Antifeedant and toxicity effects of thiophenes from four Echinops species against the Formosan subterranean termite, Coptotermes formosanus

Echinops spinosissimus Turra Root Methanolic Extract: Characterization of the Bioactive Components and Relative Wound Healing, Antimicrobial and Antioxidant Properties

Echinops spinosissimus Turra subsp. bovei (Asteraceae) is a medicinal plant in western Algeria. Traditionally, roots and inflorescences are employed as hypertensive agents and in the treatment of hemorrhoids. The current study evaluates the chemical composition, antioxidant, antimicrobial, and wound-healing properties of the root methanolic extract from E. spinosissimus subsp. bovei. The content of total phenolics, flavonoids, and tannins was determined. In addition, the phenolic profile was typified. The studied plant extract resulted in being primarily composed of Apigenin, Kaempferol, and their derivatives. The total phenolic content was equal to 95.31 ± 2.90 mg GAE/g DW, while the number of flavonoids and condensed tannins was 16.01 ± 0.16 mg CE/g DW and 8.30 ± 0.65 mg CE/g DW, respectively. The methanolic extract was found to exhibit antioxidant activity towards the DPPH radical, with an IC₅₀ of 7.99 ± 0.28 mg/mL and a TAC of 30.30 ± 0.54 mg AAE/g DW, as well as an antibacterial effect, especially against P. aeruginosa. No significant wound-healing property was observed, even though the histopathological observations showed enhanced wound-healing quality. According to our evidence, E. spinosissimus could represent a source of phytochemicals with potential beneficial effects for human health in terms of antioxidant and antibiotic properties, although further investigations on this species are needed.

Phenolic profile (HPLC-UV) analysis and biological activities of two organic extracts from Echinops spinosissimus Turra roots growing in Tunisia

Echinops spinosissimus Turra subsp. roots was investigated, after extraction with two different solvents: ethanol and ethyl acetate, for its phenolic profile as well as biological activities. Echinops spinosissimus Turra subsp. spinosus roots ethanolic extract was characterized by the highest content of total polyphenols (19.3 mg GAE/100 g of DW). In addition, the phenolic profiles of the two studied extracts were analysed using HPLC-UV, where p-coumaric (8.59 mg/kg of DW) and cinnamic acids (4.68 mg/kg of DW) were detected as the most abundant phenolic acids, and kaempferol was the predominant flavonoids (30.37 mg/kg of DM) followed by quercetin and rutin in the ethanolic extract. While, only p-coumaric acid, epicatechin, kaempferol and quercetin were identified and quantified in ethyl acetate roots extract. All tested extracts exhibited an antimicrobial effect against Gram-positive and Gram-negative bacteria. These findings indicate that Echinops spinosissimus Turra subsp. spinosus roots can be regarded as a new source of edible oil having health benefits and nutritional properties.

New antibacterial thiophenes from Eclipta prostrata

Three new thiophene derivatives, ecliprostins A-C (1-3), have been isolated from the aerial parts of a Compositae medicinal plant Eclipta prostrata, and structures of them have been elucidated by comprehensive spectroscopic analyses. Both ecliprostins A (1) and B (2) feature an acetylenic bithiophenyl backbone and also incorporate an isovalerate moiety, while ecliprostin C (3) is a symmetrical dimer of compound 1 and represents the first example bonded via an ether bridge among the very limited natural dimers. All three compounds show antibacterial activity against Staphylococcus aureus.

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.

Thiophenes from Echinops grijsii as a Preliminary Approach To Control Disease Complex of Root-Knot Nematodes and Soil-Borne Fungi: Isolation, Activities, and Structure-Nonphototoxic Activity Relationship Analysis

Naturally occurring thiophenes possess excellent nematicidal and fungicidal activities. However, thiophenes often have limited application in soil due to their light-dependent toxicity given the living and reproductive condition of soil-borne pathogens. In this study, six new (1-6) and six known thiophenes (7-12) were isolated from Echinops grijsii. Compounds 1-2, 4-5, 8-9, 11 , and 12 showed stronger nematicidal activity against Meloidogyne incognita than commercial nematicide abamectin. 4-10 were demonstrated as nonphototoxic thiophenes. Among these, 4 and 8 were the most potent thiophenes (LC₅₀ values 2.57 and 0.91 μg/mL in light, 1.80 and 0.86 μg/mL in dark, respectively) against M. incognita. SAR revealed that thiophene skeleton was essential for nematicidal activity, while disubstituted groups were helpful for nonphototoxicity. Although an increased number of acetylenes improved activity, it decreased nonphototoxicity. Acyl groups could suppress the effects of light on activity, with the level of inhibitory effects depending on its number and chain length, while chlorine played important roles in promoting activity. Additionally, compounds 1-2, 4-5, 7, 8, and 10 displayed antifungal activity against six soil-borne fungi in various degrees. The discovery of nonphototoxic thiophenes and elucidation of SAR provide important information for the exploitation and utilization of thiophenes in the integrative management regarding disease complexes caused by the combination of root-knot nematode and soil-borne fungi.

