Biomarkers for the prediction of the resistance and susceptibility of grapevine leaves to downy mildew.

We examined metabolic profiles of acetone and butanol extracts obtained from the leaves of 18 seedlings of the Bulgarian wine-making cultivar Storgozia. The acetone extracts contained the components from the leaf surface, while the butanol extracts were enriched with polar components from inside the leaf tissue. The leaves displayed different degrees of resistance and susceptibility to the etiological agent downy mildew, Plasmopara viticola. Based on the statistically significant correlations (P<0.05) between the GC-MS data of the identified metabolites and the estimated leaf resistances, 10 individual components were proposed as possible biomarkers for the downy mildew resistance and susceptibility in grapevine. All were found in the butanol extracts, and can be considered to form two groups: compounds with high correlations (r=+/-0.50 to +/-1.00) - 3-hydroxybutanoic acid, 2,3,4-trihydroxybutanoic acid, 2,3,4-trihydroxybutanoic acid (isomer), hexadecanoic acid, 3-hydroxyhexanoic acid and myo-inositol, and compounds with moderate correlations (r=+/-0.30 to +/-0.49) hydroxybutanedioic acid, alanine, glutamine, arabinoic acid and aldohexoses. Among them, the more polar compounds were related to sensitivity, and only hexadecanoic and the monohydroxycarboxylic acids were related to resistance in grapevine.

Examination of growth inhibitory properties of synthetic chalcones for which antibacterial activity was predicted.

A large series of chalcones were synthesized and studied against Staphylococcus aureus and Escherichia coli. Chalcones were either unsubstituted in ring A or possessed 4'-chloro or 3',4',5'-trimethoxy groups. Their other ring B was variously substituted. It was found that the anti-staphylococcal activity of chalcones was related to the energy difference between the two highest occupied molecular orbitals (HOMO and HOMO-1). Presence of hydroxyl group in ring B was not a determinant factor for the anti-staphylococcal activity, but the lipophilicity of ring A of the hydroxyl chalcones was of importance.

Evaluation of antibacterial activity of synthetic aliphatic and aromatic monoacylglycerols.

The antibacterial activity of synthetic aliphatic and aromatic monoacylglycerols (MAGs) was studied against two human pathogens: Staphylococcus aureus and Escherichia coli. The active compounds inhibited selectively S. aureus. The most active compounds amongst them were those with medium size aliphatic chain and aromatic MAGs with electron withdrawing substituents at the aryl ring. The introduction of one or two-carbon spacer between the aryl ring and the carboxylic function did not influence antibacterial effectiveness.

MDR-reversal activity of chalcones.

The ability of 11 chalcones with 3,4,5-trimethoxy substitution on ring A to inhibit the transport activity of P-glycoprotein was studied. Flow cytometry was applied in multidrug-resistant human mdr1 gene-transfected mouse lymphoma cells (L 5178 Y). The reversal of multidrug resistance (MDR) was investigated by measuring the accumulation of rhodamine-123 in cancer cells. Verapamil was applied as a positive control. The majority of the tested compounds were proved to be effective inhibitors of the outward transport of rhodamine-123. In the MTT test, chalcones 2, 3, 5 and 7 exhibited the strongest antiproliferative effects, with 50% inhibitory dose (ID50) =0.19, 0.19, 0.29 and 0.14 microg/mL, respectively. The least effective compounds were 1, 4, 8 and 11, with ID50 values in the range of 1.5-3.5 microg/mL. The antiproliferative effect was shown to be affected by the type of substitution at the p-position on ring B. Chalcone 7, with a p-chloro group on ring B, was the most effective in MDR reversal, causing a marked increase in drug accumulation from 0.4 to 40 microg/mL. In combination with epirubicin, compound 7 displayed synergistic properties while compound 3 exhibited an additive effect. The data presented here indicated that some calcone derivatives can be regarded as effective compounds for reversal of MDR.

Preliminary study on biomarkers for the fungal resistance in Vitis vinifera leaves.

We examined the leaf chemical composition of six seedlings obtained by self-pollination of the Bulgarian wine-making variety Storgozia as well as the cultivar Bouquet, which is the susceptible parent of Storgozia. The chemical composition was investigated in the framework of a program for identification of metabolites associated with disease resistance in grape-vine. Acetone, dichloromethane and butanol extracts, as well as volatiles obtained from fresh material were analyzed by GC/MS. Based on the correlations of the GC/MS data and estimated resistance of the leaves towards the etiological agents of powdery mildew, downy mildew and botrytis as biomarkers for the fungal resistance, we proposed 16 individual metabolites--alpha- and gamma-tocopherol, squalene, alpha-amyrine, stigmasta-3,5-diene-7-one, hexahydrofarnesyl acetone, glycolic acid, 3-hydroxybutanoic acid, 3-hydroxycaproic acid, malic acid, tartaric acid, erythronic acid, arabinoic acid, monoethyl phosphate, undecyl laurate and isopropyl myristate. The obtained correlations were confirmed by cluster analysis.