Quantitative studies on structure–ORAC relationships of anthocyanins from eggplant and radish using 3D-QSAR

Recent advances in computational prediction of molecular properties in food chemistry

The combination of food chemistry and computational simulation has brought many impacts to food research, moving from experimental chemistry to computer chemistry. This paper will systematically review in detail the important role played by computational simulations in the development of the molecular structure of food, mainly from the atomic, molecular, and multicomponent dimension. It will also discuss how different computational chemistry models can be constructed and analyzed to obtain reliable conclusions. From the calculation principle to case analysis, this paper focuses on the selection and application of quantum mechanics, molecular mechanics and coarse-grained molecular dynamics in food chemistry research. Finally, experiments and computations of food chemistry are compared and summarized to obtain the best balance between them. The above review and outlook will provide an important reference for the intersection of food chemistry and computational chemistry, and is expected to provide innovative thinking for structural research in food chemistry.

Analytical and Theoretical Studies of Antioxidant Properties of Chosen Anthocyanins; A Structure-Dependent Relationships

The relationship between the structure and the antiradical and antioxidant activities of three anthocyanidins, namely peonidin, petunidin, and delphinidin, and their glucosides was investigated in this study. The ability of anthocyanins to scavenge free radicals was determined using DPPH● assay, whereas the inhibition of peroxidation in liposomes in relation to a model membrane that imitated the composition of a lipid membrane in tumor cells was specified using the fluorimetric method. To explore this issue at the atomistic level, density functional theory studies were applied. It was shown that glycosides performed better than anthocyanidins in protecting membranes against oxidation. The highest redox potential was demonstrated by anthocyanidins with the highest number of hydroxyl groups in the B ring in the order as follows: (Dp > Pt > Pn), and the same relationship was proven for their glucosides. The majority of the compounds studied here proved to be better antioxidants than ascorbic acid. They showed consistent electrodonating properties and though the f-HAT mechanism became more feasible with each consecutive deprotonation. Glycosylation did not have a direct impact on reactivity, apart from peonidin and petunidin in the study of which it was found that this process was responsible for lifting off steric hindrance between B and C rings and rendering certain pathways more feasible. Kinetic and molecular dynamics are essential to properly describe the membrane’s lipid oxidation.

In silico methods and tools for drug discovery

In the past, conventional drug discovery strategies have been successfully employed to develop new drugs, but the process from lead identification to clinical trials takes more than 12 years and costs approximately $1.8 billion USD on average. Recently, in silico approaches have been attracting considerable interest because of their potential to accelerate drug discovery in terms of time, labor, and costs. Many new drug compounds have been successfully developed using computational methods. In this review, we briefly introduce computational drug discovery strategies and outline up-to-date tools to perform the strategies as well as available knowledge bases for those who develop their own computational models. Finally, we introduce successful examples of anti-bacterial, anti-viral, and anti-cancer drug discoveries that were made using computational methods.

Anthocyanin Pigments: Beyond Aesthetics

Anthocyanins are polyphenol compounds that render various hues of pink, red, purple, and blue in flowers, vegetables, and fruits. Anthocyanins also play significant roles in plant propagation, ecophysiology, and plant defense mechanisms. Structurally, anthocyanins are anthocyanidins modified by sugars and acyl acids. Anthocyanin colors are susceptible to pH, light, temperatures, and metal ions. The stability of anthocyanins is controlled by various factors, including inter and intramolecular complexations. Chromatographic and spectrometric methods have been extensively used for the extraction, isolation, and identification of anthocyanins. Anthocyanins play a major role in the pharmaceutical; nutraceutical; and food coloring, flavoring, and preserving industries. Research in these areas has not satisfied the urge for natural and sustainable colors and supplemental products. The lability of anthocyanins under various formulated conditions is the primary reason for this delay. New gene editing technologies to modify anthocyanin structures in vivo and the structural modification of anthocyanin via semi-synthetic methods offer new opportunities in this area. This review focusses on the biogenetics of anthocyanins; their colors, structural modifications, and stability; their various applications in human health and welfare; and advances in the field.

Rational design of small molecule RHOA inhibitors for gastric cancer

Previously, we identified Ras homologous A (RHOA) as a major signaling hub in gastric cancer (GC), the third most common cause of cancer death in the world, prompting us to rationally design an efficacious inhibitor of this oncogenic GTPase. Here, based on that previous work, we extend those computational analyses to further pharmacologically optimize anti-RHOA hydrazide derivatives for greater anti-GC potency. Two of these, JK-136 and JK-139, potently inhibited cell viability and migration/invasion of GC cell lines, and mouse xenografts, diversely expressing RHOA. Moreover, JK-136's binding affinity for RHOA was >140-fold greater than Rhosin, a nonclinical RHOA inhibitor. Network analysis of JK-136/-139 vs. Rhosin treatments indicated downregulation of the sphingosine-1-phosphate, as an emerging cancer metabolic pathway in cell migration and motility. We assert that identifying and targeting oncogenic signaling hubs, such as RHOA, represents an emerging strategy for the design, characterization, and translation of new antineoplastics, against gastric and other cancers.

