Comparison and QSAR study of thermodynamic pKBH+ values of benzoylhydrazones determined by UV-Vis spectroscopy

Thermodynamic dissociation constants of fifteen protonated aromatic hydrazones were determined by UV-Vis spectroscopic method, as one of the main methods for determination of pKBH+ values of a weak acids and bases. The stoichiometric pKBH+ values of investigated compounds were determined at three different ionic strengths (0.1, 0.25 and 0.5 mol/dm3) in acidic media (1 < pH < 7). The thermodynamic pKBH+ values were evaluated graphically as an intercept with extrapolation to zero ionic strength of the curve which represents dependence of ionization constants on square root of ionic strength. The obtained results showed that there are no significant differences in the values of thermodynamic dissociation constants of investigated hydrazones with no substituent and metoxy group (–OCH3) on hydrazide part of the molecule. The differences in the pKBH+ values were noticed for hydrazones with nitro group (-NO2) on the benzene ring of benzaldehyde. Nitro hydrazones have lower pKBH+ values, probably due to the influence of the -NO2 group present in their molecule. The obtained pKBH+ values were in accordance with those for similar class of compounds. QSAR study has been made by correlation thermodynamic ionization constants with structure using various physicochemical parameters

Protonation of citraconic and glutaconic acid in perchloric acid media

The protonation process of citraconic and glutaconic acid in perchloric acid media was followed using the method of UV spectroscopy. The observed changes in the UV spectra of investigated acids confirmed that the protonation process in perchloric acid with concentration from 5 to 10 mol/dm3 occurred. Glutaconic acid behaved as weak organic base in perchloric acid media and existed in its monoprotonated form. On the other hand, citraconic acid existed in its protonated form and as protonated anhydride at higher perchloric acid concentration. Using the absorbance data the thermodynamic dissociation constants were calculated applying the methods of Yates and McClelland, Bunnett and Olsen, and the “excess acidity” function method. The solvatation parameters m, m* and were evaluated, as well. In order to correct the medium effect the method of characteristic vector analysis was applied. The possible site where the protonation may take place was discussed using the partial atomic charge values determined according to AM1 and PM3 semiempirical methods

SPECTROPHPTPMETRIC METHOD FOR DETERMINATION OF TOTAL POLYHENOLIC CONTENT IN SWEET CORN

Polyphenolic compounds also known as polyhydroxyphenols, are a group of secondary plant metabolites that can be found as simple molecules but also as highly polymerized compounds such as tannins. Many food types are considered as a great source of polyphenolic compounds, such as fruit, herbs, vegetables, grains and so on. Therefore, the goal of the present study was the determination of total polyphenolic content (TPC) in two sweet corn cultivars Messenger F1 and Sentinel F1 using UV – Vis spectroscopy. TPC in sweet corn are evaluated by Folin – Ciocâlteu method in relation with gallic acid as a reference standard. The obtained results reveled that the TPC in the hybrid Messenger F1 i

FOLIN–CIOCÂLTEU METHOD FOR DETERMINATION OF TOTAL POLYPHENOLS IN ONION

Onion is one of the most important crop in the world and the richest source of polyphenols. Polyphenols are organic compounds that are naturally present in onions and influence to its quality. The content of polyphenols depends on different factors. In this research determination of total polyphenols and flavonoids in two Macedonian local populations of onions was done by UV-Vis spectroscopy. The extraction of polyphenols from onions was performed with 60% methanol, while time for extraction was 120 minutes. Required time for completion of the reaction between polyphenols and Folin – Ciocâlteu reagent was examined. The total polyphenolic content was determined by the Folin – Ciocâlteu method with gallic acid as a reference standard. The obtained results were presented as mg GAE/100 g onion. Furthermore, the content of flavonoids in analyzed onions was determined with quercetin as a reference standard. The results were presented as mg QE/100 g onion. Polyphenols and flavonoids were determined in the onions’ extracts immediately after extraction and in the extracts stored 18 hours in a refrigerator at 4 °C. The results showed that there is no significant difference in content of polyphenols in analyzed onions, while the flavonoid content was higher in a population Melnik

