Pigments of the Moss Paraleucobryum longifolium: Isolation and Structure Elucidation of Prenyl-Substituted 8,8'-Linked 9,10-Phenanthrenequinone Dimers.

In a search for new secondary metabolites from mosses, leucobryns A-E, axially chiral 9,10-phenanthrenequinone dimers, were isolated from Paraleucobryum longifolium (1-5), together with diosmetin triglycoside. Leucobryns B (2) and C (3) were proved to be homodimeric atropodiastereomers containing both axial and central chirality elements, while leucobryns D (4) and E (5) were found to be heterodimeric atropodiastereomers containing central chirality in only one of the two monomeric units. Axial chirality of the compounds was determined by ECD measurements and sTDA ECD calculations, while the central chirality elements were assigned by TDDFT-SOR calculations. Leucobryns represent the first 9,10-phenanthrenequinone dimers, the monomers of which are linked through their C-8 atoms. Leucobryns B-E contain an uncommon C10 monoterpenoid side chain, in which isoprenoid units are joined by 3,4 linkages. Leucobryns A and B exhibited weak antiproliferative activity against several human cancer cell lines.

Antiproliferative and Antimicrobial Activities of Selected Bryophytes.

One-hundred and sixty-eight aqueous and organic extracts of 42 selected bryophyte species were screened in vitro for antiproliferative activity on a panel of human gynecological cancer cell lines containing HeLa (cervix epithelial adenocarcinoma), A2780 (ovarian carcinoma), and T47D (invasive ductal breast carcinoma) cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and for antibacterial activity on 11 strains using the disc-diffusion method. A total of 99 extracts derived from 41 species exerted ≥25% inhibition of proliferation of at least one of the cancer cell lines at 10 µg/mL. In the cases of Brachythecium rutabulum, Encalypta streptocarpa, Climacium dendroides, Neckera besseri, Pleurozium schreberi, and Pseudoleskeella nervosa, more than one extract was active in the antiproliferative assay, whereas the highest activity was observed in the case of Paraleucobryum longifolium. From the tested families, Brachytheciaceae and Amblystegiaceae provided the highest number of antiproliferative extracts. Only 19 samples of 15 taxa showed moderate antibacterial activity, including the most active Plagiomnium cuspidatum, being active on 8 tested strains. Methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus were the most susceptible to the assayed species. This is the first report on the bioactivities of these 14 species.

Photosynthetic responses, carbohydrate composition and invertase activity in fructan accumulating bryophytes (Porella platyphylla and Sphagnum flexuosum) under different environmental conditions (carbohydrate treatments, dark starvation, low temperature, desiccation).

Photosynthetic responses, the non-structural carbohydrate pool and its alterations, and the acid invertase activity under different environmental conditions in the fructan synthesising Porella platyphylla and Sphagnum flexuosum are discussed. Sucrose and fructan are the major soluble carbohydrates in both species. TLC showed that fructans form a homologous series of increasing DP in a similar manner to fructans in Angiosperms and belong to the inulin type. Exogenous sugars (glucose, fructose, sucrose) applied in light and dark resulted in down-regulation of photosynthetic activity, but a long period (1 week) of dark starvation did not cause a significant decrease in the photosynthetic capacity. Light and exogenous sugars increased soluble carbohydrate content due to fructan-accumulation. Dark starvation, desiccation and low temperature did not influence significantly the amount of the total soluble carbohydrates, indicating the existence of a well-buffered carbohydrate pool, although changes in the ratio of fructans of different molecular weight can be detected. Alterations in the activity of acid invertase correlated well with the changes of the amount of the main soluble carbohydrates, showing the role of the enzyme in general carbohydrate and fructan metabolism.

Heat acclimation of grapevine leaf photosynthesis: mezo- and macroclimatic aspects.

Heat sensitivity of grapevine (Vitis vinifera L. cv. Kékfrankos) photosynthesis was studied in two vineyards (Eger-Kolyukteto, flat; and Eger-Nagyeged hill, steep slope) with different mesoclimates and water supply conditions in two climatically different years. 2007 was drier and warmer, with higher vapour pressure deficit (VPD) than 2005. Pre-dawn water potential measurements indicated mild water deficit at the steep-sloped vineyard. In July 2005 mild water deficit enhanced the thermostability of grapevine photosynthesis, as reflected in the temperature dependence of optimal quantum yield (Fv/Fm) and in the critical temperature of initial fluorescence (F0Tc). Decreased Fv/Fm and actual quantum yield (ΔF/Fm') was recorded at most temperatures in September at the water-stressed (steep slope) site. This time, F0Tcs were also lower due to early leaf senescence. In September 2007, heat sensitivity of Fv/Fm was similar to 2005, and ΔF/Fm' indicated higher thermostability at both sites, but keeping the consistent difference between the two vineyards. The critical points of steady-state fluorescence (FsTc) were higher by 3-6°C at both vineyards in 2007 than in 2005. Although, in September thermolabile F0 signals were measured at the water-stressed vineyard, the heat sensitivity was not decreased in light adapted state, assumingly as a result of enhanced xanthophyll cycle pigment pool size. The higher xanthophyll pigments pool size (V + A + Z) in 2007 (compared to 2005) at the unstressed (flat) vineyard suggests that high temperature and VPD play a role in changing (V + A + Z)/(chl a + b), and, thus, results in higher thermostability under high light conditions.