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

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).

Chemical Composition and Biological Activities of Essential Oils of Echinops spinosus and Carlina vulgaris Rich in Polyacetylene Compounds

Background:

The essential oils of aromatic plants are increasingly used as new biocontrol alternative agents against microbial strains and insect pests of fruits and vegetables, because of their specificity of biodegradable nature.

Objective:

This work, treats for the first time the chemical composition, antioxidant, antifungal and insecticidal activities of the essential oils obtained from Echinops spinosus and Carlina vulgaris from Algeria.

Methods:

The chemical compositions of oils were investigated using GC-FID and GC/MS. Antioxidant activity was assessed using three methods (2,2-diphenyl-1-picrylhydrazyl, Ferric-Reducing Antioxidant Power (FRAP) and β-carotene assay). Fumigation toxicity of E. spinosus and C. vulgaris essential oils was tested against Bactrocera oleae pests of olives.

Results:

Eighteen and thirteen components representing 95.4 and 97.9% were identified in root essential oils from Echinops spinosus and Carlina vulgaris, respectively. Polyacetylenes were the majority compounds of essential oils. 5 (But-1-yn-3-enyl).2,2'bithiophene and α-terthienyle were highly dominants in the E. spinosus essential oil from the roots (54.4 and 26.3%, respectively). Roots of C. vulgaris produce an essential oil dominated by carlina oxide (33.7%) and 13-methoxy carlina oxide (11.5%). Comparison of the antioxidant activity of E. spinosus essential oil showed more important antioxidant effect than C. vulgaris essential oil and the synthetic antioxidant (BHT). Evaluation of the antifungal activity showed an interesting efficiency of both essential oils against P. expansum and A. niger with EC50s varied from 5 to 14.5 mg/L. C. arvensis essential oil exhibited good larvicidal properties. At the concentration of 325 μL/L air, the oil caused mortality of 100% for Bactrocera Oleae adults after 24 h of exposure.

Conclusion:

Both essential oils rich to polyacetylenes and polythiophenes.components have shown interesting biological activities, which suggests that plants have the potential to be used as biopesticides and provide an alternative to chemical pesticides.

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.

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.

Essential-Oil Constituents and Alkanes of Cephalaria ambrosioides Roem. & Schult. (Family Caprifoliaceae, Subfamily Dipsacaceae) and (Chemo)taxonomic Discernment of the Subfamilies Dipsacaceae and Morinaceae

Herein, the results of the first study of the volatile and alkane profiles of Cephalaria ambrosioides Roem. & Schult. (Caprifoliaceae, subfamily Dipsacaceae) were reported. The GC-FID and GC/MS analyses of the essential oils hydrodistilled from leaves and stems (CA1) and flowers (CA2) of C. ambrosioides allowed the identification of 284 different components. The main compounds of the studied oil samples were palmitic acid (24.3 and 32.5% for CA1 and CA2, resp.), hexahydrofarnesyl acetone (1.4 and 10.8% for CA1 and CA2, resp.), (Z)-hex-3-en-1-ol (7.0 and <0.1% for CA1 and CA2, resp.), and linoleic acid (1.9 and 6.5% for CA1 and CA2, resp.). Essential-oil compositional data of selected plant species belonging to the Dipsacaceae (15) and Morinaceae (2) subfamilies were used to resolve taxonomical ambiguities regarding the genus Cephalaria and its infrageneric relations, especially concerning the subfamily Morinaceae (formerly a genus within Dipsacaceae). The results of multivariate statistical analyses (25 different essential-oil samples) supported the exclusion of Morina species from the Dipsacaceae subfamily. The relative abundances of alkanes from n-, iso-, and anteiso-series followed a (distorted) Gaussian-like distribution and suggested that the biosyntheses of n- and branched alkanes in C. ambrosioides are possibly not controlled by the same elongase. Also, the obtained results suggested that there was a difference in the biosynthesis/accumulation of alkanes in the vegetative and reproductive parts of C. ambrosioides.

GC-MS Analysis of Insecticidal Essential Oil of Aerial Parts ofEchinops latifoliusTausch

The roots ofEchinops latifoliusTausch (Asteraceae) have been used in the traditional medicine. However, no report on chemical composition and insecticidal activities of the essential oil of this plant exists. The aim of this research was to determine chemical composition and insecticidal activities of the essential oil ofE. latifoliusaerial parts against maize weevils (Sitophilus zeamaisMotschulsky) for the first time. Essential oil ofE. latifoliusaerial parts at flowering stage was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 35 components of the essential oil ofE. latifoliusaerial parts were identified. The major compounds in the essential oil were 1,8-cineole (19.63%), (Z)-β-ocimene (18.44%), andβ-pinene (15.56%) followed byβ-myrcene (4.75%) and carvone (4.39%). The essential oil ofE. latifoliuspossessed contact toxicity againstS. zeamaiswith an LD50value of 36.40 µg/adult. The essential oil also exhibited fumigant toxicity againstS. zeamaiswith an LC50value of 9.98 mg/L. The study indicates that the essential oil ofE. latifoliusaerial parts has a potential for development into a natural insecticide/fumigant for control of insects in stored grains.