Chemical Profiling and Bioactivity Assessment of Helichrysum italicum (Roth) G. Don. Essential Oil: Exploring Pure Compounds and Synergistic Combinations

Helichrysum italicum (Roth) G. Don., immortelle, is a plant species used in ethnomedicine and the food industry as a spice added to food, beverages, and bakery products. It has been shown to possess various biological activities, such as antioxidant and antibacterial activity, making it useful as a natural preservative. We investigated the phytochemical profile and biological activity of H. italicum essential oils from wild-grown plant material collected from natural habitats in the Republic of Croatia and Bosnia and Herzegovina. Using high-resolution scanning electron microscopy (SEM), a visual investigation of plant organs (stem, leaf, and flower) was performed, confirming the presence of essential oil reservoirs on the surface of all examined plant organs. Essential oils were isolated by hydrodistillation in the Clevenger apparatus. The chemical composition of the essential oils was determined using the GC-MS analytical technique. Cytotoxic activity tests were performed in vitro on three cell lines: skin (fibroblast), lung, and breast cancer. Using statistical tools, the synergistic and selective effects of H. italicum essential oil on healthy and tumor cells were correlated to chemical composition and cytotoxic activity. The synergistic and antagonistic effects of H. italicum essential oil's individual components were simulated by testing pure compounds and their mixture of cytotoxic activity on fibroblasts and breast cancer cells. The results confirm that essential oil's biological activity is much greater than the sum of the effects of its components. The present data are novel contributions to the body of knowledge on the biological activity of this species used in the food industry.

Seasonality of Polyaromatic Hydrocarbons (PAHs) and Their Derivatives in PM2.5 from Ljubljana, Combustion Aerosol Source Apportionment, and Cytotoxicity of Selected Nitrated Polyaromatic Hydrocarbons (NPAHs)

Airborne particulate matter (PM) is a vector of many toxic pollutants, including polyaromatic hydrocarbons (PAHs) and their derivatives. Especially harmful is the fine fraction (PM_2.5), which penetrates deep into the lungs during inhalation and causes various diseases. Amongst PM_2.5 components with toxic potential are nitrated PAHs (NPAHs), knowledge of which is still rudimentary. Three of the measured NPAHs (1-nitropyrene (1-nP), 9-nitroanthracene (9-nA), and 6-nitrochrysene (6-nC)) were detected in ambient PM_2.5 from Ljubljana, Slovenia, along with thirteen non-nitrated PAHs. The highest concentrations of pollutants, which are closely linked with incomplete combustion, were observed in the cold part of the year, whereas the concentrations of NPAHs were roughly an order of magnitude lower than those of PAHs throughout the year. Further on, we have evaluated the toxicity of four NPAHs, including 6-nitrobenzo[a]pyrene (6-nBaP), to the human kidney cell line, HEK293T. The most potent was 1-nP (IC₅₀ = 28.7 µM), followed by the other three NPAHs, whose IC₅₀ was above 400 or 800 µM. According to our cytotoxicity assessment, atmospheric 1-nP is the most harmful NPAH among the investigated ones. Despite low airborne concentrations of NPAHs in ambient air, they are generally considered harmful to human health. Therefore, systematic toxicological assessment of NPAHs at different trophic levels, starting with cytotoxicity testing, is necessary in order to accurately evaluate their threat and adopt appropriate abatement strategies.

Centaurea triumfetii essential oil chemical composition, comparative analysis, and antimicrobial activity of selected compounds

The essential oils from the Centaurea genus are well known for their pharmacological properties. The most abundant and dominant chemical components in Centaurea essential oils are ß-caryophyllene, hexadecanoic acid, spathulenol, pentacosane, caryophyllene oxide, and phytol. However, whether these dominant components are the key drivers for observed antimicrobial activity remains unclear. Thus, the aim of this study was dual. Here we provide comprehensive, literature-based data to correlate the chemical compounds in Centaurea essential oils with the tested antimicrobial activity. Secondly, we characterized the essential oil of Centaurea triumfettii All. squarrose knapweed using coupled system gas chromatography-mass spectrometry and tested its phytochemicals for antimicrobial activity against E. coli and S. epidermis using disc diffusion assay and monitoring their growth in Muller Hinton broth. The most abundant compounds in C. triumfettii essential oil were hexadecanoic acid (11.1%), spathulenol (10.8%), longifolene (8.8%), germacrene D (8.4%), aromadendrene oxide (6.0%) and linoleic acid (5.3%). Based on our analysis of literature data from other Centaurea essential oils, they were positively correlated with antimicrobial activity. Using an agar disk diffusion method, tested chemical constituents did not show experimental evidence to support this positive correlation to antimicrobial activity when we tested them as pure components. The antibacterial effect of essential oil constituents may be related to a complex synergistic, rather than a single component as suggested by performed network pharmacology analysis, underlying the theoretical interactions between the essential oil phytochemicals listed as potentially responsible for antimicrobial activity and should be confirmed in further in-depth studies. This is the first report on the comparative analysis of Centaurea essential oils with good antimicrobial activity, as well as the first analysis of chemical components of the essential oil from C. triumfettii and the first report of antimicrobial activity of the representative, pure components: aromadendrene, germacrene D, spathulenol, longifolene, and the mixture of selected chemical compounds. This work contributes to the body of knowledge on the genus Centaurea and C. triumfettii species.

