Biochemical characteristics of urban maple trees

The study, which covers the period between 2014 and 2018, was carried out in the city of Naberezhnye Chelny, Republic of Tatarstan, Russia. The aim of the study was to examine the biochemical response of maple trees growing in the anthropogenic environments. Leaf samples from 600 trees (Acer platanoides L. and Acer negundo L.) were collected at monthly intervals from June through August. Sampling was performed early in the morning (11 a.m.) in the middle of the month. The study offers statistical data on the tannin content, determined via permanganometry; the ascorbic acid concentration, found via titration with 2.6-dichlorophenolindophenol; the ascorbate oxidase activity determined by absorbance at 265 nm; and the polyphenol oxidase activity, found by the spectrophotometric method. Relatively higher ascorbate oxidase activity was detected in August among ash-leaved Acer platanoides L. and Acer negundo L. in areas with strong anthropogenic impact. Due to increased air pollution, maple trees were found to exhibit an increase of polyphenol oxidase activities. The condensed tannin content in Norway maple trees dropped over time: by 1.24 in July (avenue); by 0.94 (buffer area) and 0.76 (avenue) in August. The condensed tannin content in the ash-leaved maple trees also decreased: by 0.69 (buffer area) and 0.22 (avenue) in July; by 0.37 (buffer area) and 0.61(avenue) in August.     

The plant vigour hypothesis revisited – how is browsing by ungulates and elephant related to woody species growth rate?

The way herbivores select what to eat is of considerable practical and theoretical interest, and has given rise to different theories and hypotheses. The plant vigour hypothesis predicts that herbivores feed preferentially on vigorous, i.e., large and/or fast-growing plants or plant parts. These predictions have previously primarily been tested on variation within plant species. Here we test whether differences in vigour among plant species in the same environment can explain differences in herbivore attack. We studied variation in browsing pressure by a guild of large herbivores on different woody species in an African savanna ecosystem. Shoot growth rate, annual shoot length, basal shoot diameter and annual shoot volume of 14 woody plant species were measured in the field. Plant species’ shoot vigour represented by the first PCA axis scores generated from the four shoot variables were then related to browsing pressure (% utilisation) on each of the species by native ungulates and elephant. Nutrient and fibre concentrations and tannin activity were also determined for the 14 woody plant species. We found ungulate browsing pressure to show a unimodal relationship with plant species’ shoot vigour. The heaviest browsing pressure was on plant species with shoots of intermediate vigour. We suggest that species with less vigorous shoots had low nutrient and high fibre concentrations and offered small bite sizes, whereas species with vigorous shoots had high nutrient concentrations but larger shoot diameters than the bite diameters of browsing ungulates. Elephant browsing pressure was not related to plant species’ shoot vigour.     

Concentration of <Emphasis Type="Italic">Cupriavidus necator</Emphasis> cells by flocculation and sedimentation

Separation and cells concentration constitute important stages in most biotechnological processes. Particularly, use of flocculation/sedimentation can improve significantly the extraction of biopolymers accumulated by microorganisms and the biodegradation of xenobiotic compounds by cell sludge. In this work the use of tannin and aluminum sulphate (Al₂(SO₄)₃) as flocculating agents for concentration of cells of Cupriavidus necator DSM 545 is evaluated. Cells were grown in broth nutrient medium in Erlenmeyer flasks, submitted to orbital agitation of 160 rpm at 30 °C for 21 h. The optimal concentrations of flocculating agents, as determined with a standard jar test method, were equal to 2,800 mg/L for tannin and 800 mg/L for Al₂(SO₄)₃, allowing for recovery of 95% of the cells in both cases. Obtained flocs presented density and average diameter of 1.03 g/mL ± 0.01 g/mL and 158 μm ± 19 μm for tannin and of 1.05 g/mL ± 0.01 g/mL and 146 μm ± 14 μm for Al₂(SO₄)₃, respectively. Batch settling tests were performed in order to determine the operational capacity of continuous settlers to be used for separation of the investigated flocculent suspensions. Finally, cultivation of cells using flocs as inoculum indicated that the cells remained viable after flocculation with usage of the optimum flocculating agent concentrations.     

