Roman Przybylski

Chemical composition, antioxidant and antimicrobial activities of basil (Ocimum basilicum) essential oils depends on seasonal variations.

Chemical composition, antioxidant and antimicrobial activities of the essential oils from aerial parts of basil (Ocimum basilicum L.) as affected by four seasonal, namely summer, autumn, winter and spring growing variation were investigated. The hydro-distilled essential oils content ranged from 0.5% to 0.8%, the maximum amounts were observed in winter while minimum in summer. The essential oils consisted of linalool as the most abundant component (56.7-60.6%), followed by epi-α-cadinol (8.6-11.4%), α-bergamotene (7.4-9.2%) and γ-cadinene (3.2-5.4%). Samples collected in winter were found to be richer in oxygenated monoterpenes (68.9%), while those of summer were higher in sesquiterpene hydrocarbons (24.3%). The contents of most of the chemical constituents varied significantly (p<0.05) with different seasons. The essential oils investigated, exhibited good antioxidant activity as measurements by DPPH free radical-scavenging ability, bleaching β-carotene in linoleic acid system and inhibition of linoleic acid oxidation. Evaluation of antimicrobial activity of the essential oils and linalool, the most abundant component, against bacterial strains: Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pasteurella multocida and pathogenic fungi Aspergillus niger, Mucor mucedo, Fusarium solani, Botryodiplodia theobromae, Rhizopus solani was assessed by disc diffusion method and measurement of determination of minimum inhibitory concentration. The results of antimicrobial assays indicated that all the tested microorganisms were affected. Both the antioxidant and antimicrobial activities of the oils varied significantly (p<0.05), as seasons changed.

Chemical Composition, and Antioxidant and Antimicrobial Activities of Essential Oil of Spearmint (Mentha spicata L.) From Pakistan

Abstract Chemical composition, and antioxidant and antimicrobial activities of the essential oil isolated from aerial parts of Mentha spicata L. (spearmint) were investigated. The oil content was found to be 1.2%. A total of 19 chemical constituents were identified in the spearmint oil using GC and GC/MS. The main components were carvone (51.7%) and cis-carveol (24.3%), followed by limonene (5.3%), 1,8 cineol (4.0%), cis-dihydrocarvone (2.2%), carvyl acetate (2.1%) and cis-sabinene hydrate (1.0%). The investigated oil exhibited good antioxidant activity as assessed by DPPH free radical-scavenging ability, bleaching β-carotene in linoleic acid system, and inhibition of linoleic acid oxidation. Antimicrobial activity of spearmint oil and its major components (cis-carveol and carvone) was followed by disc diffusion and minimum inhibitory concentration (MIC) assays against four strains of bacteria: Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pasturella multocida and five pathogenic fungi: Aspergillus niger, Mucor mucedo, Fusarium solani, Botryodiplodia theobromae, and Rhizopus solani. All the tested microorganisms were strongly affected indicating an appreciable antimicrobial potential of spearmint oil.

Frying stability of high oleic sunflower oils as affected by composition of tocopherol isomers and linoleic acid content.

The influence of linoleic acid content and tocopherol isomeric composition on the frying performance of high oleic sunflower oil was evaluated during a 14-day restaurant style frying operation. At equal linoleic acid content, no significant difference was observed between high oleic sunflower oil containing only α-tocopherol and the sample containing a mixture of α-, γ-, and δ-isomers as measured by the amount of total polar components, oligomers, anisidine value, and free fatty acids. On the contrary, at similar tocopherol isomeric composition, high oleic sunflower oil containing lower amount of linoleic acid showed superior frying stability compared to the sample with a higher content of linoleic acid, suggesting that the frying performance of high oleic sunflower oil is dictated primarily by the level of linoleic acid, with the tocopherol isomeric composition of the oil having no significant influence. In all oil samples, the loss of γ-tocopherol was higher than the corresponding loss of α-tocopherol.

