Development of White Cabbage, Coffee, and Red Onion Extracts as Natural Phosphodiesterase-4B (PDE4B) Inhibitors for Cognitive Dysfunction: In Vitro and In Silico Studies

Human cognition fundamentally depends on memory. Alzheimer's disease exhibits a strong correlation with a decline in this factor. Phosphodiesterase-4 B (PDE4B) plays a crucial role in neurodegenerative disorders, and its inhibition is one of the promising approaches for memory enhancement. This study aimed to identify secondary metabolites in white cabbage, coffee, and red onion extracts and identify their molecular interaction with PDE4B by in silico and in vitro experiments. Crushed white cabbage and red onion were macerated separately with ethanol to yield respective extracts, and ground coffee was boiled with water to produce aqueous extract. Thin layer chromatography (TLC)-densitometry was used to examine the phytochemicals present in white cabbage, coffee, and red onion extracts. Molecular docking studies were performed to know the interaction of test compounds with PDE4B. TLC-densitometry analysis showed that chlorogenic acid and quercetin were detected as major compounds in coffee and red onion extracts, respectively. In silico studies revealed that alpha-tocopherol (binding free energy (∆Gbind) = -38.00 kcal/mol) has the strongest interaction with PDE4B whereas chlorogenic acid (∆Gbind = -21.50 kcal/mol) and quercetin (∆Gbind = -17.25 kcal/mol) exhibited moderate interaction. In vitro assay showed that the combination extracts (cabbage, coffee, and red onion) had a stronger activity (half-maximal inhibitory concentration (IC50) = 0.12 ± 0.03 µM) than combination standards (sinigrin, chlorogenic acid, and quercetin) (IC50 = 0.17 ± 0.03 µM) and rolipram (IC50 = 0.15 ± 0.008 µM). Thus, the combination extracts are a promising cognitive enhancer by blocking PDE4B activity.

In Vitro Anti-Diabetic, Anti-Inflammatory, Antioxidant Activities and Toxicological Study of Optimized Psychotria malayana Jack Leaves Extract

Psychotria malayana Jack (Family: Rubiaceae, local name: Salung) is a traditional herb used to treat diabetes. A previous study by our research group demonstrated that P. malayana methanolic and water extract exhibits significant potential as an effective agent for managing diabetes. Further research has been performed on the extraction optimization of this plant to enhance its inhibitory activity against α-glucosidase, a key enzyme associated with diabetes, and to reduce its toxicity. The objectives of this study are to evaluate the anti-diabetic, anti-inflammatory, and antioxidant properties of the optimized P. malayana leaf extract (OE), to evaluate its toxicity using a zebrafish embryo/larvae model, and to analyze its metabolites. The anti-diabetic effects were assessed by investigating α-glucosidase inhibition (AGI), while the inflammation inhibitory activity was performed using the soybean lipoxygenase inhibitory (SLOXI) test. The assessment of antioxidant activity was performed utilizing FRAP and DPPH assays. The toxicology study was conducted using the zebrafish embryo/larvae (Danio rerio) model. The metabolites present in the extracts were analyzed using GC-MS and LC-MS. OE demonstrated significant AGI and SLOXI activities, represented as 2.02 and 4.92 µg/mL for IC50 values, respectively. It exhibited potent antioxidant activities as determined by IC50 values of 13.08 µg/mL (using the DPPH assay) and 95.44 mmol TE/mg DW (using the FRAP assay), and also demonstrated an LC50 value of 224.29 µg/mL, which surpasses its therapeutic index of 111.03. OE exhibited a higher therapeutic index compared to that of the methanol extract (13.84) stated in the previous state of the art. This suggests that OE exhibits a lower level of toxicity, making it safer for use, and has the potential to be highly effective in its anti-diabetic activity. Liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) demonstrated the presence of several constituents in this extract. Among them, several compounds, such as propanoic acid, succinic acid, D-tagatose, myo-inositol, isorhamnetin, moracin M-3'-O-β-D-glucopyranoside, procyanidin B3, and leucopelargonidin, have been reported as possessing anti-diabetic and antioxidant activities. This finding offers great potential for future research in diabetes treatment.

