New thiophenes from Echinops grijisii

A Review of the Phytochemistry and Biological Activities of Echinopsis Radix

The main varieties of Echinopsis Radix recorded in the Chinese Pharmacopoeia are the roots of Echinops latifolius Tausch or Echinops grijsii Hance. However, the chemical constituents and biological activities of this herb have not been reviewed. In order to clarify the chemical constituents of the main varieties of this herb and improve the quality of Chinese medicinal material resources, this paper systematically reviewed their chemical constituents and related biological activities. Phytochemical investigations reveal eighty-five compounds including fort y-nine thiophenes (1-49), eight flavonoids (50-57), seven caffeic acids and its derivatives (58-64), eight sesquiterpenoids (65-72), and thirteen triterpenoids and other compounds (73-85) were reported from Echinopsis Radix. The review of biological activities suggests that thiophenes are the main secondary metabolites of the medicinal material which exert antitumor, insecticidal and antifungal activities. In addition, caffeic acid and its derivatives and sesquiterpenes are potential active ingredients worthy of further study. This review provides an important scientific basis for the development of active ingredients and resource quality evaluation of Echinopsis Radix.

Unveiling the Anticancer Mechanism of Echinops davuricus: Isolation and Evaluation of AKR1B10 Inhibitors

Five compounds (1-5), one long-chain fatty acid (1), two thiophenes (2 and 3), one alkaloid (4), and one phenyl ester (5), were isolated from the aerial part of Echinops davuricus. The structures of the products were established by performing detailed nuclear magnetic resonance (NMR) analysis, and the structure of compound 1 was determined via high-resolution electrospray ionization mass spectrometry (HRESIMS) and NMR. Compounds 1, 4, and 5 were isolated from Echinops davuricus for the first time. Based on network pharmacology methods, AKR1B10 was selected as a key anticancer target. Compounds 1 and 5 exhibited significant AKR1B10 inhibitory activities, with IC50 values of 156.0±1.00 and 146.2±1.50 nM, respectively, with epalrestat used as the positive control (81.09±0.61 nM). Additionally, the interactions between the active compounds and AKR1B10 were evaluated via molecular docking. Ultimately, the GO and KEGG enrichment analysis indicated that the key signaling pathways associated with the active compounds may be related to the PI3K-Akt, MAPK, apoptotic, cellular senescence, and TNF signaling pathways and the human diseases corresponding to the targets are cancer. Our study reveals for the first time the anticancer properties of Echinops davuricus and provides a comprehensive understanding of its application in traditional medicine.

Novel cationic aryl bithiophene/terthiophene derivatives as corrosion inhibitors by chemical, electrochemical and surface investigations

Two novel bithienyl fluorobenzamidine derivatives namely, 4-([2,2':5',2''-terthiophen]-5-yl)-2-fluorobenzamidine hydrochloride salt (MA-1615), 5'-(4-amidino-3-fluorophenyl)-[2,2'-bithiophene]-5-carboxamidine dihydrochloride salt (MA-1740) were synthesized, characterized and their corrosion inhibition properties were evaluated by electrochemical methods for carbon steel (C-steel) in 1 M HCl. Experimental investigations revealed that the inhibition effectiveness of the investigated inhibitors (INHs) by the Tafel polarization method followed the order: MA-1740 (96.9%) > MA-1615 (95.6%), demonstrating higher efficiency than inhibitors of similar structure reported in the literature. The investigated bithiophene derivatives exhibit mixed-type corrosion inhibition characteristics by blocking the active sites on the surface of C-steel. EIS study revealed that the INHs behave as interface-type corrosion inhibitors. UV-Visible spectrometric measurements confirmed a complex formation between the Fe2+ cation released during the corrosion reactions and inhibitor molecules.

