Acetylenic thiophenes from the roots ofEchinops ellenbeckiifrom Ethiopia

Echinograciolide, a new antibacterial nor-triterpenoid and other constituents from Echinops gracilis O. Hoffm. (Asteraceae)

Antibacterial resistance is a serious threat against humankind and the search for new therapeutics is needed. This study aims to investigate the antibacterial activity of extracts and compounds from Echinops gracilis O. Hoffm. Standard chromatographic and spectroscopic methods were used to isolate and characterize compounds (1-15) from the methanol extract. The extract, chromatographic fractions and compounds 1-3, 8, 11, 13 and 14 were subjected to in vitro antibacterial assays against Staphylococcus aureus ATCC25923, Salmonella Typhi ATCC6539, Klebsiella pneumoniae 22, and Salmonella Typhi 68, using broth micro-dilution method. As results, a new nor-triterpenoid (1) and fourteen known compounds (2-15) were characterized. The extract and fractions displayed moderate (128 ≤ MIC ≤ 512 μg/mL) and significant (MIC 64 μg/mL) antibacterial activities. Compounds 1 and 14 showed the best anti-staphylococcal and anti-salmonella activity (MIC 16 µg/mL), respectively. These results partially justified the antimicrobial uses of E. gracilis in traditional medicine.

Phytochemical, Antimicrobial, Antioxidant, and In Vitro Cytotoxicity Evaluation of Echinops erinaceus Kit Tan

Wild plants are used by many cultures for the treatment of diverse ailments. However, they are formed from mixtures of many wanted and unwanted phytochemicals. Thus, there is a necessity to separate the bioactive compounds responsible for their biological activity. In this study, the chemical composition as well as antimicrobial and cytotoxic activities of Echinops erinaceus Kit Tan (Asteraceae) were investigated. This led to the isolation and identification of seven compounds, two of which are new (erinaceosin C3 and erinaceol C5), in addition to methyl oleate (C1) and ethyl oleate (C2), loliolide (C4), (E)-p-coumaric acid (C6), and 5,7,3`,5`-tetrahydroxy flavanone (C7). The structures of the isolated compounds were elucidated by 1D, 2D NMR, and HR-ESI-MS. The methanol extract showed the highest antimicrobial activity among the tested extracts and fractions. The n-hexane and EtOAc extracts showed remarkable antimicrobial activity against B. subtilus, P. aeruginosa, E. coli, and C. albicans. A cytotoxicity-guided fractionation of the most bioactive chloroform extract resulted in the isolation of bioactive compounds C1/C2, which showed significant cytotoxicity against HCT-116 and CACO2 cell lines (IC50 24.95 and 19.74 µg/mL, respectively), followed by compounds C3 (IC50 82.82 and 76.70 µg/mL) and C5 (IC50 99.09 and 87.27 µg/mL), respectively. The antioxidant activity of the bioactive chloroform fractions was screened. Molecular docking was used to explain the results of the antimicrobial and anticancer activities against five protein targets, including DNA gyrase topoisomerase II, enoyl-acyl carrier protein reductase of S. aureus (FabI), dihydrofolate reductase (DHFR), β-catenin, and human P-glycoprotein (P-gp).

Antibacterial and Antioxidant Activities of the Extract and Some Flavonoids From Aerial Parts of Echinops Gracilis O. Hoffm. (Asteraceae)

Mortality due to microbial diseases continues to be a major problem in many developing countries. The present study aims to evaluate the antibacterial and antioxidant activities of the ethyl acetate extract and some isolated compounds from aerial parts of Echinops gracilis. The phytochemical study resulted in the isolation of a new flavonoid derivative named apigenin-7- O-(4″-feruloyl)-β-D-glucoside (1), together with 2 known compounds: apigenin -7-O-(4″-trans- p-hydroxycinnamoyl) -β-D-glucoside (2), and apigenin -7-O-glucoside (3). Their chemical structures were determined using a combination of NMR and IR spectroscopic and MS techniques, as well as by comparison with literature data. The extract and isolates were evaluated for their antibacterial and antioxydant properties. The EtOAc extract and compounds 1 and 2 showed the ability to scavenge 2,2′-zino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS) with scavenging concentration (SC50) values of 13.6 ± 0.8 µg/mL, 108.2 ± 4.3 µg/mL, and 28.5 ± 2.2 µg/mL, respectively. In addition, compound 1 displayed significant activity against Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia, with minimum inhibition concentration (MIC) values of 31.2, 15.6, and 31.2 µg/mL respectively.

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.

Antimalarial Activity of Acetylenic Thiophenes from Echinops hoehnelii Schweinf

Malaria is one of the world’s most severe endemic diseases and due to the emergence of resistance to the currently available medicines, the need for new targets and relevant antimalarial drugs remains acute. The crude extract, four solvent fractions and two isolated compounds from the roots of Echinops hoehnelii were tested for their antimalarial activity using the standard four-day suppressive method in Plasmodium berghei-infected mice. The 80% methanol extract exhibited suppression of 4.6%, 27.8%, 68.5% and 78.7% at dose of 50, 100, 200 and 400 mg/kg respectively. The dichloromethane fraction displayed chemosuppression of 24.9, 33.5 and 43.0% dose of 100, 200 and 400 mg/kg of body weight. Five acetylenicthiophenes were isolated from the dichloromethane fraction of which 5-(penta-1,3-diynyl)-2-(3,4-dihydroxybut-1-ynyl)-thiophene decreased the level of parasitaemia by 43.2% and 50.2% while 5-(penta-1,3-diynyl)-2-(3-chloro-4-acetoxy-but-1-yn)-thiophene suppressed by 18.8% and 32.7% at 50 and 100 mg/kg, respectively. The study confirmed the traditional claim of the plant to treat malaria and could be used as a new lead for the development of antimalarial drugs.

