No abstract

The object of presented study was the evaluation of antioxidant activity of extract from Zingiber officinale. A method for the preparation of the extract was chosen, which enabled to isolate mostly phenolic compounds. According to the measurements with Folin-Ciocalteu reagent, obtained extract comprised total polyphenols (181.41 mg GAE /g of extract) from which flavonoids contributed to 7.8 % (14.15 mg quercetin /g of extract). Nuclear magnetic resonance (NMR) analysis showed that the phenolic ketones were predominant in the extracts of whole phenolic compounds. According to results of two spectrophotometric methods (ABTS and DPPH test), ginger extract showed stronger ability to scavenge DPPH radical than ABTS cation radical.

Trichoderma viride was capable of growth and conidiation in the presence of high concentrations of the uncoupler 3,3',4',5-tetrachlorosalicylanilide (up to 100 micromol x L(-1) and of the respiration inhibitor mucidin (up to 100 micromol x L(-1) ) in both submerged and surface cultivation. When vegetative mycelia were cultivated on the solid Czapek-Dox medium with yeast autolysate under an anaerobic and CO2-containing atmosphere, the growth was observed only rarely but the microorganism survived as long as 3 months under these conditions. Major products of metabolism of both aerobic and anaerobic submerged mycelia were identified by means of 1H-NMR measurements. Major products excreted to the medium under aerobic conditions were succinic and citric acids. Major metabolites present in the submerged mycelia were gamma-aminobutyric (and glutamic) acid and alanine. Under anaerobic conditions, citric acid was not excreted into the medium but ethanol appeared. Its production could not be increased upon increasing the sugar concentration. The appearance of secondary metabolites was found to be modified by oxygen availability during the mycelial growth. Results suggest that the vegetative form of T. viride is capable of fermentative metabolism characterized by the production of ethanol and succinate and that the excretion of carboxylic acids is developmentally regulated and modified by oxygen availability.

The evaluation of antioxidant potential of food has received much attention in recent years. Antioxidant compounds can scavenge free radicals and thereby can protect the human body from free radicals. This study was focused on the isolation of curcuminoids from the dried turmeric rhizome, and studying their antioxidant activity. The presence of curcuminoids was identified in turmeric sample by Nuclear Magnetic Resonance (NMR) analysis. Since neutral curcumin is known to be poorly soluble, the synthesis of curcumincyclodextrin and curcumin-phospholipid complexes was also performed. The antioxidant activity of isolated curcuminoids was assessed by two methods (ABTS and FRAP assay) and their scavenging activities were compared with those of prepared complexes. The ability to reduce ABTS radical cation decreased as follows: quercetin > trolox > curcuminoids > curcumin-cyclodextrin complex > curcumin-phospholipid complex. The reducing potential of tested samples in descending order was quercetin > trolox > curcumin-cyclodextrin complex > curcuminoids > curcumin-phospholipid complex.

Glutamate decarboxylase (GAD) catalyses decarboxylation of glutamate to gamma-aminobutyrate (GABA) in a metabolic pathway connected to citrate cycle and known as GABA shunt. The gene (gad) was disrupted in Trichoderma atroviride CCM F-534 and viable mutants were characterized. Two of them were found to arise by homologous recombination and were devoid of both GAD activity and GABA. Mutants grew slower as compared to the wild type (F534). In the submerged culture, mutants developed less CO2 and consumed less O2 than the F534 without changing their respiratory quotients. Hyphae of mutants were more ramified than those of F534. Their ramification, in contrast to F534, was not increased by cyclosporin A, a drug causing hyphae ramification of several fungi and which is a calcineurin/cyclophilin inhibitor, or by FK506. Rapamycin, which is a cyclophilin but not calcineurin inhibitor, had a different effect on hyphae ramification in F534 and mutants. To examine the presence of GABA receptors in the fungus the effect of mammalian GABA-receptor modulators, such as bicuculline, gabapentin or carbamazepine on fungal morphology were investigated. Conidia of mutants germinated in a multipolar manner more frequently (up to 80 %) than those of F534. This trait was modified with cyclosporine A, FK506 and GABA receptor modulators in a different manner. Transport of chlorides, an intimate feature of GABA-regulated receptors/channels in animal cells, was measured in vegetative mycelia by means (36)Cl(-) uptake. It was significantly reduced in gad mutants. The results suggest that T. atroviride possesses a signalling pathway that involves GABA, putative GABA receptor(s), calcineurin, target of rapamycin and chloride transporter(s) to regulate physiological functions.