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The distribution, absorption, metabolism and tissue binding of radioactivity were studied in hamsters after oral and intraperitoneal administration of alpha-chaconine- (3H). The material was well absorbed from the gastrointestinal tract and nearly 22 percent of the label was excreted via urine and feces in 7 days. The excretion was higher in urine (21 percent) than in feces ( < 1 percent). Tissue concentrations of radioactivity peaked at 12 hours following oral administration, with the highest concentrations found in lungs, liver, spleen, skeletal muscle, kidney and pancreas, with heart and brain containing moderate amounts. Concentrations of radioactivity in tissues following intraperitoneal administration were significantly higher than those observed after oral treatment. Excretion of chloroform-soluble products in the feces was 10 times higher than that of the chloroform-insoluble metabolites after both oral and intraperitoneal administration. In the urine, the activity was predominantly in the chloroform-insoluble form and the chloroform-soluble metabolites were relatively minor in amounts (0.27, 0.85, and 2.45 percent versus 0.005, 0.14 and 0.19 percent of dose for 12, 24 and 72 hours, respectively). After 7 days, the chloroform-soluble metabolites in urine increased to 20 percent of the excreted radioactivity, while the amount of chloroform-insoluble metabolites was less than 1 percent. Subcellular distribution of the labeled compound indicated the highest concentration of radioactivity in the nuclear and microsomal fractions of brain, liver and heart tissues. A small amount of radioactivity, shown by a minor peak, was also observed in the fractions between the mitochondrial and microsomal fractions on a sucrose gradient. Binding of radioactivity was observed in brain, testes, kidney, lung, liver and heart . All of the label in the brain appeared to be in the bound form . The results indicated that alpha-chaconine is slowly absorbed from the gastrointestinal tract after oral administration, and persists in various tissues, much of it in bound (non-extractable) form (in nuclear and microsomal fractions). Excretion of alpha-chaconine- (3H) and its metabolites was investigated after oral and intraperitoneal administration in hamsters. The separation of the glycoalkaloid and its metabolites in feces and urine was accomplished by thin-layer chromatography. An increase in the concentration of excreted alpha-chaconine metabolites in feces and urine was observed. In urine over 50 percent of the eliminated radioactivity during the initial 24 hours was due to the aglycone, solanidine. The fraction of the total dose administered which was excreted represented only 27 percent (26 percent in feces and less than 1 percent in urine) during the 7 day test period. Contrary to the general belief that potato glycoalkaloid absorption is poor following oral administration, only 5 percent or less was excreted in feces during the initial 72 hours, a fact explained by the binding of radioactivity to tissues. Inhibition of acetylcholinesterases by alpha-chaconine was studied. The inhibition of purified erythrocyte acetylcholinesterase and horse serum cholinesterase by alpha-chaconine was found to be a mixed-type with kinetic constants. An inhibition constant (Ki) for both the specific and pseudocholinesterases was 8.3 x 10-6 M and 4.0 x 10-4 M, respectively. Kinetic constants obtained for both enzymes were as follows: Vmax of 7.14 x 10-5 and 3.76 x 10-4 max moles/liter/min, respectively, and Km of 6.2 x 10-5 and 1.33 x 10-4, respectively. The distribution of acetylcholinesterase among the subcellular fractions of rat brain homogenate separated by sucrose density gradient centrifugation was determined, as well as the inhibition pattern of these fractions following in vitro incubation with 0.016 M alpha-chaconine. Enzyme activity was found to be distributed equally between the mitochondrial and microsomal fractions, with the nuclear fraction having the least activity. Percentage inhibition of the various fractions obtained was: whole homogenate 43, nuclear fraction 55, mitochondria 35, and microsomes 33. Brain acetyl cholinesterase activity of animals given intraperitoneal doses (10, 30, 60 mg / Kg) of alpha-chaconine was 79, 55 and 18 percent of the control group. Acetylcholinesterase activity of heart and plasma of animals administered alpha-chaconine did not show the dose-related response observed in the brain. Inhibition of heart acetylcholinesterase was 61 percent, while plasma gave 51 percent for the rats given a dose of 10 mg/Kg and no inhibition for rats given 30 mg/ Kg. Acrylamide gel electrophoretic separation of cholinesterases in aqueous homogenates from whole brain and heart of adult