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.

This study was designed to evaluate the effects of purple potato extract of the Blue Congo variety (PP) on diabetes and its antioxidant activities after two-week administration tostreptozotocin (STZ)-induced diabetic rats. The activities of PP were evaluated at a dose of 165 mg/kg body weight (b.w.) by estimating biochemical changes in blood plasma and through a histopathological study of kidney, muscles, and liver tissue. We evaluated the effect of treatment with extract on glucose level, glycated hemoglobin, activities of enzymatic antioxidants (including superoxide dismutase, glutathione peroxidase, and catalase), and lipid peroxidation. Moreover, we determined advanced glycation end-products (AGEs), advanced oxidation protein products (AOPPs), and the level of oxidative modified proteins (OMPs) as markers of carbonyl-oxidative stress in rats with diabetes. Using high-performance liquid chromatography, we identified five anthocyanins and six phenolic acids in the extract from Blue Congo with the dominant acylated anthocyanin as petunidin-3-p-coumaroyl-rutinoside-5-glucoside. The administration of Blue Congo extract lowered blood glucose, improved glucose tolerance, and decreased the amount of glycated hemoglobin. Furthermore, PP demonstrated an antioxidative effect, suppressed malondialdehyde levels, and restored antioxidant enzyme activities in diabetic rats. After administration of PP, we also noticed inhibition of OMP, AGE, and AOPP formation in the rats′ blood plasma.

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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.

We investigated the effects of acylated cyanidin-3-O-β-(6″-O-E-p-coumaroyl-sambubioside)-5-O-β-glucoside (C3cs-5G) and nonacylated cyanidin, cyanidin-3,5-di-O-β-glucoside (C3,5G) and cyanidin-3-O-β-glucoside (C3G), on cell-mimic membranes (MM) that reflected the membrane lipid composition of tumor cells. The relationship between structural derivatives of cyanidin (Cy-d), membrane interactivity, their antioxidant activity, and interaction with albumin were characterized. Studies showed that Cy-d caused an increase in packing order mainly in the hydrophilic region of the membranes. Cy-d have shown high antioxidant activity against liposome oxidation induced by AAPH and ability to bind to albumin through a static quenching mechanism. The results showed that glycosylation number and the presence of aromatic acid attached to sugars affected the membrane properties, according to the sequence C3-cs-5G > C3,5G > C3G. It can be stated that Cy-d in the process of interaction with MM caused a rigidifying effect, which is fundamental for understanding their anticancer and antioxidant activity and is one of the possible pharmaceutical mechanisms.

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.

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 coeffi cient on 1-octanol:water and affi nity to liposome membranes were determined as well. The results show that the IC 50 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 coeffi cient and extracts affi nity 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 study of ethanol extracts as potential dietary supplements has shown that extracts of chokeberry (IC 50 24.6 mg/mL) and, to a lesser extent, blackcurrant, rosehip, and hawthorn (IC 50 30.9, 33.5, and 45.9 mg/mL) are good antioxidants in relation to UVB-oxidized phosphatidylcholine liposomes. All tested fruit extracts protect the bilayer against oxidation by reducing fluidity of the membrane hydrophilic/hydrophobic region (in the presence of extracts the generalized polarization of the Laurdan probe and fluorescence anisotropy of DPH and TMA-DPH increased). The major phenolic compounds were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC/MS). The extracts caused inhibition of the pro-inflammatory enzymes cyclooxygenase-1 and cyclooxygenase-2, the highest for blackcurrant (77.6 and 70.5%, respectively) and rosehip (64.9 and 72.5%). Another aspect of the research demonstrated antioxidant and antiradical stability of the extracts during 12-month storage. With the exception of hawthorn, they stabilized the profile of unsaturated fatty acids of linseed oil during storage. The investigated fruit extracts in combination with polyunsaturated fatty acids may provide stable and effective dietary anti-inflammatory and antioxidant benefits.Practical applications: By combining two different groups of bioactive compounds (fruit extracts þ omega-3 fatty acids), a new attractive product has been obtained of broad biological activity, which could potentially be useful as a functional food ingredient. The study enabled us to specify the regions where fruit extracts become imbedded in the membrane, based on changes in physical parameters induced in the regions, and will allow us to explain at the molecular level a possible way to protect lipid membranes against attack by free radicals.Keywords: Anti-inflammatory activity / Dietary supplements / Liposomal antioxidants / Membrane fluidity / Profile of unsaturated fatty acids of linseed oil