Interaction of cyanidin-3-O-glucoside with three proteins

Cyanidin-3-O-glucoside functions like chemical chaperone and attenuates the glycation mediated amyloid formation in albumin

In this study, chemical chaperone like function of cyanidin-3-O-glucoside (C3G) was investigated through fluorescence spectroscopy, UV-visible spectroscopy, circular dichroism spectroscopy, confocal microscopy, scanning electron microscopy and molecular docking studies. Early and advanced glycation inhibitory effect was evaluated by fluorescence spectroscopy and agarose gel electrophoresis. Amyloids were investigated based on their propensity to bind Congo Red (CR) and Thioflavin T (ThT) by multiple microscopic approaches. Circular dichroism studies were used to analyze the changes in the secondary structure due to glycation. C3G effectively inhibited early and advanced glycation by masking like function, carbonyl scavenging and chemical chaperone activity. C3G had molecular interaction with Glu186, Arg427, Ser428, Lys431, Arg435, and Arg458 of BSA. Based on the microscopic analysis, it is evident that C3G can inhibit protein aggregation and amyloid formation. Circular dichroism studies suggested that glycation had resulted in augmented β-sheet propensity, whereas C3G had a protective effect on the helical conformation of BSA. We conclude that C3G has a chemical chaperone like function on the event of glycation mediated amyloid formation in BSA.

Spectrofluorimetric and molecular docking studies on the interaction of cyanidin-3-O-glucoside with whey protein, β-lactoglobulin

The interaction of β-Lactoglobulin (β-Lg) with cyanidin-3-O-glucoside (C3G) was characterized using fluorescence, circular dichroism spectroscopy, and docking studies under physiological conditions. Fluorescence studies showed that β-Lg has a strong binding affinity for C3G via hydrophobic interaction with the binding constant, K_a, of 3.14×10⁴M^-1 at 298K. The secondary structure of β-Lg displayed an increase in the major structure of β-sheet upon binding with C3G, whereas a decrease in the minor structure of α-helix was also observed. In addition, evidenced by near UV-CD, the interaction also disrupted the environments of Trp residues. The molecular docking results illustrated that both hydrogen bonding and the hydrophobic interaction are involved as an acting force during the binding process. These results may contribute to a better understanding over the enhanced physicochemical proprieties of anthocyanins due to the complexation with milk proteins.

Cancer chemoprevention through dietary flavonoids: what's limiting?

Flavonoids are polyphenols that are found in numerous edible plant species. Data obtained from preclinical and clinical studies suggest that specific flavonoids are chemo-preventive and cytotoxic against various cancers via a multitude of mechanisms. However, the clinical use of flavonoids is limited due to challenges associated with their effective use, including (1) the isolation and purification of flavonoids from their natural resources; (2) demonstration of the effects of flavonoids in reducing the risk of certain cancer, in tandem with the cost and time needed for epidemiological studies, and (3) numerous pharmacokinetic challenges (e.g., bioavailability, drug–drug interactions, and metabolic instability). Currently, numerous approaches are being used to surmount some of these challenges, thereby increasing the likelihood of flavonoids being used as chemo-preventive drugs in the clinic. In this review, we summarize the most important challenges and efforts that are being made to surmount these challenges.

The study on interactions between levofloxacin and model proteins by using multi-spectroscopic and molecular docking methods

The interactions of levofloxacin (LEV) with lysozyme (LYZ), trypsin and bovine hemoglobin (BHb) were investigated, respectively, by using multi-spectral techniques and molecular docking in vitro. Fluorescence studies showed that LEV quenched LYZ/trypsin fluorescence in a combined quenching ways and BHb fluorescence in a static quenching with binding constants of .14, .51 and .20 × 10⁵ L mol^-1 at 298 K, respectively. The thermodynamic parameters demonstrated that hydrophobic forces, hydrogen bonds, and van der Waals forces played the major role in the binding process. The binding distances between LEV and the inner tryptophan residues of LYZ, trypsin, and BHb were calculated to be 4.04, 3.38, and 4.52 nm, respectively. Furthermore, the results of circular dichroism spectra (CD), UV-vis, and three-dimensional fluorescence spectra indicated that the secondary structures of LYZ, trypsin, and BHb were partially changed by LEV with the α-helix percentage of LYZ-LEV system increased while that of BHb-LEV system was decreased, the β-sheet percentage of trypsin-LEV system increased from 41.3 to 42.9%. UV-vis spectral results showed that the binding interactions could cause conformational and some micro-environmental changes of LYZ, trypsin, and BHb. The results of molecular docking revealed that in LYZ and trypsin systems, LEV bound to the active sites residues GLU 35 and ASP 52 of LYZ and trypsin at the active site SER 195, and in BHb system, LEV was located in the central cavity, which was consistent with the results of synchronous fluorescence experiment. Besides, LEV made the activity of LYZ decrease while the activity of trypsin increased.

