Comparative Studies on Bioactive Constituents in Hawk Tea Infusions with Different Maturity Degree and Their Antioxidant Activities

Hawk tea (Litsea coreanavar.lanuginose) is a very popular herbal tea in the southwest of China. According to the maturity degree of raw materials, Hawk tea can usually be divided into three types: Hawk bud tea (HB), Hawk primary leaf tea (HP), and Hawk mature leaf tea (HM). In this study, some of the bioactive constituents and antioxidant properties of the three kinds of Hawk tea infusions were comparatively investigated. The results showed that the contents of total flavonoids, vitamin C, and carbohydrates in Hawk bud tea infusion (HBI) were higher than those in Hawk primary leaf tea infusion (HPI) and Hawk mature leaf tea infusion (HMI). HPI had higher contents of total polyphenols and exhibited better DPPH radical scavenging activity and ferric reducing activity power. HBI could provide more effective protection against erythrocyte hemolysis. As age is going from bud to mature leaf, the ability to inhibit the formation of low density lipoprotein (LDL) conjugated diene and the loss of tryptophan fluorescence decreased. The bioactive constituents and antioxidant activities of Hawk tea infusions were significantly affected by the maturity degree of the raw material.

Scanning electron microscope studies of Avena coleoptiles during primary leaf emergence

A scanning electron microscope study of the fine structure of coleoptiles of <em>Avena sativa</em> L. cv. Clintford has revealed information about the relationship between aspects of coleoptilar structure and the emergence of the primary leaf. Stomata are located on the lateral sides of the coleoptile and arch across the apex. The location of the stomata and associated vascular tissue may play a role in the splitting of the coleoptile pore and influence the manner in which the primary leaf emerges. Details of the surface fine structure of the coleoptile pore, its associated cells, stomata and guard cells are presented.

Some aspects of runner bean plant response to cadmium at different stages of the primary leaf growth

Changes in morphology of primary leaves and ultrastructure of chloroplasts have been studied in runner bean plants (<i>Phaseolus coccineus</i> L., cv. Piękny Jaś) grown on Knop nutrient solution either without Cd or supplied with 2.5-10^-5 M Cd (in the form of 3CdSO₄•8H₂O) in different stages of growth. The metal applied to the nutrient solution during the early stages of growth resulted in a reduction of the leaf area, chlorophyll accumulation increase and small decrease in PSII activity. Conversely to it Cd added at the end of primary leaf growth revealed almost unchanged leaf area but a significant decrease of chlorophyll level and PSII activity. Changes in the leaf morphology (large intercellular spaces in pallisade as well as spongy mesophyll) and ultrastructure of chloroplasts (degradation of intergranal thylakoids and appearance of numerous plastoglobuli) indicating their disorganization were observed only in plants treated with Cd at the end of primary leaf growth. Morphological and ultrastructural disturbances related to the growth stages are discussed in relation to functional changes of the photosynthetic apparatus.