Chemical Composition and Biological Activity of Salvia officinalis L. Essential Oil

In our study, we investigated the chemical composition and cytotoxic activity of essential oils isolated from Dalmatian sage (Salvia officinalis L.) collected along the Adriatic coast of Croatia. Scanning electron microscopy (SEM) was used to examine the morphology of the stem and leaf surfaces. Essential oil excretory glands were detected on both the leaves and stem surfaces. The essential oils were isolated by hydrodistillation, and their chemical composition was determined by gas chromatography and mass spectrometry (GC-MS). Sage essential oils were mixtures of terpene compounds, among which the most common were: α- and β-thujone, camphor, and 1,8-cineol. Cytotoxic activity was tested using MTS assay on multiple cell lines: normal and immortalized fibroblasts (HF77FA and HDF-Tert), immortalized lung line (BEAS-2B), and breast adenocarcinoma (MDA-MB-231). The growth of treated cells was determined relative to control conditions without treatment. The immortalized lung line was the least resistant to the activity of the essential oils, whereas immortalized fibroblasts were the most resistant. Statistical analysis has connected the cytotoxic effect and chemical composition of the studied essential oils. To the best of our knowledge, this work is the first testing of the cytotoxic activity of S. officinalis EO's on the BEAS-2B, HF77FA, and HDF-Tert cell lines. The presented data on essential oil chemical composition and cytotoxic effect on 4 types of human cells supports pharmacotherapeutic potential this plant is known to have.

Phytochemical and cytogenetic study of two Centaurea species from Croatia: the particular case of diploid and tetraploid C. salonitana

Natural wild populations of C. rupestris and C. salonitana. were studied to determine possible relationships between the volatile oil (VO) composition and ploidy level. The chemical composition of the volatile oil was investigated using the GC/MS technique. The predominant components of the VO of diploid and tetraploid C. salonitana were hexadecanoic acid and α - linoleic acids, while in C. rupestris they were germacrene D and β-caryophillene in one population and heptacosane and germacrene D, in another. The nuclear DNA amounts (2C DNA), determined by flow cytometry, were 3.54 pg for C. rupestris, 3.39 pg for the diploid and 6.79 pg for the tetraploid population of C. salonitana. Evidence that the degree of ploidy solely influences the chemical composition of the essential oil of C. salonitana was not found. The results presented are the first data to be reported on the DNA content of the studied Centaurea populations from Croatia, as well as on the chemical composition of C. salonitana volatile oil.

Volatile Oil Chemical Composition of Wild, Edible Centaurea scabiosa L. and Its Cytotoxic Activity

Centaurea species are well known as a source of phytopharmaceuticals having both beneficial and harmful influences on human health. Centaurea scabiosa L. is a wild edible plant used in Mediterranean cuisine in the Dalmatian region of Croatia. We have assessed the volatile oil's chemical composition using GC/MS chromatography and its cytotoxic activity on human fibroblasts using the MTT test. Data on chromosome number, obtained by classical karyological methods, and genome size, assessed by flow cytometry, of the same plant material of C. scabiosa, were also given. The major chemical compounds found in C. scabiosa volatile oil were heptacosane, caryophyllene oxide, alloaromadendrene epoxide, α-cyperone, and α-bisabolol. This volatile oil showed no cytotoxicity on human fibroblasts in a dose range of 0.01-1 g/L. The chromosome number of a C. scabiosa sample from Croatia showed 2n = 20 + 2B chromosomes. The total genome DNA amount of 2C = 3.3 ± 0.01 pg or 1 Cx = 1628 Mbp presents the first report on the genome size of this species from Croatia. The presented results support the idea of using this plant in the human diet. To our knowledge, this is the first report on edible C. scabiosa species in general and in particular from Croatia.

