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Lettuce (Lactuca sativa L.) is a popular vegetable with the health-enhancing properties determined by high levels of antioxidant polyphenols as chlorogenic acids and other derivatives of caffeic acid or flavonoids. In this study, changes in the phenolic compound profiles in the lettuce leaves induced by application of CaCl2 before harvest and cold storage were studied. For the first time quantitative analysis of individual phenolic compounds on the basis of standards isolated from lettuce leaves was performed. Compounds were identified using HPLC, LC-MS, 1H and 13CNMR techniques. The dominant compounds were 2,3-dicaffeoyltartaric (2,3-diCTA), 5-O-caffeoylquinic (5-OCQA) and caffeoyltartaric (CTA) acids, with content of 5.7, 2.5 and 0.981 mg/g DM, respectively. The levels of individual phenolic compounds, total phenolics and antioxidant activity (DPPH assay) in plants treated by CaCl2 were determined throughout the storage period (7 and 14 days) at 4 °C. To ascertain the relationship between the content of individual compounds, total phenols, antioxidant activities and storage time, Pearson's correlation analysis was used. The best correlation between the storage length and compound concentration was observed for 2,3-diCTA (R2 = 0.866) and caffeoylmalic acid (CMA) (R2 = 0.750). Application of CaCl2 (0.05M) on lettuce resulted in an increase in the levels of CTA, 2.3-diCTA and 5-OCQA about 120, 65 and 57%, respectively, compared to the control stored for 7 days in the same conditions and had a favourable effect on the antioxidant activity (R2 = 0.985). The present paper shows that CaCl2 may be used as an agent that influences the stability of health-promoting compounds of cold-stored lettuce. [ABSTRACT FROM AUTHOR]

Background. The aim of this study was to isolate phenolic compounds fraction (PCF) from hot pepper and to characterise their composition and antiradical activity. Material and methods. PCF was isolated from hot pepper fruits by solid phase extraction technique and separated by medium pressure liquid chromatography on Büchi system. HPLC quantitative analysis of subfractions constituents and of standards was made on Empower-Pro chromatograph (Waters) with DAD detection. Total phenolics content was assessed by Folin-Ciocalteu method. Antioxidant activity was measured according to superoxide radical, generated in NADH/PMS model and DPPH radical. Results. The separation yielded three subfractions with different composition. In fraction 1, the predominant component was quercetin 3-O-rhamnoside-7-O-glucoside. The presence of luteolin 7-O-apiosyl-glucoside was observed in fraction 2, and the key component of fraction 3 was quercetin 3-O-rhamnoside. The highest antioxidant activity was noted for fraction 2, both in reducing superoxide radicals (IC50 = 97 μg⋅cm-3) and DPPH• (IC50 = 43 μg⋅cm-3). Conclusion. Pepper fruits are a rich source of phenolic compounds with a considerable lipophilicity and different chemical activity. They can be used as supplements to enhance food products. [ABSTRACT FROM AUTHOR]

Background. Phenolic compounds are secondary plant metabolites, which occur in different parts of cell, according to they lipophilicity. The objective of this study was to determine differences in the content and stability of those compounds in herbal extract fractions marked by increasing lipophilicity. Material and methods. Eight herbal plants were analysed: basil, savory, lovage, lemon balm, peppermint, parsley, oregano and sage. Extracts were prepared from fresh plants harvested in late July, and they were separated into aqueous fractions and isolated with a 40% and 70% methanol solution on C18 silica gel. The total content of phenolics was determined using the Folin-Ciocalteu method directly after preparation and after three and six months of storage. Results. The stability of fresh herb extracts varied subject to plant species. The lemo balm leaf extract was most abundant in phenolic compounds and showed the highest polyphenol concentrations throughout the storage period. The greatest drop in phenolic compound levels was observed in parsley extracts. Following the separation of raw extracts into three fractions, the highest phenolic compound concentrations were noted in fractions isolated with a 40% methanol solution. The most dynamic changes in polyphenol content were reported in the initial period of storage (three months) regardless of the fraction's lipophilicity. Compounds that were not degraded after this period were marked by high stability. Conclusions. Phenolic compounds found in herbal plants are hydrophilic to lipophilic substances which are stable compounds regardless of their affinity for water. [ABSTRACT FROM AUTHOR]

Quercetin is one of the major dietary flavonoids belonging to a group of flavonols. It occurs mainly as glycosides, but other derivatives of quercetin have been identified as well. Attached substituents change the biochemical activity and bioavailability of molecules when compared to the aglycone. This paper reviews some of recent advances in quercetin derivatives according to physical, chemical and biological properties as well as their content in some plant derived food. [ABSTRACT FROM AUTHOR]

The effect of treatment of pepper fruits with gaseous ozone and storage time following the ozonation process on changes in the content of lipophilic fraction is analyzed for the first time in this paper. The aim of the present study was to assess the impact of ozone treatment on the composition of lipophilic compound fraction and its antioxidant activity (AA). Pepper fruits of cv. Cyklon were ozonated for 1 and 3 h immediately after harvesting. Then, the fruits were stored for 30 days under refrigeration conditions. The total content of phenolic compounds and the AA of the lipophilic fraction isolated from the pericarp and placenta of the fruits were investigated after 10, 20, and 30 days of storage. Additionally, quantitative high-performance liquid chromatography diode array detection analysis of individual phenolic compounds was performed. The results revealed that the content and activity of secondary metabolites varied during storage, with the highest values recorded on the 20th day after harvest, both in control and ozonated fruits, regardless of the ozone dosage used. Treatment of the fruits with ozone for 3 h, but not for 1 h, exhibited a positive effect on the phenolic composition and AA during the prolonged storage of pepper fruits. Three hours of ozonation seems to be the appropriate time to increase the persistence of pepper fruits during storage. [ABSTRACT FROM AUTHOR]

Nowadays, legume plants have been considered not only a source of valuable proteins necessary for the proper functioning and growth of the body but also a source of bioactive compounds such as bioactive peptides, that may be beneficial to human health and protect against negative change in food. The aim of this study was to investigate the effect of heat treatment on the release of antioxidant peptides obtained by hydrolysis of the yellow string beans protein. The antioxidant properties of the hydrolysates were evaluated through free radical scavenging activities (DPPH and ABTS) and inhibition of iron activities (chelation of Fe2+). The results show that the heat treatment had influence on both increased peptides content and antioxidant activity after pepsin hydrolysis of string bean protein. The peptides content after protein hydrolysis derived from raw and heat treated beans were noted 2.10 and 2.50 mg ⋅ ml-1, respectively. The hydrolysates obtained from raw (PHR) and heat treated (PHT) beans showed better antioxidant properties than protein isolates (PIR and PIT). Moreover, the hydrolysates obtained from heat treated beans showed the higher ability to scavenge DPPH• (46.12%) and ABTS+• (92.32%) than obtained from raw beans (38.02% and 88.24%, correspondingly). The IC50 value for Fe2+ chelating ability for pepsin hydrolysates obtained from raw and heat treatment beans were noted 0.81 and 0.19 mg ⋅ ml-1, respectively. In conclusion, the results of this study showed that the heat treatment string beans caused increase in the antioxidant activities of peptide-rich hydrolysates. [ABSTRACT FROM AUTHOR]