Microwave-Induced CuO Nanorods: A Comparative Approach between Curcumin, Quercetin, and Rutin to Study Their Antioxidant, Antimicrobial, and Anticancer Effects against Normal Skin Cells and Human Breast Cancer Cell Lines MCF-7 and T-47D

Herein, we explore the biological properties of curcumin, quercetin, and rutin by loading them onto porous CuO nanorods (NRs). The CuO NRs were synthesized using the microwave irradiation method through a chemical reaction between CuSO₄·5H₂O and NaOH in the presence of the anionic stabilizer sodium dodecyl sulfate. The shape and surface morphology of CuO NRs were examined with two microscopic techniques: high-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FESEM). Their average diameter was measured by TEM to be 15 ± 2 nm. The porosity and interfacial area of the fabricated material were determined by Brunauer-Emmett-Teller analysis. After successful synthesis, CuO NRs were loaded with polyphenolic curcumin, quercetin, and rutin, with the loading efficiency of 57.8, 62.2, and 81.2%, respectively, which was confirmed by UV-visible and infra-red spectroscopy and finally with a thermal gravimetric technique. Their radical scavenging activity was measured with the 2,2-diphenyl-1-picrylhydrazyl radical and compared with the control (ascorbic acid). Further, good bactericidal effects were observed against both Gram-positive bacterial strains, including Staphylococcus aureus and Bacillus subtilis, and Gram-negative bacterial strains, including Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae. Excellent anticancer activity was observed against normal skin cells and breast cancer cells T-47D and MCF-7.

Crosstalk between xanthine oxidase (XO) inhibiting and cancer chemotherapeutic properties of comestible flavonoids- a comprehensive update

Gout is an inflammatory disease caused by metabolic disorder or genetic inheritance. People throughout the world are strongly dependent on ethnomedicine for the treatment of gout and some receive satisfactory curative treatment. The natural remedies as well as established drugs derived from natural sources or synthetically made exert their action by mechanisms that are closely associated with anticancer treatment mechanisms regarding inhibition of xanthine oxidase, feedback inhibition of de novo purine synthesis, depolymerization and disappearance of microtubule, inhibition of NF-ĸB activation, induction of TRAIL, promotion of apoptosis, and caspase activation and proteasome inhibition. Some anti-gout and anticancer novel compounds interact with same receptors for their action, e.g., colchicine and colchicine analogues. Dietary flavonoids, i.e., chrysin, kaempferol, quercetin, fisetin, pelargonidin, apigenin, luteolin, myricetin, isorhamnetin, phloretinetc etc. have comparable IC₅₀ values with established anti-gout drug and effective against both cancer and gout. Moreover, a noticeable number of newer anticancer compounds have already been isolated from plants that have been using by local traditional healers and herbal practitioners to treat gout. Therefore, the anti-gout plants might have greater potentiality to become selective candidates for screening of newer anticancer leads.

Enhancement of Antioxidant Activities in Black Soy Milk through Isoflavone Aglycone Production during Indigenous Lactic Acid Bacteria Fermentation

Black soybeans contain high antioxidant compounds such as isoflavone but mainly in glucoside form, with low antioxidant activities. Fermentation by lactic acid bacteria (LAB) can enhance the antioxidant properties, but its ability is strain-dependent. This study aims to study the ability of Indonesian indigenous LAB, Lactiplantibacillus plantarum WGK 4, Streptococcus thermophilus Dad 11, and Lactiplantibacillus plantarum Dad 13, to enhance the antioxidant properties during black soy milk fermentation. Fermentation was carried out at 37 °C for 24 h. Viable cell, acid production, Folin–Ciocalteu assay, antioxidant activity (DPPH), isoflavone aglycone daidzein and genistein, and β-glucosidase activity were measured every six hours. All LAB strains could grow well during the fermentation of black soy milk. Lactiplantibacillus plantarum WGK 4 produced the highest acid (1.50%). All three LAB strains could enhance antioxidant activity (DPPH) from 24.90% to 31.22–38.20%, followed by increased isoflavone aglycone. All strains could increase daidzein and genistein content, ranging from 61% to 107% and 81% to 132%, respectively. All three Indonesian indigenous LAB enhanced antioxidant properties of black soy milk relatively at the same level and potentially could be used as a starter culture of black soy milk fermentation.

Chromatographic Profile and Redox-Modulating Capacity of Methanol Extract from Seeds of Ginkgo biloba L. Originating from Plovdiv Region in Bulgaria

Oxidative stress underlies the pathogenesis of many diseases, which determines the interest in natural substances with antioxidant properties. Ginkgo biloba L. leaves are well known and widely used in the pharmaceutical industry, but the therapeutic properties of the seeds are less studied. This study aimed to identify the chromatographic profile and to evaluate the antioxidant properties of methanol extract from seeds of G. biloba (GBSE). In the GBSE, flavonoids and terpenes were found as terpenes predominated. The GBSE antioxidant capacity determined by 2,2 azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) and 1-diphenyl-2-picrylhydrazyl (DPPH) methods were equal to 1.34% and 0.58% of the activity of reference substance Trolox, respectively. The results of the ferric reducing antioxidant power method showed that the effect of concentration 1 mg/mL (w/v) GBSE was equal to 7.418 mM FeSO₄ used as a standard. The cupric reducing antioxidant capacity activity of the GBSE was found to be 215.39 µmol Trolox/g GBSE and is presented as Trolox equivalent. The metal chelation effect of 1 mg/mL (w/v) GBSE was equal to that obtained for 0.018 mM EDTA. In conclusion, GBSE showed a good ability to neutralize ABTS and DPPH radicals and could have a beneficial effect in pathological conditions with oxidative stress etiology.

