Jan Oszmiański

In Vitro Antileukaemic Activity of Extracts from Chokeberry (Aronia melanocarpa [Michx] Elliott) and Mulberry (Morus alba L.) Leaves against Sensitive and Multidrug Resistant HL60 Cells

The aim of the present study was to determine in vitro antileukaemic activities of extracts obtained from chokeberry (Aronia melanocarpa [Michx] Elliot) and mulberry (Morus alba L.) leaves against promyelocytic HL60 cell line and its multidrug resistant sublines exhibiting two different MDR phenotypes: HL60/VINC (overexpressing P‐glycoprotein) and HL60/DOX (overexpressing MRP1 protein). It was found that the extracts from chokeberry and mulberry leaves were active against the sensitive leukaemic cell line HL60 and retained the in vitro activity against multidrug resistant sublines (HL60/VINC and HL60/DOX). The values of resistance factor (RF) found for these extracts were very low lying in the range 1.2–1.6. Copyright

Biological Activity of Blackcurrant Extracts (Ribes nigrum L.) in Relation to Erythrocyte Membranes

Compounds contained in fruits and leaves of blackcurrant (Ribes nigrum L.) are known as agents acting preventively and therapeutically on the organism. The HPLC analysis showed they are rich in polyphenol anthocyanins in fruits and flavonoids in leaves, that have antioxidant activity and are beneficial for health. The aim of the research was to determine the effect of blackcurrant fruit and leaf extracts on the physical properties of the erythrocyte membranes and assess their antioxidant properties. The effect of the extracts on osmotic resistance, shape of erythrocytes and hemolytic and antioxidant activity of the extracts were examined with spectrophotometric methods. The FTIR investigation showed that extracts modify the erythrocyte membrane and protect it against free radicals induced by UV radiation. The results show that the extracts do not induce hemolysis and even protect erythrocytes against the harmful action of UVC radiation, while slightly strengthening the membrane and inducing echinocytes. The compounds contained in the extracts do not penetrate into the hydrophobic region, but bind to the membrane surface inducing small changes in the packing arrangement of the polar head groups of membrane lipids. The extracts have a high antioxidant activity. Their presence on the surface of the erythrocyte membrane entails protection against free radicals.

The Content of Phenolic Compounds in Leaf Tissues of White (Aesculus hippocastanum L.) and Red Horse Chestnut (Aesculus carea H.) Colonized by the Horse Chestnut Leaf Miner (Cameraria ohridella Deschka & Dimić)

Normally, plant phenolics are secondary metabolites involved in the defense mechanisms of plants against fungal pathogens. Therefore, in this study we attempted to quantify and characterize phenolic compounds in leaves of white and red horse chestnut with leaf miner larvae before and after Cameraria ohridella attack. A total of 17 phenolic compounds belonging to the hydroxycinnamic acid, flavan-3-ols and flavonol groups were identified and quantified in white and red horse chestnut leaf extracts. Significantly decreased concentrations of some phenolic compounds, especially of flavan-3-ols, were observed in infected leaves compared to the non-infected ones. Additionally, a higher content of polyphenolic compounds especially (−)-epicatechin and procyanidins in leaves of red-flowering than in white-flowering horse chestnut may explain their greater resistance to C. ohridella insects.

The content of phenolic compounds in leaf tissues of Aesculus glabra and Aesculus parviflora walt.

In plants, flavonoids play an important role in biological processes. They are involved in UV-scavenging, fertility and disease resistance. Therefore, in this study, we attempted to quantify and characterize phenolic compounds in Aesculus parviflora Walt. leaves and Aesculus glabra leaves partly suffering from attack by a leaf mining insect (C. ohridella). A total of 28 phenolic compounds belonging to the hydroxycinnamic acid, flavan-3-ols and flavonol groups were identified and quantified in Aesculus parviflora and A. glabra leaf extracts. Significantly decreased concentrations of some phenolic compounds, especially of flavan-3-ols, were observed in infected leaves compared to the non-infected ones. Additionally, a higher content of polymeric procyanidins in leaves of Aesculus parviflora than in Aesculus glabra may explain their greater resistance to C. ohridella insects.

Hawthorn (Crataegus oxyacantha L.) Bark Extract Regulates Antioxidant Response Element (ARE)-Mediated Enzyme Expression Via Nrf2 Pathway Activation in Normal Hepatocyte Cell Line

Hawthorn (Crataegus oxyacantha L.), a plant used in traditional medicine, is a rich source of procyanidins which have been reported to exhibit antioxidant and anti‐carcinogenic activity. In this study, we assessed the effect of hawthorn bark extract (HBE) on Nrf2 pathway activation in THLE‐2 and HepG2 cells. Treatment with 1.1 µg/mL, 5.5 µg/mL and 11 µg/mL of HBE resulted in the translocation of Nrf2 from the cytosol to the nucleus in both cell lines; however, the accumulation of phosphorylated Nrf2 was observed only in THLE‐2. Accordingly, treatment of cells with HBE was associated with an increase in the mRNA and protein level of such Nrf2‐dependent genes as glutathione S‐transferases (GSTA, GSTP, GSTM, GSTT), NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase‐1 (HO‐1) (0.2–1.1‐fold change, p < 0.05), however, only in normal THLE‐2 hepatocytes. The induction of NQO1 correlated with an increased level of p53 (0.21–0.42‐fold change, p < 0.05). These effects may be related to induction of phosphorylation of upstream ERK and JNK kinases. Collectively, the results suggest that the Nrf2/ARE pathway may play an important role in the regulation of procyanidin‐mediated antioxidant/detoxifying effects in hepatocytes, and this may explain the hepatoprotective and chemopreventive properties of these phytochemicals. Copyright

Antioxidant Activity of Extracts from Apple, Chokeberry and Strawberry

The aim of the study was to determine the protective action of extracts from apple, strawberry and chokeberry with respect to linoleic acid and the biological membrane exposed to oxidation induced by physicochemical factors. The activity of the extracts was determined by measuring inhibition of lipid oxidation in red blood cell membrane, induced with UVC radiation and the AAPH radical. The protective effect of the extracts was essayed fl uorimetrically and spectrophotometrically. These results together with the ones obtained earlier explain the mechanism of the interaction between the extracts and the red blood cell membrane. The mechanism consists in the incorporation into the membrane and screening the cell against oxidation. The results indicate that the extracts possess very good antioxidant properties, since at the highest concentrations used (0.1 mg/mL) they protect the biological membranes almost entirely against oxidation. Among the extracts studied the best antioxidant properties were exhibited by the apple fruit, which gave 80% or 100% protection of the membrane at 0.05 mg/mL concentration of dry matter, for UVC and AAPH inductors, respectively.