Molecular docking and molecular dynamic simulation-based phytoconstituents against SARS-CoV-2 with dual inhibition of the primary protease targets

A novel coronavirus has caused major health problems and is spreading globally. The main protease enzyme plays a significant role in the number of copies of ss-RNA produced during the proteolytic cleavage of polypeptides. This work aims to find possible dual inhibitors of the 3-Chymotrypsin-like proteases PDB-6W63 and 6LU7 which increase efficiency and faster inhibition activity. By using an in-silico technique, polyphenols are molecularly docked against these targets to inhibit protease enzymes. Some polyphenols, such as pelargonidin and naringin, have significant dual inhibition characteristics with remarkable binding affinities with active scaffolds of both proteins, which have important ADMET parameters. These organic molecules are strongly bonded with amino acids of protein via mostly hydrogen bonding. These polyphenols also have outstanding docking scores and MMGBSA energies. The validity of the docking score was evaluated using a molecular dynamics simulation that assessed the stability of the complex. With the aid of computer-aided drug design, we hypothesise that the dual inhibition of compounds pelargonidin and naringin could effectively and potentially oppose SARS-CoV-2.

Pelargonidin alleviates acrolein-induced inflammation in human umbilical vein endothelial cells by reducing COX-2 expression through the NF-κB pathway

Acrolein, a common environmental pollutant, is linked to the development of cardiovascular inflammatory diseases. Pelargonidin is a natural compound with anti-inflammation activity. In this study, we aimed to explore the effects of pelargonidin on inflammation induced by acrolein in human umbilical vein endothelial cells (HUVECs). MTT assay was utilized for assessing cell viability in HUVECs. LDH release in HUVECs was measured using the LDH kit. Western blot was used to detect the protein expression of p-p65, p65 and COX-2. Inflammation was evaluated through determining the levels of PGE2, IL-1β, IL-6, IL-8 and TNF-α in HUVECs after treatment. COX-2 mRNA expression and COX-2 content were examined using RT-qPCR and a human COX-2 ELISA kit, respectively. Acrolein treatment at 50 μM resulted in a 45% decrease in the viability and an increase in LDH release (2.2-fold) in HUVECs. Pelargonidin at 5, 10, 20, and 40 μM alleviated acrolein-caused inhibitory effect on cell viability (increased to 1.3-, 1.5-, 1.8-, and 1.9-fold, respectively, compared to acrolein treatment group) and promoting effect on LDH release (decreased to 82%, 75%, 62%, and 58%, respectively, compared to acrolein treatment group) in HUVECs. Moreover, pelargonidin or pyrrolidine dithiocarbamate (PDTC; an NF-κB pathway inhibitor) inhibited acrolein-induced activation of the NF-κB pathway. Acrolein elevated the levels of PGE2, IL-1β, IL-6, IL-8 and TNF-α (from 40.2, 27.3, 67.2, 29.0, 24.8 pg/mL in control group to 224.0, 167.3, 618.3, 104.6, and 275.1 pg/mL in acrolein treatment group, respectively), which were retarded after pelargonidin (decreased to 134.8, 82.3, 246.2, 70.2, and 120.8 pg/mL in acrolein + pelargonidin treatment group) or PDTC (decreased to 107.9, 80.1, 214.6, 64.0, and 96.6 pg/mL in acrolein + PDTC treatment group) treatment in HUVECs. Pelargonidin inactivated the NF-κB pathway to reduce acrolein-induced COX-2 expression. Furthermore, pelargonidin relieved acrolein-triggered inflammation through decreasing COX-2 expression by inactivating the NF-κB pathway in HUVECs. In conclusion, pelargonidin could protect against acrolein-triggered inflammation in HUVECs through attenuating COX-2 expression by inactivating the NF-κB pathway.

