Tõnu Püssa

Evaluation of antioxidative capability of the tomato (Solanum lycopersicum) skin constituents by capillary electrophoresis and high-performance liquid chromatography.

In the current study, phenolic compounds of the tomato (Solanum lycopersicum) skin extract were separated and their composition was determined by capillary electrophoresis and tandem high‐performance liquid chromatography diode array detection‐mass spectrometry (HPLC‐DAD‐MS/MS). Both the total phenolic and flavonoid contents of the extract were determined. The antioxidative capability of the extract was measured using a stable free radical 2,2‐diphenyl‐1‐picrylhydrazyl assay. The monitoring of the radical scavenging capability of specific phenolic compounds was carried out both by capillary electrophoresis and HPLC‐MS/MS.

Analysis of the stable free radical scavenging capability of artificial polyphenol mixtures and plant extracts by capillary electrophoresis and liquid chromatography–diode array detection–tandem mass spectrometry

The oxidation process of phenolic compounds of an artificial mixture consisting of six polyphenols and the extract of eggplant (Solanum melongena) skin was monitored by using capillary zone electrophoresis and liquid chromatography-diode array detection-tandem mass spectrometry. The methods developed enabled simultaneous evaluation of the antioxidative capability of each compound. The above oxidation process was carried out using two radicals, viz. the 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals generated via the Fenton reaction. The radical scavenging effects of artificial and natural polyphenol mixtures were compared.

Polyphenolic composition of roots and petioles of Rheum rhaponticum L.

INTRODUCTION Various species of the genus Rheum (Polygonaceae) are known for their high content of medicinally important hydroxyanthraquinones. However, little information is available concerning the polyphenolic composition of garden or dietary rhubarb Rheum rhaponticum L. (R. rhaponticum). OBJECTIVE Determination of further polyphenols in the roots and petioles of R. rhaponticum. METHODOLOGY The dried plant material was extracted with 10-fold excess (v/w) of methanol and subsequently diluted five times with methanol-water (1:1) and analysed by reversed-phase liquid chromatography using tandem UV-photodiode array and mass selective detection (RP-HPLC-UV-ESI/MS(2)). Polyphenols were identified using either HPLC-ESI/MS(2) data obtained for respective commercial standards or by comparison of a parent ion fragmentation picture with the respective MS(2 )spectrum from the literature. RESULTS The roots of R. rhaponticum were very rich in various hydroxystilbenes and contained four main substance groups--derivatives of trans-piceatannol, trans-resveratrol, trans-rhapontigenin and trans-deoxyrhapontigenin. Additionally, pterostilbene acetylglucosides and a number of hydroxyanthraquinones and their glycosides were identified in the root samples. The profile of polyphenols in the petioles of R. rhaponticum was similar to that of the roots but the content of individual substances was remarkably lower. The petioles of the R. rhaponticum additionally contained significant amounts of derivatives of flavonol quercetin, which is a good antioxidant. CONCLUSION The study has shown that roots of R. rhaponticum contain a wide variety of hydroxystilbenes and deserve further consideration as a source of medicinally interesting compounds.

Beetroot (Beta vulgaris L.) and naturally fermented beetroot juices from organic and conventional production: metabolomics, antioxidant levels and anticancer activity

BACKGROUND The aim of the paper was to determine the level of antioxidants and metabolomic fingerprinting in both raw beetroots and naturally fermented beetroot juices from organic (ORG) versus conventional (CONV) production. In addition, the anticancer properties of the fermented beetroot juices were evaluated. RESULTS The obtained results showed that ORG fresh beetroots contained significantly more dry matter, vitamin C and some individual phenolic compounds than CONV beetroots. The content of total phenolic acids was significantly higher in CONV beetroots compared with the ORG ones. The level of flavonoids was similar in ORG and CONV beetroots. There were only slight differences in the chemical composition of ORG and CONV beetroot juices. Metabolomic analysis provided a possibility to distinguish clearly between ORG and CONV fermented beetroot juices. However, this method was less useful in the case of fresh whole beetroots. It was found that anticancer activity was stronger in the case of ORG fermented juices when compared with CONV ones. CONCLUSION The obtained results indicate that ORG- and CONV-produced beetroots and fermented beetroot juices have different chemical properties and different impacts on cancer cells. It is necessary to continue research on this topic in order to confirm and understand the achieved results.

Trans-Resveratrol Alone and Hydroxystilbenes of Rhubarb (Rheum rhaponticum L.) Root Reduce Liver Damage Induced by Chronic Ethanol Administration : a Comparative Study in Mice

The hepatoprotective effects and pharmacokinetics of trans‐resveratrol and hydroxystilbenes of the garden rhubarb (Rheum rhaponticum L., R. rhaponticum) root ethanol extract were studied.

