Microstructural and histochemical analysis of aboveground organs of Centaurea cyanus used in herbal medicine

Abstract

Centaurea cyanus L. is a valuable source of many different bioactive substances. It is used in herbal medicine, but the structure of its organs used as raw material and secretory tissues has been insufficiently examined. The aim of this paper was to investigate the microstructure of C. cyanus flowers, bracts, stems and leaves with particular emphasis on secretory structures. Moreover, the main classes of secondary metabolites present in the secretion were identified and the taxonomic value of some micromorphological and anatomical features was analysed. Histochemical, micromorphological and ultrastructural analyses of aboveground organs of C. cyanus were carried out using light, fluorescence, scanning and transmission electron microscopy. The analyses revealed the presence of petal papillae and a characteristic cuticular pattern on the petals, stamens and stylar hairs. There were four types of non-glandular trichomes on the bracts, leaves and stem surfaces. The epidermal cells of the bracts contained prismatic calcium oxalate crystals. Two kinds of secretory structures, i.e. glandular trichomes and ducts, were observed in the C. cyanus organs. The glandular trichomes were located on the bract and stem surfaces, and the ducts were detected in the leaves and stems. Ultrastructural analyses of the epithelium of the ducts showed the presence of strongly osmiophilic insoluble phenolic material in vacuoles as well as moderately osmiophilic insoluble lipidic material in elaioplasts and vesicles. The results of histochemical assays showed a heterogeneous nature of the duct secretion, which contained essential oil, lipids, flavonoids, tannins and terpenes containing steroids.

Comparison of Ambrosia L. Pollen Seasons in Lublin (Poland) and Ivano-Frankivsk (Ukraine) and Presentation of the Morphotypes of Trichomes on A. artemisiifolia L. Shoots in Terms of the Allergenic Properties of the Plant

“…The same trichome structure, typical for Asteraceae, has been found in, e.g., Artemisia annua [74], Chamomilla recutita [75], and Chrysanthemum morifolium [76]. In turn, the presence of biseriate glandular trichomes with 6-7 tiers of cells was reported by Werker [77] in Artemisia dracunculus and by Haratym et al [70] in Centaurea cyanus.…”

“…Biseriate glandular trichomes were also observed on floret corollas in other Asteraceae representatives, e.g., Helichrysum [78], Artemisia [74], Chamomilla, and Inula [75,79]. In contrast, no glandular trichomes were detected on the corolla in Petasites [80] and Centaurea [70].…”

“…They differ in the number of cells, length, diameter, and the presence of secretion in their cells. Several types of non-glandular trichomes have been observed in Centaurea cyanus by Chiru et al [69] and Haratym et al [70].…”

Structural and histochemical attributes of secretory ducts and cavities in leaves of four species of Calophyllaceae J. Agardh in Amazonian savannas

“…The occurrence of ducts and cavities as structural attributes of leaves in Cerrado plants provides an important mechanism for protection, adaptation and resistance to xeric conditions (Bieras & Sajo 2009), as well as protection against herbivores, pathogenic microorganisms and other pests (Franco & Albiero 2018;Haratym et al, 2020) and in water retention (Galloway et al, 2020). To date, there have been no studies that have made this association in plants of Amazonian savannas.…”

Anatomy of Carlina corymbosa L., Carthamus dentatus Vahl. and Picnomon acarna (L.) Cass. (Asteraceae)

“…For example, the micromorphology of trichome is a feature that can be used in the systematics of the Asteraceae [6]. Glandular and non-glandular trichomes are used as distinguished [7].…”