Petunia dihydroflavonol 4-reductase is only a few amino acids away from producing orange pelargonidin-based anthocyanins

Anthocyanins are responsible for the color spectrum of both ornamental and natural flowers. However, not all plant species produce all colors. For example, roses are not blue because they do not naturally possess a hydroxylase that opens the pathway for delphinidin and its derivatives. It is more intriguing why some plants do not carry orange or scarlet red flowers with anthocyanins based on pelargonidin, because the precursor for these anthocyanins should be available if anthocyanins are made at all. The key to this is the substrate specificity of dihydroflavonol 4-reductase (DFR), an enzyme located at the branch point between flavonols and anthocyanins. The most common example is petunia, which does not bear orange flowers unless the enzyme is complemented by biotechnology. We changed a few amino acids in the active site of the enzyme and showed that the mutated petunia DFR started to favor dihydrokaempferol, the precursor to orange pelargonidin, in vitro. When transferred to petunia, it produced an orange hue and dramatically more pelargonidin-based anthocyanins in the flowers.

Pelargonidin ameliorates reserpine-induced neuronal mitochondrial dysfunction and apoptotic cascade: a comparative in vivo study

BACKGROUND

Targeting the neuronal mitochondria as a possible intervention to guard against neurodegenerative disorder progression has been investigated in the current work via the administration of pelargonidin (PEL) to rats intoxicated by the mitochondrial toxin reserpine. The main criteria for choosing PEL were its reported antioxidant, anti-apoptotic and anti-inflammatory activities.

METHODS

Male albino Wistar rats were randomized into five experimental groups; normal control, reserpinized to induce mitochondrial failure, standard PARP-1-inhibitor 1,5-isoquinolinediol (DIQ)-treated reserpinized, PEL-treated reserpinized, and GSK-3β inhibitor (AR-A 014418) -treated reserpinized.

RESULTS

PEL administration reversed the reserpine-induced abnormal behaviors marked by decreased catalepsy time. In addition, PEL restored brain glutathione with a reduction in nitric oxide content as compared to the reserpine-challenged group. Meanwhile, it improved neuronal mitochondrial function by the elevation of complex I activity associated with a low ADP/ATP ratio. Likely through its anti-inflammatory effect, PEL reduced the elevation of serum interleukin-1ß level and inhibited serum lactate dehydrogenase activity. These findings are aligned with the reduced expression of cleaved PARP and cleaved caspase-3 proteins, indicating PEL's suppressive effect on the intrinsic apoptotic pathway. Those biochemical findings were confirmed through comparable histopathological tissue examination among the experimental groups.

CONCLUSIONS

In conclusion, PEL is a promising candidate for future use in the management of mitochondria-associated neuronal complications via controlling the ongoing inflammatory and degeneration cascades.

Structural Activity and HAD Inhibition Efficiency of Pelargonidin and Its Glucoside-A Theoretical Approach

Anthocyanins are an important pharmaceutical ingredient possessing diet regulatory, antioxidant, anticancer, antidiabetic, anti-obesity, antimicrobial, and anti-inflammatory properties. Pelargonidin is an important anthocyanin-based orange-red flavonoid compound used in drugs for treating hypoglycemia, retinopathy, skeletal myopathy, etc. The main sources of pelargonidin are strawberries and food products with red pigmentation. There is a lack of evidence for supporting its use as an independent supplement. In the present study, pelargonidin and pelargonidin-3-O-glucoside are studied for their structural properties using quantum chemical calculations based on density functional theory. The results confirmed that the parent compound and its glycosylated derivative acted as good electron donors. Electrostatic potential, frontier molecular orbitals, and molecular descriptor analyses also substantiated their electron donating properties. Furthermore, based on the probability, a target prediction was performed for pelargonidin and pelargonidin-3-O-glucoside. Hydroxyacyl-coenzyme A dehydrogenase was chosen as an enzymatic target of interest, since the presence work focuses on glucuronidated compounds and their efficacy over diabetes. Possible interactions between these compounds and a target with nominable binding energies were also evaluated. Further, the structural stability of these two compounds were also analyzed using a molecular dynamics simulation.

