Comparative Study on the MDR Reversal Effects of Selected Chalcones.

Based on the structure of three previously established lead compounds, fifteen selected chalcones were synthesized and evaluated for their multidrug resistance (MDR) reversal activity on mouse lymphoma cells. The most active chalcones were stronger revertants than the positive control, verapamil. In the model of combination chemotherapy, the interactions between the anticancer drug doxorubicin and two of the most effective compounds were measured in vitro, on human MDR1 gene transfected mouse lymphoma cells, showing that the type of interaction for one of these compounds was indifferent while that for the other one was additive. Furthermore, two chalcones inhibited 50% of cell proliferation in concentration of around 0.4 µg/mL and were from 2- to 100-fold more active than the most chalcones. The structure-activity relationships were obtained and discussed in view of their usefulness for the design of chalcone-like P-gp modulators and drugs able to treat resistant cancers.

GC-MS analysis of the leaf surface components of four Bulgarian grapevines grown under different conditions.

Four grapevine seedlings were propagated and planted both in a greenhouse and in an experimental field. Surface components of their fresh leaves were easily obtained and analysed by gas chromatography-mass spectrometry. In total, 21 surface metabolites were identified. Unlike the greenhouse samples, the field ones possessed semiochemicals and compounds contributing to their survival under environmental stress. This study shows that the leaf surface of the grapevine possesses compounds indicating the conditions of breeding.

Surface metabolic composition of berries collected from 13 Bulgarian grapevine plants.

The surface metabolic composition of berries, collected from the Bulgarian grapevine variety Storgozia, and 12 of its seedlings were studied by GC/MS. Diverse surface metabolites were identified. The main components were long chain n-alkanes, terpenoids, and esterified long-chain fatty acids. Amongst them, the terpenoids were most abundant, including, as are typical for plants, sesquiterpenoids, diterpenoids and triterpenoids. Cyperene, a sesquiterpene hydrocarbon, was identified for the first time in grapes. This compound and most of the other identified metabolites are known to possess biological functions that most probably contribute to the quality of grape berries and their defences against biotic and abiotic stressors.

Seasonal variations in the chemical composition of vine-grape leaf surface.

Surface leaf metabolites of two seedlings of a Bulgarian winemaking cultivar Storgozia I(1) were analyzed in two seasons - summer (July) and autumn (October). The resistance towards some fungal pathogens of one of the plants was estimated as superior to the resistance of the other one. Significant seasonal variations in the chemical constituents of the two seedlings were observed. The main metabolites of the summer samples were sterols, terpenes, fatty acids and heterocyclic compounds. In autumn, sterol and fatty acid contents decreased, mono- and diterpenes and heterocyclic compounds disappeared and instead of them hydrocarbons and alcohols were detected. Some individual components - stearic acid, alpha-amyrin, lupeol and squalene - correlated with the estimated resistance and were therefore proposed as biomarkers for the fungal resistance in grape-vine leaves.

Antifungal activity of chalcones: a mechanistic study using various yeast strains.

We reported the synthesis, antifungal evaluation and study on substituent effects of 21 chalcones. A lot of genetically defined strains belonging to different yeast genera and species, namely Saccharomyces cerevisiae, Hansenula polymorpha and Kluyveromyces lactis, were used as test organisms. Concerning the mode of the antifungal action of chalcones it was shown that DNA was probably not the main target for the chalcones. It was revealed that the yeast's intracellular glutathione and cysteine molecules play significant role as defence barrier against the chalcone action. It was also shown that chalcones may react with some proteins involved in cell separation.