UV-C–Irradiated Arabidopsis and Tobacco Emit Volatiles That Trigger Genomic Instability in Neighboring Plants

This work shows that volatile signals, including methyl jasmonate and methyl salicylate, emitted by UV-irradiated plants can cause an increase in homologous recombination in nearby, nonirradiated bystander plants. Emission of these signals is triggered by the formation of necrotic lesions and depends on NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 function. We have previously shown that local exposure of plants to stress results in a systemic increase in genome instability. Here, we show that UV-C–irradiated plants produce a volatile signal that triggers an increase in genome instability in neighboring nonirradiated Arabidopsis thaliana plants. This volatile signal is interspecific, as UV-C–irradiated Arabidopsis plants transmit genome destabilization to naive tobacco (Nicotiana tabacum) plants and vice versa. We report that plants exposed to the volatile hormones methyl salicylate (MeSA) or methyl jasmonate (MeJA) exhibit a similar level of genome destabilization as UV-C–irradiated plants. We also found that irradiated Arabidopsis plants produce MeSA and MeJA. The analysis of mutants impaired in the synthesis and/or response to salicylic acid (SA) and/or jasmonic acid showed that at least one other volatile compound besides MeSA and MeJA can communicate interplant genome instability. The NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (npr1) mutant, defective in SA signaling, is impaired in both the production and the perception of the volatile signals, demonstrating a key role for NPR1 as a central regulator of genome stability. Finally, various forms of stress resulting in the formation of necrotic lesions also generate a volatile signal that leads to genomic instability.

Sitosterol Thermo-oxidative Degradation Leads to the Formation of Dimers, Trimers and Oligomers: A Study Using Combined Size Exclusion Chromatography/Mass Spectrometry

Phytosterols are recognized as functional food components with cholesterol reducing properties in humans. The formation of phytosterol oligomers as a result of the thermo-oxidative degradation of sitosterol is shown to occur. The existence of oligomers is demonstrated by size exclusion chromatography (SEC) and confirmed by combined SEC-atmospheric pressure chemical ionization mass spectrometry (SEC/APCI-MS). A speculative structure for the sitosterol dimer with 3,7′ linkage is proposed consistent with data from tandem mass spectrometry and exact mass measurements. Higher molecular weight species arising from the formation of trimers or higher oligomers are seen in the mass spectra. Fragments of sitosterol formed by thermo-oxidative processes are also shown to oligomerize and their common structural characteristics are demonstrated by tandem mass spectrometry. The results presented provide evidence for the possible formation of oligomeric species involving sterols in addition to those known for acylglycerides in vegetable oils subjected to extreme oxidative stress such as in frying.

Spectroscopic characterisation of dimeric oxidation products of phytosterols

Sterol dimers are the main oxidation products formed during sterols degradation at elevated temperatures. An investigation was carried out to decipher the structure of dimers differing in polarity, formed during β-sitosterol thermo-oxidation. The oxidation products were fractionated using silica gel into non-polar (NP), mid-polar (MP) and polar fractions (P). Oligomers were further separated by size-exclusion chromatography (SEC). Tentative chemical structures of non-polar, mid-polar and polar dimers were identified using Ag(+)/CIS-MS and APCI-MS procedures after on-line RP-HPLC separation. Further structures were verified by NMR and FT-IR spectroscopies.

Performance of antioxidative compounds under frying conditions: A review

ABSTRACT Although much study has been done assessing activity of antioxidants at ambient and accelerated storage temperatures, the results cannot correctly depict their performance under frying conditions. Due to the stringent conditions imposed, most conventional antioxidative compounds failed under frying conditions, suggesting the need for a continuous modification to improve their effectiveness. Although syntheses and performance evaluation of over a hundred (semi)synthetic antioxidants have been reported in literature, only a small fraction have been specifically designed and/or evaluated under frying conditions. Here, the performance under frying conditions of major natural and synthetic antioxidants is reviewed. The recent trend in the designing of antioxidants for frying applications is also reviewed with the view of stimulating further study in this direction.