Antioxidant activity of delphinidin and pelargonidin: Theory and practice

The quantum chemical density functional theory and in vitro chemical-based antioxidant assays were used to research the reaction mechanism of delphinidin/pelargonidin with free radicals including superoxide anion radicals (O₂ ^- ∙) and hydroperoxide radicals (OOH∙). The geometric configuration, bond dissociation energy, PCM (polarizable continuum model) solvent model reaction enthalpy changes were studied to explain the transition states, and the reaction enthalpy change value was calculated to determine the active site. From the results of spatial configuration, delphinidin showed a stronger conjugation effect than that of pelargonidin. The dihedral angle between the three rings of delphinidin was almost 180°, and the angle between the B and C rings was only -2.81868°. Both coplanar and antioxidant activity of delphinidin was better than pelargonidin. The consequences of reaction enthalpy change in PCM were consistent with the bond dissociation energy. The phenolic hydroxyl bond dissociation energy of delphinidin was slightly smaller than that of pelargonidin. Moreover, the C4' site of delphinidin and the C3 site of pelargonidin were the active sites for scavenging free radicals. The free radical scavenging ability of delphinidin was marginally higher than that of pelargonidin. On the other hand, in vitro antioxidant results proved the scavenging ability of delphinidin and pelargonidin on superoxide anions, DPPH, and ABTS^∙+ free radicals. It was shown that the chemical-based antioxidant activity was consistent with the theoretical calculation results, with delphinidin showing greater antioxidant activity. These results could explain the antioxidant mechanism of delphinidin/pelargonidin in scavenging free radicals from chemical reactions. PRACTICAL APPLICATIONS: This manuscript explained the antioxidant mechanism of delphinidin/pelargonidin in scavenging free radicals through the analysis of the geometric configuration of delphinidin/pelargonidin and the theoretical calculation of the reaction transition state. It could also speculate on the possible reaction sites, and provide a basis for judging how to efficiently select antioxidants with great antioxidant activity.

Isolation and characterization of the anthocyanins derived from red radishes (Raphanus sativus L.) and the protective ability of β-lactoglobulin against heat-induced oxidation

This study employed the "two-step dialysis" method and AB-8 or D101 macroporous resin chromatography to isolate the anthocyanins in red radishes (ARR). The red radish juice was dialyzed twice at 3000 and 500 Da, respectively. UHPLC-QqQ-MS/MS revealed 24 types of ARRs, of which pelargonidin (Pg)-3-diglucoside-5-(malonyl)glucoside (P3D5MG), Pg-3-diglucoside-5-glucoside (P3D5G), Pg-3-(feruloyl)diglucoside-5-(malonyl)glucoside (P3FD5MG), Pg, and malvidin (Mv) represented the main compounds. The total anthocyanin content in the ARR prepared via the "two-step dialysis" method was 29.69% and 18.44% higher than that obtained using AB-8 and D101 macroporous resins, respectively. The ARRs inhibited heat-induced β-lactoglobulin (β-Lg) oxidation. The amino acid residue microenvironment and secondary β-Lg structure were modified via ARR binding. The energy involved in P3D5MG and β-Lg binding was -392 kJ/mol, which was significantly lower than that during the binding process of P3D5M, P3FD5MG, Pg, and Mv to β-Lg (-338 to -168 kJ/mol). These results indicated that "two-step dialysis" was a promising method for deriving natural pigment with strong antioxidant activity from red radishes. PRACTICAL APPLICATION: As a natural food colorant, anthocyanins have attracted increasing attention in the food industry in recent years. This study used "two-step dialysis" to effectively separate ARRs. Moreover, the anthocyanins in ARR can bind to β-Lg to protect against heating-induced oxidation. Therefore, ARRs may not only act as a food pigment but also as antioxidants.

Pelargonidin and Berry Intake Association with Alzheimer's Disease Neuropathology: A Community-Based Study

BACKGROUND

An anthocyanidin, pelargonidin, primarily found in berries, has antioxidant and anti-inflammatory properties, and is associated with better cognition and reduced Alzheimer's dementia risk.

OBJECTIVE

This study investigated if pelargonidin or berry intake is associated with Alzheimer's disease (AD) neuropathology in human brains.