UPLC-MS/MS Phytochemical Analysis of Two Croatian Cistus Species and Their Biological Activity

Aqueous extracts of two Cistus species wild growing in Croatia-Cistus creticus (CC) and Cistus salviifolius (CS)-have been assessed with UPLC-MS/MS, showing 43 different phytochemicals, with flavonol glycosides: myricetin-3-hexoside and myricetin-rhamnoside, predominate ones in CC and myricetin-3-hexoside in CS. Antioxidant potential tested with the FRAP method showed no difference between CS and CC aqueous extracts, while higher phenolic content of CC comparing to CS, determined with a Folin-Cicolateu reagent correlated to its higher antioxidant capacity observed by the DPPH method. Both extracts were assessed for antimicrobial activity, using disc-diffusion and broth microdilution assays, targeting the opportunistic pathogens, associated with food poisoning, urinary, respiratory tract, blood stream and wound infections in humans. Antimicrobial assays revealed that fungi were in general more sensitive to both Cistus aqueous extracts, comparing to the bacteria where two extracts showed very similar activity. The most potent activity was observed against A. baumannii for both extracts. The extracts were tested on human lung cancer (A549) cell line using the MTT assay, showing very similar antiproliferative activity. After 72 h treatment with CC and CS aqueous extracts in concentration of 0.5 g/L, the viability of the cells were 37% and 50% respectively, compared to non-treated cells.

Halogenated boroxine dipotassium trioxohydroxytetrafluorotriborate K2[B3O3F4OH] inhibits emerging multidrug-resistant and β-lactamase-producing opportunistic pathogens

Halogenated boroxine dipotassium trioxohydroxytetrafluorotriborate, K₂[B₃O₃F₄OH] (boroxine) was previously shown to be very effective in inhibition of several carcinoma cell lines, including the skin cancer. Here, we investigated its antimicrobial potential by targeting the multidrug-resistant opportunistic pathogens associated with skin and wound infections. The antimicrobial testing against eleven bacterial and four fungal species revealed good activity of boroxine against pathogenic filamentous fungi Penicillium funiculosum and Aspergillus niger (MIC₅₀ 64 and 128 µg/ml), and a moderate bioactivity against the yeast Candida albicans (MIC₅₀ 512 µg/ml). Among the tested multidrug-resistant bacteria, the best antibacterial effect, stable over a 24-h period, was observed against the methicillin-resistant Staphylococcus aureus strain (MRSA) at MIC of 1024 µg/ml. The atomic force microscopy (AFM) used to investigate the morphology of S. aureus cells revealed indentations on its cell envelope after the boroxine exposure. These results show that in addition to the antitumor effect, boroxine exerts wide spectrum antimicrobial activity, thus may help preventing the development of skin and wound-related opportunistic infections.

Phytochemical Composition, Antiradical and Anticholinesterase Potentials of Centaurea alba and Centaurea jacea Volatile Oils

This paper reports on the phytochemical composition as well as antiradical and anticholinesterase potential of volatile oils isolated from Centaurea alba and Centaurea jacea, from Croatia. The volatile components, obtained by hydrodistillation, were determined by GC and GC-MS analyses. A total of 18 compounds were identified in C. alba volatile oil with hexadecanoic acid, germacrene D and tetradecanoic acid as main compounds. A total of 29 compounds were identified in C. jacea volatile oil, with epi-bicyclosesquiphellandrene, aromadendrene and hexadecanoic acid as a major compounds. The tested volatile oils showed low DPPH inhibition potential as well as low to moderate antiAChE potential and low antiBuChE potential.

Phytochemical Composition, Antioxidant Potential and Cholinesterase Inhibition Potential of Extracts from Mentha pulegium L

The aim of this work was to perform the phytochemical analysis as well as antioxidant and anticholinesterase potential of hot water and methanolic extracts from Mentha pulegium L., Lamiaceae, wild growing in Bosnia and Herzegovina. It is a plant that is traditionally used in Bosnia and Herzegovina medicine to treat gastrointestinal and neurological disorders. By HPLC-DAD analysis of tested extracts, 15 phenol compounds were identified and quantified. Rosmarinic acid was the most abundant compound in both extracts, followed by ellagic acid, eriodictyol, naringenin and chlorogenic acid. Both extracts were demonstrated good radical scavenging potential, reducing power and ability to inhibit lipid oxidation. The tested extracts also showed low ability to inhibit protein oxidation and low or no acetylcholinesterase and butyrylcholinesterase inhibition potential. The promising radical scavenging potential, reducing power and lipid protection potential of tested extracts indicates that the extracts of M. pulegium could be useful in preventing free radical linked diseases, as well as food protecting antioxidants.