HPLC METHOD FOR DETERMINATION OF ACTIVE INGREDIENTS IN PESTICIDE FORMULATION SWITCH 62,5 WG

Analytical quality control for pesticides achieved using appropriate methods is essential in providing their safe and adequate use in agriculture. This study presents a precise, fast, and a simple analytical method for determining active ingredients cyprodinil and fludioxonil in a fungicide formulation Switch 62,5 WG using high-performance liquid chromatography (HPLC). The development of the HPLC method was performed on a ZORBAX Eclipse Plus C18 (50 x 4.6 mm, 1.8 µm) analytical column using isocratic elution with a mobile phase consisting of acetonitrile and water in volume ratio 70:30, a flow rate of 1 mL/min, a constant column temperature at 25 ºC and UV detection at 220 and 270 nm. The run time of analysis under these chromatographic conditions was about 1.5 min. The method was validated by testing specificity, linearity, precision, recovery, LOD, LOQ, and accuracy according to the CIPAC (Collaborative International Pesticides Analytical Council) and SANCO (Directorate General Health and Consumer Protection) guidelines, and all the tested parameters were found within acceptance criteria. The values for multiple correlation coefficient (R2 ≥ 0.99), relative standard deviation (RSD < 1 %), recoveries ranged from 98.95 - 102.26 %, revealed that the developed method has a good linearity, precision and accuracy. The proposed method is suitable for routine analysis of active ingredients cyprodinil and fludioxonil in the formulation Switch 62,5 WG

VARIATION OF FRUIT MORPHOLOGICAL TRAITS IN CAPSICUM ANNUUM L. GERMPLASM COLLECTION FROM NORTH MACEDONIA

The aim of this research was to evaluate the phenotypic divergence of 33 local pepper landraces from North Macedonia based on their fruit traits, that have not been evaluated before. According to the vernacular names they belong to the longum group and are traditionally consumed mostly in technological maturity. The experiment was laid out in randomized block design in three replications in 2018. Six quantitative fruit traits were evaluated: fruit length, fruit width, fruit weight, fruit pedicel length, fruit wall thickness and number of locules, as well as several quantitative traits: colour at intermediate stage, colour at mature stage, fruit shape, shape at blossom end, cross-sectional corrugation, ripe fruit persistence – pedicel with fruit and pedicel with stem. The PCA analysis identified that two principal components explain more than 77% of the variability based on the quantitative fruit parameters. The cluster analysis classified the accessions in three clusters, where the third cluster grouped seven local landraces that had highest values for fruit width, fruit weight and pericarp thickness and are major yield components. It can be concluded that the results obtained for the fruit variability in the investigated 33 local pepper landraces from North Macedonia provided valuable information about the diversity of the collection. Furthermore, the local landraces identified in cluster three can be considered as potential source for selection of preferred traits or for further utilization in development of recommendations for direct production in the rural areas

