Dorota Sosnowska

In vitro inhibitory effect on digestive enzymes and antioxidant potential of commonly consumed fruits.

Dietary inhibitors of fats and carbohydrates degrading enzymes can reduce obesity and type 2 diabetes. In this study, we screened crude extracts from 30 commonly consumed fruits to test their in vitro inhibitory effect against key enzymes relevant for obesity (pancreatic lipase) and type 2 diabetes (α-glucosidase and α-amylase), total phenolic content (Folin-Ciocalteu method), and antioxidant capacity (ABTS and FRAP). The IC50 values of the fruits tested varied from 39.91 to >400 mg/mL, from 1.04 to >80 mg/mL, and from 0.72 to 135.07 mg/mL against α-glucosidase, α-amylase, and pancreatic lipase, respectively. Antioxidant capacity ranged from 0.66 to 124.66 μmol of TE/g of fruit and strongly correlated with phenolic content, while the enzyme inhibition was poorly correlated with total phenolic and antioxidant capacity. Among fruits tested, blue honeysuckle and red gooseberry exhibited the highest inhibitory activity with respect to the carbohydrate degrading enzymes, while lingonberry had the strongest anti-lipase activity.

Polyphenols from Evening Primrose (Oenothera paradoxa) Defatted Seeds Induce Apoptosis in Human Colon Cancer Caco-2 Cells

Polyphenols extracted from evening primrose seeds (industrial waste product) were studied as apoptosis inducers in human colorectal adenocarcinoma Caco-2 and HT-29 cell lines and in rat normal intestinal IEC-6 cells. The extract dose-dependently inhibited the growth of Caco-2, HT-29, and IEC-6 cells. However, nuclear DNA fragmentation characteristic of apoptosis was observed only in Caco-2. After 72 h of incubation with the extract at 150 μM gallic acid equivalents (44.1 μg extract/mL), Caco-2 cell numbers decreased to 19% of control and 48.8% of the cells were identified by flow cytometry as apoptotic. Under the same conditions only 8% of HT-29 cells and 12.6% of IEC-6 cells exhibited hypodiploid DNA content. The effects of the extract and its fractions on phosphatidylserine exposure and cell membrane integrity were assessed by high content screening image cytometry. The fractions strongly and dose-dependently reduced Caco-2 cell numbers, whereas HT-29 and IEC-6 cells were affected to lesser extents.

Procyanidins from Evening Primrose (Oenothera paradoxa) Defatted Seeds Inhibit Invasiveness of Breast Cancer Cells and Modulate the Expression of Selected Genes Involved in Angiogenesis, Metastasis, and Apoptosis

There is a growing interest in plant polyphenols (including flavanols) that exhibit pleiotropic biological activities such as antiinflammatory, antioxidant, and anticancer effects. Here, we report for the first time the inhibition of MDA-MB-231 breast cancer cell viability and invasiveness by an evening primrose flavanol preparation (EPFP). We observed a decrease in MDA-MB-231 viability of 50% vs. a control after 72 h of incubation with EPFP at a concentration of 58 μM gallic acid equivalents (GAE) and an inhibition of their invasiveness of 65% vs. a control at 75 μM GAE after 48 h of incubation. EPFP caused a 10-fold reduction in matrix metalloproteinase-9 (MMP-9) activity at 100 μM GAE. Furthermore, through modulation of mRNA expression, EPFP reduced the expression levels of the following proteins: antiapoptotic Bcl-2, angiogenic vascular endothelial growth factor (VEGF), and 2 transcription factors (c-Jun, c-Fos). Moreover, analysis by flow cytometry revealed that EPFP induced apoptosis in MDA-MB-231 cells. In conclusion, our data shows that EPFP inhibits cell viability by increasing apoptosis and decreases cell invasiveness by decreasing angiogenesis.

Polyphenol extract from evening primrose pomace alleviates experimental colitis after intracolonic and oral administration in mice

Oenothera paradoxa (EP) preparations are commonly used in folk medicine to treat skin diseases, neuralgia, and gastrointestinal (GI) disorders. Several reports suggested that EP preparations exhibit potent anti-inflammatory and antioxidant activities both in vitro and in vivo. Here, we aimed to characterize the action of EP pomace polyphenol extract in mouse model of colitis. We analyzed the composition of EP pomace polyphenol extract using reversed phase HPLC system and ultra-performance liquid chromatography (UPLC) system coupled with a quadrupole-time of flight (Q-TOF) MS instrument. Then, we used a well-established animal model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis to determine the anti-inflammatory action of EP pomace polyphenol extract. We also investigated the effect of the EP pomace polyphenol extract on pro-inflammatory (IL-1β and TNF-α) cytokine mRNA levels and hydrogen peroxide concentration in the inflamed colon. Administration of EP pomace polyphenol extract significantly improved macroscopic and microscopic damage scores, as well as myeloperoxidase (MPO) activity in TNBS-treated mice. The anti-inflammatory effect of the extract was observed after intracolonic and oral administration and was dose-dependent. Significant reduction of tissue hydrogen peroxide level after treatment with EP pomace polyphenol extract suggests that its therapeutic effect is a result of free radical scavenging. This novel finding indicates that the application of the EP pomace polyphenol extract in patients with inflammatory bowel diseases (IBDs) may become an attractive supplementary treatment for conventional anti-inflammatory therapy.

