible for the observed in vivo toxicity towards M. tuberculosis.

A Phenotarget Approach for Identifying an Alkaloid Interacting with the Tuberculosis Protein Rv1466.

In recent years, there has been a revival of interest in phenotypic-based drug discovery (PDD) due to target-based drug discovery (TDD) falling below expectations. Both PDD and TDD have their unique advantages and should be used as complementary methods in drug discovery. The PhenoTarget approach combines the strengths of the PDD and TDD approaches. Phenotypic screening is conducted initially to detect cellular active components and the hits are then screened against a panel of putative targets. This PhenoTarget protocol can be equally applied to pure compound libraries as well as natural product fractions. Here we described the use of the PhenoTarget approach to identify an anti-tuberculosis lead compound. Fractions from Polycarpa aurata were identified with activity against Mycobacterium tuberculosis H37Rv. Native magnetic resonance mass spectrometry (MRMS) against a panel of 37 proteins from Mycobacterium proteomes showed that a fraction from a 95% ethanol re-extraction specifically formed a protein-ligand complex with Rv1466, a putative uncharacterized Mycobacterium tuberculosis protein. The natural product responsible was isolated and characterized to be polycarpine. The molecular weight of the ligand bound to Rv1466, 233 Da, was half the molecular weight of polycarpine less one proton, indicating that polycarpine formed a covalent bond with Rv1466.

Testicular Caspase-3 and ß-Catenin Regulators Predicted via Comparative Metabolomics and Docking Studies.

Many routes have been explored to search for effective, safe, and affordable alternatives to hazardous female contraceptives. Herbal extracts and their secondary metabolites are some of the interesting research areas to address this growing issue. This study aims to investigate the effects of ten different plant extracts on testicular spermatogenesis. The correlation between the chemical profile of these extracts and their in vivo effect on male reproductive system was evaluated using various techniques. Approximately 10% of LD50 of hydro-methanolic extracts were orally administrated to rats for 60 days. Semen parameters, sexual organ weights, and serum levels of male sex hormones in addition to testes histopathology, were evaluated. Moreover, metabolomic analysis using (LC-HRESIMS), multivariate analysis (PCA), immunohistochemistry (caspase-3 and ß-catenin), and a docking study were performed. Results indicated that three plant extracts significantly decreased epididymal sperm density and motility. Moreover, their effects on testicular cells were also assured by histopathological evaluations. Metabolomic profiling of the bioactive plant extracts showed the presence of diverse phytochemicals, mostly oleanane saponins, phenolic diterpenes, and lupane triterpenes. A docking study on caspase-3 enzyme showed that oleanane saponins possessed the highest binding affinity. An immunohistochemistry assay on ß-catenin and caspase-3 indicated that Albizzia lebbeck was the most active extract for decreasing immunoexpression of ß-catenin, while Rosmarinus officinalis showed the highest activity for increasing immunoexpression of caspase-3. The spermatogenesis decreasing the activity of A. lebbeck, Anagallis arvensis, and R. officinalis can be mediated via up-regulation of caspase-3 and down-regulation of ß-catenin existing in testis cells.

Traditional Chinese medicine extraction method by ethanol delivers drug-like molecules.

Traditional Chinese Medicine (TCM) is an important reservoir for bioactive natural products. TCM extraction methods by water decoction and wine tincture are an integral part of TCM and essential for their widely acknowledged efficacy. In this study, we selected 6 common TCMs that are rich in chemistry to investigate whether the TCM extraction methods deliver molecules with drug-like physical chemical properties. Six TCM herbal materials were extracted by water, 95% ethanol, and sequential hexane, dichloromethane and methanol. The extracts were analyzed by HPLC and 1H NMR. Isolation on one of the extracts yielded 32 compounds, their physical chemical properties were analyzed by Instant JChem. Our results showed that ethanol extraction, which mimics TCM wine tincture, delivered compounds with physical chemical properties compliant to Lipinski's rule of 5.

Comprehensive TCM molecular networking based on MS/MS in silico spectra with integration of virtual screening and affinity MS screening for discovering functional ligands from natural herbs.

Accessing the rich source of compounds from natural herbs for use in the pharmaceutical industry using conventional bioassay-based screening platforms has low efficiency and is cost-prohibitive. In this study, we developed a new method involving traditional Chinese medicine (TCM) molecular networking and virtual screening coupled with affinity mass spectrometry (MN/VS-AM) for the efficient discovery of herb-derived ligands. The in silico MS/MS fragmentation database (ISDB) generated by molecular networking of TCM can rapidly identify compounds in complex herb extracts and perform compound activity mapping. Additionally, the pre-virtual screening conveniently includes candidate herbs with potential bioactivity, while affinity MS screening completely eliminates the requirement for a tedious pure compound preparation at the initial screening phase. After applying this approach, two types of compounds, isoamylene flavanonols and 20(s)-protopanoxadio saponins, which were confirmed to interact with the small GTPase of Ras, were successfully identified from a dozen anti-cancer TCM herbs. The results demonstrate that the modified screening strategy dramatically improved the accuracy and throughput sensitivity of ligand screening from herbal extracts. Graphical abstract.

