Microscopic characteristics and quality evaluation of selected biologically active compounds in Panzerina lanata (L.)

Abstract

Background: Panzerina lanata (L.) is widely distributed across various ecosystems in the mountain, steppe, and Gobi regions of Mongolia and has traditionally been used in folk medicine to alleviate joint and muscle inflammation, reduce liver heat, lower blood pressure, promote diuresis, and treat edema and tumors. Its similar applications in Mongolian and Chinese traditional medicine suggest considerable therapeutic potential and biological activity. Studies conducted since 2019 have reported that P.lanata (L.) is rich in phenolic compounds, flavonoids, and antioxidant-active constituents; however, studies on the microscopic and histochemical characteristics of the species growing under Mongolian conditions remain limited, providing the rationale for this study. Aim: To characterize the microscopic features of Panzerina lanata (L.), determine the distribution of starch, polysaccharides, and phenolic compounds using histochemical methods, and evaluate the total polyphenol and flavonoid contents and antioxidant activity. Materials and Methods: For microscopic analysis, plant materials were softened by soaking for 24 h in a 1:1:1 water– ethanol–glycerin mixture (Strich–Fleming solution), followed by preparation of manual transverse and longitudinal sections of the stems, roots, and petals. A 10% chloral hydrate solution was used for clearing. Histochemical analyses were performed using potassium dichromate (K₂Cr₂O₇), ferric chloride (FeCl₃), Lugol’s solution (I₂/KI), thymol (C₁₀H₁₄O) with concentrated sulfuric acid (H₂SO₄), methylene blue (C₁₆H₁₈ClN₃S), and Dragendorff’s reagent. The prepared sections were cleared with glycerin and examined under an Olympus light microscope at ×40 and ×100 magnifications, with images documented using a 12-MP camera. Results: Microscopic examination of the roots, stems, and petals revealed that the root stele exhibited a polyarchy arrangement, with clearly differentiated xylem, phloem, and cambial tissues in both transverse and longitudinal sections. Scalariform tracheary elements in the xylem contributed to water and mineral transport and mechanical support. The stem xylem contained both spiral and scalariform tracheary elements. The petals consisted of cells with double walls and single nuclei, while the floral seed tissue was composed of meristematic tissue associated with continuous cell division, growth, and tissue differentiation. Histochemical analysis of transverse and longitudinal sections of the stems and roots, as well as petal sections, revealed the presence of essential oils, polyphenolic compounds (tannins and flavonoids), and starch. Conclusion: Microscopic, histochemical, and phytochemical analyses of Panzerina lanata (L.) revealed the presence of biologically active compounds, indicating its potential for use in the quality evaluation of medicinal plant raw materials.