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-caryophyllene in one population and heptacosane and germacrene D, in another. The nuclear DNA amounts (2 C 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.

Interactions between Natural Products-A Review

Plant-based natural products have been used as a source for therapeutics since the dawn of civilization. According to the World Health Organization (WHO), more than 80% of the world's population relies on traditional medicine for their primary healthcare. Numerous natural extracts, widely known in Traditional Chinese Medicine, Indian Ayurveda medicine and other practices, have led to the modern discovery and development of new drugs. Plants continuously interact with their environment, producing new compounds and ever-changing combinations of existing ones. Interestingly, some of the compounds have shown lower therapeutic activity in comparison to the extract they were isolated from. These findings suggest that the higher therapeutic activity of the source extract was due to the synergistic effect of several compounds. In other words, the total therapeutic potential of the extract cannot be explained only by the sum of its parts alone. In traditional medicine, most herbal remedies are based on a mixture of plants, and it is the interaction between different constituents that amplifies their therapeutic potential. Considering the significant influence traditional medicine has on human healthcare, knowing and studying the synergistic effect of compounds is paramount in designing smart therapeutic agents.

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.

Secretory Products in Petals of Centaurea cyanus L. Flowers: A Histochemistry, Ultrastructure, and Phytochemical Study of Volatile Compounds

(1) Background: Centaurea cyanus L. is a medicinal plant whose flowers are widely used in herbal medicine. The aim of the study was to localise flower tissues that are responsible for the production of secretory products in petals and to analyse the volatile compounds. The volatile compounds of the flowers of this species have not been investigated to date. (2) Methods: Light, fluorescence, scanning and transmission electron microscopy techniques were used in the study. Lipophilic compounds were localised in the tissues using histochemical assays. Volatile compounds were determined with the use of solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). (3) Results: The study showed production of secretion in the petal parenchyma, whose ultrastructure has features of a secretory tissue. The lipophilic secretion was localised in the cells and intercellular spaces of the parenchyma and in the walls and surface of epidermal cells, where it accumulated after release through cuticle microchannels. Sesquiterpenes were found to constitute the main group of volatile compounds, with the highest content of β-caryophyllene (26.17%) and α-humulene (9.77%). (4) Conclusions: Given the presence of some volatile components that are often found in resins (caryophyllene, delta-cadinene) and the abundant secretion residues on the epidermal surface, we suppose that the C. cyanus secretion released by the flowers is a resinaceous mixture (oleoresin), which is frequently found in plants, as shown by literature data. This secretion may play an important role in the therapeutic effects of C. cyanus flowers.

The essential oil composition of Centaurea immanuelis-loewii Degen growing wild in Bulgaria and chemotaxonomy of section Acrocentron

In the present study, the chemical composition of the essential oil from aerial parts of the Balkan endemic, Centaurea immanuelis-loewii Degen (sect. Acrocentron, Asteraceae), collected in Bulgaria was evaluated by GC-MS. The main components of the oil were β-caryophyllene (23.2%), germacrene D (13.7%) and caryophyllene oxide (12.4%). Furthermore, a complete literature review on the composition of the essential oils of all the other taxa of Centaurea, belonging to section Acrocentron, studied so far, was performed and the chemotaxonomical variations in the composition of the essential oils is discussed.