MICROMORPHOLOGICAL FEATURES OF THE EPIDERMIS AND HYSTOCHEMICAL TECHNIQUE OF IDENTIFICATION OF SECONDARY METABOLITES IN THE LEAVES OF BORAGINACEAE HERBAСEOUS PLANTS

Abstract

Aim. In conventional medicine, the species of the Boraginaceae family are not used due to the poor scientific knowledge of the products of secondary metabolism and the lack of information about most of the species. We investigated micromorphological features of the epidermis and conducted histochemical analysis of the products of secondary metabolism in the leaves of Pulmonaria mollis Wulfen ex Hornem., Echium vulgare L., Symphytum asperum Lepech. and S. caucasicum M. Bieb. Methods. Micromorphological analysis included the study of the shape of the main cells of the epidermis, the structure of trichomes and stomata. The number of stomata and trichomes was calculated per 1 mm2. Were used the histochemical reactions in order to identify the products of secondary metabolism. Results. The studied species are characterized by the bifacial type of leaves, numerous trichomes, including long leaf fuzz with a rosette of epidermal cells. The anomocytic type of stomata is characteristic for P. mollis and E. vulgare, anomocytic and anisocytic for S. asperum and S. caucasicum. The leaves of P. mollis, E. vulgare and S. caucasicum are amphistomatic while S. asperum is hypostomatic. The ratio of the non- glandular and glandular trichomes of the intercostal zones of the lower epidermis to the upper in P. mollis was 1.08 and 1.83, respectively, in S. caucasicum 1.61 and 2.67, in S. asperum 7.21 and 2.50, in E. vulgare 1.65 (glandular trichomes in the interstitial zones are absent). In the leaves of the studied species, the products of secondary metabolism (tannins, alkaloids, essential oils, anthracene derivatives and mucus) are localized in bases of non-glandular, glandular trichomes, veins and the main cells of the epidermis. Conclusions. Genus signs of the epidermis of leaves of Boraginaceae are the structure and location of trichomes. Species differences are due to the location of stomata, glandular trichomes and shape of the main epidermal cells. The intensity of staining of secondary metabolites depends on their content in the leaves. The presence of biologically active substances in the leaves of P. mollis, S. caucasicum, S. asperum and E. vulgare determines the value of these species in the creation of new phytopreparations.

Keywords

• pulmonaria mollis
• echium vulgare
• symphytum asperum
• s. caucasicum
• leaf
• epidermis
• trichomes
• secondary metabolites.