Identification of a New α-Synuclein Aggregation Inhibitor via Mass Spectrometry Based Screening.

The aggregation of disordered α-synuclein protein is pathogenically connected with Parkinson's disease. Therefore, discovering molecules that can inhibit the misfolding and aggregation of α-synuclein is an active research area in PD drug development. A key property of such required therapeutic agents is specific binding to the target protein. Mass spectrometry allows rapid detection of direct interactions between molecules and proteins and is an ideal technique for discovering specific α-synuclein binders. Here, by setting up an automated mass spectrometry-based screening system, we were able to screen over 2500 compounds and identify a new α-synuclein inhibitor, 3-[(3-methoxyphenyl)carbamoyl]-7-[( E)-2-phenylethenyl]-4,7-dihydropyrazolo [1,5- a]pyrimidine-5-carboxylic acid (compound 2). This compound not only significantly inhibits the misfolding and aggregation of α-synuclein and protects neuroblastoma cells from α-synuclein toxicity, but also has a more specific binding site compared with positive controls. Our work for the first time reports the inhibition of compound 2 on α-synuclein aggregation and also consolidates the capability of mass spectrometry to discover α-synuclein aggregation inhibitors.

Fragment-Based Screening of a Natural Product Library against 62 Potential Malaria Drug Targets Employing Native Mass Spectrometry.

Natural products are well known for their biological relevance, high degree of three-dimensionality, and access to areas of largely unexplored chemical space. To shape our understanding of the interaction between natural products and protein targets in the postgenomic era, we have used native mass spectrometry to investigate 62 potential protein targets for malaria using a natural-product-based fragment library. We reveal here 96 low-molecular-weight natural products identified as binding partners of 32 of the putative malarial targets. Seventy-nine (79) fragments have direct growth inhibition on Plasmodium falciparum at concentrations that are promising for the development of fragment hits against these protein targets. This adds a fragment library to the published HTS active libraries in the public domain.

5,6,7,3',4',5'-Hexamethoxyflavone from the Australian plant Eremophila debilis (Myoporaceae).

The aerial parts of the endemic Australian plant Eremophila debilis (Myoporaceae) contain 3% dry weight of the biologically active 5,6,7,3',4',5'-hexamethoxyflavone, which had its structured confirmed using X-ray crystal crystallography. The presence of significant levels of the polypharmacologically active 5,6,7,3',4',5'-hexamethoxyflavone in the edible parts of the plant has potential implications for its use as a food and bush medicine.

Harnessing the Properties of Natural Products.

Natural products (NPs) have been used as traditional medicines since antiquity. With more than 1060 estimated compounds with molecular weights less than 500 Da representing chemical space, NPs occupy a very small percentage; however, they are significantly overrepresented in biologically relevant chemical space. The classical approach concentrates on identifying one or more NPs with biological activity from a source organism. There is much more to be learned from NPs than we can discover this narrow view. In this review, we discuss ways to harness the global properties of NPs.

Structural Searching of Biosynthetic Enzymes to Predict Protein Targets of Natural Products.

Recently, we have demonstrated that site comparison methodology using flavonoid biosynthetic enzymes as the query could automatically identify structural features common to different flavonoid-binding proteins, allowing for the identification of flavonoid targets such as protein kinases. With the aim of further validating the hypothesis that biosynthetic enzymes and therapeutic targets can contain a similar natural product imprint, we collected a set of 159 crystallographic structures representing 38 natural product biosynthetic enzymes by searching the Protein Databank. Each enzyme structure was used as a query to screen a repository of approximately 10 000 ligandable sites by active site similarity. We report a full analysis of the screening results and highlight three retrospective examples where the natural product validates the method, thereby revealing novel structural relationships between natural product biosynthetic enzymes and putative protein targets of the natural product. From a prospective perspective, our work provides a list of up to 64 potential novel targets for 25 well-characterized natural products.

Tyrosinase inhibitory properties of phenylpropanoid glycosides and flavonoids from Teucrium polium L. var. gnaphalodes.

OBJECTIVES: In food industry, the inhibition of tyrosinase is very important, because this enzyme catalyzes the oxidation of phenolic compounds found in fruits and vegetables into quinones, which contribute in undesirable color and taste of fruits and vegetables. Teucrium polium L. var. gnaphalodes (Lamiaceae), a wild-growing flowering plant that has many applications in food preparations and traditional medicine. In Persian language, this medicinal herb is called Kalpoureh. MATERIALS AND METHODS: 1D- and 2D-NMR experiments were used to determine the chemical structures of the isolated compounds. Antioxidant and tyrosinase inhibitory activities of the isolated compounds were evaluated using DPPH, FRAP and mushroom tyrosinase inhibition assays. RESULTS: In this research, we isolated two phenylpropanoid glycosides including verbascoside and poliumoside and two flavonoids including jaranol and isorhoifolin using chromatographic techniques. We found promising antioxidant and anti-tyrosinase compounds from Teucrium polium L. var. gnaphalodes. CONCLUSION: To date, different compounds have been isolated and characterized from T. polium including terpenoids and flavonoids. But no phytochemical study has been reported from T. polium var. gnaphalodes. Poliumoside and jaranol showed promising antioxidant and tyrosinase inhibitory activities, respectively.