METHODS

The study was conducted among 575 deceased participants (age at death = 91.3±6.1 years; 70% females) of the Rush Memory and Aging Project, with dietary data (assessed using a food frequency questionnaire) and neuropathological evaluations. Calorie-adjusted pelargonidin intake was modeled in quartiles and berry intake as continuous (servings/week). Mean amyloid-beta load and phosphorylated tau neuronal neurofibrillary tangle density across multiple cortical regions were assessed using immunohistochemistry. Global AD pathology burden, a quantitative summary score of neurofibrillary tangles, and diffuse and neuritic plaques using Bielschowsky silver stains in multiple brain regions, was also assessed.

RESULTS

In a linear regression model adjusted for age at death, sex, education, APOE ɛ4 status, vitamin E, and vitamin C, participants in the highest quartile of pelargonidin intake when compared to those in the lowest quartile, had less amyloid-β load (β (SE) = -0.293 (0.14), p = 0.038), and fewer phosphorylated tau tangles (β (SE) = -0.310, p = 0.051). Among APOE ɛ4 non-carriers, higher strawberry (β (SE) = -0.227 (0.11), p = 0.037) and pelargonidin (Q4 versus Q1: β (SE) = -0.401 (0.16), p = 0.011; p trend = 0.010) intake was associated with less phosphorylated tau tangles, no association was observed in APOE ɛ4 carriers. Berry intake was not associated with AD pathology. However, excluding participants with dementia or mild cognitive impairment at baseline, strawberry (p = 0.004) and pelargonidin (ptrend = 0.007) intake were associated with fewer phosphorylated tau tangles.

CONCLUSION

Higher intake of pelargonidin, a bioactive present in strawberries, is associated with less AD neuropathology, primarily phosphorylated tau tangles.

Changes at a Critical Branchpoint in the Anthocyanin Biosynthetic Pathway Underlie the Blue to Orange Flower Color Transition in Lysimachia arvensis

Anthocyanins are the primary pigments contributing to the variety of flower colors among angiosperms and are considered essential for survival and reproduction. Anthocyanins are members of the flavonoids, a broader class of secondary metabolites, of which there are numerous structural genes and regulators thereof. In western European populations of Lysimachia arvensis, there are blue- and orange-petaled individuals. The proportion of blue-flowered plants increases with temperature and daylength yet decreases with precipitation. Here, we performed a transcriptome analysis to characterize the coding sequences of a large group of flavonoid biosynthetic genes, examine their expression and compare our results to flavonoid biochemical analysis for blue and orange petals. Among a set of 140 structural and regulatory genes broadly representing the flavonoid biosynthetic pathway, we found 39 genes with significant differential expression including some that have previously been reported to be involved in similar flower color transitions. In particular, F3'5'H and DFR, two genes at a critical branchpoint in the ABP for determining flower color, showed differential expression. The expression results were complemented by careful examination of the SNPs that differentiate the two color types for these two critical genes. The decreased expression of F3'5'H in orange petals and differential expression of two distinct copies of DFR, which also exhibit amino acid changes in the color-determining substrate specificity region, strongly correlate with the blue to orange transition. Our biochemical analysis was consistent with the transcriptome data indicating that the shift from blue to orange petals is caused by a change from primarily malvidin to largely pelargonidin forms of anthocyanins. Overall, we have identified several flavonoid biosynthetic pathway loci likely involved in the shift in flower color in L. arvensis and even more loci that may represent the complex network of genetic and physiological consequences of this flower color polymorphism.

Pelargonidin ameliorates MCAO-induced cerebral ischemia/reperfusion injury in rats by the action on the Nrf2/HO-1 pathway

BACKGROUND

Morbidity and mortality remain high for ischemic stroke victims, and at present these patients lack effective neuroprotective agents, which improve the cure rate. In recent years, studies have shown that pelargonidin has many biological actions. However, few studies are available regarding the pelargonidin treatment of cerebral ischemia.

METHODS

The rat middle cerebral artery occlusion (MCAO) model was established to investigate the neuroprotective effect of pelargonidin on cerebral ischemia/reperfusion injury. Reperfusion was performed 2 h after ischemia; magnetic resonance imaging (MRI) and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining were used to measure the volume of cerebral ischemia. Both modified neurological severity scores (mNSSs) and Morris water maze test were used to assess the neurological functions. ELISA was applied to determine the levels of TNF-α, TGF-β, IL-6, IL-10, MDA, and SOD. The expression of Nuclear factor-E2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) protein in brain tissue was measured by immunofluorescence and Western blot assays.