HR-LC-ESI-Orbitrap-MS-Based Metabolic Profiling Coupled with Chemometrics for the Discrimination of Different Echinops spinosus Organs and Evaluation of Their Antioxidant Activity

This study aimed to assess and correlate the phenolic content and the antioxidant activity of the methanol extracts of the stems, roots, flowers, and leaves of Echinops spinosus L. from north-eastern Algeria. Qualitative analysis was performed by high-resolution mass spectrometry (HR) LC-ESI-Orbitrap-MS and (HR) LC-ESI-Orbitrap-MS/MS). Forty-five compounds were identified in the methanol extracts; some are described for the first time in E. spinosus. Targeted phenolic compounds were quantified by HPLC-DAD and it was shown that caffeoyl quinic derivatives were the most abundant compounds. Chemometric analysis was performed using principal component analysis (PCA) and hierarchical cluster analysis (HCA) based on the qualitative and quantitative LC data. The score plot discriminates different Echinopsis spinosus organs into three distinct clusters, with the stems and flowers allocated in the same cluster, reflecting their resemblance in their secondary metabolites. The antioxidant activities of the methanol extracts were assessed using cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant assay (FRAP), diphenyl picryl hydrazyl radical-scavenging capacity assay (DPPH●), and 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS●+). The root extract exhibited the highest antioxidant activity, evidenced by 3.26 and 1.61 mmol Fe2+/g dried residue for CUPRAC and FRAP, respectively, and great free radical-scavenging activities estimated by 0.53 and 0.82 mmol TEAC/g dried residue for DPPH● and ABTS●+, respectively. The methanol extract of the roots demonstrated a significant level of total phenolics (TP: 125.16 mg GAE/g dried residue) and flavonoids (TFI: 25.40 QE/g dried residue TFII: 140 CE/g dried residue). Molecular docking revealed that tricaffeoyl-altraric acid and dicaffeoyl-altraric acid exhibited the best fit within the active sites of NADPH oxidase (NO) and myeloperoxidase (MP). From ADME/TOPAKT analyses, it can be concluded that tricaffeoyl-altraric acid and dicaffeoyl-altraric acid also revealed reasonable pharmacokinetic and pharmacodynamic characteristics with a significant safety profile.

The Genus Echinops: Phytochemistry and Biological Activities: A Review

The genus Echinops belongs to the family of Asteraceae and comprises about 130 species. Many species belonging to the genus Echinops are traditionally used as medicinals mainly in Africa and Asia. The genus is reported to contain diverse secondary metabolites. The aim of this review is to critically evaluate the available research reports on the genus and systematically organize the findings. Information for this study was obtained using various search engines including PubMed and Google Scholar. This review revealed that the genus is used traditionally to treat pain, inflammation, respiratory diseases, diseases caused by different microorganisms, as an aphrodisiac, to fasten expulsion of placenta, and for removal of renal stones. More than 151 secondary metabolites have been reported from the genus in which thiophenic compounds held the biggest share. Various extracts, essential oils, and isolated compounds from members of this genus are shown to exhibit different biological effects mainly anti-microbial, anti-proliferative, and anti-inflammatory. However, there are a number of species in this genus that are claimed to have traditional medicinal uses but their biological effect not yet been evaluated.

Novel Substituted Thiophenes and Sulf-Polyacetylene Ester from Echinops ritro L

Three new substituted bithiophenes (1⁻3), and one new sulf-polyacetylene ester, ritroyne A (16) were isolated from the whole plant of Echinops ritro together with twelve known substituted thiophenes. The structures were elucidated on the basis of extensive spectroscopic analysis including 1D and 2D NMR as well as MS. Furthermore, the absolute configuration of ritroyne A (16) was established by computational methods. In bioscreening experiments, four compounds (2, 4, 12, 14) showed similar antibacterial activity against Staphylococcus aureus ATCC 2592 with levofloxacin (8 µg/mL). Five compounds (2, 4, 9, 12, 14) exhibited antibacterial activities against Escherichia coli ATCC 25922, with minimum inhibitory concentration (MIC) values of 32⁻64 µg/mL. Three compounds (2, 4, 12) exhibited antifungal activities against Candida albicans ATCC 2002 with MIC values of 32⁻64 µg/mL. However, compound 16 did not exhibit antimicrobial activities against three microorganisms.