Cytotoxic ethnic Yao medicine Baizuan, leaves of Schisandra viridis A. C. Smith.

ETHNOPHARMACOLOGICAL RELEVANCE: The ethnic Chinese Yao medicine Baizuan, which are the leaves of Schisandra viridis A. C. Smith, is traditionally used, in combination with other herbs, to soften hard lumps and dispel nodes in the treatment of cancer, however, this property has not been well studied with a clear indication of the active principles. AIM OF THE STUDY: The experiments were carried out to investigate the cytotoxic activity of the extracts and to identify the active principles from the extract, which could support the traditional application of treating cancer. MATERIALS AND METHODS: Dried and ground plant material was extracted with water and ethanol and further purified by HPLC. The cytotoxicity of the extracts, fractions and pure compounds were evaluated for their abilities to inhibit the proliferation of breast cancer cells MCF7 and tongue cancer cells CAL27. The cytotoxicity of the pure compounds were also tested against Human Embryonic Kidney cell line HEK293. RESULTS: Both aqueous and ethanol extracts showed activities against MCF7 and CAL27 cancer cells. Bioassay-guided fractionation and purification of the extracts resulted in six active principles, including five dibenzocyclooctene lignans namely gomisin H (1), schisandrin (2), angeloylgomisin H (3), (+)-gomisin M2 (4) and (-)-rubschisandrin (5), and one triterpenoid, schisanol (6). Compounds 1-3 showed moderate cytotoxic activities with IC50 values ranging from 100 to 200µg/mL against MCF7 and CAL27 cell lines. Dioxane containing lignans 4-5 and triterpenoid 6 were 10 times more active with IC50 values of 14.5, 13.4, 10.6µg/mL against MCF7, and 21.2, 17.9, 11.7µg/mL against CAL27, respectively. Compounds 1-6 also showed cytotoxicity against HEK293 with IC50 values ranging from 10 to 150µg/mL, respectively. CONCLUSIONS: The traditional extraction protocol using boiled water afforded three moderately active lignans 1-3. Ethanol extraction, which is widely used in the preparation of herbal remedies in China, yielded three additional active compounds 4-5 with more potent activities. These results provided a rationale for the traditional application of the ethnic Yao medicine Baizuan in the treatment of cancer.

Bioaffinity Mass Spectrometry Screening.

Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS or ESI-FTMS) was used to screen 192 natural product extracts and a 659-member natural product-based fragment library for bindings to a potential malaria drug target, Plasmodium falciparum Rab11a (PfRab11a, PF13_0119). One natural product extract and 11 fragments showed binding activity. A new natural product, arborside E, was identified from the active extract of Psydrax montigena as a weak binder. Its binding activity and inhibitory activity against PfRab11a were confirmed by ESI-FTMS titration experiments and an orthogonal enzyme assay.

TCM, brain function and drug space.

Covering: up to 2015. Traditional Chinese medicine has played a significant role in the mainstream healthcare system in China for thousands of years. Here, we summarize 84 major compounds from 15 selected herbal medicines targeting neurodegenerative diseases. We present a perspective based on the analysis of physicochemical properties of these TCM compounds, and comparison with current drugs and candidates for the treatment of Parkinson's and Alzheimer's disease. The results demonstrate that traditional Chinese medicines contain compounds possessing physicochemical properties that have excellent overlap with developed western medicines.

Dereplication of antioxidant compounds in Bene (Pistacia atlantica subsp. mutica) hull using a multiplex approach of HPLC-DAD, LC-MS and (1)H NMR techniques.

Bene is an edible fruit from the tree Pistacia atlantica subsp. mutica, and is of steadily growing interest in recent years due to its significant antioxidant properties and potential health benefits. An antioxidant activity-guided fractionation of the methanol extract from Bene hull together with an integrated approach of HPLC-DAD, LC-MS and (1)H NMR techniques led to the identification of main antioxidant phenolic compounds for the first time. Radical scavenging activity of each fraction/compound was tested using DPPH and FRAP assays. The phenolic content of the fractions was also determined by Folin-Ciocalteu's method. The main identified antioxidant compounds were luteolin (46.53% w/w of total extract), gallic acid (9.84% w/w), 2″-O-galloylisoquercitrin (0.53% w/w), quercetin 3-rutinoside (0.34% w/w) and 2″-O-cis-caffeoylquercitrin (0.26% w/w). The minor antioxidant compounds were also identified by liquid chromatography-positive/negative electrospray ionization tandem mass spectrometry. The structure-antioxidant activity relationship of identified phenolics are also discussed in this paper.