Comparison of in vitro anti-lipase and antioxidant activities, and composition of commercial chokeberry juices

Inhibition of digestive lipases refers to the suppression of dietary fat absorption and, to some extent, to a strategy against overweight and obesity. In this study, the effect of five commercial black chokeberry juices on pancreatic lipase as a key enzyme relevant to obesity was investigated using as substrates triolein, sunflower oil, and rapeseed oil emulsions as well as 4-methylumbelliferyl oleate. The juices were also analyzed for antioxidant capacity (ABTS·+, DPPH·, FRAP methods), qualitative and quantitative composition of phenolic compounds and nutrients. Significant differences were observed among their chemical compositions and biological activities. Chokeberry juices were rich in proanthocyanidins, followed by the hydroxycinnamic acids, anthocyanins, and flavonols. Their inhibitory activity against pancreatic lipase was related to polyphenol content, that of proanthocyanidins. The results reported herein have shown the influence of proanthocyanidin degree of polymerization on the inhibitory activity, especially in lipid emulsions. In conclusion, this work suggests that chokeberry juice may be a potential source of dietary fat absorption inhibitors, especially if it contains high molecular phenolic compounds.

CD39/NTPDase-1 expression and activity in human umbilical vein endothelial cells are differentially regulated by leaf extracts from Rubus caesius and Rubus idaeus.

Many experimental studies have demonstrated the favorable biological activities of plants belonging to the genus Rubus, but little is known of the role of Rubus leaf extracts in the modulation of the surface membrane expression and activity of endothelial apyrase. The aim of this study was to assess the influence of 1–15 μg/ml Rubus extracts on CD39 expression and enzymatic activity, and on the activation (ICAM-1 expression) and viability of human umbilical vein endothelial cells (HUVEC). The polyphenolic contents and antioxidative capacities of extracts from dewberry (R. caesius L.) and raspberry (R. idaeus L.) leaves were also investigated. The techniques applied were flow cytometry (endothelial surface membrane expression of ICAM-1 and CD39), malachite green assay (CD39 activity), HPLC-DAD (quantitative analysis of polyphenolic extract), ABTS, DPPH and FRAP spectrometric assays (antioxidant capacity), and the MTT test (cell viability). Significantly increased CD39 expressions and significantly decreased ATPDase activities were found in the cells treated with 15 μg/ml of either extract compared to the results for the controls. Neither of the extracts affected cell proliferation, but both significantly augmented endothelial cell ICAM-1 expression. The overall antioxidant capacities of the examined extracts remained relatively high and corresponded well to the determined total polyphenol contents. Overall, the results indicate that under in vitro conditions dewberry and raspberry leaf extracts have unfavorable impact on endothelial cells.

Flavanols from Japanese quince (Chaenomeles japonica) fruit suppress expression of cyclooxygenase-2, metalloproteinase-9, and nuclear factor-kappaB in human colon cancer cells

Natural polyphenols and polyphenol-rich extracts have been found to possess preventive and therapeutic potential against several types of cancers, including colorectal cancer (CRC), which is an example of an inflammation-associated cancer. This study examines the chemopreventive effect of a Japanese quince (Chaenomeles japonica) fruit flavanol preparation (JQFFP) on colon cancer SW-480 cells. JQFFP, rich in procyanidin monomers and oligomers, was found to inhibit the SW-480 cell viability by 40% at 150 µM catechin equivalents (CE) after 72 h incubation when compared to control, but it was non-toxic to normal colon fibroblast CCD-18Co cells. Furthermore, 100 µM CE JQFFP suppressed COX-2 mRNA expression to 36.7% of control values and protein expression to 77%. In addition, JQFFP reduced the MMP-9 protein expression (to 24% vs. control at 100 µM CE) and caused inhibition of its enzymatic activity (to 35% vs. control at 100 µM CE). Not only did JQFFP inhibit the COX-2 and MMP-9 levels, but it also reduced the NF-κB protein expression (to 65% of control) and phosphorylation of its p65 subunit (to 51%) at 100 µM CE. These results provide the first evidence that JQFFP inhibits COX-2, MMP-9, and NF-κB expression, suggesting that it has cytotoxic, anti-inflammatory, and anti-metastatic activities towards the colon cancer SW-480 cells.

