Centaurea polyacantha and C. maroccana: the chemical composition of the aerial parts essential oils of these Centaurea species (Asteraceae) collected in Morocco

In the present study, the chemical composition of the essential oil from the aerial parts of two Centaurea species not previously investigated, C. polyacantha Willd. (sect. Seridia, Asteraceae) and C. maroccana Ball. (sect. Calcitrapa, Asteraceae), collected in Morocco, was evaluated by GC-MS. The main components of the essential oil of the first one were limonene (18.2%), β-bisabolene (11.5%), (Z)-β-farnesene (8.6%), and spathulenol (8.3%), whereas the C. maroccana essential oil, practically devoid of terpenoids, was shown to be rich in some unusual Centaurea metabolites: 1-hexadecanol (24.9%), docosane (23.7%), and 1-octadecanol (19.5%). Furthermore, a complete literature review on the composition of the essential oils of all the other taxa of Centaurea, belonging to sections Seridia and Calcitrapa, studied so far, was performed.

Insecticidal and Enzyme Inhibition Activities of Leaf/Bark Extracts, Fractions, Seed Oil and Isolated Compounds from Triadica sebifera (L.) Small against Aphis craccivora Koch

Aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is a major sap-sucking insect pest of leguminous crops and also transmits plant viruses, leading to economic yield loss. Indiscriminate and repeated use of insecticides for control of aphid leads to the development of resistance, and is harmful to the environment, non-target organisms, etc. Plant-based extracts/seed oils (SO) are the best alternatives to insecticides. Insecticidal activities of Triadica sebifera have not been reported against A. craccivora and other insect pests to date. In the current study, the main objective was to study the insecticidal activities of leaf/bark extracts/fractions, seed oil, isolated compounds, and their combinations against A. craccivora. Results showed that, among the extracts, ethanolic bark extract 80% (LC₅₀ = 5115.98 mg/L) was more effective against A. craccivora. Among fractions, the n-hexane fraction of leaves (LC₅₀ = 425.73 mg/L) and the ethyl acetate fraction of bark (LC₅₀ = 813.45 mg/L) were promising. Among compounds, gallic acid was the most effective (LC₅₀ = 1303.68 mg/L) compared to shikimic acid and quercetin. SO (LC₅₀ = 850.94 mg/L) was superior compared to extracts/fractions/compounds. All the combinations showed toxicity and synergistic activity. Leaf/bark extracts and SO significantly inhibited the AChE and GST activity in A. craccivora. Based on field bio-efficacy, the leaf extract/SO or their combinations can be recommended for the control of aphids.

Comparative Study on the Essential Oils from Five Wild Egyptian Centaurea Species: Effective Extraction Techniques, Antimicrobial Activity and In-Silico Analyses

The genus Centaurea is recognized in folk medicine for anti-inflammatory, anti-itch, antitussive, purgative, astringent, and tonic activities. To study the chemical determinant for antimicrobial activity essential oils (EOs), five Centaurea species were analyzed including: C. scoparia, C. calcitrapa, C. glomerata, C. lipii and C. alexandrina. Conventional hydro-distillation (HD) and microwave-assisted extraction (MAE), as new green technologies, were compared for the extraction of essential oils. GC/MS analysis identified 120 EOs including mostly terpenoid except from C. lipii and C. alexandrina in which nonterpenoids were the major constituents. Major terpenoids included spathulenol, caryophyllene oxide and alloaromadendrene oxide-2. To probe antibacterial activity, potential EO inhibitors of a bacterial type II DNA topoisomerase, DNA gyrase B were screened via an in silico molecular docking approach. Spathulenol and alloaromadendrene oxide-2 possessed the best binding affinity in the ATP- binding pocket of Gyrase B enzyme. Principal component analysis and agglomerative hierarchical clustering were used for sample classification and revealed that sesquiterpenes contributed the most for accessions classification. In vitro antimicrobial activity against Staphylococcus aureus, Escherichia coli and Aspergillus niger for all EOs were also evaluated. EOs from C. lipii, C. glomerata and C. calcitrapa exhibited significant MIC against S. aureus with an MIC value of 31.25 µg/mL.

