Samo Kreft

Nutrient Content in Buckwheat Milling Fractions

ABSTRACT Buckwheat seeds (Fagopyrum esculentum Moench) were milled into 23 fractions: seven fine flours, three coarse flours, four small semolina, two big semolina, six bran, and one husk fraction. A considerable variation in gross chemical composition was found among the milling fractions. The protein content varied from 4.4 to 11.9% (db) in flours and from 19.2 to 31.3% in bran fractions; starch varied from 91.7 to 70.4% in flours and from 42.6 to 20.3 in bran. The percentage of soluble dietary fiber contained in total dietary fiber was higher in flours than in semolina and bran fractions. Ash, Fe, P, tannin, phytate content, and color were also investigated. A unique distribution of phytate was found in starch. Correlation is significantly positive in husk, bran, and semolina fractions, while correlation is significantly negative in flour fractions. Depending on technological or nutritional demands, appropriate fractions may be chosen to achieve the desired end-use product.

Screening of selected food and medicinal plant extracts for pancreatic lipase inhibition

Lipids are important components in human nutrition; however, their increased intake contributes to the development of obesity and can lead to multiple long‐term complications. Pancreatic lipase (triacylglycerol acylhydrolase, EC 3.1.1.3) is a key enzyme for the absorption of dietary triglycerides. Interference with fat hydrolysis results in the reduced utilization of ingested lipids, therefore inhibition of lipases decreases fat absorption. Extracts from 106 species of medicinal plants, vegetables and fruits were screened for potential lipase inhibitory activity. p‐Nitrophenylpalmitate and 5‐bromo‐4‐chloro‐3‐indoxylpalmitate were used as substrates in an in vitro test with crude porcine pancreatic lipase. Bearberry (Arctostaphylos uva‐ursi), garden pea (Pisum sativum), Norway spruce (Picea abies) and large‐leaved lime (Tilia platyphyllos) extracts were the most active. Additionally, the activity of selected extracts with removed polyphenols was measured. Extracts of bearberry, garden pea and large‐leaved lime are a promising source for developing functional foods or isolating active compounds. Copyright

Salicylaldehyde is a characteristic aroma component of buckwheat groats.

Salicylaldehyde (2-hydroxybenzaldehyde) was identified as a characteristic component of buckwheat groats aroma by a sensory analysis guided fractionation of the extract. The extract with the strongest odour was prepared by petroleum ether extraction of water soaked groats. This extract was further extracted with sodium hydrogen carbonate solution and purified by a preparative layer chromatography and identified by NMR, MS and IR spectroscopy. A capillary electrophoresis method was developed and used to determine salicylaldehyde content in buckwheat groats and flour samples. Traditionally dehulled buckwheat grain, which had the strongest odour, contained the highest concentration (1.6ppm) of salicylaldehyde with an odour activity value (OAV) of 216.

Comparison of capillary electrophoresis and high performance liquid chromatography for determination of flavonoids in Achillea millefolium

Flavonoids represent an important bioactive component in Achillea millefolium. The comparison of the most commonly used analytical methods for the identification and quantification of flavonoids, capillary electrophoresis (CE) and high performance liquid chromatography (HPLC), is presented. The methods were optimized and validated. Using a 20 mM borate buffer with 30% (v/v) of methanol (pH 9.3) in the CE analysis and a gradient elution with water-acetonitrile mobile phase in the HPLC analysis, sufficient separation of the analytes was achieved. A relatively high injection volume in the CE analysis (30 mbar x 30s) enabled low limit of detection (LOD) (0.3-0.7 mg/L). Repeatability of both methods was acceptable (relative standard deviation of peak area were <6%). Additionally, the amount of flavonoids in a real sample of the dried herbal drug was determined.

JASMONIC ACID INDUCIBLE ASPARTIC PROTEINASE INHIBITORS FROM POTATO

A new cDNA clone coding for an aspartic proteinase inhibitor homologue was isolated from a potato tuber cDNA library. Southern blot analysis was used to study the structural diversity of the aspartic proteinase inhibitor gene family in several species of the Solanaceae. The existence of sequence-homologous genes was confirmed in the genomic DNA of different potato cultivars (Solanum tuberosum L. cv. Désirée, Pentland Squire and Igor), tomato (Lycopersicon esculentum Mill.), aubergine (S. melongena L.) and a wild type of bittersweet (S. dulcamara L.). Northern blot hybridization of total RNA, isolated from leaves under non-stress conditions, of different solanaceous species and of potato tubers showed that the gene transcripts encoding aspartic proteinase inhibitors occur mainly in potato tubers. The presence of several cathepsin D inhibitor isoforms has been detected at the protein level. At least four isoforms were isolated by affinity chromatography on cathepsin D-Sepharose and characterized. Additionally, exogenous treatment of potato plantlets by jasmonic acid (JA) over a wide range of concentrations (0-100 microM) was performed in a stem node culture in vitro. We demonstrated that the expression of aspartic proteinase inhibitor mRNA was drastically induced in potato shoots at concentrations of 50-100 microM JA.