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.

Interactive effects of gallic/ferulic/caffeic acids and anthocyanins on pigment thermal stabilities

The data presented in this article are related to the research article entitled “The effects of gallic/ferulic/caffeic acids on colour intensification and anthocyanin stability” (Qian et al., 2017) [1]. This paper described preparation and isolation of anthocyanins from purple sweet potatoes (PSP) and the time-course of anthocyanin profiles treated with gallic, ferulic, or caffeic acids at 95 °C. The color appearance of PSPanthocyanins alone, or with gallic, ferulic, or caffeic acids was described after the 15 h of thermal treatment. The high resolution mass spectrographs of PSP anthocyanins were determined using UPLC-ESI-HRMS. The spatial interaction of peonidin 3-O-(2-O-β-D-glucopyranocyl-β-D-glucopyranoide)-5-O-β-D-glucopyranoside and gallic/ferulic/caffeic acids was illustrated by molecular dynamic simulation.

The effects of gallic/ferulic/caffeic acids on colour intensification and anthocyanin stability

The mechanism by which copigments stabilize colour, by protecting anthocyanin chromophores from nucleophilic attack, seems well accepted. This study was to determine effects of gallic/ferulic/caffeic acids on colour intensification and anthocyanin stability. Molecular dynamics simulations were applied to explore molecular interactions. Phenolic acids intensified the colour by 19%∼27%. Colour fading during heating followed first-order reactions with half-lives of 3.66, 9.64, 3.50, and 3.39h, whereas anthocyanin degradation, determined by the pH differential method (or HPLC-PDA), followed second-order reactions with half-lives of 3.29 (3.40), 3.43 (3.39), 2.29 (0.39), and 2.72 (0.32)h alone or with gallic/ferulic/caffeic acids, respectively, suggesting that anthocyanin degradation was faster than the colour fading. The strongest protection of gallic acids might be attributed to the shortest distance (4.37Å) of its aromatic ring to the anthocyanin (AC) panel. Hyperchromic effects induced by phenolic acids were pronounced and they obscured the accelerated anthocyanin degradation due to self-association interruption.

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.

Metabolic Profiling and Antioxidant Assay of Metabolites from Three Radish Cultivars (Raphanus sativus)

A total of 13 anthocyanins and 33 metabolites; including organic acids, phenolic acids, amino acids, organic compounds, sugar acids, sugar alcohols, and sugars, were profiled in three radish cultivars by using high-performance liquid chromatography (HPLC) and gas chromatography time-of-flight mass spectrometry (GC-TOFMS)-based metabolite profiling. Total phenolics and flavonoids and their in vitro antioxidant activities were assessed. Pelargonidins were found to be the major anthocyanin in the cultivars studied. The cultivar Man Tang Hong showed the highest level of anthocyanins (1.89 ± 0.07 mg/g), phenolics (0.0664 ± 0.0033 mg/g) and flavonoids (0.0096 ± 0.0004 mg/g). Here; the variation of secondary metabolites in the radishes is described, as well as their association with primary metabolites. The low-molecular-weight hydrophilic metabolite profiles were subjected to principal component analysis (PCA), hierarchical clustering analysis (HCA), Pearson’s correlation analysis. PCA fully distinguished the three radish cultivars tested. The polar metabolites were strongly correlated between metabolites that participate in the TCA cycle. The chemometrics results revealed that TCA cycle intermediates and free phenolic acids as well as anthocyanins were higher in the cultivar Man Tang Hong than in the others. Furthermore; superoxide radical scavenging activities and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging were investigated to elucidate the antioxidant activity of secondary metabolites in the cultivars. Man Tang Hong showed the highest superoxide radical scavenging activity (68.87%) at 1000 μg/mL, and DPPH activity (20.78%), followed by Seo Ho and then Hong Feng No. 1. The results demonstrate that GC-TOFMS-based metabolite profiling, integrated with chemometrics, is an applicable method for distinguishing phenotypic variation and determining biochemical reactions connecting primary and secondary metabolism. Therefore; this study might provide information on the relationship between primary and secondary metabolites and a synergistic antioxidant ability derived from the secondary metabolites in the radish cultivars.