male rats administered alpha-chaconine was investigated. Brain acetylcholinesterase isoenzymes were found to be inhibited by 30 and 60 mg/ Kg dosage levels of alpha-chaconine administered intraperitoneally. Electrophoretic separation of plasma from the treated animals resulted in five anodally migrating zones having properties of cholinesterases. These sites hydrolyze acetylthiocholine and alpha-naphthylacetate, and all were inhibited by alpha-chaconine except the slowest migrating band (band 5). Inhibition of isoenzyme activity of bands 1 and 2 is observed for the groups administered 10 and 30 mg/Kg alpha-chaconine with the percentage inhibition of both bands (l and 2) being 40 and 77 percent for animals given 10 mg/Kg and 100 and 75 percent for the latter group. Isoenzyme bands 3 and 4 were completely absent in the alkaloid treated animals. Inhibition of non-specific cholinesterase isoenzymes (butyrylthiocholine hydrolyzable bands) by alpha-chaconine was clearly demonstrated. In vitro inhibition of plasma, erythrocyte and brain esterase isoenzymes was estimated by incubating gels with 10-4 M alpha-chaconine after the electrophoretic separations. With this concentration of alpha-chaconine, the various isoenzymes in rat plasma, erythrocyte and brain showed some response to the inhibitory potency of alpha-chaconine. The slower-moving isoenzyme bands were inhibited to 100 percent with the different concentrations of inhibitor. The fast migrating isoenzyme bands in plasma and erythrocytes were least affected by alpha-chaconine (10-4 M), with no inhibition. Plasma protein isoenzymes from adult male rats were not affected by alphachaconine.

Research objective. To investigate the effects of organic and conventional farming types on antioxidant activity of potato tubers and on the amounts of accumulated amino acids (tyrosine and tryptophan) and phenolic compounds. Research tasks 1. To develop and validate the HPLC method for quantification of phenolic compounds, tyrosine and tryptophan, accumulated by potatoes. 2. To investigate the effects of organic and conventional farming types, properties of a variety, and tuber time of maturity on the amounts of tyrosine, tryptophan, and phenolic compounds accumulated in potato tubers. 3. To evaluate the impacts of organic and conventional farming types on total antioxidant activity of potato tubers. 4. To determine the prevailing compounds with antioxidant activity accumulated in potato tubers, and quantify of their antioxidant activity. 5. To evaluate the influence of storage time on the amount of the accumulated phenolic compounds in organically and conventionally grown potato tubers. Research subject. Potato (Solanum tuberosum L.) tubers of several varieties with different time of maturity: • Very early: ‘VB Venta’, ‘Fresco’, ‘Acapella’ • Early: ‘Santa’, ‘Goda’, ‘VB Liepa’ • Medium: ‘Lady Rosetta’, ‘Red Lady’, ‘Courage’ • Late: ‘VB Rasa’, ‘VB Aista’, ‘Saturna’ Originality of the research work. The effects of organic and conventional farming types, tuber time of maturity, and properties of a potato variety on the amount of antioxidant compounds accumulated in potato... [to full text] / Darbo tikslas. Ištirti ekologinės ir intensyviosios žemdirbystės sistemų įtaką bulvių gumbų antioksidaciniam aktyvumui ir jų kaupiamų amino rūgščių (tirozino ir triptofano) ir fenolinių junginių kiekiui. Uždaviniai 1. Sukurti ir validuoti ESC metodiką bulvių kaupiamų fenolinių junginių, tirozino ir triptofano kiekybiniam įvertinimui. 2. Ištirti ekologinės ir intensyviosios žemdirbystės sistemų, veislės savybių ir gumbų subrendimo laiko įtaką bulvių gumbų kaupiamų tirozino, triptofano ir fenolinių junginių kiekiui. 3. Įvertinti ekologinės ir intensyviosios žemdirbystės sistemų įtaką suminiam bulvių gumbų antioksidaciniam aktyvumui. 4. Nustatyti dominuojančius bulvių gumbų kaupiamus antioksidaciniu aktyvumu pasižyminčius junginius ir kiekybiškai įvertinti jų antioksidacinį aktyvumą. 5. Įvertinti sandėliavimo trukmės įtaką ekologiškai ir intensyviai augintų bulvių gumbų kaupiamų fenolinių junginių kiekiui. Tyrimo objektas. Skirtingo subrendimo laiko įvairių veislių valgomųjų bulvių (lot. Solanum tuberosum L.) gumbai: • Labai ankstyvos: ‘VB Venta’, ‘Fresco’, ‘Acapella’ • Ankstyvos: ‘Sante’, ‘Goda’, ‘VB Liepa’ • Vidutinio ankstyvumo: ‘Lady Rosetta’, ‘Red Lady’, ‘Courage’ • Vėlyvos: ‘VB Rasa’, ‘VB Aista’, ‘Saturna’ Mokslinio darbo naujumas. Ištirta ekologinės ir intensyviosios žemdirbystės sistemos, gumbų subrendimo laiko ir veislės įtaka bulvių gumbų kaupiamų antioksidacinių junginių kiekiui. Įvertintas bulvių gumbų antioksidacinis aktyvumas ekologiškai ir intensyviai augintuose... [toliau žr. visą tekstą]

