High-performance liquid chromatographic analysis of phlorotannins from the brown alga Fucus vesiculosus.

Separating individual compounds by HPLC represents an effective method for the detection and quantification of phenolic compounds and has been widely utilised. However, phlorotannins are commonly quantified using colorimetric methods, as the total amount of the whole compound group. In the present paper the separation of a set of individual soluble phlorotannins from the phenolic crude extract of Fucus vesiculosus was achieved by HPLC with UV photodiode array detection. Different gradient programs for reversed- and normal-phase HPLC methods were developed and tested. Normal-phase (NP) conditions with a silica stationary phase and a mobile phase with a linear gradient of increasing polarity were found to separate 16 individual components of the phenolic extract. The suitability of the NP-HPLC method for mass spectrometric application was preliminarily tested. Sample preparation was found to be a critical step in the analysis owing to the rapid oxidation of phlorotannins; ascorbic acid was used as an antioxidant.

Reversed-phase HPLC-ESI/MS analysis of birch leaf proanthocyanidins after their acidic degradation in the presence of nucleophiles.

Mountain birch leaves contain large amounts of structurally variable polymeric proanthocyanidins. Their isolation procedure was enhanced by the addition of liquid-liquid extractions prior to column chromatography over Sephadex LH-20. Isolated polymeric proanthocyanidins were depolymerised by acid-catalysis in the presence of benzyl mercaptan or phloroglucinol in order to study their composition. The resulting degradation products, flavan-3-ols and flavan-3-ol adducts, were analysed with reversed-phase high-performance liquid chromatography using UV photodiode array detection for quantification and electrospray ionisation mass spectrometry for identification. The results showed that polymeric proanthocyanidins contained (epi)gallocatechins and (epi)catechins as the extension units and, mainly, (+)-catechin as the terminal unit. The mean degree of polymerisation was found to be 26 based on thiolysis and 31 based on phloroglucinol degradation.

Macroalgal communities face the challenge of changing biotic interactions: review with focus on the Baltic Sea.

In diverse littoral communities, biotic interactions play an important role in community regulation. This article reviews how eutrophication modifies biotic interactions in littoral macroalgal communities. Eutrophication causes blooms of opportunistic algae, increases epibiotism, and affects regulation by grazers. Opportunistic algae and epibionts harm colonization and growth of perennial algae. Grazing regulates the density and species composition of macroalgal communities, especially at the early stage of algal colonization. Eutrophication supports higher grazer densities by increasing the availability and quality of algae to grazers. This may, on the one hand, enhance the capability of grazers to regulate and counteract the increase of harmful, bloom-forming macroalgae; on the other hand, it may increase grazing pressure on perennial species, with a poor tolerance of grazing. In highly eutrophic conditions, bloom-forming algae may also escape grazing control and accumulate. Increasing epibiotism and grazing threaten in particular the persistence of habitat-forming perennials such as the bladderwrack. An interesting property of biotic interactions is that they do not remain fixed but are able to evolve, as the traits of the interacting species adapt to each other and to abiotic conditions. The potential of plants and grazers to adapt is crucial to their chances to survive in changing environment.

Quantitative analysis of polymeric proanthocyanidins in birch leaves with normal-phase HPLC.

The proanthocyanidin composition and content in the leaves of nine birch species (Betula albosinensis, B. ermanii B. maximowicziana, B. nana, B. papyrifera, B. pendula, B. platyphylla, B. pubescens, and B. pubescens ssp. czerepanovii) were studied with different methods including colorimetric assay, HPLC coupled with PAD or ESI/MS and NMR. Total proanthocyanidin content was determined using the acid butanol assay. A normal phase-HPLC method was applied for the analysis of polymeric proanthocyanidins. The content of polymeric proanthocyanidins was estimated from a late eluting peak in the chromatogram. With this HPLC method, quantitative analysis of polymeric proanthocyanidins could be performed directly from leaf extracts: no additional purification or preparation steps were required. It was shown that birch leaves contained mainly polymeric proanthocyanidins with a degree of polymerisation greater than 10. Total proanthocyanidin content (expressed as dry weight) was found to vary from 44mg/g (B. papyrifera) to 145mg/g (B. nana), and polymeric proanthocyanidin content from 39mg/g (B. pendula) to 119 mg/g (B. nana).

Effects of elevated carbon dioxide and ozone on foliar proanthocyanidins in Betula platyphylla, Betula ermanii, and Fagus crenata seedlings.

