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Phyllotaxis of inflorescences in Carlina acaulis L. is spiral. In the majority of capitula it is represented by the main Fibonacci series. From the one thousand of specimens, that were examined, thirty five new phyllotactic series were found: eighteen monojugies, for instance (2,17), (4,11), (7,37) and seventeen multijugies, such as 2(8,9), 2(5,11), 8(2,3). The patterns had been identified on the basic of two or more consecutive numbers of phyllotactic series. Both, the continuous and discontinous transformations of phyllotactic patterns, as well as \"deviations\" from the parastichy group numbers were observed. The deviations were distinguished as the probable cases of the discontinuous transformations in which the sectorial change in the parastichy number occured, but the ultimate phyllotactic series could not be determined.

Carlina acaulis root essential oil (EO) is one of the most potent mosquito larvicides (LC 50  < 2 ppm). This EO is mainly composed of carlina oxide (> 90%). Poor water solubility and rapid degradation from UV light and oxygen in the environment limit the real-world use of this EO. Herein, we developed nanocarrier-based formulations, namely micro- and nanoemulsions (ME and NE, respectively) containing C. acaulis EO or carlina oxide (both at 0.5%) as active ingredients (a.i.). The larvicidal activity of ME and NE was evaluated against Culex quinquefasciatus . The highest larvicidal activity was achieved by the ME containing 0.5% of the EO (M1); its LC 50(90) was 579.1 (791.3) µL L −1 . Sublethal effects of this ME and its a.i. were assessed testing both at the LC 16 , LC 30 , LC 50 and LC 90 on mosquito larvae exposed to each product for 1–7 h, and then monitoring mortality for 18 days. At variance with the EO, ME application, even at LC 16 , led to 100% mortality at 18 days. The EO and its encapsulated form were scarcely toxic to human keratinocytes (HaCaT) and human fibroblast (NHF A12) cell lines. The acute toxicity of C. acaulis EO and its ME (M1) was also evaluated in Wistar rats through oral administration; EO LD 50 was 1098 mg kg −1 bw, whereas its ME, even at 5000 mg kg −1 bw (considered the upper testing limit to establish safety to mammals), was not toxic. This study highlights the outstanding efficacy of C. acaulis EO ME for developing long-lasting and safe larvicides against Cx. quinquefasciatus .

Carlina acaulis L. (Asteraceae) is a medicinal plant with a long history of use as an herbal remedy. Recently, this species attracted the interest of agrochemical companies due to the presence of valuable biopesticides among which the most promising is carlina oxide (COx). To stimulate the biosynthesis of its specialised metabolites by elicitation, a polysaccharide – chitosan was supplemented as chitosan lactate (ChL). The aim was to evaluate the effects of ChL soil and foliar application on the C. acaulis biomass, photosynthetic efficiency, and levels of the COx, chlorogenic acids, protocatechuic acid, schaftosides, and triterpenic acids. ChL has been shown to have no effect on shoot growth while considerably increasing root biomass. It improved photosynthetic efficiency and enhanced levels of specialised metabolites. Soil application of ChL significantly increased chlorogenic and neochlorogenic acid content in leaves, by approximately 330% and 70%, respectively compared to controls. In contrast, foliar application more strongly increased COx levels in roots (55% for foliar vs. 16% for soil treatment). This study has demonstrated that the application of ChL can be used as an inexpensive and accessible way to boost the production of valuable compounds in C. acaulis .

Carlina acaulis is a medicinal plant that has shown antioxidant activity in in vitro studies, but to date no corresponding in vivo data is available. Therefore, in the present study the antioxidant activity and its impact in counteracting Aβ toxicity were studied in the Caenorhabditis elegans model. A dichloromethane extract of the roots of C. acaulis was prepared and characterised via gas-liquid-chromatography/mass-spectrometry (GLC-MS). The in vitro antioxidant activity was confirmed via 2,2-diphenyl-1-picrylhydracyl assay. The extract was further separated by thin layer chromatography into two fractions, one of which was a fraction of the dichloromethane extract of C. acaulis containing mostly Carlina oxide (CarOx). Different strains of C. elegans were employed to study the expression of hsp-16.2p::GFP as a marker for oxidative stress, delocalisation of the transcription factor DAF-16 as a possible mechanism of antioxidant activity, the effect of the drug under lethal oxidative stress, and the effect against beta-amyloid (Aβ) toxicity in a paralysis assay. The C. acaulis extract and CarOx showed high antioxidant activity (stress reduction by 47% and 64%, respectively) in C. elegans and could activate the transcription factor DAF-16 which directs the expression of anti-stress genes. In paralysis assay, only the total extract was significantly active, delaying paralysis by 1.6 h. In conclusion, in vivo antioxidant activity was shown for C. acaulis for the first time in the C. elegans model. The active antioxidant compound is Carlina oxide. This activity, however, is not sufficient to counteract Aβ toxicity. Other mechanisms and possibly other active compounds are involved in this effect.