Fatty Acid and Tocopherol Profiles of Industrial Hemp Cultivars Grown in the High Latitude Prairie Region of Canada

Abstract Hemp (Cannabis sativa L.) is being promoted as a diversification option with applications in fiber, paper, particleboard, and biodegradable plastics. Hemp seed oil is valued for its nutritional properties and health benefits. Seed protein content and oil composition show promise for animal feed opportunities. The beneficial effects of hemp oil need to be studied to improve the profitability of industrial hemp seed in Canada. This study examined the influence of cultivar on fatty acid profiles and tocopherol content of hemp grown in Alberta in 1997 and 1998. The average seed yield varied between years (1997, 987 kg ha-1; 1998, 1633 kg ha-1). Linoleic acid concentrations ranged from 47% (Yugo) to 57% (Felina 34) of total fatty acid. Linolenic acid concentrations ranged from 16% (Irene) to 23% (Yugo) of total fatty acid. The gamma-linolenic acid varied between 1.5%-4.0% among cultivars. The hemp cultivars varied greatly in the ratio of omega-6 to omega-3 fatty acids, but certain cultivars produced ratios at the 3:1 level, which has been identified as nutritionally optimal. There were varietal differences in both specific and total tocopherol content. The high tocopherol antioxidant capacity, in addition to linolenic acid, alpha-linolenic acid and gamma-linolenic acid, ultimately adds to the nutritional profile of hemp seed oil. All of the cultivars grown in the trials had levels of delta-9tetrahydrocannabinol (THC) below the Government of Canada limit of 0.3%.

Model studies on the formation of volatile compounds generated by a thermal treatment of steryl esters with different fatty acid moieties

The consumption of plant sterols is reported to have a beneficial effects on human health, i.e. phytosterols are known for their cholesterol-lowering properties. Whereas, they are prone to oxidation and currently there is ongoing worldwide research aimed at the biological effect of phytosterol oxides. In this study volatile compounds formed during thermal degradation of stigmasteryl esters were identified. The research was conducted using standards of stigmasterol, fatty acids and stigmasteryl esters as well as fat enriched with stigmasteryl esters which were thermally treated at 60°C and 180°C for 12h. Volatile compounds were characterised by SPME-GC-MS. Among the volatiles formed during heating of stigmasteryl esters aldehydes, ketones, alcohols and hydrocarbons were found. The mechanism of the formation of volatile compounds from sterol esters was related to oxidation of steryl and fatty acid moieties. In particular, 2-methyl-3-pentanone and 5-ethyl-6-methyl-3-hepten-2-one were identified as unique degradation products formed from degradation of the steryl moiety specifically, and a mechanism of their formation was suggested. Both volatiles could be a good indicator of thermo-oxidative degradation of functional food products enriched in phytosterols and their esters.

Antioxidant activity of flaxseed meal components

Barthet, V. J., Klensporf-Pawlik, D. and Przybylski, R. 2014. Antioxidant activity of flaxseed meal components. Can. J. Plant Sci. 94: 593-602. The meals of borage, hemp, Solin, golden, and brown flaxseed, including the meals of dehulled flaxseed and their corresponding hulls, were reconstituted with 40% of standard flaxseed oil and stored for 2 wk to assess if these meals had any antioxidant activity to protect in situ oil from oxidation. Weekly measured peroxide and aldehyde values showed that Solin, golden and brown flaxseed meals had more effective antioxidant activity than hemp and borage meals. Flaxseed hull showed very weak antioxidant potential, whereas dehulled meals maintained their antioxidant activity. This suggested that secoisolariciresinol diglucoside was not acting as the primary antioxidant of flaxseed meal. The seed antioxidant activity was greatly affected by water extraction, suggesting that the system contains water-soluble components. When flaxseed oil was recombined with the freeze-dried water extracts of flaxseed meal some loses of antioxidant activity were observed. The results showed that the water-extracted components retained some antioxidant activity compared with the original flaxseed meal antioxidant activity. These results indicate that the flaxseed antioxidant activities were mainly due to a water-soluble system - probably proteins: however, more than one group of components of the flax meal may be involved to provide the seed with its effective and unique antioxidant properties.