Influence of Polyphenol Extract from Evening Primrose (Oenothera Paradoxa) Seeds on Proliferation of Caco-2 Cells and on Expression, Synthesis and Activity of Matrix Metalloproteinases and Their Inhibitors

Abstract Evening primrose (Oenothera paradoxa Hudziok) seeds are a rich source of not only a valuable oil containing an essential fatty acid - ᵧ-linolenic acid (GLA) - but also polyphenols which can be obtained from the biomass remaining after oil pressing. The aim of our studies was to evaluate the influence of a polyphenol extract from defatted seeds of evening primrose on human colorectal adenocarcinoma Caco-2 cell proliferation and matrix metalloproteinases (MMPs) synthesis and activity. To assess the effect of evening primrose extract on Caco-2 cell proliferation, crystal violet staining and sulforhodamine B (SRB) assays were used whereas mRNA expression and activity of MMPs were evaluated by RT-PCR and gelatin zymography. The results revealed that the examined polyphenol extract had little influence on Caco-2 proliferation, but effectively in a time- and dose-dependent manner inhibited MMP-1, MMP-7, MMP-9 and MMP-14 mRNA synthesis induced by TNF-α and TPA. Additionally, zymographic analysis revealed that after 24 h, the polyphenol extract at a concentration of 50 μmol/L GAE caused a 10-fold reduction in MMP-9 synthesis. Moreover, this extract might be a potent inhibitor of MMP activity. The results showed that polyphenol extract from evening primrose inhibited PBMC-derived MMP-2 and MMP-9 enzymatic activity in dose-dependent manner. The obtained results indicate that the polyphenol extract from evening primrose seeds could be an inhibitor of proteases involved in tumor progression and metastasis.

Differentiated impact of procyanidins from evening primrose on human breast cancer cells

This study examines some of the biological activities of an evening primrose flavanol preparation (EPFP) against non-invasive human breast cancer cells (MCF-7). The results are compared with those obtained for highly invasive human breast cancer cells (MDAMB-231). The results show, for the first time, that EPFP reduces MCF-7 cell number, IC50 = 75 µM gallic acid equivalents/GAE for 72 h incubation, and reduces migration to 52% of the control value at 100 µM L−1 GAE. EPFP caused favorable changes in Bcl-2/Bax mRNA ratio, which rendered MCF-7 cells more sensitive to apoptosis: the number of apoptotic cells increased 2.2-fold vs. control at 100 µM GAE. Furthermore, 100 µ M L−1 GAE EPFP caused a 1.8-fold reduction in the activity of metalloproteinase-9 (MMP-9) secreted to the culture medium by MCF-7 cells. Moreover, EPFP suppressed the expression of selected genes of matrix metalloproteinases (MMPs), a proliferation marker (Ki67), and vascular endothelial growth factor (VEGF). In conclusion, the results of this study suggest that EPFP may exhibit proapoptotic, antiproliferative, antimigratory, and antimetastatic potential towards both selected human breast cancer cell lines, which is more pronounced in the case of the highly invasive MDA-MB-231 cells.

Is it true that plant-derived polyphenols are always beneficial for the human? In vitro study on Leonurus cardiaca extract properties in the context of the pathogenesis of Staphylococcus aureus infections

The aim of the study was to determine whether Leonurus cardiaca L. herb extract (LCE) used at subinhibitory concentration modifies the characteristics of Staphylococcus aureus, which is important in the pathogenesis of invasive infections originating from the bloodstream, in a way favourable for the human host. Polyphenol-rich LCE, a common ingredient in pharmaceutical products used for various cardiovascular and nervous system disorders, had shown interesting antibacterial and antibiofilm properties in our previous studies. Our current findings indicate that the following S. aureus characteristics decreased, depending on the LCE concentration: (i) formation of aggregates in plasma, (ii) adherence to a fibrin-coated surface, (iii) staphylocoagulase-dependent plasma clotting, (iv) bacterial survival in whole human blood in an ex vivo model, (v) expression of cell surface protein A and (vi) synthesis of α-toxin. However, staphylococcal tolerance to exogenous hydrogen peroxide was enhanced after pre-incubation with LCE, possibly due to the increased activity of bacterial antioxidant enzymes, a possibility confirmed by the higher production of superoxide dismutase and slightly higher production of catalase. The use of LCE at sub-MIC in in vitro and ex vivo models resulted in the weakening of some important staphylococcal immunoprotective attributes but the strengthening of such virulence factors as those responsible for oxidative stress tolerance. Some of these results and the fact that LCE has direct anticoagulant properties, reflected in a reduced thrombin-dependent fibrinogen polymerization rate, suggest a risk of adverse effects, which could be important in the context of S. aureus survival in the host.