Isolation, identification and activity of natural antioxidants from sweet grass (Hierochloe odorata), costmary (Chhrysanthemum balsamita) and horehound (Marrubium vulgare), cultivated in Lithuania

Food products are susceptible to oxidation processes. Oxidation of lipids (fat) is the major cause of food deterioration however also proteins and carbohydrates can be affected. To prevent or retard this process, antioxidants are used. With regard to foods, more and more natural products are preferred by consumers so new natural sources of compounds able to retard oxidation processes and prevent spoilage of food products are continuously investigated. The research described in this study is aimed at the evaluation of several herbs as possible sources of food antioxidants. An initial screening of extracts from roman camomile, tansy, sweet grass, costmary, sea-buckthorn and sage for antioxidant activity in rapeseed oil has been performed Sweet grass and sage acetone extracts retarded oxidation processes in oil best. Sweet grass was chosen for further investigation as the herb having the highest antioxidant activity. Two other herbs, namely horehound and costmary were further selected for the evaluation of their antioxidant activity in different assays. At first preliminary fractionation of the selected herb extracts was performed. Fractions were tested in three different assays: -carotene oxidation, DPPH• reduction and rapeseed oil oxidation. The experiments did not provide any straightforward answers, which fractions contained the most active antioxidants. Different assays gave different results. More polar fractions were more active in model systems like DPPH• while in the edible oil assay these fractions acted as weak antioxidants, or some even exhibited a prooxidation effect. Acetone extracts performed better than methanol-water extracts in retarding oil oxidation probably due to their higher compatibility with the medium or the more non-polar nature of the contained analytes. In further steps the structures of the radical scavenging compounds present in extracts of sweet grass, horehound and costmary were elucidated. Two compounds, namely 5,8-dihydroxybenzopyranone and 5-hydroxy-8-O--D-glucopyranosyl benzopyranone were isolated and identified from sweet grass extract. Both compounds were identified for the first time as natural products. Four compounds, namely 5-O-caffeoyl quinic acid (chlorogenic acid), 3,5-dicaffeoyl quinic acid, 5,7,4'-trihydroxy-3',8-dimethoxy flavone and 5,7,3',4'-tetrahydroxy-3,8-dimethoxyflavonol were identified in costmary extracts. These compounds are quite common in plant kingdom. However, they have not previously been isolated from costmary. Five compounds, namely 5,8-dihydroxy-7,4-dimethoxy flavone, 7-O--glucopyranosyl luteolin, 7-O--glucuronyl luteolin, verbascoside and forsythoside B were isolated from horehound extracts. These compounds are common in the Labiatae family. Their radical scavenging activity was measured using DPPH• and ABTS•+ scavenging assays and compared with the activity of rosmarinic acid and Trolox. An on-line HPLC-DPPH-DAD-NMR system for the rapid identification of compounds in complex mixtures was developed. The developed system was tested on commercial rosemary extract and six compounds were identified without the need to isolate them. This proved that simultaneous detection and identification of radical scavengers is possible. Several solvents, namely hexane, acetone ant ethanol and their combinations were tested for their suitability to extract all known radical scavengers from sweet grass, costmary and horehound. It was found that initial extraction of the plant material with hexane increased the concentrations of radical scavengers in the following extraction stages. <br/

The influence of turpentine additive on the ecological parameters of diesel engines

After Lithuania’s accession to the EU it is very important to use a larger amount of renewable fuel. Based on economic and environmental considerations in Lithuania, we are interested in studying the effects of turpentine contents in the blended turpentine-diesel fuel on the engine performance and pollutant emission of compression ignition (CI) engine. Therefore, we used engine test facilities to investigate the effects on the engine performance and pollutant emission of 5 % turpentine in the fuel blend. The tests were carried out in the laboratory on an engine dynamometer of the car Audi 1Z and tractor D21 diesel engines. The experimental results showed that turpentine used in the fuel blend for these diesel engines had a positive influence on the engine performance and exhaust emission

Development of a triple hyphenated HPLC-radical scavenging detection-DAD-SPE-NMR system for the rapid identification of antioxidants in complex plant extracts

A rapid method for the simultaneous detection and identification of radical scavenging compounds in plant extracts was developed by combining an HPLC with on-line radical scavenging using DPPH as a model radical and an HPLC¿DAD¿SPE¿NMR system. Using this method a commercial rosemary extract was investigated. All major compounds present in the extract were collected on SPE cartridges after their separation. Advantages of on-line SPE peak trapping are the possibility to perform HPLC with non-deuterated solvents, a concentration effect and being able to record NMR spectra in pure 100% deuterated solvents. After comparing DAD and DPPH scavenging chromatograms, 1H NMR spectra of compounds having radical scavenging activities were recorded. Afterwards all compounds were collected and infused into an ESI-MS. The five main active compounds ¿ carnosol, carnosic acid carnosaldehyde, 12-methoxycarnosic acid and epiisorosmanol ¿ could be identified from the combined UV, NMR and mass spectral data without actually isolating them. It was possible to record on-line an HMBC spectrum of carnosic acid. Also one compound was tentatively identified as epirosmanol methyl ethe