RESULTS

The results showed that pelargonidin could effectively reduce the volume of cerebral ischemia and improve the neurological function in MCAO rats, thereby improving memory and learning ability. With the corresponding decreases in the expression of TNF-α, TGF-β, IL-6, and MDA, the level of IL-10 and SOD increased and also promoted the nuclear metastasis of Nrf2 and the expression of HO-1 in ischemic brain tissues.

CONCLUSIONS

Our data demonstrated that pelargonidin ameliorated neurological function deficits in MCAO rats, and its potential mechanism of action was associated with overexpression of the Nrf2/HO-1-signaling pathway. This study will provide a new approach to treat cerebral ischemia/reperfusion injury.

Association of Strawberries and Anthocyanidin Intake with Alzheimer's Dementia Risk

Background: Strawberries have been identified to have antioxidant and anti-inflammatory properties that improve neuronal function and cognition, mostly in animal studies. It is unknown if the consumption of strawberries or related bioactives may reduce the risk of Alzheimer’s dementia risk. Material and Methods: The study was conducted in 925 participants, aged 58–98 years of the Rush Memory and Aging Project. Participants were dementia-free at baseline, completed a food frequency questionnaire, and had at least two annual neurological evaluations. The diagnosis of Alzheimer’s dementia was based on structured clinical neurological examination and standardized diagnostic criteria. The association of strawberry intake and incident Alzheimer’s dementia was analyzed using proportional hazard models adjusted for age, sex, education, physical activity, participation in cognitive activities, APOE-ɛ4 genotype, dietary intake of other fruits, and total calorie intake. Results: A total of 245 participants developed Alzheimer’s dementia over the mean follow-up of 6.7 (±3.6) years. Higher strawberry intake was associated with reduced risk of Alzheimer’s dementia (HR = 0.76, 95% CI: 0.60–0.96). In separate adjusted models, highest vs. lowest quartile intakes of Vitamin C (HR = 0.64, 95% CI: 0.45, 0.92), Pelargonidin (0.63, 95% CI: 0.43, 0.92), total anthocyanidins (0.69, 95% CI: 0.48, 0.99), and total flavonoids (0.67, 95% CI: 0.46, 0.98) were each associated with lower Alzheimer’s dementia risk. These associations remained after further adjustment for cardiovascular conditions. Conclusion: Consumption of strawberries and foods rich in vitamin C, pelargonidin, anthocyanidins, and total flavonoids may reduce the risk of Alzheimer’s dementia.

Anthocyanins-Nature's Bold, Beautiful, and Health-Promoting Colors

Anthocyanins are among the most interesting and vigorously studied plant compounds, representing a large class of over 700 polyphenolic pigments within the flavonoid family that exist ubiquitously in the human diet. They are "nature's colors," responsible for providing the beautiful red-orange to blue-violet hues present in many leaves, flowers, vegetables, and fruits, especially berries. The beginning of the 21st century has witnessed a renaissance in research activities on anthocyanins in several areas, mainly related to their potential health-promoting properties and their increased use as alternatives to synthetic food colors. There is increasingly convincing scientific evidence that supports both a preventative and therapeutic role of anthocyanins towards certain chronic disease states. Many anthocyanin-based extracts and juice concentrates from crop and/or food processing waste have become commercially available as colorants and/or value-added food ingredients. There is a large and evolving peer-reviewed literature on how anthocyanin chemistry and concentration may affect their coloring properties in food. Equally as important is the food matrix, which can have large impacts on anthocyanin color expression, stability and degradation, particularly regarding the applications of anthocyanins as food colorants and their health-promoting properties. This Special Edition of Foods, titled "Anthocyanins in Foods," presents original research that extends our understanding of these exciting and complex compounds.

