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

Antioxidant and Cytotoxic Potential of Carlina vulgaris Extract and Bioactivity-Guided Isolation of Cytotoxic Components

Carlina vulgaris is a poorly understood plant in the context of biological activity, despite its widespread application in ethnomedicine in numerous European countries. The aim of this study was to assess the cytotoxic potential of the plant against human colorectal adenocarcinoma (HT29) and to isolate the plant components linked to this effect. Ultra-high performance liquid chromatography with a high-resolution/quadrupole time-of-flight mass spectrometer (UHPLC-HR/QTOF/MS-PDA) was used for the phytochemical characterization of the extract. Liquid-liquid extraction and preparative chromatography were employed for fractionation purposes. Our investigation demonstrated that the ethyl acetate fraction from C. vulgaris showed significant cytotoxicity, and a bioactivity-guided approach led to the isolation of oxylipins, including traumatic acid, pinellic acid, and 9,10-dihydroxy-8-oxsooctadec-12-enic acid. The structures of the compounds were confirmed by nuclear magnetic resonance spectroscopy. Among these compounds, the last one exhibited significant cytotoxicity, though without selectivity, and traumatic acid was characterized by mild cytotoxicity. The cytotoxicity was linked to intracellular reactive oxygen species generation.

Phytochemical Profiling, Antioxidant Activity, and Protective Effect against H2O2-Induced Oxidative Stress of Carlina vulgaris Extract

Carlina vulgaris is a little-understood plant with unexplored biological potential, and the papers regarding its chemical composition are scarce. In our study, for the first time, the phytochemical profile of the plant, focusing on polar metabolites, was established using modern chromatographic techniques including LC-HRMS-QTOF-CAD, UHPLC-PDA-MS. Phytochemical analysis revealed that the species is a rich source of polyphenolic components, with the most abundant being chlorogenic acid and C-glycosides of luteolin, including carlinoside, orientin, isoorientin, and C-glycosides of apigenin, schaftoside, isoschaftoside, and vitexin. Furthermore, we assessed the impact of the polyphenolic-rich fraction of C. vulgaris extracts on human skin fibroblasts using the MTT and NR assays. It was found that the extract was non-toxic and exhibited potent antioxidant activity in the cells subjected to induced oxidative stress. Additionally, it effectively protected the cells against H₂O₂-induced cytotoxicity. Our study contributes to the general trend of searching for new phytotherapeutics with potential applications in pharmacy and medicine. The results indicate that further exploration of C. vulgaris species is worthwhile, as they can serve as valuable plant material for cosmetic use.

Exploring Echinops polyceras Boiss. from Jordan: Essential Oil Composition, COX, Protein Denaturation Inhibitory Power and Antimicrobial Activity of the Alcoholic Extract

In this article, we present the first detailed analysis of the hydro-distilled essential oil (HDEO) of the inflorescence heads of Echinops polyceras Boiss. (Asteraceae) from the flora of Jordan, offering observations at different growth (pre-flowering, full-flowering and post-flowering) stages. Additionally, we investigated the methanolic extract obtained from the aerial parts of the plant material at the full flowering stage in order to determine its inhibitory activity in terms of COX and protein denaturation and evaluate its antimicrobial effects against S. aureus (Gram-positive) and E. coli (Gram-negative) bacteria. Performing GC/MS analysis of HDEO, obtained from the fresh inflorescence heads at the different growth stages, resulted in the identification of 192 constituents. The main class of compounds detected in these three stages comprised aliphatic hydrocarbons and their derivatives, which amounted to 50.04% (pre-flower), 40.28% (full-flower) and 41.34% (post-flower) of the total composition. The oils also contained appreciable amounts of oxygenated terpenoids, primarily sesquiterpenoids and diterpenoids. The pre-flowering stage was dominated by (2E)-hexenal (8.03%) in addition to the oxygenated diterpene (6E,10E)-pseudo phytol (7.54%). The full-flowering stage primarily contained (6E,10E)-pseudo phytol (7.84%), β-bisabolene (7.53%, SH) and the diterpene hydrocarbon dolabradiene (5.50%). The major constituents detected in the HDEO obtained at the post-flowering stage included the oxygenated sesquiterpenoid intermedeol (5.53%), the sesquiterpene hydrocarbon (E)-caryophyllene (5.01%) and (6E,10E)-pseudo phytol (4.47%). The methanolic extract obtained from air-dried aerial parts of E. polyceras displayed more COX-2 inhibition than COX-1 inhibition at a concentration level of 200 µg/mL. The extract exhibited a capacity to inhibit protein denaturation that was comparable with respect to the activity of diclofenac sodium and displayed moderate levels of antimicrobial activity against both bacterial species. The current results demonstrate the need to perform further detailed phytochemical investigations to isolate and characterize active constituents.