RESEARCH OF OPERATION OF A DIESEL ENGINE WITH SUPPLEMENTARY ETHANOL FEED

Abstract Technica

Operation of a Spark-Ignition Engine on Mixtures of Petrol and N-Butanol

The Article analyses the use of n-butanol (biobutanol) in mixtures with petrol in spark-ignition (SI) internal combustion engines (ICE). Analysis of the scientific literature allowed determining that n-butanol content had a different effect on the same engine parameters in different tests, thus a decision was made to conduct additional research, where, having assembled the necessary equipment and conducted experimental planning, experimental studies of n-butanol (with its volumetric content being 0%, 20% and 40%) and petrol blends in a SI engine were carried out. Regression analysis of research results was conducted and regression dependences were formed allowing evaluating the impact of the key variables (delta and theta) on engine parameters (M-e, P-e and b(e)). The research results have shown that without changing the ignition advance angle theta, petrol blend with 10% n-butanol has essentially no adverse effect on engine power P-e, engine torque M-e and specific fuel consumption be. Increasing n-butanol concentration d, the maximum engine torque M-e and effective power P-e decrease, while the specific fuel consumption b(e) increases. Energy engine indicators decline as a result of a lower calorific capacity of n-butanol compared to that of petrol and lower combustion rate of n-butanol. Increasing n-butanol concentration d in fuel mixture, engine parameters can be improved by advancing the ignition angle thet

Isolation, identification and activity of natural antioxidants from costmary (Chrysanthemum balsamita) cultivated in Lithuania

The sweet, minty-lemony leaves of costmary (Chrysanthemum balsamita) are used for salads and tea, and as flavourings in meats, sausages, cakes and ale. In this study, the extracts isolated from costmary aerial parts were investigated as antioxidants in rapeseed oil and as free radical-scavengers in DPPH and ABTS(+) assays. It was found that costmary extracts and their fractions were weak antioxidants in rapeseed oil; however, some fractions were active in scavenging synthetic free radicals. Crude methanol-water extract, its tertbutyl methyl ether and butanol fractions were the most effective in DPPH assay by scavenging 87.0%, 86.9% and 86.4% of radicals present in the reaction, respectively. Several active compounds were detected in these fractions, using HPLC with on-line radical-scavenging detection. After multi-step fractionation of these fractions, four radical-scavenging constituents were isolated and their properties were assessed by DPPH (antiradical power, ARP, calculated as an inverse value of the effective concentration, 1/EC50) and ABTS(+) (Trolox equivalent antioxidant capacity, TEAC(6min)) free radical-scavenging assays. The following structures were elucidated by NMR and MS: 5-O-caffeoylquinic acid (ARP = 3.85: TEAC(6min) = 0.60), 3,5-O-dicaffeoylquinic acid (ARP = 6.25: TEAC(6min) = 1.16), 5,7,4'-trihydroxy-3',8-dimethoxyflavone (ARP = 0.03) and 5,7,3',4'-tetrahydroxy-3,8-dimethoxyflavonol (ARP = 3.79; TEAC(6min) = 1.50)

Operation of a Spark-Ignition Engine on Mixtures of Petrol and N-Butanol

The Article analyses the use of n-butanol (biobutanol) in mixtures with petrol in spark-ignition (SI) internal combustion engines (ICE). Analysis of the scientific literature allowed determining that n-butanol content had a different effect on the same engine parameters in different tests, thus a decision was made to conduct additional research, where, having assembled the necessary equipment and conducted experimental planning, experimental studies of n-butanol (with its volumetric content being 0%, 20% and 40%) and petrol blends in a SI engine were carried out. Regression analysis of research results was conducted and regression dependences were formed allowing evaluating the impact of the key variables (delta and theta) on engine parameters (M-e, P-e and b(e)). The research results have shown that without changing the ignition advance angle theta, petrol blend with 10% n-butanol has essentially no adverse effect on engine power P-e, engine torque M-e and specific fuel consumption be. Increasing n-butanol concentration d, the maximum engine torque M-e and effective power P-e decrease, while the specific fuel consumption b(e) increases. Energy engine indicators decline as a result of a lower calorific capacity of n-butanol compared to that of petrol and lower combustion rate of n-butanol. Increasing n-butanol concentration d in fuel mixture, engine parameters can be improved by advancing the ignition angle theta