Controlled protein adsorption and delivery of thermosensitive poly(N-isopropylacrylamide) nanogels

Controlled protein adsorption and delivery of thermosensitive poly(N-isopropylacrylamide) nanogels by tailoring the temperature and pH value of the medium.

Interaction between Mimic Lipid Membranes and Acylated and Nonacylated Cyanidin and Its Bioactivity

We investigated the effects of acylated cyanidin-3-O-β-(6″-O-E-p-coumaroyl-sambubioside)-5-O-β-glucoside (C3-cs-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.

Cyanidin-3-O-glucoside: Physical-Chemistry, Foodomics and Health Effects

Anthocyanins (ACNs) are plant secondary metabolites from the flavonoid family. Red to blue fruits are major dietary sources of ACNs (up to 1 g/100 g FW), being cyanidin-3-O-glucoside (Cy3G) one of the most widely distributed. Cy3G confers a red hue to fruits, but its content in raspberries and strawberries is low. It has a good radical scavenging capacity (RSC) against superoxide but not hydroxyl radicals, and its oxidative potential is pH-dependent (58 mV/pH unit). After intake, Cy3G can be metabolized (phases I, II) by oral epithelial cells, absorbed by the gastric epithelium (1%-10%) and it is gut-transformed (phase II &amp; microbial metabolism), reaching the bloodstream (<1%) and urine (about 0.02%) in low amounts. In humans and Caco-2 cells, Cy3G's major metabolites are protocatechuic acid and phloroglucinaldehyde which are also subjected to entero-hepatic recycling, although caffeic acid and peonidin-3-glucoside seem to be strictly produced in the large bowel and renal tissues. Solid evidence supports Cy3G's bioactivity as DNA-RSC, gastro protective, anti-inflammatory, anti-thrombotic chemo-preventive and as an epigenetic factor, exerting protection against Helicobacter pylori infection, age-related diseases, type 2 diabetes, cardiovascular disease, metabolic syndrome and oral cancer. Most relevant mechanisms include RSC, epigenetic action, competitive protein-binding and enzyme inhibition. These and other novel aspects on Cy3G's physical-chemistry, foodomics, and health effects are discussed.

Physico-Chemical Characterization, Bioactive Compounds and Antioxidant Activity of Malay Apple [Syzygium malaccense (L.) Merr. & L.M. Perry]

The purpose of this study was to evaluate the physico-chemical characteristics, bioactive compounds and antioxidant activity of Malay apple fruit (Syzygium malaccense) grown in Brazil with regard to the geographical origin and its peel fractions and edible portion analyzed independently. Fruit diameter, weight, yield, and centesimal composition, ascorbic acid, reductive sugars, total soluble solids, pH and fiber content were determined. Total phenolics (1293 mg gallic acid equivalent/100 g) and total anthocyanins (1045 mg/100 g) contents were higher in the peel, with the major anthocyanin identified using HPLC-DAD-MS/MS as cyanidin 3-glucoside. Higher values for DPPH antiradical scavenging activity (47.52 μMol trolox equivalent antioxidant capacity/g) and Ferric Reducing Antioxidant Potential (FRAP, 0.19 mM ferreous sulfate/g) were also observed in the peel fraction. All extracts tested showed the ability to inhibit oxidation in the β-carotene/linoleic acid system. This study highlights the potential of Malay apple fruit as a good source of antioxidant compounds with potential benefits to human health.