Toxicological issues associated with production and processing of meat.

Meat is a very complex and continuously changing ex vivo system of various high- and low-molecular substances that can be used for satisfying needs of the human organism for metabolic energy, building material and fulfilling of the other vital functions. A great majority of these substances are useful and safe for the consumer. Yet, meat and meat products may always contain substances exerting detrimental effects to the consumers organism. The present paper is a literature review of the most important potentially toxic substances found in meat and meat products; their classification, ways of getting into the meat or formation during meat processing, undesirable physiological outcomes and biochemical mechanisms of their toxic effects, and methods for reduction of these responses.

Three-Year Comparative Study of Polyphenol Contents and Antioxidant Capacities in Fruits of Tomato (Lycopersicon esculentum Mill.) Cultivars Grown under Organic and Conventional Conditions

In the present study, four tomato cultivars were grown under organic and conventional conditions in separate unheated greenhouses in three consecutive years. The objective was to assess the influence of the cultivation system on the content of individual polyphenols, total phenolics, and antioxidant capacity of tomatoes. The fruits were analyzed for total phenolic content by the Folin-Ciocalteau method and antioxidant capacity by the DPPH free radical scavenging assay. Individual phenolic compounds were analyzed using HPLC-DAD-MS/MS. Among 30 identified and quantified polyphenols, significantly higher contents of apigenin acetylhexoside, caffeic acid hexoside I, and phloretin dihexoside were found in all organic samples. The content of polyphenols was more dependent on year and cultivar than on cultivation conditions. Generally, the cultivation system had minor impact on polyphenols content, and only a few compounds were influenced by the mode of cultivation in all tested cultivars during all three years.

Variation in the composition of the essential oils, phenolic compounds and mineral elements of Hypericum perforatum L. growing in Estonia

A comprehensive investigation of the chemical composition of the aerial parts of Hypericum perforatum L. collected in three habitations in Estonia was carried out. An analysis by gas chromatography–mass spectrometry and gas chromatography–flame ionisation detection established the main components of the essential oils. The phenolic compounds both in ethanol and water extracts of the plant were analysed using liquid chromatography–mass spectrometry (LC–MS) and capillary zone electrophoresis. In addition to the earlier published polyphenols, several new phenolic acids and flavonoids, such as quercetin hexoside malonates and an A-type catechin–epicatechin trimer were identified in this Hypericum for the first time. The contents of the pharmaceutically important antidepressants hyperforin and hypericin were also estimated by LC–MS and compared with the data in the literature. The composition of the mineral elements was determined by atomic absorption spectroscopy. The results of the study demonstrate a rather high variability in the content of different substance groups in H. perforatum L. and, hence, the need for a survey of the raw material in the course of selection of raw materials for pharmaceutical preparations.

Inhibitory effects of human and porcine alpha-amylase on CCK-8-stimulated lipase secretion of isolated rat pancreatic acini.

Previously we have demonstrated inhibitory effects of the plant lectin wheat germ agglutinin (WGA) on 125I-CCK-8 binding to pancreatic AR42J cells as well as on CCK-8-stimulated Ca2+ release and α-amylase secretion of rat pancreatic acini or acinar cells. Therefore, it is entirely conceivable that α-amylase having several lectin-like carbohydrate recognition domains can modulate the CCK-8 stimulated lipase secretion. Human α-amylase, purified from pancreatic juice by affinity chromatography to homogeneity, and commercial porcine pancreatic α-amylase inhibit CCK-8-stimulated lipase secretion of rat pancreatic acini in a concentration-dependent manner. Acarbose, a specific inhibitor of α-amylase, was without effect on CCK-8-induced cellular lipase secretion. The data presented here provide evidence for a regulatory function of α-amylase in CCK-8-stimulated pancreatic secretion.

The effect of tenderizing acids on linoleic acid oxidation during marination of pork.

The oxidation of lipids in different prefabricated meat products may have detrimental effects on the organoleptic properties and/or safety of meat, and poses a serious health concern. The oxidation processes may be accelerated by acids that are added to some products, e.g., marinated meat. In this work, the oxidation of free polyunsaturated fatty acids during pork marination in the presence of different acidifiers was investigated. It was demonstrated by the measurement of thiobarbituric acid reactive substances (TBARS) and by liquid chromatography - tandem mass spectroscopy that the highest degree of oxidation occurred in acetic acid and lactic acid marinades, whereas the oxidation was significantly suppressed by citric and ascorbic acids. Among the primary products of oxidation, 9,12,13-trihydroxy-10-octadecenoic acid and two isomers of hydroxy-epoxy-octadecenoic acid were dominating. A nearly linear correlation between TBARS values and total content of these two hydroxy-fatty acids was observed.