ent-Eudesmane sesquiterpenoids, galloyl esters of the oak lactone precursor, and a 3-O-methylellagic acid glycoside from the wood of Platycarya strobilacea

ent-Eudesmane sesquiterpenoids, 8,11-dihydroxy-2,4-cycloeudesmane, 11-hydroxy-2,4-cycloeudesman-8-one and 2,4-cyclo-7(11)-eudesmen-8-one, were isolated from the wood of Platycarya strobilacea, which has been used as an aromatic tree since at least the 18th century. On charring the wood, 2,4-cyclo-7(11)-eudesmen-8-one was detected in the smoke. In the charred wood, the concentrations of ellagitannins, such as galloyl pedunculagin, dramatically decreased, whereas concentrations of pentagalloyl glucose, and other gallotannins were relatively stable. In addition, two other compounds, the 6′-O-m- and p-digalloyl oak lactone precursor and the 3-O-methylellagic acid 4′-O-(4″-O-galloyl)-xylopyranoside, were isolated from the charred wood along with m- and p-digallic acid.     

Processing conditions analysis of Eucalyptus globulus plywood bonded with resol-tannin adhesives

Phenol-formaldehyde resol containing mimosa tannin extract was employed to produce plywood panels with two plies from Eucalyptus globulus veneers. The effect of processing conditions and tannin content on the gelation time of the adhesive in the glue line was evaluated by dynamic-mechanical analysis (DMA). These results were related with shear strength and wood failure of glue line in the final panels. Hazardous petrochemical phenol could be partially substituted in resols in industrial applications by addition of mimosa tannin extracts.     

From lignins to tannins: forty years of enzyme studies on the biosynthesis of phenolic compounds

In the early 1960s, enzyme studies increasingly began to replace the common ‘feeding’ experiments in which labeled tracers were applied to living plants or plant parts for elucidating metabolic pathways. This advanced technique allowed to gain much deeper insights into individual details of metabolic sequences, and particularly on the previously inaccessible role of activated ‘energy-rich’ intermediates. Based on the author’s own experience for the past 40+ years in this field, principal findings and trends elucidating the pathways to lignin and lignin precursors, acyl amides and hydrolyzable tannins (gallotannins, ellagitannins) by enzyme studies are reported.     

Formation of tannin-albumin nano-particles at neutral pH as measured by light scattering techniques

Aggregation phenomena of tannin with bovine serum albumin were investigated by light scattering techniques including photon correlation spectroscopy and Rayleigh scattering. Tannin and albumin formed particles with diameters less than 1 microm at neutral pH. As revealed by this study, light scattering methods are useful in investigating aggregation phenomena of biomolecules and in directly quantifying tannin content.     

外生菌根的形态学、解剖学及分类学研究进展

本文综述了外生菌根的形态学和解剖学特征,评价了这些特征用于外生菌根分类的价值,同时指出各种类型的形态学特征和解剖学特征与其营养吸收的关系。这些特征包括了菌根的颜色类型及变化、形状及分枝方式、外伸菌丝的多少及特征、根状菌索有无及分化、菌核有无及特征、菌套内外表面的菌丝排列及分化,菌套的切面特征,丹宁层厚度及分化、哈氏网的菌丝排列及厚度等。较详细阐述了100多年来,人们为外生菌根分类所作出的种种努力,并对各种分类方式作了简单的评价。     

In vitro pharmacological evaluation and phenolic content of ten South African medicinal plants used as anthelmintics

Helminth infection is regarded as one of the neglected tropical diseases (NTDs). Although the disease is common in rural areas, information on the pharmacology of South African medicinal plants used against this disease is limited. We investigated the efficacy of ten South African medicinal plants against Caenorhabditis elegans. Because of the increased susceptibility of a host to microbial infections and other inflammatory responses associated with helminth infections, the antimicrobial and cyclooxygenase (COX) inhibitory activities of the plants were also investigated. Phenolics including flavonoids, condensed tannins and gallotannins have been linked to many pharmacological activities. Thus, the phenolic content of the plant extracts were quantitatively evaluated. In the three bioassays, organic solvent extracts from Cyathea dregei (roots and leaves), Felicia erigeroides (leaves and stems), Hypoxis colchicifolia (leaves) and Senna petersiana (leaves) exhibited noteworthy pharmacological activities while Acokanthera oppositifolia (leaves) had good COX inhibitory activity. The concentration of phenolics ranged from 56.7 to 1.7 mg GAE/g dry matter in Ocimum basilicum and Cotyledon orbiculata var. dactylopsis, respectively. Flavonoids, condensed tannin and gallotannin content also varied greatly among the plant extracts investigated.