Michał Świeca

Antioxidant and anticancer activities of Chenopodium quinoa leaves extracts – In vitro study

The nutraceutical potential of Chenopodium quinoa Leaves (ChL) was assessed through analyses of their phenolic content, elucidation of the effect of ChL phenolic compounds on cancer cell properties and estimation of their antioxidative activity, bioaccessibility and bioavailability in vitro. Considerable amounts of ferulic, sinapinic and gallic acids, kaempferol, isorhamnetin and rutin were observed in the chemical ChL extract and were linked with its inhibitory effect on prostate cancer cell proliferation, motility and cellular competence for gap junctional communication. Both extracts, chemical and obtained after simulated digestion, exerted an inhibitory effect on lipoxygenase activity, paralleled by their considerable chelating, antioxidative, antiradical and reducing power. These observations indicate that phenolic ChL compounds may exert a chemopreventive and anticarcinogenic effect on oxidative stress and ROS-dependent intracellular signaling via synergic effects. The relatively high potential bioaccessibility and bioavailability of the compounds probably responsible for these effects demonstrates the suitability of ChL for dietary supplementation.

The influence of protein–flavonoid interactions on protein digestibility in vitro and the antioxidant quality of breads enriched with onion skin

Different types of breads enriched with onion skin were studied. The objectives were twofold: to show and examine protein-phenolic interactions and to discuss results concerning phenolic content, antioxidant activity and protein digestibility in the light of in vitro bioaccessibility. Phenolic contents and antiradical abilities were linked with the level of onion skin supplement however, the amounts determined were significantly lower than expected. Fortification influenced protein digestibility (a reduction from 78.4% for control breads to 55% for breads with a 4% supplement). Electrophoretic and chromatographic studies showed the presence of indigestible protein-flavonoid complexes - with molecular weights about 25 kDa and 14.5 kDa; however, the reduction of free amino group levels and the increase in chromatogram areas suggest that flavonoids also bind to other bread proteins. The interaction of phenolics with proteins affects antioxidant efficacy and protein digestibility; thus, they have multiple effects on food quality and pro-health properties.

Bread enriched with quinoa leaves – The influence of protein–phenolics interactions on the nutritional and antioxidant quality

This paper investigates the functional and potential biological properties of bread fortified with quinoa leaves (QL) in the light of protein-phenolic interactions. The addition of QL changed the textural properties of bread crumb. With the replacement of wheat flour by QL (1-5%), a linear increase in crumb hardness, cohesiveness and gumminess was observed. Fortification positively affected antioxidant properties and phenolic contents; however, in some cases experimental values were significantly lower than those predicted. The QL addition affected nutrient content and digestibility. The starch digestibility of the bread investigated in this study was inversely proportional to the percentage content of QL (the changes in protein digestibility were not so pronounced). Increasing peak areas of extracts obtained after digestion of fortified bread and the significant reduction of free amino groups confirm the presence of interactions between phenolics and proteins. The quality of fortified bread is strongly affected by phenolic compounds and food matrix interactions.

Effect of abiotic elicitation on main health-promoting compounds, antioxidant activity and commercial quality of butter lettuce (Lactuca sativa L.)

The study presents changes in the phytochemical levels, antiradical activity and quality of lettuce caused by different chemical elicitors: arachidonic acid (AA), jasmonic acid (JA), and abscisic acid (ABA). The application of 1 μM and 100 μM JA induced an increase in the concentration of phenolic compounds, including flavonoids and phenolic acids. Flavonoid levels were also increased after treatment with 100 μM AA and ABA. Some of the elicitor concentrations used also caused an increase in the levels of other phytochemicals, such as chlorophyll a (1 μM and 100 μM AA, 50 μM ABA); chlorophyll b (100 μM AA); carotenoids (100 μM AA, 1 μM JA and 100 μM ABA) and vitamin C (100 μM AA, 100 μM JA). The highest antiradical activity was noted after treatment with 100 μM AA, 100 μM JA. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging ability was positively and significantly correlated with flavonoid, chlorophyll and carotenoid levels. These results may suggest that the antiradical activity of lettuce was determined not only by phenolics, but also by other bioactive compounds. Elicitation did not change the sensory quality of lettuce. Therefore, treatment with elicitors could be a useful tool for improving the health-promoting qualities of lettuce without the loss of sensory quality.

Quality and antioxidant properties of breads enriched with dry onion (Allium cepa L.) skin

The aim of the study was to investigate the effect on the antioxidant properties and sensory value of bread of adding ground onion skin (OS). For a determination of bioaccessibility and bioavailability in vitro the human gastrointestinal tract model was used. OS contained mastication-extractable quercetin (4.6 mg/g). Quercetin from OS was highly bioaccessible during in vitro conditions, but only approximately 4% of quercetin released during simulated digestion was bioavailable in vitro. The antioxidant potential of bread with OS was significantly higher than the activity noted in the control. In particular, OS addition significantly fortificated bread with bioaccessible lipid oxidation preventers and compounds with reducing and chelating abilities. The 2-3% OS addition caused significant improvement of antioxidant abilities (further increases in the OS supplement did not increase the activity of bread). Sensory evaluation showed that replacement of wheat flour in bread with up to 3% OS powder gave satisfactory consumer acceptability.

