Polarographic Investigations of Some Metal lVIonocarhoxylato Complexes. II. Monocarboxylato Complexes of Zinc

The stability constants of zinc monocarboxylato complexes n ave been determined by the polarographic method of DeFord and Hume in water solutions of a constant ionic strength 2 and a constant monocarboxylic acid concentration of 2 M. The examinations were carried out in the monocarboxylate concentration range up to 2 M. The following values for cumulative stability constants were obtained: formato complexes f31 = 4, [32 = 3, [33 = 4, p4 = 6; acetato complexes Pt = 4, f32 = 9, p3 = 1:2, p4 = 31; propionato complexes p1 = 8, p2 = 2, p3 = 15, p4 = 43; butyrato complexes Pl= 7, p2 = 3, p3 = 26, p4 = 103

Exo-polygalacturonase production by Penicillium roqueforti on pumpkin oil cake in solid state fermentation

The feasibility of using pumpkin oil cake (PuOC), individual and in combination with wheat bran (WB), as substrate for the production of Exo-polygalacturonase (Exo-p) by starter culture Penicillium roqueforti in solid state fermentation (SSF) has been evaluated. The kinetics of enzyme production was investigated using PuOC alone in the range from 13 to 168 h, with moisture contents varying from 44% the ability to grow and produce Exo-p activity on this substrate, reaching a maximum value of 1451.75 U/g.d.w PuOC by the 5th day of fermentation. Fermentation experiments indicated that the water activity (aw) influenced the enzyme production. A medium with aw 0.932 and the fermentation time of 5 days were selected, as these conditions resulted in the highest pectolytic activity and were used for further investigation. A next step in this research was to examine the effect of the substrate combination, PuOC with wheat bran (WB), in different ratios. The addition of WB as carbon sources was found to have a significant influence on the enzymes yields. Exo-p activities were the highest with initial water activity of a w 0.932 and PuOC supplementation with WB (1:0.67)

The designing of the four – component composition of the blend of the polymer fibres on the basis of the numerical simulation

In the paper is presented a part of the project for determining basically permissible the four – component coposition of the (4K) mixture of the polymer fibres on the basis of the numerical simulation. The mathematical models of the composition are developed on the basis of the linear equations. The computer solution of some variants of these models is performed by Gaus procedures in combination with the numerical method of Monte Carlo simulation

Prirodna mikobiota i prisustvo aflatoksina B1 u polenu prikupljenom u Srbiji

Total fungal count, incidence of fungi and aflatoxin B1 (AFB1) concentration were studied in 33 samples of bee pollen randomly collected from beekeepers in Serbia. The total number of fungi was determined by dilution method whereas AFB1 was detected using the Enzyme-Linked Immuno-Sorbent Assay (ELISA). The mycological estimation showed the presence of nine genera of fungi as followed: Acremonium, Alternaría, Aspergillus, Cladosporium, Epiccocum, Fusarium, Mucor, Pénicillium and Rhizopus, with total number ranging from 1 x 103 to 1 x 105 CFU g-1. The results have shown the predominance of the fungi from the genera Aspergillus and Alternaria. Among Aspergillus species it was observed that the most frequent species was A. flavus with incidence of 27.27 %. Mycotoxin AFB1 was detected as 100% positive in all samples (100%) with an average concentration of 8.61 μg kg-1. The obtained results indicated that honey bee pollen must be strictly controlled during its manipulation in the harvesting and manufacturing. Therefore, the implementation of good manufacturing (beekeeping) practice to define procedures for honeybee products could be crucial to reduce the risk of possible contamination and provide natural and safety product without risk on the human health.Ukupan broj gljiva, učestalost (incidenca) gljiva i koncentracija aflatoksina B1 (AFB1) ispitivani su u 33 uzoraka polena sakupljenih od pčelara iz različitih regiona u Srbiji. Ukupan broj gljiva određen je primenom metode razređenja a AFB1 je određen primenom imunoadsorpcione enzimske metode (ELISA). Mikološkim ispitivanjima identifikovano je devet rodova gljiva: Acremonium, Alternaria, Aspergillus, Cladosporium, Epiccocum, Fusarium, Mucor, Penicillium i Rhizopus, sa ukupnim brojem od 1 x 103 to 1 x 105 CFU g-1. Najučestalije vrste gljiva su u rodovima Aspergillus i Alternaria. Među Aspergillus vrstama najučestalija je vrsta A. flavus sa incidencom od 27,27%. AFB1 je detektovan u svim uzorcima sa prosečnom koncentracijom od 8,61 μg kg-1. Dobijeni rezultati ukazuju da pčelarski polen mora biti strogo kontrolisan tokom prikupljanja i njegove dalje prerade. Zbog toga, sprovođenje dobre proizvođačke (pčelarske) prakse podrazumeva definisanje procedura za pčelarske proizvode što bi moglo biti presudno za smanjenje rizika od moguće kontaminacije i dobijanje prirodnih i bezbednih proizvoda bez rizika po zdravlje ljudi

