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Abstract:The analytical method based on the high-per formance liquid chromatography coupled with UV detection (HPLC/ UV) for determination of selected antioxidants (i.e., esculetin, scopoletin, 7-hydroxycoumarine, r utin, xanthotoxin, 5-methoxypsoralen and quercetin) in plant material was developed. Pressurised fluid extraction (PFE) and ultrasonic extraction (USE) methods for the isolation of these compounds from ten real plant samples were used. Both extraction methods were optimised and compared to each other. For the proposed HPLC/UV method the LOQ values (limit of quantification) in the range from 22.7 (xanthotoxin) to 97.2 ng mL -1 (r utin) were obtained. For all extracts the antioxidant capacity based on the reduction of free 2,2-diphenyl-1-picr ylhydrazyl radical (DPPH) was also determined. Results ranged from 82.04 to 94.43% of DPPH radical inhibition for PFE method and from 76.01 to 89.94% in the case of USE method.

This paper summarises the findings obtained by using multi-electrode detector CoulArray in HPLC analysis of biologically active compounds. The methods for analysis of selected phenolic compounds were optimized. Optimal conditions of separation and detection were applied to real sample analysis. White and red wines as well as meads were analyzed and the content of phenolic acid was evaluated. Further the roots of Japanese knotweed were analyzed.

The roots of three varieties of Polygonum cuspidatum were analyzed for resveratrol and its analogs. The powder of the dried roots was extracted with aqueous ethanol (60% v/v) and the extracts obtained were analyzed using RP HPLC with coulometric detection. A simple HPLC method with a multichannel CoulArray detector was developed for the determination of four stilbenes: resveratrol, its glucoside piceid, piceatannol, and its glucoside astringin. Analyses were carried out on a LiChrospher C18 (125 x 4.6 mm id, particle size 5 microm) column with a mobile phase of ammonium acetate (pH 3) and ACN in gradient mode. Four compounds were monitored by a CoulArray electrochemical detector. Potentials of eight electrochemical cells in series were set in the range of 200-900 mV. Optimization of the mobile phase pH was performed. Calibration curves showed good linearity with correlation coefficients (r(2))--more than 0.9975.

Various biotic and abiotic factors may change the quality of cast spruce needles or induce premature casting, subsequently altering the composition of needle litter. We tested the decomposition efficiency of Setulipes androsaceus, a key litter decomposer in spruce forests, on needles of the Norway spruce (Picea abies) that fell into three different categories of quality. We designed a cultivation experiment to test the decomposition rate of the following needle categories: (1) naturally senesced brown needles, (2) intact, prematurely fallen green needles, and (3) frass pellets produced by caterpillars of the spruce web-spinning sawfly (Cephalcia spp.). Needles from each category were cultivated both independently and in combination. After a 4-month incubation, dry weight loss and the decrease of phydroxyacetophenone (p-HAP) and catechin were measured as markers of decomposition. Colonization of green needles by mycelia of S. androsaceus was initially inhibited. However, within the experimental period, those green needles successfully colonized by S. androsaceus lost more mass (22% of dry weight) than the brown needles (18% of dry weight). S. androsaceus also decreased the p-HAP and catechin contents of the green needles. Another fungal decomposer, Thysanophora penicillioides, was introduced only to the treatment that contained all three needle categories, and it induced less weight loss than S. androsaceus, but degraded the two phenolics to a similar extent. Neither the green nor the brown needles exhibited a more rapid rate of decomposition when cultivated in combination with another category of needles. We conclude that the increased proportions of green needles and frass pellets in the litter will be connected with temporarily increased decomposition activity of S. androsaceus.