Paulina Strugała

Concentrated green tea supplement: Biological activity and molecular mechanisms

AIM This study was undertaken to determine the biological activity of a green tea supplement with respect to cells and erythrocyte membranes and the molecular mechanism of that activity. MAIN METHODS The extracts activity was evaluated on the basis of its hemolytic, antioxidant and antiinflammatory actions. In addition, the extracts effect on the physical properties of the erythrocyte membrane was examined. We also conducted a detailed analysis of supplement ingredients using high-yield liquid chromatography, supplemented with standard tests of total content of polyphenols and flavonoids in the supplement. KEY FINDINGS The study showed that green tea extract has a high antioxidant and anti-inflammatory capacity with no deleterious effect on red blood cells. The extract modifies the physical properties of the erythrocyte membrane, apparently by binding to its hydrophilic region, with consequent rigidity of the hydrophobic region, increased hydration and a moderate increase in its resistance to changes in tonicity of the medium. Because the extracts components anchor in the polar region of membrane lipids, they are able to effectively scavenge free radicals in the immediate vicinity of the membrane and hinder their diffusion into its interior. SIGNIFICANCE Green tea supplement at concentrations markedly exceeding the blood plasma physiological polyphenol concentrations has no destructive effect on the erythrocyte membrane. Due to the high content of flavan-3-ols, the supplement exhibits high biological activity, which makes it an alternative source of those substances to the commonly used infusion of green tea leaves.

Biological Activity of Japanese Quince Extract and Its Interactions with Lipids, Erythrocyte Membrane, and Human Albumin.

The aim of the study was to determine in vitro biological activity of fruit ethanol extract from Chaenomeles speciosa (Sweet) Nakai (Japanese quince, JQ) and its important constituents (−)-epicatechin (EC) and chlorogenic acid (CA). The study also investigated the structural changes in phosphatidylcholine (PC) liposomes, dipalmitoylphosphatidylcholine liposomes, and erythrocyte membranes (RBC) induced by the extract. It was found that the extract effectively inhibits oxidation of RBC, induced by 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH), and PC liposomes, induced by UVB radiation and AAPH. Furthermore, JQ extract to a significant degree inhibited the activity of the enzymes COX-1 and COX-2, involved in inflammatory reactions. The extract has more than 2 times greater activity in relation to COX-2 than COX-1 (selectivity ratio 0.48). JQ extract stimulated growth of the beneficial intestinal bacteria Lactobacillus casei and Lactobacillus plantarum. In the fluorimetric method by means of the probes Laurdan, DPH and TMA-DPH, and 1H-NMR, we examined the structural changes induced by JQ and its EC and CA components. The results show that JQ and its components induce a considerable increase of the packing order of the polar heads of lipids with a slight decrease in mobility of the acyl chains. Lipid membrane rigidification could hinder the diffusion of free radicals, resulting in inhibition of oxidative damage induced by physicochemical agents. JQ extract has the ability to quench the intrinsic fluorescence of human serum albumin through static quenching. This report thus could be of huge significance in the food industry, pharmacology, and clinical medicine.

A comprehensive study on antioxidant properties of crude extracts from fruits of Berberis vulgaris L., Cornus mas L. and Mahonia aquifolium Nutt.