Comprehensive investigations on the action of cationic terthiophene and bithiophene as corrosion inhibitors: experimental and theoretical studies

A modified form of a naturally occurring α-terthienyl compound as a highly efficient corrosion inhibitor used at a very low dose.

Identification of Larvicidal Constituents of the Essential Oil of Echinops grijsii Roots against the Three Species of Mosquitoes

The screening of Chinese medicinal herbs for insecticidal principles showed that the essential oil of Echinops grijsii Hance roots possessed significant larvicidal activity against mosquitoes. The essential oil was extracted via hydrodistillation and its constituents were determined by gas chromatography-mass spectrometry (GC-MS) analysis. GC-MS analyses revealed the presence of 31 components, with 5-(3-buten-1-yn-1-yl)-2,2'-bithiophene (5-BBT, 27.63%), αterthienyl (α-T, 14.95%),1,8-cineole (5.56%) and cis-β-ocimene (5.01%) being the four major constituents. Based bioactivity-directed chromatographic separation of the essential oil led to the isolation of 5-BBT, 5-(4-isovaleroyloxybut-1-ynyl)-2,2'-bithiophene (5-IBT) and αT as active compounds. The essential oil of E. grijsii exhibited larvicidal activity against the fourth instar larvae of Aedes albopictus, Anopheles sinensis and Culex pipiens pallens with LC50 values of 2.65 μg/mL, 3.43 μg/mL and 1.47 μg/mL, respectively. The isolated thiophenes, 5-BBT and 5-IBT, possessed strong larvicidal activity against the fourth instar larvae of Ae. albopictus(LC50 = 0.34 μg/mL and 0.45 μg/mL, respectively) and An. sinensis(LC50 = 1.36 μg/mL and 5.36 μg/mL, respectively). The two isolated thiophenes also had LC50 values against the fourth instar larvae of C. pipiens pallens of 0.12 μg/mL and 0.33 μg/mL, respectively. The findings indicated that the essential oil of E. grijsii roots and the isolated thiophenes have an excellent potential for use in the control of Ae.albopictus, An. sinensis and C. pipiens pallens larvae and could be used in the search for new, safer and more effective natural compounds as larvicides.

Palladium-catalyzed 2,5-diheteroarylation of 2,5-dibromothiophene derivatives

Conditions allowing the one pot 2,5-diheteroarylation of 2,5-dibromothiophene derivatives in the presence of palladium catalysts are reported. Using KOAc as the base, DMA as the solvent and only 0.5–2 mol % palladium catalysts, the target 2,5-diheteroarylated thiophenes were obtained in moderate to good yields and with a wide variety of heteroarenes such as thiazoles, thiophenes, furans, pyrroles, pyrazoles or isoxazoles. Moreover, sequential heteroarylation reactions allow the access to 2,5-diheteroarylated thiophenes bearing two different heteroaryl units.

Essential oils from the roots of Echinops bannaticus Rochel ex Schrad. and Echinops sphaerocephalus L. (Asteraceae): chemotaxonomic and biosynthetic aspects

Herein, we report, for the first time, the results of detailed chemical and statistical analyses of the essential oils from the roots of two Echinops species (Asteraceae), E. bannaticus Rochel ex Schrad., and E. sphaerocephalus L., from the weed flora of Serbia. Among 106 and 81 constituents, respectively, S-containing polyacetylene compounds and triquinane sesquiterpenoids made up ca. 80% of the oils. Several of these compounds are reported here as new metabolites for the two species or even for the genus Echinops. A multivariate statistical comparison of the essential-oil composition data for these two and additional six taxa of this genus available from the literature permitted an examination of the mutual relationships of the taxa within this morphologically highly uniform genus. Principal component analysis (PCA) and agglomerative hierarchical clustering revealed a grouping of E. bannaticus and E. sphaerocephalus (both belonging to the section Echinops), and their close relationship with E. grijsii, suggesting a circumscription of this Chinese taxon to the section Echinops. PCA Correlation matrix offered valuable insight into the biosynthetic links between essential-oil constituents, and these agreed excellently with the currently proposed ones for the polyacetylene S-containing compounds, triquinanes, and monoterpenes.