BACILLUS SPP. – A POTENT BIOLOGICAL CONTROL AGENTS AGAINST DOWNY MILDEW OF GRAPEVINE

Plasmopara viticola, the causal agent of downy mildew of grapevine, is one of the most devastating and economically most important grapevine pathogens worldwide (Perazzolli et al., 2012). In the Republic of North Macedonia, control of downy mildew in grapevine is mainly achieved by application of synthetic fungicides. However, the long-term and continuous use of synthetic fungicides leads to appearance of resistant strains of the pathogen, residues and environmental pollution. Alternatives to chemical control such as the use of biological control agents or resistant cultivars, currently play a small role in controlling this disease. A promising alternative strategy that could replace or be combined with fungicides are biofungicides. The main goal of the experiment was to observe the possibility for biological control of grape downy mildew by the use of two novel biofungicides, Sonata (a.m. Bacillus pumilus QST 2808) and Serenade Aso (a.m. Bacillus subtilis QST 713). Experiment was conducted during the 2019 in two vineyard regions in the Republic of North Macedonia (Demir Kapija and Negotino), on three grape varieties (Merlot, Riesling and Vranec). Both tested biofungicides showed almost equal efficacy, with more than 94% reduction of disease severity index on leaves in Vranec and Riesling varieties and with more than 97% reduction of disease severity index on leaves in Merlot variety. On bunches, both biofungicides achieved 100% reduction of disease incidence and severity index in all three varieties. The results showed that Bacillus pumilus and Bacillus subtilis are potent biological agents and have a prospective use for control of downy mildew in grapevine

BIOLOGICAL CONTROL OF BOTRYTIS BUNCH ROT OF GRAPES IN THE REPUBLIC OF MACEDONIA

Bunch rot disease of grapes, caused by the necrotrophic fungus Botrytis cinerea is a chronic and serious problem in most of the vineyards in Republic of Macedonia. Its control is mostly achieved by application of synthetic fungicides. However, chemical control of B. cinerea is often difficult and incomplete, especially in vineyards where resistant strains have developed. A promising alternative strategy that could replace or be combined with fungicides are biofungicides. The main goal of the experiment was to observe the possibility for biological control of Botrytis bunch rot disease by the use of three novel biofungicides (Serenade Aso, Polyversum and Timorex gold). Experiment was conducted during the 2016 in two vineyard regions of Republic of Macedonia (Negotino and Kavadarci), on two grape varieties, Chardonnay and Cardinal. The destructive potential of this grape disease was confirmed in the untreated variant of the Chardonnay variety, where the intensity of infection was higher than 48%. Biofungicides Serenade Aso (a.m. Bacillus subtilis QST 713) andTimorex gold (extract of Malaleuca alternifolia) had similar efficacy, with average of 89% reduction of disease incidence in the region of Negotino and 91,66% in the region of Kavadarci. Biofungicide Polyversum (a.m. Pythium oligandrum M1), applied as preventive sprays achieved more than 85% reduction of the disease in both regions. The results showed that all tested biofungicides have a prospective use for control of bunch rot disease in grapes

The effects of nitrogen on protein, oil and trypsin inhibitor content of soybean

Nitrogen fertilization have influence on protein, oil and trypsin inhibitor content of different soybean genotypes. Seed protein content was increased over control by 60 kg ha-1 nitrogen while trypsin inhibitor was reduced by all treatmens (30, 60,90 N kg ha-1) as compared to controls. Significant genetic variation in TI was found both within the genotype class with the Kunitz inhibitor present as well as within the class lacking this inhibitor. Genotypes containing the Kunitz trypsin inhibitor protein (KTI) exhibit a higher TI than genotypes lacking this protein, however, in both groups of genotypes TI was similary affected by nitrogen application. Oil content was reduced following nitrogen fertilisation

SPECTROPHOTOMETRIC DETERMINATION OF TOTAL POLYPHENOLIC AND FLAVONOID CONTENT IN TOMATO

Polyphenolic compounds are a heterogeneous group of secondary plant metabolites and one of the most important classes of natural antioxidants. Polyphenols can be found in apples, onions, dark chocolate, red cabbage, tomatoes, and many other fruits and vegetables. The aim of the present investigation was the determination of total polyphenolic content (TPC) and total flavonoid content (TFC) in two tomato cultivars "Belle F1" and "Perugino F1" by UV-Vis spectroscopy. Determination of TPC was performed by Folin–Ciocâlteu assay with gallic acid as a reference standard. In order to determine TFC, quercetin was used as a reference standard. The obtained results showed that the TPC is higher in the tomato Perugino F1 (9.18 ± 0.16 mg / 100 g) compared to the hybrid "Belle F1" (6.23 ± 0.03 mg / 100 g)