Abstract The antioxidant capacity of methanolic crude extracts of Berberis vulgaris L., Cornus mas L. and Mahonia aquifolium Nutt. was tested with the thiobarbituric acid reactive substances formation assay, the ferric reducing power (FRAP) and 2,2-diphenyl-2-picrylhydrazyl (DPPH•) radical scavenging assay. The content of antioxidant components in the extracts, their partition coefficient on 1-octanol:water and affinity to liposome membranes were determined as well. The results show that the IC50 parameter connected with the antioxidant activity on phosphatidylcholine liposome membrane decreased as follows: B. vulgaris (0.14±0.01 mg/mL) > M. aquifolium (0.34±0.03 mg/mL) > C. mas (1.13±0.01 mg/mL) for AAPH-induced oxidation and M. aquifolium (0.29±0.03 mg/mL) > C. mas (1.24±0.07 mg/mL) > B. vulgaris (1.50±0.05 mg/mL) for Fe(II)/ascorbic acid-induced oxidation, and M. aquifolium (2.35±0.10 mg/mL) > B. vulgaris (2.69±0.04 mg/mL) > C. mas (6.17±0.06 mg/mL) for UVC irradiation. All the extracts exhibited the ability to quench DPPH• and to reduce Fe(III) ions to Fe(II) via redox reaction. The content of active components in the extracts, the partition coefficient and extracts affinity to membranes correlated well with their antioxidant activities. This study has shown that fruits of B. vulgaris, M. aquifolium and C. mas, from which the extracts were obtained, are attractive for consumption and can potentially be used in production of new processed fruit.

The Influence of Glycosylation of Natural and Synthetic Prenylated Flavonoids on Binding to Human Serum Albumin and Inhibition of Cyclooxygenases COX-1 and COX-2

The synthesis of different classes of prenylated aglycones (α,β-dihydroxanthohumol (2) and (Z)-6,4’-dihydroxy-4-methoxy-7-prenylaurone (3)) was performed in one step reactions from xanthohumol (1)—major prenylated chalcone naturally occurring in hops. Obtained flavonoids (2–3) and xanthohumol (1) were used as substrates for regioselective fungal glycosylation catalyzed by two Absidia species and Beauveria bassiana. As a result six glycosides (4–9) were formed, of which four glycosides (6–9) have not been published so far. The influence of flavonoid skeleton and the presence of glucopyranose and 4-O-methylglucopyranose moiety in flavonoid molecule on binding to main protein in plasma, human serum albumin (HSA), and inhibition of cyclooxygenases COX-1 and COX-2 were investigated. Results showed that chalcone (1) had the highest binding affinity to HSA (8.624 × 104 M−1) of all tested compounds. It has also exhibited the highest inhibition of cyclooxygenases activity, and it was a two-fold stronger inhibitor than α,β-dihydrochalcone (2) and aurone (3). The presence of sugar moiety in flavonoid molecule caused the loss of HSA binding activity as well as the decrease in inhibition of cyclooxygenases activity.

Physical Effects of Buckwheat Extract on Biological Membrane In Vitro and Its Protective Properties.

Buckwheat is a valuable source of many biologically active compounds and nutrients. It has properties that reduce blood cholesterol levels, and so reduces the risk of atherosclerosis, seals the capillaries, and lowers blood pressure. The aim of the study was to determine quantitative and qualitative characteristics of polyphenols contained in extracts from buckwheat husks and stalks, the biological activity of the extracts, and biophysical effects of their interaction with the erythrocyte membrane, treated as a model of the cell. An analysis of the extract’s composition has shown that buckwheat husk and stalk extracts are a rich source of polyphenolic compounds, the stalk extracts showing more compounds than the husk extract. The study allowed to determine the location which incorporated polyphenols occupy in the erythrocyte membrane and changes in the membrane properties caused by them. It was found that the extracts do not induce hemolysis of red blood cells, causing an increase in osmotic resistance of erythrocytes. They affect mainly the hydrophilic region by changing the degree of order of the polar heads of lipids, but do little to change the fluidity of the membrane and its hydration. The results showed also that polyphenolic substances included in the extracts well protect the membranes of red blood cells against oxidation and exhibit anti-inflammatory effect.