Qualitative HPLC-DAD/ESI-TOF-MS Analysis, Cytotoxic, and Apoptotic Effects of Croatian Endemic Centaurea ragusina L. Aqueous Extracts

Centaurea ragusina L., an endemic Croatian plant species, revealed a good cytotoxic activity of aqueous extracts (AE) on human bladder (T24) and human glioblastoma (A1235) cancer cell lines. The chemical constituents were tentatively identified using high performance liquid chromatography HPLC-DAD/ESI-TOF-MS in negative ionization mode. The main compounds of herba extract were sesquiterpene lactones: solstitialin A 3,13-diacetate and epoxyrepdiolide; organic acid: quinic acid. The main compounds of flower extract were organic acids: quinic acid, citric acid, and malic acid; sesquiterpene lactone: cynaropicrin; phenolic compounds: chlorogenic acid and phenylpropanoid: syringin. The AE of C. ragusina were investigated for correlation of their effects on human bladder (T24) and human glioblastoma (A1235) cancer cell lines using the MTT assay. Although both extracts showed significant dose- and time-dependent cytotoxic activity against both cancer cell lines, the flower extract exhibited slightly higher activity. In order to determine type of cell death induced by treatment, cell lines were exposed subsequently to a treatment with both flower and herba AE. The majority of the cells died by induced apoptosis treatment. Flower AE (26.25%), compared to a leaf AE (22.15%) showed slightly higher percentage of an apoptosis in T24 cells, when compared to a non-treated cells (0.04%).

Phytochemical and Cytogenetic Characterization of Centaurea solstitialis L. (Asteraceae) from Croatia

The cytogenetic characterization of Centaurea solstitialis L. (Asteraceae) showed a chromosome number of 2n = 16. Karyotype is composed by four pairs of metacentric, two pairs of submetacentric and two pairs of subtelocentric chromosomes. Physical mapping of two rDNA probes revealed two loci of 35S and one locus of 5S rRNA genes. Chromomycin fluorochrome banding revealed that all rDNA loci were GC rich. The genome size (2C-value) of 1.95 pg classes this species in the group of very small genomes. Chemical composition of C. solstitialis volatile oil (VO) from Croatia, studied with gas chromatography-mass spectrometry showed dominant components as it follows: hexadecanoic acid, α-linolenic acid, germacrene D and heptacosane. Antioxidant capacity, measured by ferric reducing power assay and 2,2-diphenyl-1-picrylhydrazyl methods, as well as inhibition of acetyl- and butyrylcholinesterase of VO was lower comparing to a standard solutions. Volatile oil tested with disc diffusion method showed good inhibitory potential against Pseudomonas aeruginosa, Escherichia coli and all tested fungi: Candida albicans, Penicillium funiculosum and Aspergillus fumigatus. The microdilution method showed best activity against Chronobacter sakazakii and A. fumigatus.

Phytochemical profiles of volatile constituents from Centaurea ragusina leaves and flowers and their antimicrobial effects

The volatile oils obtained from the leaves and flowers of the Croatian endemic plant Centaurea ragusina L. were evaluated for antimicrobial activity. The chemical compositions, determined by GC and GC-MS, were complex, with sesquiterpenes the most abundant class of compound. Nonterpene hydrocarbons were also identified in high quantities, while acids and ketones were found in high quantities only in the leaf volatile oil. Aldehydes, alcohols, esters and other compounds were identified in lower quantities. Antimicrobial effects of the volatile samples were investigated by using the disc diffusion and microdilution assays. They were found to inhibit a wide range of bacteria and fungi, causing in vitro growth inhibition at a concentration of 250 microg/mL. The volatile oils displayed great antibacterial potential with MIC values ranging from 16 to 128 microg/mL against the Gram-positive bacteria Bacillus cereus, Clostridium perfringens, Enterococcus faecalis and Staphylococcus aureus, and lesser activity against the Gram-negative bacteria Cronobacter sakazakii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa, as well as fungal strains (MIC = 32-128 microg/mL).