Lipoxygenase (LOX) from opium poppy (Papaver somniferum L.) chloroplasts was isolated and 126.1-fold purified to electrophoretic homogeneity by combination of ion-exchange chromatography on HA-Ultragel column and affinity chromatography on a linoleyl-aminopropyl agarose column. The relative molecular mass of the LOX determined by SDS-PAGE was 92 kDa. Kinetic properties of purified LOX were determined in spectrophotometric assay by using of linoleic acid (K M = 1.78 mM and V max = 11.4 μmol mg -1 min -1 ) and linolenic acid (K M = 1.27 mM and V max = 10.2 μmol mg -1 min -1 ). The optimum pH was 6.0 for both linoleic and linolenic acid dioxygenation catalyzed by LOX. HPLC analysis of the products revealed a dual positional specificity of linoleic acid dioxygenation at pH 6.0 with ratio of 9-and 13-hydroperoxide products being about 1:1. The activity of purified LOX was stimulated by Mg 2+ and Ca 2+ . Abbreviations: GrB -grinding buffer; HOD -hydroxyoctadecadienoic acid; HPOD -hydroperoxyoctadecadienoic acid; KPB -potassium phosphate buffer; LA -linoleic acid; LAPA -linoleyl-aminopropyl agarose; LeA -linolenic acid; LOD -limit of detection; LOQ -limit of quantification; LOX -lipoxygenase; PMSF -phenylmethylsulfonyl fluoride; RP HPLC -reversed-phase highperformance liquid chromatography; SP HPLC -straight-phase high-performance liquid chromatography; TX-114 -Triton X-114. Acknowledgements: This work was supported by grant of Slovak ministry of education VEGA

The aim of the study was a HPLC evaluation of the lipoxygenase activity inhibiting activity of a water infusion of Ligustrum vulgare L. leaves and selected isolates from it. The antiradical activity of the water infusion was determined using DPPH, ABTS and FRAP tests. Oleuropein and echinacoside concentrations in the water infusion were determined by HPLC. Water infusion, echinacoside and oleuropein were used for an antilipoxygenase activity assay using lipoxygenase isolated from rat lung cytosol fraction. Activity of 8-LOX, 12-LOX and 15-LOX were monitored through formation of 8-HETE, 12-HETE and 15-HETE, respectively. The water infusion exhibited the highest activity against all lipoxygenases, followed by oleuropein. Echinacoside was ineffective against LOXs in lower concentrations, while higher concentration showed similar inhibition on 8-LOX and 12-LOX. 15-LOX was affected more and the presence of echinacoside remarkably decreased its activity.

In traditional medicine, several medicinal plants or their extracts have been used to treat diabetes. Zingiber officinale Roscoe, known commonly as ginger, is consumed worldwide in cookeries as a spice and flavouring agent. It has been used as the spice and medicine for thousands of years. The present study was undertaken to investigate the potential protective effect of Zingiber officinale Rosc. in a model of oxidative damage to pancreatic β cells. The free radical scavenging activities and composition of the isolated n-hexane and ethanolic extracts were confronted with their protective, antioxidant and cytotoxic effects in INS-1E β cells. Unlike the n-hexane extract (exerting, paradoxically, stronger antiradical capacity), both low cytotoxicity and remarkable protective effects on β cell viability, followed by lowering oxidative stress markers were found for the ethanolic extract Zingiber officinale Rosc. The present study is the first pilot study to assess the protective potential of Zingiber officinale Rosc. in a model of cytotoxic conditions imposed by diabetes in β cells.

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There is an optimized, validated and implemented method for determination of kaempferol through liquid chromatography in terms of isocratic separation in the proportion: 0.05% phosphoric acid and acetonitril (50:50) v/v. The limits of detection (LOD) and quantification (LOQ) were determined. The content of kaempferol in samples from Lilium candidum L. with the use of different concentrations of extract agent and after releasing kaempferol from dermal semisolid medicaments was investigated. The samples were prepared by various producers. The results obtained proved that the implemented method shows good validated parameters and is favourable for determination of kaempferol in samples from Lilium candidum L. It was kaempferol that evaluated best from the samples that were prepared by extraction of 80% ethanol. The contents in the samples were determined using the method, after releasing kaempferol from dermal semisolid medicaments.