Bioactivity In Vitro of Quercetin Glycoside Obtained in Beauveria bassiana Culture and Its Interaction with Liposome Membranes

Quercetin (Q) was used as substrate for regioselective glycosylation at the C-7 position catalyzed by Beauveria bassiana AM278 strain. As a result the glycoside quercetin 7-O-β-d-(4″-O-methyl)glucopyranoside (Q 7-MeGlu) was formed. The goal of the studies was to determine the anti-oxidative (liposome membrane protection against free radicals IC50Q 7-MeGlu = 5.47 and IC50Q = 4.49 µM) and anti-inflammatory (COX-1 and COX-2 enzymes activity inhibition) properties of Q 7-MeGlu as compared to Q. Every attempt was made to clarify the antioxidant activity of these molecules, which are able to interact with egg phosphatidylcholine liposomes, using a fluorometric method (by applying the probes MC540, TMA-DPH and DPH). The results indicated that Q 7-MeGlu and Q are responsible for increasing the packing order, mainly in the hydrophilic but also in hydrophobic regions of the membrane (Q > Q 7-MeGlu). These observations, confirmed by a 1H-NMR method, are key to understanding their antioxidant activity which is probably caused by the stabilizing effect on the lipid membranes. The results showed that Q 7-MeGlu and Q have ability to quench the human serum albumin (HSA) intrinsic fluorescence through a static quenching mechanism. The results of thermodynamic parameters indicated that the process of formation complexes between studied molecules and HSA was spontaneous and caused through Van der Waals interactions and hydrogen bonding.

Biological activity and stability in vitro of polyphenolic extracts as potential dietary supplements.

INTRODUCTION In times of worsening civilization diseases the interest in natural healing substances is on the increase. To reduce unwanted side effects of many synthetic drugs, it is reasonable to introduce to the daily diet foods rich in natural compounds of plant origin that are beneficial for health. The purpose of the study was to determine the biological activity and stability of selected ethanol extracts of the fruit of chokeberry, blackcurrant, hawthorn, rosehip, quince and Japanese quince as potential nutraceuticals. MATERIALS AND METHODS Antioxidant activity of the extracts was determined in relation to model phospholipid membranes (IC50(PC)). Antiradical activity was determined in a test with the DPPH• radical (IC50(DPPH)). Also the inhibition of enzymatic (1-LOX) oxidation of linoleic acid was determined at the beginning of the period of storage of the extracts at room temperature and after 12 months. RESULTS After 12 months of storage the highest antioxidant stability was shown by blackcurrant extract (1.5% increase in IC50(PC)), the highest antiradical stability by quince extract (1.0% reduction in IC50(DPPH)), and the highest stability of 1-LOX enzyme inhibition by chokeberry extract (6.3% reduction in inhibition at a concentration of 8 μg∙(-1)). Japanese quince extract showed the strongest regenerating properties with respect to oxidized phospholipid membranes and the highest ability to eliminate the free radical DPPH•. CONCLUSION It can be concluded that the ethanol extracts of the fruits (in particular blackcurrant, chokeberry and Japanese quince) are a potential source of dietary supplements of expected effectiveness in preventive treatment.

A Comprehensive Study on the Biological Activity of Elderberry Extract and Cyanidin 3-O-Glucoside and Their Interactions with Membranes and Human Serum Albumin

In our research we used the extract from dietary supplement of elderberry (EE) and its dominant anthocyanin—cyanidin 3-O-glucoside (Cy 3-gluc). By interacting with a model membrane that reflects the main lipid composition of tumor membranes, the extract components, including Cy 3-gluc, caused an increase in packing order, mainly in the hydrophilic region of the membrane. It can thus be stated that EE caused a rigidifying effect, which is fundamental for understanding its anticancer and antioxidant activity. This study represents the first attempt to unravel the mechanism of interaction of elderberry extract with membranes. The results of the interaction with human serum albumin (HSA) proved that the studied substance quenches the fluorescence of HSA through a static mechanism in which the main interaction forces are Van der Waals and hydrogen bonding. The antioxidant activity of EE and Cy 3-gluc on liposomal membranes, antiradical properties and ability to inhibited the activity of the enzymes cyclooxygenase-1 and cyclooxygenase-2 were also demonstrated. Moreover, the anticancer activity of EE and Cy 3-gluc on human breast adenocarcinoma cell line were investigated. In addition, EE also exhibited the ability to form lipid aggregates in the form of liposomal capsules that can be applied as carriers of active biological substances, and the highest efficacy of EE encapsulation was obtained for multilayered liposome formulations.