Effects of Isorhamnetin on Diabetes and Its Associated Complications: A Review of In Vitro and In Vivo Studies and a Post Hoc Transcriptome Analysis of Involved Molecular Pathways

Diabetes mellitus, especially type 2 (T2DM), is a major public health problem globally. DM is characterized by high levels of glycemia and insulinemia due to impaired insulin secretion and insulin sensitivity of the cells, known as insulin resistance. T2DM causes multiple and severe complications such as nephropathy, neuropathy, and retinopathy causing cell oxidative damages in different internal tissues, particularly the pancreas, heart, adipose tissue, liver, and kidneys. Plant extracts and their bioactive phytochemicals are gaining interest as new therapeutic and preventive alternatives for T2DM and its associated complications. In this regard, isorhamnetin, a plant flavonoid, has long been studied for its potential anti-diabetic effects. This review describes its impact on reducing diabetes-related disorders by decreasing glucose levels, ameliorating the oxidative status, alleviating inflammation, and modulating lipid metabolism and adipocyte differentiation by regulating involved signaling pathways reported in the in vitro and in vivo studies. Additionally, we include a post hoc whole-genome transcriptome analysis of biological activities of isorhamnetin using a stem cell-based tool.

Optimization of Quercetin-Assisted Silver Nanoparticles Synthesis and Evaluation of Their Hemocompatibility, Antioxidant, Anti-Inflammatory, and Antibacterial effects

In the present study, different effective parameters (temperature, reaction time, and pH) on the synthesis of quercetin-assisted silver nanoparticles (QE-AgNPs) are optimized. These biogenic NPs are characterized by different physico-chemical analyses, including transmission electron microscopy, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and UV-visible spectroscopy. In addition, the biological properties of QE-AgNPs are evaluated through antioxidant, antimicrobial, anti-inflammatory, hemolysis, and coagulation time assays. The formation of QE-AgNPs is affected by different parameters. The optimum condition for the synthesis of QE-AgNPs is attained at 70 °C and pH 7. Prepared QE-AgNPs show a spherical shape with a crystalline nature and an average particle size of 20 ± 3.6 nm. The role of QE as a reducing and capping agent in the preparation process of QE-AgNPs is demonstrated using FTIR analysis. These NPs with excellent antioxidant activity (82.3% at a concentration of 400 µg mL-1) and anti-inflammatory properties (82.5% and 100% at concentrations of 37.25 and 500 µg mL-1, respectively), show good antimicrobial effects, particularly against Staphylococcus aureus. Furthermore, the results of the hemolytic and coagulation assay of QE-AgNPs indicate their hemo-compatibility. Therefore, hemo/bio-compatible QE-AgNPs with excellent and unique properties can be employed in different medicinal and pharmacological applications.

Evaluation of Pediococcus pentosaceus strains as probiotic adjunct cultures for soybean milk post-fermentation

Soybean milk is an economical substitute for dairy products. Pediococcus pentosaceus has been used as a food additive to improve taste, nutrition, and food safety. In this study, four P. pentosaceus strains (CICC 24444, QK-1, MQ-1 and RQ-1) isolated from various food sources and known to exhibit broad-spectrum antibacterial activities were used to ferment soybean milk, and their fermentation characteristics and the properties of the resulting beverages were evaluated. The results revealed that the P. pentosaceus strains can inhibited the growth of five types of pathogenic bacteria (Salmonella enterica subsp. enterica serotype Enteritidis, Yersinia enterocolitica, Shigella dysenteriae, Escherichia coli, and Staphylococcus aureus), and their in vitro survival rates in the simulated stomach and intestinal environments were above 90%, satisfying the probiotic requirements. Isomaltose oligosaccharide was used as a protective agent to resist low-temperature freeze-drying damage and ensure a high survival rate, and P. pentosaceus was directly injected into fermented soymilk. The acidification of fermented soybean milk was the weakest with P. pentosaceus QK-1, and the viable bacterial counts of all strains were stable after 28 days of storage. After fermentation, the antioxidant ability was enhanced. Arginine and β-alanine levels increased after fermentation, and the adjunct culture of P. pentosaceus QK-1 increased proline levels. Our data indicate that P. pentosaceus QK-1 is a suitable strain for the development of functional plant-based beverages.