Comparative chemical analysis of volatile compounds of Echinops ilicifolius using hydrodistillation and headspace solid-phase microextraction and the antibacterial activities of its essential oil

The volatile compounds from various parts of Echinops ilicifolius (Compositae) such as flowers, leaves and roots obtained by hydrodistillation (HD) and headspace solid-phase microextraction (HS-SPME) methods were subsequently analysed by GC and GC/MS and compared. Thirty-seven and 20 components of the flower of E. ilicifolius were characterized, representing 99.7% and 100.0% of the total compositions using the HD and HS-SPME methods, respectively. The major constituents of the hydrodistilled oil were identified as linalool (58.6%), geraniol (17.4%), n-dodecane (10.9%) and nerol (5.4%), whereas HS-SPME extract was rich in n-octane (34.0%), n-decane (25.1%), p-cymene (11.1%), γ-terpinene (5.3%) and 1,8-cineole (5.1%). n-Hexadecanoic acid (32.3%), linalool (16.4%) and geraniol (8.3%) were the main components among 43 constituents identified in hydrodistilled extract of the leaf, representing 99.5% of the total components detected, whereas 16 compounds representing 99.9% of the HS-SPME method were identified, among which n-decane (32.6%), p-cymene (14.0%), n-octane (10.3%), limonene (9.2%), γ-terpinene (9.1%), 1,8-cineole (7.9%) and α-pinene (5.9%) were the major ones. Among 23 components comprising 91.2% of the total hydrodistilled oil detected, n-decane (23.1%), n-dodecane (14.5%), silphiperfol-4,7(14)-diene (11.1%), selin-11-en-4-a-ol (9.5%), n-hexadecanoic acid (7.8%) and n-tetradecane (5.3%) were the main constituents in the root of E. ilicifolius, whereas 1,8-cineole (29.0%), n-decane (12.6%), n-octane (12.6%), camphor (12.0%), p-cymene (9.6%) and γ-terpinene (5.9%) were the main components among the 20 constituents characterized in HS-SPME extract, representing 99.9% of the total components detected. The antibacterial activity of the flower, leaf and root oils of E. ilicifolius against six Gram-positive and Gram-negative bacteria was determined using the MIC method. The growth inhibitory zone (mm) was also measured.

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.

Chemical Composition and Termiticidal Activity of Essential Oils from Different Tissues of Chinese Cedar (Cryptomeria fortunei)

In this study antitermitic activities of essential oils from different tissues of Chinese cedar (Cryptomeria fortunei Hooibrenk) against Reticulitermes chinensis were investigated. In addition, the yields of essential oils obtained by water distillation were compared and their constituents determined by GC-MS analyses. The yields of bark, sapwood, heartwood, and leaf essential oils of Chinese cedar were 0.9, 0.4, 1.0, and 1.5%, respectively. GC-MS analyses showed that the major compounds of bark, sapwood, heartwood, and leaf essential oils of Chinese cedar were ferruginol (30.6%), γ-cadinene (18.3%), γ-cadinene (31.0%), and kaurene (30.6%), respectively. Bioactivity tests against R. chinensis demonstrated that the leaf and heartwood essential oils had an excellent effect, and the LC50 values after 5 days were 0.9 and 1.8 μL/mL (LC90=1.4 and 2.9 μL/mL), respectively. The results of this study showed that the leaf and heartwood essential oils of Chinese cedar might be considered as a potential source of a fine natural termiticide.

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.