Synthesis of Carlina Oxide Analogues and Evaluation of Their Insecticidal Efficacy and Cytotoxicity

Compounds isolated from botanical sources represent innovative and promising alternatives to conventional insecticides. Carlina oxide is a compound isolated from Carlina acaulis L. (Asteraceae) essential oil (EO) with great potential as bioinsecticide, being effective on various arthropod vectors and agricultural pests, with moderate toxicity on non-target species. Since the production from the wild source is limited, there is the need of exploring new synthetic routes for obtaining this compound and analogues with improved bioactivity and lower toxicity. Herein, the chemical synthesis of carlina oxide analogues was developed. Their insecticidal activity was assessed on the vectors Musca domestica L. and Culex quinquefasciatus Say, and their cytotoxicity was evaluated on a human keratinocyte cell line (HaCaT). The compounds' activity was compared with that of the natural counterparts EO and carlina oxide. In housefly tests, the analogues were comparably effective to purified carlina oxide. In Cx. quinquefasciatus assays, the meta-chloro analogue provided a significantly higher efficacy (LC₅₀ of 0.71 μg mL^-1) than the EO and carlina oxide (LC₅₀ 1.21 and 1.31 μg mL^-1, respectively) and a better safety profile than carlina oxide on keratinocytes. Overall, this study can open the way to an agrochemical production of carlina oxide analogues employable as nature-inspired insecticides.

Comprehensive Evaluation of the Antibacterial and Antifungal Activities of Carlina acaulis L. Essential Oil and Its Nanoemulsion

Plants are considered to be an excellent source of new compounds with antibiotic activity. Carlina acaulis L. is a medicinal plant whose essential oil (EO) is mainly characterized by the polyacetylene carlina oxide, which has antimicrobial properties. The aim of this study was to evaluate the antimicrobial and antifungal activities of C. acaulis EO, carlina oxide, and nanoemulsion (NE) containing the EO. The EO was obtained through plant roots hydrodistillation, and carlina oxide was purified from it through silica gel column chromatography. The NE containing C. acaulis EO was prepared with the high-pressure homogenization method, and the minimum inhibitory concentration (MIC) was determined against several bacterial and fungal strains for all the C. acaulis-derived products. The latter resulted active versus all the screened Gram-positive bacterial strains and also on all the fungal strains with low MIC values. For yeast, the EO and carlina oxide showed good MIC values. The EO-NE demonstrated a better activity than the pure EO on all the tested bacterial and fungal strains. The results suggest that C. acaulis-derived products could be potential candidates for the development of natural antibacterial and antifungal agents.

Chemical Variability and Antioxidant Activities of the Essential Oils of the Aerial Parts of Ammoides verticillata and the Roots of Carthamus caeruleus and their Synergistic Effect in Combination

AIM AND OBJECTIVE

Oxidative stress is implicated in the development and progression of many diseases. Some of the appropriate actions that could taken to resolve the problem of these diseases are search for new antioxidant substances isolated from plants. The aims of this study were to research the intraspecies variations of A. verticillata and C. caeruleus essential oils from 8 locations using statistical analysis, the in vitro antioxidant properties of collective essential oils and in combinations.

MATERIALS AND METHODS

The essential oils were analyzed by GC and GC-MS. The intraspecies variations of the essential oil compositions were discussed using principal component analysis (PCA) and cluster analysis (CA). The antioxidant properties were evaluated DPPH-radical scavenging activity and β-carotene bleaching test.

RESULTS

The main components of Ammoides verticillata collective essential oil (Coll EO) were thymol (30.5%), carvacrol (23.2%), p-cymene (13.1%), limonene (12.5%) and terpinene-4-ol (12.3%). While roots of Carthamus caeruleus essential oil were dominated by carline oxide (86.2%). The chemical variability allowed the discrimination of two main Groups for both Coll EOs. A direct correlation between the altitudes, climate and the chemical compositions was evidenced. Ammoides verticulata and Carthamus caeruleus Coll Eos showed good antioxidant activity. In binary mixture, the interaction between both Coll Eos and between oils rich of thymol and/or carvacrol with carlina oxide produced the best synergistic effects compared to individual essential oils and the synthetic antioxidant (BHT).

CONCLUSION

Ammoides verticillata and Carthamus caeruleus essential oil blends can be used as a natural food preservative and alternative to chemical antioxidants.