Cytotoxic properties of thiophenes from Echinops grijissi Hance

The dichloromethane fraction of the crude ethanol extract of Echinops grijissi Hance roots exhibited different cytotoxicity against a panel of four human tumor cell lines, HepG2, K562, HL60 and MCF-7. By a bioassay-guided fractionation, eight thiophenes were isolated from the dichloromethane fraction, one of them was isolated from the plant for the first time. And they were assayed for their toxicity against the cell lines in order to compare their relative anti-tumor activity and find candidates of potential anti-tumor drugs. The dichloromethane fraction and isolated thiophenes showed different activity against the cell lines, and the anti-tumor activity of the dichloromethane fraction was also studied in vivo in S180 implanted ICR mice, however, it exhibited no anti-tumor activity at dosage of 20 or 40 mg/kg/d. There were also deaths recorded and the animals showed signs of toxicity when the dosage is 200 mg/kg/d.

Acetylenic thiophenes from the roots ofEchinops ellenbeckiifrom Ethiopia

The hexane fraction from the roots of Echinops ellenbeckii O. Hoffm. from Ethiopia yielded seven acetylenic thiophenes of which five compounds (1, 3, 4, 6, 7) are reported for the first time in this species: the monothiophenes 5-(penta-1,3-diynyl)-2-(but-3-en-1-ynyl)-thiophene (1), 5-(penta-1,3-diynyl)-2-(4-acetoxy-but-1-ynyl)-thiophene (2), 5-(penta-1,3-diynyl)-2-(3-hydroxy-4-acetoxy-but-1-ynyl)-thiophene (3), 5-(penta-1,3-diynyl)-2-(3,4-diacetoxy-but-1-ynyl)-thiophene (4), 5-(penta-1,3-diynyl)-2-(3-chloro-4-acetoxy-but-1-ynyl)-thiophene (5), 5-(penta-1,3-diynyl)-2-(3,4-epoxy-but-1-ynyl)-thiophene (6) and the dithiophene 5-[(5-acetoxymethyl-2-thienyl)-2-(but-3-en-1-ynyl)]-thiophene (7). Additionally, four fatty acids (C14, C15, C16 and C18), seven fatty acid esters and three long-chain hydrocarbons could be identified. All the structures were elucidated on the basis of spectral data by GC-MS, HRMS and the NMR techniques.

Screening of Echinops ellenbeckii and Echinops longisetus for biological activities and chemical constituents

Members of the genus Echinops in the family of Asteraceae are widely used in Ethiopian herbal medicine for the treatment of various diseases and illness such as migraine, diarrhea, heart pain, different forms of infections, intestinal worm infestation and hemorrhoid. Hydroalcoholic extracts of the root, flower head, leaf and stem of Echinops ellenbeckii O. Hoffm. and Echinops longisetus A. Rich were investigated for their chemical constituents and biological activities. The presence of alkaloids, saponins, phytosterols, polyphenols and carotenoids in the different parts of the plants was observed whilst anthraquinones were not detected. The leaf extracts of both plants and stem extract of E. longisetus showed strong inhibitory activity against cultures of Staphylococcus aureus. None of the extracts were found to be active against Gram-positive organisms. The flower extract of E. ellenbeckii showed strong inhibitory activity against Candida albicans. Root and flower extracts of the plants investigated showed lethal activity against earthworms. Moreover, the extracts of the roots of both plants showed molluscicidal activity against schistosome-transmitting snail hosts. The biological activities observed were dose dependent.