Conventional, ultrasound-assisted, and accelerated-solvent extractions of anthocyanins from purple sweet potatoes

Purple sweet potatoes (PSPs) are rich in anthocyanins. In this study, we investigated the extraction efficiency of anthocyanins from PSPs using conventional extraction (CE), ultrasound-assisted extraction (UAE), and accelerated-solvent extraction (ASE). Additionally, the effects of these extraction methods on antioxidant activity and anthocyanin composition of PSP extracts were evaluated. In order of decreasing extraction efficiency, the extraction methods were ASE>UAE>CE for anthocyanins (218-244 mg/100 g DW) and CE>UAE>ASE for total phenolics (631-955 mg/100 g DW) and flavonoids (28-40 mg/100 g DW). Antioxidant activities of PSP extracts were CE≈UAE>ASE for ORAC (766-1091 mg TE/100 g DW) and ASE>CE≈UAE for FRAP (1299-1705 mg TE/100 g DW). Twelve anthocyanins were identified. ASE extracts contained more diacyl anthocyanins and less nonacyl and monoacyl anthocyanins than CE and ASE extracts (P<0.05).

Antiradical and reductant activities of anthocyanidins and anthocyanins, structure-activity relationship and synthesis

Eight anthocyanidins, seven anthocyanins and two synthesized 4'-hydroxy flavyliums were examined as hydrogen donors to DPPH, ABTS and hydroxyl radicals, and as electron donors in the FRAP assay. Most compounds gave better activities than trolox and catechol. A structure-activity relationship (SAR) study showed that, in the absence of the 3-OH group, radicals of the 4, 5 or 7-OH groups can only be stabilized by resonance through pyrylium oxygen, while 3-OH group improved hydrogen atom donation because of the stabilization by anthocyanidin semiquinone-like resonance. Electron donation was also enhanced by the 3-OH group. Both anthocyanidins and their respective anthocyanins showed similar trends and close activities. Different types of sugar unit bonded to the 3-OH group or counter ion had minor effect on activities. The catechol structure improved both hydrogen and electron donation. Compounds lacking the catechol structure had a decreasing order of H-atom and electron donation (Mv>Pn>Pg>Ap>4'-OH-flavylium) consistent with the decreasing number of their hydroxyl and/or methoxy groups.

The update of anthocyanins on obesity and type 2 diabetes: experimental evidence and clinical perspectives

With the dramatically increasing prevalence of obesity and type 2 diabetes mellitus (T2DM) worldwide, there is an urgent need for new strategies to combat the growing epidemic of these metabolic diseases. Diet is an essential factor affecting the development of and risk for obesity and T2DM and it can either help or hurt. In searching for preventative and therapeutic strategies, it is therefore advantageous to consider the potential of certain foods and their bioactive compounds to reverse or prevent the pathogenic processes associated with metabolic disease. Anthocyanins are naturally occurring polyphenolic compounds abundant in dark-colored fruits, vegetables and grains. Epidemiological studies suggest that increased consumption of anthocyanins lowers the risk of T2DM. Many in vitro and in vivo studies also reveal an array of mechanisms through which anthocyanins could prevent or reverse obesity- and T2DM-related pathologies including promotion of antioxidant and anti-inflammatory activities, improvement of insulin resistance, and hypolipidemic and hypoglycemic actions. Here, we summarize the data on anthocyanin-mediated protection against obesity and T2DM and the underlying mechanisms. Further population-based and long-term human intervention studies are necessary to ultimately evaluate the use of anthocyanins for protection/prevention against the development of obesity and T2DM.

Effect of glycosylation patterns of Chinese eggplant anthocyanins and other derivatives on antioxidant effectiveness in human colon cell lines

In this study, we compared the scavenging ROS of anthocyanins from Chinese eggplant var. Niu Jiao Qie and other delphinidin derivatives with different glycosylation patterns in HT-29 and HCT-116 cell lines. The eggplant anthocyanins were isolated and identified using LC-MSn and (1)H/(13)C NMR as delphinidin-3-[(4"-trans-p-coumaroyl)-rhamnosyl (1 → 6)glucoside]-5-glucoside, also known as nasunin. Delphinidin derivatives with glycosylation only on C3 (delphinidin-3-glucoside, 3-sambubioside, or 3-rutinoside) exhibited greater effects on ROS reduction as compared to delphinidin derivatives that have glycosylation on C3 and C5 (delphinidin-3,5-diglucoside>delphinidin-3-rutinoside-5-glucoside). Nasunin has glycosylation on C3 and C5 and an acyl group (p-coumaric acid), demonstrated the least effect on ROS reduction. Meanwhile, their ROS reduction activities were consistent with glutathione reductase protein expression levels in HT-29. Although not potent in ROS reduction, nasunin and its deacylated derivatives protected cells from DNA damage in a dose-dependent manner. Taken together, our results suggest that the anthocyanins isolated from Chinese eggplant var. Niu Jiao Qie and other delphinidin have antioxidant activities in colon cancer cells and also protect cells from DNA damage.