The main purpose of the master thesis project is to investigate the influence of selected serine protease inhibitors (SPI) on the catalytic action of the serine proteases chymotrypsin and trypsin, in a conjugated and non-conjugated state. The inhibitors included for this study were extracted from Solanum tuberosum, i.e.common potato. The purification method included in this study consist of crude extraction by mixer, followed by a salt-out procedure with ammonium sulphate. Further purification steps were cation exchange chromatography and, finally, gel filtration to obtain SPI of high purity. The purified sample was then characterized by SDS-page and kinetic activity measurement of trypsin and chymotrypsin action on synthetic substrate derivate, N-Benzoyl-DL-arginine-4-nitroanilide hydrochloride (BAPA) and N-Succinyl-L-phenylalanine-p-nitroaniline (SFpNA) respectively. The characterization showed inhibitory inactivation of both pancreatic proteases. This would indicate successful extraction of SPI. To investigate inhibitory action in a conjugated state, either enzyme or inhibitor was immobilized onto aluminium oxide membranes. Then two different experimental setups were tested, called experiment 1 and 2. In experiment 1, the inhibitor was immobilized and the interaction was monitored from a retention shift of enzyme flow-through compared to a blank column, using detection at 280 nm of the enzyme. In experiment 2 the enzyme was instead immobilized and a mixture of inhibitor and substrate was circulated with monitoring of the catalytic activity. The main goal was thus to measure the effects on the kinetics in the conjugated state compared to enzyme and inhibitor in the free state. The result from both experiment 1 and 2 did not yield consistent and reliable result so the discussed method should be regarded as preliminary results. The study also includes investigation of inhibitor-enzyme interaction as revealed by molecular mass data to determine complex formation. This part was conducted with static light scattering analysis to determine the stoichiometry for the interaction between pancreas proteases and the inhibitor. Results from light scattering showed promising indication of many-to-one interaction between enzyme and inhibitor, which have been seen by previous studies. It should be considered a preliminary result as complex formation does not exclude aggregation of enzymes or inhibitor in the solution.

Traditional irrigation was practiced in Ethiopia since time immemorial. Despite this, water productivity in the sector remained low. A survey on the Godino irrigation scheme revealed that farmers used the same amount of water and intervals, regardless of crop species and growth stage. In an effort to improve the water productivity, two traditional irrigation scheduling methods were compared with two scientific methods, using furrow irrigation. The growth performance and tuber yield of potato (cv. Awash) revealed that irrigation scheduling using a neutron probe significantly outperformed the traditional methods, followed by the SWB model Irrigation Calendar. Since the NP method involves high initial cost and skills, the use of the SWB Calendar is suggested as replacement for the traditional methods. SWB is a generic crop growth model that requires parameters specific to each crop, to be determined experimentally before it could be used for irrigation scheduling. It also accurately describes deficit irrigation strategies where water supply is limited. Field trials to evaluate four potato cultivars for growth performance and assimilate partitioning, and onions' critical growth stages to water stress were conducted. Crop-specific parameters were also generated. Potato and onion crops are widely grown at the Godino scheme where water scarcity is a major constraint. These crop-specific parameters were used to calibrate and evaluate SWB model simulations. Results revealed that SWB model simulations for Top dry matter (TDM), Harvestable dry matter (HDM), Leaf area index (LAI), soil water deficit (SWD) and Fractional interception (FI) fitted well with measured data, with a high degree of statistical accuracy. The response of onions to water stress showed that bulb development (70-110 DATP) and bulb maturity (110-145) stages were most critical to water stress, which resulted in a significant reduction in onion growth and bulb yields. SWB also showed that onion yield was most sensitive to water stress during these two stages. An irrigation calendar, using the SWB model, was developed for five different schemes in Ethiopia, using long-term weather data and crop-specific parameters for potatoes and onions. The calendars revealed that water depth varied, depending on climate, crop type and growth stage. / Thesis (PhD)--University of Pretoria, 2009. / Plant Production and Soil Science / unrestricted

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