Bioactive Phytochemicals and Antioxidant Properties of the Grains and Sprouts of Colored Wheat Genotypes

The grains and sprouts of colored wheat genotypes (having blue, purple and yellow colored grains) contain specific anthocyanidins, such as pelargonidin and cyanidin derivatives, that produce beneficial health effects. The objective of the presented study is to compare the antioxidant capacity and contents of bioactive phytochemicals in grains and sprouts of wheat genotypes that differ in grain color. The methods α, α-diphenyl-β-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging activities, together with spectrophotometrical and high-performance thin-layer chromatography (HPTLC) methods, were used to study the presence of total phenolics, flavonoids, anthocyanins and anthocyanidins (pelargonidin, peonidin, cyanidin, delphinidin) content. It was predicted that the sprouts of all colored wheat genotypes would have significantly higher total flavonoids, total phenolics, anthocyanidin levels and antioxidant activity than the grains. The correlation results between antioxidant activity and contents of bioactive phytochemicals in grains and sprouts of colored wheat genotypes have shown a high correlation for cyanidin and pelargonidin, especially in grains, as well as quercetin in sprouts. It was found that total anthocyanin, quercetin and pelargonidin contents were significantly higher in the sprouts of the purple wheat genotypes than in the blue or yellow wheat genotypes. Delphinidin was detected at a higher level in the grains than in the sprouts of the blue wheat genotypes. Peonidin was present at very low quantities in the grains of all colored wheat genotypes. The sprouts of the purple wheat genotypes, among the colored wheat genotypes, had the highest pelargonidin, cyanidin and quercetin contents and, therefore, can be a promising source for functional food use.

Great Cause-Small Effect: Undeclared Genetically Engineered Orange Petunias Harbor an Inefficient Dihydroflavonol 4-Reductase

A recall campaign for commercial, orange flowering petunia varieties in spring 2017 caused economic losses worldwide. The orange varieties were identified as undeclared genetically engineered (GE)-plants, harboring a maize dihydroflavonol 4-reductase (DFR, A₁), which was used in former scientific transgenic breeding attempts to enable formation of orange pelargonidin derivatives from the precursor dihydrokaempferol (DHK) in petunia. How and when the A₁ cDNA entered the commercial breeding process is unclear. We provide an in-depth analysis of three orange petunia varieties, released by breeders from three countries, with respect to their transgenic construct, transcriptomes, anthocyanin composition, and flavonoid metabolism at the level of selected enzymes and genes. The two possible sources of the A₁ cDNA in the undeclared GE-petunia can be discriminated by PCR. A special version of the A₁ gene, the A₁ type 2 allele, is present, which includes, at the 3'-end, an additional 144 bp segment from the non-viral transposable Cin4-1 sequence, which does not add any functional advantage with respect to DFR activity. This unequivocally points at the first scientific GE-petunia from the 1980s as the A₁ source, which is further underpinned e.g., by the presence of specific restriction sites, parts of the untranslated sequences, and the same arrangement of the building blocks of the transformation plasmid used. Surprisingly, however, the GE-petunia cannot be distinguished from native red and blue varieties by their ability to convert DHK in common in vitro enzyme assays, as DHK is an inadequate substrate for both the petunia and maize DFR. Recombinant maize DFR underpins the low DHK acceptance, and, thus, the strikingly limited suitability of the A₁ protein for a transgenic approach for breeding pelargonidin-based flower color. The effect of single amino acid mutations on the substrate specificity of DFRs is demonstrated. Expression of the A₁ gene is generally lower than the petunia DFR expression despite being under the control of the strong, constitutive p35S promoter. We show that a rare constellation in flavonoid metabolism-absence or strongly reduced activity of both flavonol synthase and B-ring hydroxylating enzymes-allows pelargonidin formation in the presence of DFRs with poor DHK acceptance.

