Małgorzata Materska

Isolation and structure elucidation of flavonoid and phenolic acid glycosides from pericarp of hot pepper fruit Capsicum annuum L.

Hot pepper fruits (Capsicum annuum L.) var. Bronowicka Ostra have been studied with regard to content of flavonoids and other phenolics. Nine compounds were isolated from pericarp of pepper fruits by preparative HPLC. Their structures were identified by chromatographic (analytical HPLC) and spectroscopic (UV, NMR) techniques. Two of the identified compounds, trans-p-ferulylalcohol-4-O-(6-(2-methyl-3-hydroxypropionyl) glucopyranoside and luteolin-7-O-(2-apiofuranosyl-4-glucopyranosyl-6-malonyl)-glucopyranoside were found for the first time in the plant kingdom. Additionally compounds: trans-p-feruloyl-beta-D-glucopyranoside, trans-p-sinapoyl-beta- D-glucopyranoside, quercetin 3-O-alpha-L-rhamnopyranoside-7-O-beta-D-glucopyranoside, luteolin 6-C-beta-D-glucopyranoside-8-C-alpha-L-arabinopyranoside, apigenin 6-C-beta-D-glucopyranoside-8-C-alpha-L-arabinopyranoside and luteolin 7-O-[2-(beta-D-apiofuranosyl)-beta-D-glucopyranoside] were found for the first time in pepper fruit Capsicum annuum L.

Phenylalanine ammonia-lyase and antioxidant activities of lipophilic fraction of fresh pepper fruits Capsicum annum L.

Capsaicin and dihydrocapsaicin content, their antioxidant activity, the activity of the fraction containing flavonoids, as well as the activity of l-phenylalanine ammonia-lyase (PAL) were studied in the fruit of the hot pepper Capsicum annuum L., var. Cyklon and Bronowicka Ostra. For analyses, pericarps of fruit at two stages were used: before the beginning of maturation — green; and mature — red. The fruit of the cv. Bronowicka Ostra was characterized by a higher PAL activity, capsaicinoid level and higher antioxidant activity than that found in Cyklon. It was found that red fruit of both cultivars had higher antioxidant activity in the capsaicinoid and flavonoid fractions. The PAL activity was as much higher in the red than in the green (unripe) fruits. The antioxidant activity under the same experimental conditions was similar in both capsaicinoid and flavonoid fractions of cv. Bronowicka Ostra.

Antioxidant activity and protective effects against oxidative damage of human cells induced by X-radiation of phenolic glycosides isolated from pepper fruits Capsicum annuum L.

The antioxidant and radioprotective effects of the phenolic glycosides from Capsicum annuum L. were examined. There were: sinapoyl-E-glucoside, quercetin-3-O-rhamnoside-7-O-glucoside, quercetin-3-O-rhamnoside and luteolin-7-O-(2-apiosyl)-glucoside. To the best of our knowledge, this is the first study to assay these compounds for their radioprotective effect on human cell lymphocytes in response to oxidative damage induced by X radiation and their antioxidant abilities. Investigated compounds showed weaker antiradical activities, but their radioprotective potentials were higher than those of their aglycones. Quercetin-3-O-rhamnoside showed the highest radioprotective activity (50% according to control). Furthermore, quercetin and luteolin derivatives, in contrast to free aglycones, were not cytotoxic against human lymphocytes for all concentrations tested. The best correlation between radioprotective and antiradical activities of the investigated compounds was observed in the relationship to O2(-) generated using the NADH/PMS method (R(2)=0.859). Thus, we propose that superoxide radical scavenging activity is a useful method for screening for compounds with promising radioprotective potential.

Adsorption and degradation of phenoxyalkanoic acid herbicides in soils: A review.

The primary aim of the present review on phenoxyalkanoic acid herbicides-2-(2,4-dichlorophenoxy) acetic acid (2,4-D), 2-(4-chloro-2-methylphenoxy) acetic acid (MCPA), (2R)-2-(2,4-dichlorophenoxy) propanoic acid (dichlorprop-P), (2R)-2-(4-chloro-2-methylphenoxy) propanoic acid (mecoprop-P), 4-(2,4-dichlorophenoxy) butanoic acid (2,4-DB), and 4-(4-chloro-2-methylphenoxy) butanoic acid (MCPB)-was to compare the extent of their adsorption in soils and degradation rates to assess their potential for groundwater contamination. The authors found that adsorption decreased in the sequence of 2,4-DB > 2,4-D > MCPA > dichlorprop-P > mecoprop-P. Herbicides are predominantly adsorbed as anions-on organic matter and through a water-bridging mechanism with adsorbed Fe cations-and their neutral forms are adsorbed mainly on organic matter. Adsorption of anions of 2,4-D, MCPA, dichlorprop-P, and mecoprop-P is inversely correlated with their lipophilicity values, and modeling of adsorption of the compounds based on this relationship is possible. The predominant dissipation mechanism of herbicides in soils is bacterial degradation. The contribution of other mechanisms, such as degradation by fungi, photodegradation, or volatilization from soils, is much smaller. The rate of bacterial degradation decreased in the following order: 2,4-D > MCPA > mecoprop-P > dichlorprop-P. It was found that 2,4-D and MCPA have the lowest potential for leaching into groundwater and that mecoprop-P and dichlorprop-P have slightly higher potential. Because of limited data on adsorption and degradation of 2,4-DB and MCPB, estimation of their leaching potential was not possible.

Ozone-induced changes in the content of bioactive compounds and enzyme activity during storage of pepper fruits.

This paper presents for the first time the results of investigations concerning the effect of treatment of whole pepper fruits with gaseous ozone and the refrigeration storage period conditions on pepper quality. The effects are reflected in changes in the flavonoid contents, the antioxidant activity of the phenolic compound fraction and the enzymes involved in phenylpropanoid metabolism. The investigations were carried out on a hot pepper fruit cultivar, Cyklon. It was found that the levels of a majority of flavonoids, in particular those of quercetin 3-O-rhamnoside and quercetin 3-O-rhamnoside-7-O-glucoside increased in the pericarp of fruits treated with ozone for 3h and stored for 20days (by 25% relative to the control). Simultaneously, reduced phenylalanine ammonia-lyase and tyrosine ammonia-lyase activity were noted, which implies slight degradation of enzymes caused by the ozone treatment and enhancement of the polyphenol oxidase and guaiacol oxidase activity involved in response to increased oxidative stress.

ANTIOXIDANT ACTIVITY OF PROTEIN HYDROLYSATES FROM RAW AND HEAT-TREATED YELLOW STRING BEANS (PHASEOLUS VULGARIS L.)

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.