Isolation and identification of Flavobacterium columnare and Streptococcus iniae antibacterial compounds from the terrestrial plant Atraphaxis laetevirens

Columnaris disease, enteric septicemia of catfish, and streptococcosis are common bacterial diseases of certain freshwater fish and are caused by Flavobacterium columnare , Edwardsiella ictaluri , and Streptococcus iniae , respectively. During the process of evaluating several species of plants to isolate and identify compounds with toxicity against these bacteria, a promising extract from the aerial parts of the terrestrial plant Atraphaxis laetevirens (Ledeb.) Jaub. et Spach (Polygonaceae Juss.) was selected for bioassay-guided fractionation using a rapid microplate bioassay. The active dichloromethane extract was subjected to liquid-liquid partitioning, and active fractions were further separated by normal-phase column chromatography and normal-phase high-performance liquid chromatography (HPLC). Nepodin (3) and emodin (4) were isolated from two fractions with strong toxicities against S. iniae . A chloroform fraction was further separated by normal-phase column chromatography to yield two active fractions against F. columnare , and these fractions contained chrysophanol (1), physcion (2), and nepodin (3). Compound 1 had strong activity, and compound 3 had moderate activity against F. columnare , while compounds 2 and 4 were not toxic at the concentrations tested.

Acromyrmex octospinosus (Hymenoptera: Formicidae) management. Part 1: Effects of TRAMIL's insecticidal plant extracts

BACKGROUND

Leaf-cutting ants are considered to be one of the most important pest species of the New World. Until now, control strategies against these leaf-cutting ants have mainly been synthetic chemicals. The aim of the present study was to test the action of several plant extracts quoted as an example by TRAMIL participative surveys for their insecticidal properties on adult major workers of Acromyrmex octospinosus. Three tests were used to that end: contact toxicity, repellent test and ingestion bioassay. Six traditional plant uses recommended by interviewed people in surveys were tested: (1) maceration of Mammea americana fresh crushed seeds; (2) decoction of Nerium oleander fresh leaves; (3) Nerium oleander dried leaf water juice; (4) decoction of Nicotiana tabacum dried leaves; (5) Trichillia pallida dried leaf water juice; (6) decoction of Rollinia mucosa dried seeds.

RESULTS

Two plant extracts with contact toxicity (Mammea americana and Nicotiana tabacum), six plant extracts with repellent activity and four plant extracts with ingestion toxicity (Mammea americana, Nicotiana tabacum and both extracts of Nerium oleander) were found.

CONCLUSION

The data presented in this study showed that plant extracts cited by TRAMIL ethnopharmacological surveys have the potential to control the leaf-cutting ant, Acromyrmex octospinosus. In particular, the Mammea americana extract, with its natural low repellent effect and its high toxicity by ingestion, and Nerium oleander extracts, with their natural delay action, are possibly the best extracts for the control of these ants.

Echinopsacetylenes A and B, new thiophenes from Echinops transiliensis

Two new polyacetylene thiophenes, echinopsacetylenes A and B (1 and 2), were isolated from the roots of Echinops transiliensis. The structures of 1 and 2 were elucidated on the basis of spectroscopic analyses and chemical transformations. Echinopsacetylenes A (1) is the first natural product possessing an α-terthienyl moiety covalently linked with another thiophene moiety. Echinopsacetylenes B (2) is the first natural thiophene conjugated with a fatty acid moiety. Echinopsacetylene A (1) showed toxicity against the Formosoan subterranean termite (Coptotermes formosanus).

Bacillus subtilis subspecies virginiana, a new subspecies of antitermitic compound-producing endophytic bacteria isolated from Juniperus virginiana

Termites are worldwide pests causing considerable damage to agriculture, forestry and buildings. Although physical and chemical methods have been tried to eliminate termite populations, they have the limitations such as low effectiveness, high-toxicity residue, environmentally harmful and high cost. Therefore, it has attracted much attention to develop highly effective, low-toxic, long residual period, environmentally friendly and low-cost termiticidals. Here, we report the characterization and antitermitic activities of a new antitermitic compound-producing endophytic bacterium HUB-I-47 isolated from eastern red-cedar, Juniperus virginiana L. The morphological, physiochemical characteristics of strain HUB-I-47 and its 16S rDNA sequences, and the antitermitic compound were analyzed by gas chromatography-mass spectrometry were studied. We found that the morphology of HUB-I-47 was very similar to that of Bacillus subtilis but presented some differences in shape and cell size. Growth evaluation showed that the lowest, highest, and optimum growth temperatures of HUB-I-47 were 12, 47, and 31 degrees C, respectively, which were different from those of reference strains. The 16S rDNA sequence analysis revealed a high similarity of 99% to those of B. subtilis. Based on these analyses, we named strain HUB-I-47 as B. subtilis subsp. virginiana D. P. Zhou, K. Zhao, J. Liu et W. X. Ping, subsp. nov. This is the first report on the analysis of antitermitic compounds from endophytic bacteria. Our study identified a new resource of antitermitic compounds through endophytic bacteria fermentation.