In vitro antioxidant, DNA-damaged protection and antiproliferative activities of ethyl acetate and n-butanol extracts of Centaurea sphaerocephalaL

This study aimed to evaluate the in vitro antiproliferative and inhibition of oxidative DNA-damage activities of n-butanol (n-BuOH) extract of Centaurea sphaerocephala. The in vitro antioxidant activity of the ethyl acetate (EtOAc) and the n-BuOH extracts of this plant were also assayed. To investigate the antioxidant potential, extracts were tested for their capacity to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH·) and to inhibit lipid peroxidation using the TBARs method. The contents of total phenolics and flavonoids were measured. Additionally, antiproliferative activity and DNA-damage inhibition of the n-BuOH extract was determined using XCELLigence RTCA instrument and photolyzing 46966 plasmid, respectively. The results exhibited that the scavenging abilities of the EtOAc extract were better than the n-BuOH extract with an IC50= 11.59 µg/mL and 16.67 µg/mL for both extracts, respectively. The phenolic and flavonoid contents were found higher in the n-BuOH and EtOAc extracts. Furthermore, our results showed that n-BuOH extract exhibited a remarkable inhibition of lipid peroxidation with an IC50 of 340.94±7.49 μg/mL and had an antiproliferative effect against Hela cells. Extracts of C. sphaerocephala showed antioxidant activity on scavenging DPPH·. In addition, the n-BuOH extract inhibited the lipid peroxidation and exhibited an antiproliferative effect against HeLa cells line (human cervix carcinoma).

Chemical Composition and Biological Activity of Centaurea baseri: New Species from Turkey

The genus Centaurea L. is one of the largest and important genera of Asteraceae family. Centaurea species have been widely used as herbal remedies in folk medicine for their antidandruff, antidiarrheic, antirheumatic, anti-inflammatory, choleretic, diuretic, digestive, stomachic, astringent, antipyretic, cytotoxic, and antibacterial properties. Centaurea baseri Kose & Alan is a recently described local endemic species in Turkey and this is the first study on the chemical composition and bioactivity of its hydrodistilled essential oil and the crude extract. According to chromatospectral analysis, hexadecanoic acid (42.3%), nonacosane (8.2%), and heptacosane (8.0%) were the main compounds of the essential oil, while 16 compounds were determined in the MeOH extract using LC/MS. Furthermore, antimicrobial, antioxidant, and cytotoxic effects of the essential oil and the extract were evaluated in comparison with the standard agents. The extract showed strong antifungal effect against Candida utilis at the concentration of 60 μg/ml (MIC) where the EO showed growth inhibition at the concentration of 47.00 μg/ml (MIC) against pathogen Bacillus cereus. Both the essential oil and the extract did not show any selective antioxidant properties. The extract showed remarkably selective cytotoxic properties against MCF-7, PANC-1, A549, and C6 glioma cells.

Bioactive Volatile Content of the Stem and Root ofCentaurea carduiformisDC. subsp.carduiformisvar.carduiformis

Several species ofCentaurea, biennial (or more rarely perennial) plants which belong to the Asteraceae family, possess medicinal properties and are currently used in phytotherapy. In the present study, antiproliferative activity of hexane extract from stems and roots ofCentaurea carduiformisDC. subsp.carduiformisvar.carduiformis(CCS and CCR) on Vero cells (African green monkey kidney), C6 cells (Rat Brain tumor cells), and HeLa cells (human uterus carcinoma) was investigatedin vitro. Antiproliferative effect of the extract was tested at 500 μg/mL and 1000 μg/mL using BrDu Cell Proliferation ELISA. The hexane extract was significantly inhibited proliferation of Vero, HeLa, and C6 cancer cell lines with absorbance values. The extract of CCS and CCR showed the highest activity against the Vero, HeLa, and C6 cell lines at 500 μg/mL and 1000 μg/mL.