The root of Carlina acaulis L. has been widely used in traditional medicine for its antimicrobial properties. In this study, the fractionation of methanol extract from the root was conducted. Four fractions (A, B, C, and D) were obtained and tested against a range of bacteria and fungi. The results showed promising antibacterial activity, especially against Bacillus cereus, where the minimal inhibitory concentration (MIC) was determined to be equal to 0.08 mg/mL and 0.16 mg/mL for heptane (fraction B) and ethyl acetate (fraction C), respectively. In the case of the methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 strain, the same fractions yielded higher MIC values (2.5 and 5.0 mg/mL, respectively). This was accompanied by a lack of apparent cytotoxicity to normal human BJ foreskin fibroblasts, enterocytes derived from CaCo2 cells, and zebrafish embryos. Further analyses revealed the presence of bioactive chlorogenic acids in the fractionated extract, especially in the ethyl acetate fraction (C). These findings support the traditional use of the root from C. acaulis and pave the way for the development of new formulations for treating bacterial infections. This was further evaluated in a proof-of-concept experiment where fraction C was used in the ointment formulation, which maintained high antimicrobial activity against MRSA and displayed low toxicity towards cultured fibroblasts.

Roots and leaves of Carlina acaulis L. are still used in ethnomedicine in many European countries; however, the limited occurrence of the plants and protection of this species necessitate a search for alternative ways for obtaining this plant material. In this study, in vitro cultures, hydroponic cultures, and field cultivation were applied to obtain the C. acaulis plant material. Its quality was evaluated using antioxidant activity tests and high performance liquid chromatography analysis. Our study showed that the antioxidant activity and the content of chlorogenic and 3,5-di-caffeoylquinic acid in roots of plants cultivated in hydroponics and field conditions were comparable. However, the amount of carlina oxide was significantly higher in plants from the field. The flavonoid content in leaves obtained from both cultivation systems was at the same level; however, the antioxidant activity and the content of the investigated metabolites were higher in the soil cultivation system. The callus line exhibited high differentiation in phytochemical compositions depending on the treatments and medium compositions.

Plant essential oil (EO)-based insecticides represent a promising tool for Integrated Pest Management (IPM), though their formulation is limited by poor physicochemical properties. EO encapsulation into stable formulations, like nanoemulsions (NEs), could boost EO efficacy and stability. Carlina acaulis L. roots contain an EO recently studied for its excellent insecticidal activities, and chiefly composed of carlina oxide (> 97%). Herein, we developed two carlina oxide NEs (0.25% and 0.5% w/w) through ultrasounds exposure and characterized them by dynamic light scattering (DLS). The NE insecticidal and repellent activities were tested on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs, larvae, and adults. Nanoemulsions tested showed a monomodal size ditribution and the polydispersity index (PDI) indicaticating a low grade of polydispersity. The 0.25% (w/w) NE showed significant contact toxicity on T. absoluta eggs with high hatching inhibition. 11 days post-treatment. The highest larvicidal effect was observed in translaminar toxicity tests, with complete mortality after 24 h. The NE did not achieve significant oviposition deterrence. Overall, the tested green NE showed promising effectiveness as ovicide and larvicide on T. absoluta , highlighting the need of further research to shed  light on its modes of action, as well as to evaluate lethal and sublethal effects on tomato biological control agents and pollinators.