Biologically active peptides obtained by enzymatic hydrolysis of Adzuki bean seeds

This study investigated the antioxidant and antihypertensive activities of peptides obtained from protein fractions of Adzuki bean seeds. Peptides were obtained by the use of hydrolytic enzymes in vitro under gastrointestinal conditions. A determination was made of the activity of the peptide inhibitors of the angiotensin I converting enzyme (ACE), and the antiradical and ion chelating activity of peptides from different protein fractions. The highest peptide levels after the absorption process (<7 kDa) were noted in the albumin fraction (50.69 μg/ml). Furthermore, it was found that peptides from the prolamin fraction were characterised by the highest antiradical activity and ACE inhibitory activity (IC50=0.17 mg/ml). Peptides obtained from the globulin fraction showed the highest ability to chelate iron ions, and peptides from the glutelin fraction were characterised as being the most effective in the chelation of copper ions.

In vitro digestibility and starch content, predicted glycemic index and potential in vitro antidiabetic effect of lentil sprouts obtained by different germination techniques.

The study focuses on changes in starch content and expected glycemic index (eGI) caused by different sprouting methods of lentil. On germination, a decrease was observed in total starch content (TS), α-amylase inhibitors activity (αAI) and eGI values. After elicitation, the highest TS content was determined in 3-day-old control sprouts (100.9 mg/gf.m.), whereas the lowest was in 4-day-old sprouts induced with 300 mM NaCl (57.8 mg/gf.m.). Resistant starch (RS) content was most effectively increased by induction with 600 mM mannitol. The highest eGI values were determined for 3-day-old sprouts induced with 300 mM NaCl, whereas the lowest were for 6-day-old sprouts induced with 100mM NaCl. In treated sprouts starch digestibility was connected with αAI activity and RS content. Sprouting conditions can modify starch content, its potential bioavailability and eGI values. Optimization of this process will allow for the maximum nutritional benefit.

The effect of different solvents and number of extraction steps on the polyphenol content and antioxidant capacity of basil leaves (Ocimum basilicum L.) extracts

The objectives of this study were to determine best conditions for the extraction of phenolic compounds from fresh, frozen and lyophilized basil leaves. The acetone mixtures with the highest addition of acetic acid extracted most of the phenolic compounds when fresh and freeze-dried material have been used. The three times procedure was more effective than once shaking procedure in most of the extracts obtained from fresh basil leaves – unlike the extracts derived from frozen material. Surprisingly, there were not any significant differences in the content of phenolics between the two used procedures in the case of lyophilized basil leaves used for extraction. Additionally, the positive correlation between the phenolic compounds content and antioxidant activity of the studied extracts has been noted. It is concluded that the acetone mixtures were more effective than the methanol ones for polyphenol extraction. The number of extraction steps in most of the cases was also a statistically significant factor affecting the yield of phenolic extraction as well as antioxidant potential of basil leaf extracts.

Effect of carob (Ceratonia siliqua L.) flour on the antioxidant potential, nutritional quality, and sensory characteristics of fortified durum wheat pasta

This paper presents a study on the effect of carob flour addition from 1% to 5% (w/w) on phenolics content, antioxidant activity, nutritional quality, and sensory attributes of wheat pasta. An increase of about 2-folds, 18-folds and 3-folds in phenolics content, antiradical activity and reducing power for pasta fortified with 5% of carob flour was observed, respectively, compared to the control. Expected glycemic index (eGI) was increased proportionally to the substitution level and ranged between 72.2 and 83.9 for 1-5% of supplement, respectively. Furthermore, pasta fortification affected the in vitro bioaccessibility of nutrients. In case of 5% supplemented pasta, the digestibility of starch and protein decreased by about 9% compared to the control. The replacement of semolina with carob flour from 1% to 5% had no significant effect on pasta sensory attributes. In conclusion, carob flour seems to be a promising functional ingredient for pasta fortification.

Comparison of phenolic acids profile and antioxidant potential of six varieties of spelt (Triticum spelta L.).

Phenolic acids profile and antioxidant activity of six diverse varieties of spelt are reported. Antioxidant activity was assessed using eight methods based on different mechanism of action. Phenolic acids composition of spelt differed significantly between varieties and ranged from 506.6 to 1257.4 μg/g DW. Ferulic and sinapinic acids were the predominant phenolic acids found in spelt. Total ferulic acid content ranged from 144.2 to 691.5 μg/g DW. All analyzed spelt varieties possessed high antioxidant potential. In spite of the fact that bound phenolic acids possessed higher antioxidant activities, analysis of antioxidant potential and their relationship with phenolic acid content showed that free phenolics were more effective. Eight antioxidant methods were integrated to obtain a total antioxidant capacity index that may be used for comparison of total antioxidant capacity of spelt varieties. Total antioxidant potential of spelt cultivars were ordered as follows: Ceralio > Spelt INZ ≈ Ostro > Oberkulmer Rotkorn > Schwabenspelz > Schwabenkorn.