Impact of Anthocyanidins on Mitoxantrone-Induced Cytotoxicity and Genotoxicity: An In Vitro and In Vivo Analysis

Hypothesis Anthocyanins possess well-known biological effects and suppress DNA damage induced by therapeutic topoisomerase poisons. Our study focusses on the modulatory effects of anthocyanidins-malvidin (MAL) and pelargonidin (PEL)-on topoisomerase II poison mitoxantrone (MXT)-induced cytotoxicity and genotoxicity in in vitro and in vivo conditions. Study design HepG2 cells were treated with MXT (1-10 µM), MAL (10-100 µM,) and PEL (5-640 µM) to determine cell viability. Further, experiments on cytotoxicity and apoptosis induction by single agents or combinations were performed. In vitro and in vivo antigenotoxic effect of MAL/PEL against MXT was evaluated in human lymphocytes and mouse bone marrow cells. Methods Cytotoxicity of test agents and apoptosis induction in HepG2 cells was assessed by MTT assay, trypan blue dye exclusion assay and Hoechst 33258 staining. Antigenotoxic effects of MAL/PEL against MXT were assessed in co-treated human lymphocytes and bone marrow from mice that received MXT intraperitoneally 30 minutes post MAL/PEL oral administration Results Dose-dependent cytotoxicity was observed with all 3 test agents in HepG2 cells. Highest test concentration of 100 µM MAL, 640 µM PEL, and 10 µM MXT decreased HepG2 cell viability by 80%, 30%, and 90%, respectively. The combination of 1 µM MXT + 80 µM MAL reduced cell viability better than single agents. MAL/PEL treatment significantly reduced MXT-induced genotoxicity in human lymphocytes and micronuclei formation in mice. Conclusion Combination of MAL/PEL with lower doses of MXT, especially MAL+MXT increases the cytotoxicity in cancer cells. In addition, MXT treatment with MAL/PEL reduced MXT-induced genotoxicity and protected normal cells during chemotherapy.

Transcriptomics and Metabolite Analysis Reveals the Molecular Mechanism of Anthocyanin Biosynthesis Branch Pathway in Different Senecio cruentus Cultivars

The cyanidin (Cy), pelargonidin (Pg), and delphinidin (Dp) pathways are the three major branching anthocyanin biosynthesis pathways that regulate flavonoid metabolic flux and are responsible for red, orange, and blue flower colors, respectively. Different species have evolved to develop multiple regulation mechanisms that form the branched pathways. In the current study, five Senecio cruentus cultivars with different colors were investigated. We found that the white and yellow cultivars do not accumulate anthocyanin and that the blue, pink, and carmine cultivars mainly accumulate Dp, Pg, and Cy in differing densities. Subsequent transcriptome analysis determined that there were 43 unigenes encoding anthocyanin biosynthesis genes in the blue cultivar. We also combined chemical and transcriptomic analyses to investigate the major metabolic pathways that are related to the observed differences in flower pigmentation in the series of S. cruentus. The results showed that mutations of the ScbHLH17 and ScCHI1/2 coding regions abolish anthocyanin formation in the white and the yellow cultivars; the competition of the ScF3'H1, ScF3'5'H, and ScDFR1/2 genes for naringenin determines the differences in branching metabolic flux of the Cy, Dp, and Pg pathways. Our findings provide new insights into the regulation of anthocyanin branching and also supplement gene resources (including ScF3'5 'H, ScF3'H, and ScDFRs) for flower color modification of ornamentals.

The Occurrence of Flavonoids and Related Compounds in Flower Sections of Papaver nudicaule

Flavonoids play an important role in the pigmentation of flowers; in addition, they protect petals and other flower parts from UV irradiation and oxidative stress. Nudicaulins, flavonoid-derived indole alkaloids, along with pelargonidin, kaempferol, and gossypetin glycosides, are responsible for the color of white, red, orange, and yellow petals of different Papaver nudicaule cultivars. The color of the petals is essential to attract pollinators. We investigated the occurrence of flavonoids in basal and apical petal areas, stamens, and capsules of four differently colored P. nudicaule cultivars by means of chromatographic and spectroscopic methods. The results reveal the specific occurrence of gossypetin glycosides in the basal spot of all cultivars and demonstrate that kaempferol glycosides are the major secondary metabolites in the capsules. Unlike previous reports, the yellow-colored stamens of all four P. nudicaule cultivars are shown to contain not nudicaulins but carotenoids. In addition, the presence of nudicaulins, pelargonidin, and kaempferol glycosides in the apical petal area was confirmed. The flavonoids and related compounds in the investigated flower parts and cultivars of P. nudicaule are profiled, and their potential ecological role is discussed.