Among botanical insecticides based on essential oils (EOs) or their main components, Carlina acaulis EO and the aromatic polyacetylene carlina oxide, constituting more than 90% of its EO, were recently proven to be effective against the larvae and adults of some insect vectors and pests. In this study, the toxicity of C. acaulis EO and carlina oxide were tested on Bactrocera oleae adults using a protein bait formulation. The LC50 values of the C. acaulis EO and carlina oxide were 706 ppm and 1052 ppm, respectively. Electroantennographic (EAG) tests on B. oleae adults showed that both carlina EO and oxide elicited EAG dose-dependent responses in male and female antennae. The responses to the EO were significantly higher than those to carlina oxide, indicating that other compounds, despite their lower concentrations, can play a relevant role. Moreover, Y-tube assays carried out to assess the potential attractiveness or repellency of carlina oxide LC90 to B. oleae adults showed that it was unattractive to both males and females of B. oleae, and the time spent by both sexes in either the control or the treatment arm did not differ significantly. Overall, this study points out the potential use of C. acaulis EO and carlina oxide for the development of green and effective “lure-and-kill” tools.

The growing interest in the development of green pest management strategies is leading to the exploitation of essential oils (EOs) as promising botanical pesticides. In this respect, nanotechnology could efficiently support the use of EOs through their encapsulation into stable nanoformulations, such as nanoemulsions (NEs), to improve their stability and efficacy. This technology assures the improvement of the chemical stability, hydrophilicity, and environmental persistence of EOs, giving an added value for the fabrication of natural insecticides effective against a wide spectrum of insect vectors and pests of public and agronomical importance. Carlina acaulis (Asteraceae) root EO has been recently proposed as a promising ingredient of a new generation of botanical insecticides. In the present study, a highly stable C. acaulis-based NE was developed. Interestingly, such a nanosystem was able to encapsulate 6% (w/w) of C. acaulis EO, showing a mean diameter of around 140 nm and a SOR (surfactant-to-oil ratio) of 0.6. Its stability was evaluated in a storage period of six months and corroborated by an accelerated stability study. Therefore, the C. acaulis EO and C. acaulis-based NE were evaluated for their toxicity against 1st instar larvae of the European grapevine moth (EGVM), Lobesia botrana (Denis & Schiffermüller, 1775) (Lepidoptera: Tortricidae), a major vineyard pest. The chemical composition of C. acaulis EO was investigated by gas chromatography–mass spectrometry (GC–MS) revealing carlina oxide, a polyacetylene, as the main constituent. In toxicity assays, both the C. acaulis EO and the C. acaulis-based NE were highly toxic to L. botrana larvae, with LC50 values of 7.299 and 9.044 µL/mL for C. acaulis EO and NE, respectively. The C. acaulis-based NE represents a promising option to develop highly stable botanical insecticides for pest management. To date, this study represents the first evidence about the insecticidal toxicity of EOs and EO-based NEs against this major grapevine pest.

The tomato russet mite, Aculops lycopersici, is considered one of the most important crop pests globally. The main control strategy is based on synthetic acaricides; however, they create resistant strains and ecological risks. In this context, biopesticides could be a viable and sustainable alternative for eriophyid control. In the present study, the toxic effects of a N-alkylamides-enriched extract obtained from Acmella oleracea and of carlina oxide, the main bioactive component of Carlina acaulis, on A. lycopersici were evaluated, as well as their side effects on the phytoseiid Typhlodromus exhilaratus under laboratory conditions. Six concentrations were tested for each product against A. lycopersici adults (0, 320, 640, 1280, 2500, and 5000 μL L−1), and the median concentration (1280 μL L−1) was evaluated against eggs and females of the phytoseiid T. exhilaratus. Both the N-alkylamides-enriched extract and carlina oxide showed total lethal effects (100% of mortality) towards A. lycopersici at the two highest concentrations. Moderate-to-high mortality was also recorded with the lower concentrations: from 42.22 to 97.78%. Probit analysis identified LC50 values of 205.32 μL L−1 for carlina oxide and 253.79 μL L−1 for the N-alkylamides-enriched extract, respectively. Carlina oxide showed a moderate ovicidal effect on T. exhilaratus eggs (50.00% hatching rate) on T. exhilaratus, and caused 39.13% mortality on females, whereas the N-alkylamides-enriched extract was less toxic, with a hatching rate of 88.00% and a mortality rate of 18.75% on females. In conclusion, carlina oxide and the N-alkylamides-enriched extract showed high toxicity on A. lycopersici, with a reduced effect on phytoseiid. These results highlight the potential of these products as sustainable means for the management of tomato russet mite.