Antimicrobial activity and cytotoxicity of commercial rosemary essential oil (Rosmarinus officinalis L.)

Rosemary is well known as a spice and widely used plant in ethnomedicine worldwide. In this paper, commercial essential oil of rosemary was tested for antimicrobial and cytotoxic activity together with its effect on germination. Antimicrobial activity testing showed moderate effect to both G-positive and Gnegative bacteria. In order to determine its effect to the cell membrane, spectrophotometric analysis was performed. It was determined that rosemary affects the cell membrane of bacteria. Cytotoxic activity of Rosmarinus officinalis essential oil had been evaluated. As a plant object, germinative bulbs of Allium cepa were used. Cytotoxic activity that corresponded to the concentration of essential oil was determined. It had been noticed that rosemary essential oil affected mitotic phase i.e. it significantly slowed down the mitosis. Also, investigation of rosemary essential oil's activity to germination was performed. It was determined that it had high effect to the germination. Concentration of 5 mg/ml completely inhibited the germination of Triticum vulgare

Probing the existence of chemotypes of Helleborus odorus Waldst. & Kit. ex Willd. by essential oil analysis: a multivariate approach

Helleborus species (family Ranunculaceae) are evergreen, rhizomatous plants with scientifically demonstrated biological/pharmacological activities [1]. Nonetheless, the essential oils of the genus are general poorly phytochemically and pharmacologically investigated. Helleborus odorus Waldst. & Kit. ex Willd. (‘fragrant hellebore’ or ‘kukurek’ in Serbian) is a highly toxic plant species growing on hillsides and in forests of the submediterranean region. Up to now, steroid-related compounds (saponins, ecdysteroids, bufadienolides), fatty acids and other lipids, and sugars of H. odorus were investigated. However, to the best of our knowledge, there are no previous studies of the essential oil of this species.                Analyses by GC and GC/MS of four essential-oil samples obtained from dry aerial parts and roots of H. odorus allowed the identification of 229 components, comprising 88.8-92.2% of the total oil composition. The major identified volatile compounds were 1-pentacosene (0.0-52.8%), tricosane (0.0-15.1%), linoleic acid (0.0-11.8%), trans-phytol (0.0-12.4%), hexadecanoic acid (3.7-16.8%), (2E,4E)-decadienal (tr-13.8%), linalool (0.5-6.0%) and hexanal (0.0-7.4%). In general, there were qualitative and quantitative variations noted in the compositions between the H. odorus essential-oil samples from different locations. The most discernable differences included a change in the content of the major constituent (1-pentacosene). These differences motivated us to explore (by multivariate statistical analysis (MVA)) the possible existence of several chemotypes of this species using essential-oil compositional data. Agglomerative hierarchical clustering and principal component analysis of the chemical data on the volatiles of the herein studied and additional 37 oil samples of Ranunculaceae showed a close relationship of Helleborus with other Ranunculaceae genera and the existence of only one chemotype of this species in the Serbian flora