Description of the immature stages of Larinus vulpes and notes on its biology (Coleoptera, Curculionidae, Lixinae)

Mature larva and pupa of Larinusvulpes (Olivier, 1807) (Curculionidae: Lixinae: Lixini) are morphologically described for the first time and compared with known larvae and pupae of other Larinus species. Very high counts of larval body setae (pronotum with more than 25 setae and postdorsum on meso- and metathorax and also on abdominal segments I–VII with more than 12 setae) are characteristic features of the nominotypical subgenusLarinus. The biology of the species was studied in Ukraine. Echinopsruthenicus and E.sphaerocephalus were identified as host plants of both larvae and adults of this weevil based on the present research in Ukraine, which shows probably oligophagous. Overwintering beetles emerged at the end of May or earlier, then feeding and mating on the host plants. The highest level of adult activity was observed at the end of June. Larvae were endophagous within the flower heads. In July and August, the larvae pupated within inflorescences in a pupation cell. Adults exited the cells at the end of August and did not hibernate on the host plants. Sometimes, larvae and imagines of a new generation were found outside the flower heads in chambers constructed on the stems.

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.

Synthesis and anticancer activity of some new s-glycosyl and s-alkyl 1,2,4-triazinone derivatives

A series of S-glycosyl and S-alkyl derivatives of 4-amino-3-mercapto-6-(2-(2-thienyl)vinyl)-1,2,4-triazin-5(4H)-one (1)were synthesized using different halo compounds such as preacetylated sugar bromide, 4-bromobutylacetate, 2-acetoxyethoxy-methyl bromide, 3-chloropropanol, 1,3-dichloro-2-propanol, epichlorohydrin, allyl bromide, propargyl bromide, phthalic and succinic acids in POCl₃. The structures of the synthesized compounds have been deduced from their elemental analysis and spectral (IR, ¹H-NMR, and ¹³C-NMR) data. Some of the synthesized compounds were screened as anticancer agents. Significant anticancer activities were observed in vitro for some members of the series, and compounds 4-Amino-3-(3-hydroxypropylthio)-6-(2-(2-thienyl)vinyl)-1,2,4-triazin-5(4H)-one (12) and 3-(4-Oxo-3-(2-(2-thienyl)vinyl)-4H-[1,3,4]thiadiazolo-[2,3-c][1,2,4]tr-iazin-7-yl)propanoic acid (18) are active cytotoxic agents against different cancer cell lines.

Microwave assisted synthesis of some new fused 1,2,4-triazines bearing thiophene moieties with expected pharmacological activity

Rapid and efficient solvent-free synthesis of 4-amino-3-mercapto-6-[2-(2-thienyl)vinyl]-1,2,4-triazin-5(4H)-one 1 under microwave irradiation is described. Some new fused heterobicyclic nitrogen systems such as 1,2,4-triazino[3,4-b][1,3,4]thiadiazinones, 1,3,4-thiadiazolo[2,3-c][1,2,4]triazinone and pyrazolo[5,1-c]-[1,2,4]triazine-7-carbonitrile, have been synthesized by treatment of 1 with bifunctional oxygen and halogen compounds, CS₂/KOH and malononitrile via heterocyclization reactions, in addition to some uncondensed triazines. Structures of the products have been deduced from their elemental analysis and spectral data (IR, ¹H-NMR, ¹³C-NMR). Select new synthesized compounds were screened as anticancer agents, with some showing activity as cytotoxic agents against different cancer cell lines.

Diethyl 3,4-bis(acetoxy-meth-yl)thieno[2,3-b]thio-phene-2,5-dicarboxyl-ate

In the title compound, C₁₈H₂₀O₈S₂, the dihedral angle between the two thio­phene rings is 2.33 (7)°. The methyl C atoms of the ester groups are disordered over two positions; the site-occupancy factors of the terminal methyl C atoms are 0.632 (18):0.368 (18) and 0.623 (17):0.377 (17). The mol­ecular structure is stabilized by weak intra­molecular C—H⋯O inter­actions and the crystal structure is stabilized through weak inter­molecular C—H⋯O inter­actions.

Screening for antidepressant, sedative and analgesic activities of novel fused thiophene derivatives

This study was aimed at the synthesis of fused benzothiophene derivatives containing heterocyclic moiety. The reaction of the tetrahydrobenzo[b]thiophene derivatives 1a,b with ethoxycarbonylisothiocyanate afforded the thiourea derivatives 2a,b. Cyclization of the latter products gave the annulated benzo[b]thienopyrimidine derivatives 3a,b. Compounds 2a,b and 3a underwent a series of heterocyclization reactions through the reaction with some chemical reagents to give the new benzo[b]thienopyrimidine derivatives 5a,b to 8a-c. Also, this work was extended to study the potential role of the novel synthesized thiourea derivative 2a and benzo[b]thienopyrimidine derivatives 3a, 5b, 6a and 8b as antidepressant, sedative or analgesic agents at two doses (15 or 30 mg kg(-1) body mass). Some compounds (2a, 3a and 5b) showed mild antidepressant activity in the forced-swimming test. No compound showed sedative effect. Visceral pain evoked by i.p. injection of acetic acid in mice was significantly inhibited by all compounds at a high doses.