Proanthocyanidins (PAs) or condensed tannins are a major group of phenolic compounds in the leaves of birch trees and many other woody and herbaceous plants. These compounds constitute a significant allocation of carbon in leaves and are involved in plant responses to environmental stress factors, such as pathogens or herbivores. In some plants, PA concentrations are affected by atmospheric carbon dioxide (CO(2)) and ozone (O(3)) levels that may influence, for example, species fitness, community structure, or ecosystem nutrient cycling. Therefore, a study on the quantitative response of PAs to elevated concentrations of carbon dioxide (CO(2)) and ozone (O(3)) was undertaken in seedlings of Betula platyphylla, Betula ermanii, and Fagus crenata. Seedlings were exposed to ambient or elevated O(3) and CO(2) levels during two growing seasons in the Kanto district in Japan. Ten open-top chambers were used for five different treatments with two replicates: filtered air (FA), ambient air (ambient O(3), 43 ppb; ambient CO(2), 377 ppm), elevated O(3) (1.5 x ambient O(3), 66 ppb), elevated CO(2) (1.5 x ambient CO(2), 544 ppm), and elevated O(3) and CO(2) combined. In addition, seedlings growing in natural conditions outside of chambers were studied. Leaf samples were analyzed for total PA concentrations by butanol-HCl assay and for polymeric PA concentrations by normal-phase high-performance liquid chromatography. Total PA concentrations in leaves of all species were similarly affected by different treatments. They were significantly higher in seedlings treated with elevated CO(2) and O(3) combined, and in seedlings growing outside chambers compared with the FA controls. F. crenata contained only traces of polymeric PAs, but significant species x treatment interaction was observed in the polymeric PA concentrations in B. ermanii and B. platyphylla. In B. platyphylla, leaves treated with elevated CO(2) + O(3) differed significantly from all other treatments. It was suggested that the strongest effect of elevated CO(2) and O(3) combined on leaf PA contents resulted from the additive effect of these environmental factors on phenolic biosynthesis.

Contents of soluble, cell-wall-bound and exuded phlorotannins in the brown alga Fucus vesiculosus, with implications on their ecological functions.

Phlorotannins are ubiquitous secondary metabolites in brown algae that are phenotypically plastic and suggested to have multiple ecological roles. Traditionally, phlorotannins have been quantified as total soluble phlorotannins. Here, we modify a quantification procedure to measure, for the first time, the amount of cell-wall-bound phlorotannins. We also optimize the quantification of soluble phlorotannins. We use these methods to study the responses of soluble and cell-wall-bound phlorotannin to nutrient enrichment in growing and nongrowing parts of the brown alga Fucus vesiculosus. We also examine the effects of nutrient shortage and herbivory on the rate of phlorotannin exudation. Concentrations of cell-wall-bound phlorotannins were much lower than concentrations of soluble phlorotannins; we also found that nutrient treatment over a period of 41 days affected only soluble phlorotannins. Concentrations of each phlorotannin type correlated positively between growing and nongrowing parts of individual seaweeds. However, within nongrowing thalli, soluble and cell-wall-bound phlorotannins were negatively correlated, whereas within growing thalli there was no correlation. Phlorotannins were exuded from the thallus in all treatments. Herbivory increased exudation, while a lack of nutrients had no effect on exudation. Because the amount of cell-wall-bound phlorotannins is much smaller than the amount of soluble phlorotannins, the major function of phlorotannins appears to be a secondary one.

Phenolic extractives from the bark of Pinus sylvestris L. and their effects on inflammatory mediators nitric oxide and prostaglandin E2.

The anti-inflammatory properties of phenolic pine (Pinus sylvestris L.) bark extract were studied. The pine bark extract was fractionated by liquid-liquid extractions and semipreparative high-performance liquid chromatography to reveal the most potent constituents. The phenolic compositions of three pine bark samples obtained, a crude extract, a chloroform fraction, and a semipreparative fraction, were analyzed using high-performance liquid chromatography with UV diode array detection and/or electrospray ionization mass spectrometry. In addition, eight compounds were isolated and identified by NMR and MS techniques. In total 28 phenolic compounds were identified. The effects of the three pine bark samples on the synthesis of two proinflammatory mediators, nitric oxide and prostaglandin E(2), were measured. It was shown that pine bark contains compounds that inhibit the production of these proinflammatory mediators.

Biodegradation of dimethylphenols by bacteria with different ring-cleavage pathways of phenolic compounds.

The biodegradation of 3,4, 2,4, 2,3, 2,6 and 3,5-dimethylphenol in combination with phenol and p-cresol by axenic and mixed cultures of bacteria was investigated. The strains, which degrade phenol and p-cresol through different catabolic pathways, were isolated from river water continuously polluted with phenolic compounds of leachate of oil shale semicoke ash heaps. The proper research of degradation of 2,4 and 3,4-dimethylphenol in multinutrient environments was performed. The degradation of phenolic compounds from mixtures indicated a flux of substrates into different catabolic pathways. Catechol 2,3-dioxygenase activity was induced by dimethylphenols in Pseudomonas mendocina PC1, where meta cleavage pathway was functional during the degradation of p-cresol. In the case of strains PC18 and PC24 of P. fluorescens, the degradation of p-cresol occurred via the protocatechuate ortho pathway and the key enzyme of this pathway, p-cresol methylhydroxylase, was also induced by dimethylphenols. 2,4 and 3,4-dimethylphenols were converted into the dead-end products 4-hydroxy-3-methylbenzoic acid and 4-hydroxy-2-methylbenzoic acid. In the degradation of 3,4-dimethylphenol, the transient accumulation of 4-hydroxy-2-methylbenzaldehyde repressed the consumption of phenol from substrate mixtures. A mixed culture of strains with different catabolic types made it possible to overcome the incompatibilities at degradation of studied substrate mixtures.