Volatile Components from Aerial parts of Centaurea gracilenta and C. ovina ssp. besserana Growing Wild in Bulgaria

The essential oils of Centaurea gracilenta Velen. (CG) and C. ovina Pall. ex Willd. ssp. besserana (DC.) Dostál (COB) growing wild in Bulgaria, were studied by GC and GC-MS. Forty-five compounds for CG, representing the 90.1% of the oil, and 68 compounds for COB, representing the 91.9% of the oil, were identified. The oils were rich in sesquiterpenoids (33.4% for CG and 27.3% for COB), hydrocarbons (28.3% for CG and 10.7% for COB) and carbonylic compounds (12.7% for CG and 13.1% for COB). Fatty acids were abundant only for COB (31.3%). β-Eudesmol (12.8%), nonacosane (11.8%) and p-vinyl guiacol (7.5%) were recognized as the main constituents for CG, while hexadecanoic acid (21.4%), spathulenol (7.9%), β-eudesmol (5.8%) and caryophyllene oxide (5.7%) were the main compounds for COB.

Volatile Components of Two Endemic Species from the Apuan Alps (Tuscany, Italy), Centaurea Arachnoidea and C. Montis-Borlae (Asteraceae)

The volatile fractions of Centaurea arachnoidea and C. montis-borlae, two endemic species growing wild in the Apuan Alps (Tuscany, Italy), were isolated by steam distillation from fresh leaves and flowerheads, and analyzed by GC/FID and GC/MS. The yield of essential oil ranged from 0.01% to 0.09% of fresh material. A wide variety of volatile compounds was detected in the examined plant species and organs, both in qualitative and quantitative terms. Sesquiterpenes were the major constituents, ranging from 18.9% to 73.2% of the total oil. Alcohols (1.6-25.8%), aldehydes (1.5-12.0%), hydrocarbons (1.8-11.9%), acids (0.2-25.4%), esters (0.2-1.3%), monoterpenes (0.7-1.4%), and miscellaneous compounds (0.6-2.6%), were also detected in variable amounts in all different sample tissues. A series of unidentified compounds was also isolated from the two species, both in leaves and flowerheads, accounting for 2.4-6.7% of the total oil. According to MS spectral data, these substances were likely to be polyunsaturated compounds; moreover, they appear to be species-specific, as their presence was only detected in either one or the other Centaurea species.

Essential Oil Composition of Tanacetum vulgare Subsp. Siculum (Guss.) Raimondo et Spadaro (Asteraceae) from Sicily

Ninety-four components of the essential oils from aerial parts and capitula of Tanacetum vulgare subsp. siculum (Guss.) Raimondo et Spadaro were detected. α-Thujone, β-thujone and 1,8-cineole were the main constituents of the oils. The analysis allows the assignment of this Tanacetum species to the thujone chemotype.

Norsesquiterpene hydrocarbon, chemical composition and antimicrobial activity of Rhaponticum carthamoides root essential oil

A detailed analysis of Rhaponticum carthamoides (Willd.) Iljin root essential oil was carried out by GC, GC-MS and GC-FTIR techniques. In total, 30 components were identified, accounting for 98.0% of total volatiles. A norsesquiterpene 13-norcypera-1(5),11(12)-diene (22.6%), followed by aplotaxene (21.2%) and cyperene (17.9%), were isolated and their structures confirmed by 1D and 2D-NMR spectra (COSY, ROESY, HSQC, HMBC and INADEQUATE). Selinene type sesquiterpenes and aliphatic hydrocarbons were among minor constituents of the essential oil. The oil exhibited antimicrobial activity against 5 of 9 strains of bacteria and yeast, when tested using broth micro-dilution method. Minimum inhibitory concentrations ranged between 32 and 256 microg/ml.

Chemical Composition of the Essential Oils of Centaurea Sicana and C. Giardinae Growing Wild in Sicily

The essential oils of Centaurea sicana (S) and C. giardinae (G) were studied by GC and GC-MS. Thirty constituents for S, representing 81.5% of the total oil, and 24 compounds for G (94.2% of the total) were identified. The oils were rich in sesquiterpenoids (47.9% for S and 54.7% for G) and hydrocarbons (25.9% for S and 31.7% for G). Germacrene D (13.3%), ( E)-β-farnesene (8.3%), nonacosane (7.3%), heptacosane (6.5%) and phytol (6%) were recognized as the main constituents for S, while caryophyllene oxide (17.7%), nonacosane (14.5%), germacrene D (11.5%), caryophyllene (11.2%) and heptacosane (10.3%) were the main compounds for G.