Determination of cichoric acid content in dried press juice of purple coneflower (Echinacea purpurea) with capillary electrophoresis.

Purple coneflower (Echinacea purpurea) is an immunostimulating drug, containing multiple substances. The most important in activity are polysaccharides, caffeic acid derivatives (cichoric acid), alkamides and glycoproteins. It is not clear yet, which substances are responsible for activity. Cichoric acid is an appropriate marker of the quality of E. purpurea containing product, because it has immune stimulatory effects and it is susceptible to degradation. In this work, an improved capillary electrophoresis method for determining cichoric acid in dried press juice from purple coneflower was developed. The optimal conditions were: electrophoretic buffer-75mM borate, pH 8.8; injection 20mbar for 20s; separation at 20kV; detection at 350nm, temperature 35 degrees C.

Effect of water stress and nitrogen fertilization on the content of hyoscyamine and scopolamine in the roots of deadly nightshade (Atropa belladonna)

Abstract The study intended to elaborate the optimal environmental conditions of water supply and nitrogen fertilization for maximum content of hyoscyamine (% dw) and scopolamine (% dw). Plants grown from seeds of Slovene autochthonous population of deadly nightshade (Atropa belladonna), were treated with different water regimes (35–95% depletion of available soil water) together with enhanced nitrogen supply (0.37–1.60 g/pot N) in a greenhouse experiment. Dry plant extracts from 32-week old roots were analysed with capillary electrophoresis (CE) for the presence of tropane alkaloids (hyosciamyne, scopolamine). The results of the plant treatment responses showed that the maximal yield of tropane alkaloids (hyoscyamine: 54 mg/plant; scopolamine: 7 mg/plant) was achieved in plants grown under an optimal irrigation regime (35% depletion of available soil water) accompanied with total nitrogen supply of 0.37 g/pot. By contrast, the maximal content of alkaloids was achieved with 95% depletion of available soil water and a nitrogen supply of 1.60 g/pot.

Physicochemical and physiological basis of dichromatic colour.

Out of three perceptual characteristics of the colour of any substance, the hue depends mostly on the spectral properties of a substance, while the brightness and saturation depend also on the concentration of a substance and its thickness. Here, we report that evident change of the hue of the colour (i.e., from green to red) is due to a change in concentration or the thickness of a layer in some exceptional substances such as pumpkin seed oil or an aqueous solution of bromophenol blue. In some regions of Central Europe, salad dressing is made preferably with the pumpkin seed oil, which has a strong characteristic nut-like taste and remarkable properties of the colour: it appears red in a bottle, but green when served as a salad dressing. The colour of the pumpkin seed oil was previously described as brownish yellow, dark green, dark green to red ochre or dark reddish brown to light yellow green. We elucidated the physicochemical and physiological basis of such dichromatism by Beer-Lambert law and by the characteristics of human colour perception. Our concept was corroborated by the outcome of calculations of colour from spectral properties using colour matching functions. We found that dichromatism is observed if the absorption spectrum of any substance has at least two local minima: one wide but shallow and one narrow but deep local minimum.

A review of herbal medicines in wound healing

Herbs have been integral to both traditional and non‐traditional forms of medicine dating back at least 5000 years. The enduring popularity of herbal medicines may be explained by the perception that herbs cause minimal unwanted side effects. More recently, scientists increasingly rely on modern scientific methods and evidence‐based medicine to prove efficacy of herbal medicines and focus on better understanding of mechanisms of their action. However, information concerning quantitative human health benefits of herbal medicines is still rare or dispersed, limiting their proper valuation. Preparations from traditional medicinal plants are often used for wound healing purposes covering a broad area of different skin‐related diseases. Herbal medicines in wound management involve disinfection, debridement, and provision of a suitable environment for aiding the natural course of healing. Here we report on 22 plants used as wound healing agents in traditional medicine around the world. The aim of this review is therefore to review herbal medicines, which pose great potential for effective treatment of minor wounds.

Comparison of bacterial and phage display peptide libraries in search of target-binding motif

Genetic engineering allows modification of bacterial and bacteriophage genes, which code for surface proteins, enabling display of random peptides on the surface of these microbial vectors. Biologic peptide libraries thus formed are used for high-throughput screening of clones bearing peptides with high affinity for target proteins. There are reports of many successful affinity selections performed with phage display libraries and substantially fewer cases describing the use of bacterial display systems. In theory, bacterial display has some advantages over phage display, but the two systems have never been experimentally compared. We tested both techniques in selecting streptavidin-binding peptides from two commercially available libraries. Under similar conditions, selection of phage-displayed peptides to model protein streptavidin proved convincingly better.