Binding effect of proline-rich-proteins (PRPs) on in vitro antimicrobial activity of the flavonoids

The interaction of the cyanidin, pelargonidin, catechin, myrecetin and kaempferol with casein and gelatin, as proline rich proteins (PRPs), was studied. The binding constants calculated for both flavonoid-casein and flavonoid-gelatin were fairly large (10 ⁵ –10 ⁷ M ⁻¹ ) indicating strong interaction. Due to higher proline content in gelatin, the binding constants of flavonoid-gelatin (2.5 × 10 ⁵ –6.2 × 10 ⁷ M ⁻¹ ) were found to be higher than flavonoid-casein (1.2 × 10 ⁵ –5.0 × 10 ⁷ M ⁻¹ ). All the flavonoids showed significant antibacterial activity against the tested strains. Significant loss in activity was observed due to the complexation with PRPs confirming that binding effectively reduced the concentration of the free flavonoids to be available for antibacterial activity. The decline in activity was corresponding to the values of the binding constants. Though the activities of free catechin and myrecetin were higher compared to pelargonidin, cyanidin and kaempferol yet the decline in activity of catechin and myrecetin due to complexation with casein and gelatin was more pronounced.

Examination of small molecule losses in 5-methylpyranopelargonidin MS/MS CID spectra by DFT calculations

Pyranoanthocyanins are formed during food treatment and maturation (e.g. wine, juices), and they can be considered a natural alternative to artificial food colorants. Tandem mass spectrometry (MS/MS) is perhaps the most important technique in analysis of anthocyanin dyes. Knowledge of fragmentation pattern is a key aspect of their successful structural characterization. Polyphenolic compounds are known to lose small molecules during collision-induced dissociation (CID) in MS/MS experiments. However, the specific positions where such losses occur preferentially are unknown. The aim of this communication is to investigate the energetically most preferred places for H2 O and CO losses during the fragmentation of 5-methylpyranopelargonidin molecule by the means of computational chemistry (employing density functional theory) combined with CID MS/MS experiments and infrared multiphoton dissociation spectroscopy. Mechanisms responsible for the fragmentations were investigated, and optimal geometries and transition states were obtained. Cleavage of water as well as carbon monoxide occurs preferentially from the C-ring of flavonoid skeleton. In the most stable structure of 5-methylpyranopelargonidin, B-ring was found to be tilted with respect to the rest of the molecule. Planarization effort of the parent molecule contributes both to its decarbonylation and dehydration.

Pelargonidin activates the AhR and induces CYP1A1 in primary human hepatocytes and human cancer cell lines HepG2 and LS174T

We examined the effects of anthocyanidins (cyanidin, delphinidin, malvidin, peonidin, petunidin, pelargonidin) on the aryl hydrocarbon receptor (AhR)-CYP1A1 signaling pathway in human hepatocytes, hepatic HepG2 and intestinal LS174T cancer cells. AhR-dependent reporter gene expression in transfected HepG2 cells was increased by pelargonidin in a concentration-dependent manner at 24h. Similarly, pelargonidin induced the expression of CYP1A1 mRNA up to 5-fold in HepG2 and LS174T cells relative to the induction by 5 nM 2,3,7,8-tetrachlorodibenzodioxin (TCDD), the most potent activator of AhR. CYP1A1 and CYP1A2 mRNAs were also increased by pelargonidin in three primary human hepatocytes cultures (approximately 5% of TCDD potency) and the increase in CYP1A1 protein in HepG2 and LS174T cells was comparable to the increase in catalytic activity of CYP1A1 enzyme. Ligand binding analysis demonstrated that pelargonidin was a weak ligand of AhR. Enzyme kinetic analyses using human liver microsomes revealed inhibition of CYP1A1 activity by delphinidin (IC50 78 μM) and pelargonidin (IC50 33 μM). Overall, although most anthocyanidins had no effects on AhR-CYP1A1 signaling, pelargonidin can bind to and activate the AhR and AhR-dependent gene expression, and pelargonidin and delphinidin inhibit the CYP1A1 catalytic activity.