Metabolomic Profiling and Antioxidant Activity of Fruits Representing Diverse Apple and Pear Cultivars

The false fruits of apple (Malus domestica) and pear (Pyrus communis) are consumed all over the world, contributing to the dietary intake of health-promoting antioxidant phytochemicals. For example, polyphenols confer many beneficial effects (according to their chemical structure, bioavailability, and absorption efficiency in the gut) and the consumption of polyphenol-rich apple and pear fruits may therefore reduce the risk of some diseases. However, the content of such molecules is highly dependent on the specific fruit cultivar. To examine this metabolic diversity in detail, we used metabolomic analysis (NMR and HPLC-DAD/MS) to profile the metabolome of six apple and five pear cultivars. We also determined the antioxidant capacity of the extracts (FRAP assay) and correlated this with the metabolomic composition and abundance of specific metabolites. We observed the cultivar-specific accumulation of sugars, amino acids, malic acid, and various polyphenols, which was also related to the growing season for some cultivars. We found that the ancient Italian apple Pom Prussian was enriched for chlorogenic acid as well as more characteristic polyphenols (phloretin derivatives), the pear cultivar Abate Fetel was low in sucrose, and both cultivars displayed high in vitro antioxidant activity. These cultivars may, therefore, be particularly attractive to health-conscious consumers.

Neuroprotective Assessment of Moringa oleifera Leaves Extract against Oxidative-Stress-Induced Cytotoxicity in SHSY5Y Neuroblastoma Cells

The current trend worldwide is searching plant extracts towards prevention of neurodegenerative disorders. This study aimed to investigate the neuroprotective effect of Alpinia galanga leaves (ALE), Alpinia galanga rhizomes (ARE), Vitis vinifera seeds (VSE), Moringa oleifera leaves (MLE), Panax ginseng leaves (PLE) and Panax ginseng rhizomes (PRE) ethanolic extracts on human neuroblastoma (SHSY5Y) cells. The 1-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging of VSE and MLE were 81% and 58%, respectively. Ferric-reducing antioxidant power (FRAP) of ALE and MLE (33.57 ± 0.20 and 26.76 ± 0.30 μmol Fe(ΙΙ)/g dry wt., respectively) were higher than for the other extracts. Liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF/MS) revealed MLE active compounds. Intracellular study by nitro-blue tetrazolium (NBT) test showed that MLE and VSE had high O₂⁻ scavenging (0.83 ± 0.09 vs. 0.98 ± 0.08 mg/mL, respectively). MLE had the highest ROS scavenging followed by PRE (0.71 ± 0.08 vs. 0.83 ± 0.08 mg/mL, respectively), by 2,7-dichlorodihydrofluorescein diacetate (DCFHDA) assay. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity and neuroprotection tests on SHSY5Y showed that PRE had a better neuroprotective effect but higher cytotoxicity compared to MLE (viable cells 51% vs. 44%, IC₅₀ 1.92 ± 0.04 vs. 2.7 ± 0.2 mg/mL, respectively). In conclusion, among the studied plants, MLE has potential for developing as a neuroprotective agent.

Effect of phloretin on growth performance, serum biochemical parameters and antioxidant profile in heat-stressed broilers

The objective of this work was to evaluate the effect of phloretin on growth performance, serum biochemical parameters, antioxidant profile, glutathione (GSH)-related enzymes, nuclear factor erythroid 2-related 2 (Nrf2) and heat shock protein 70 (HSP70) in heat-stressed broilers. A total of 240, 22-day-old Arbor Acres broilers were divided into 4 groups. The control group was housed at 23.0 ± 0.61°C and fed with basal diet, while the 3 heat-stressed groups (A, B, and C groups) were housed at 30.5 ± 0.69°C and fed with basal diet containing 0, 100, and 200 mg/kg phloretin, respectively. Serum was taken form 42-day-old broilers. Results showed that heat stress decreased (P < 0.05) the final body weight (FBW), body weight gain (BWG), feed intake (FI), serum total protein (TP), triglyceride (TG), triiodothyronine (T3), thyroxine (T4), GSH, catalase (CAT), and total antioxidant capacity (T-AOC) levels, but increased (P < 0.05) the feed-to-gain ratio (FGR) and serum malondialdehyde (MDA) levels in broilers compared with that in the control group. Among the heat-stressed groups, supplementary 200 mg/kg phloretin increased (P < 0.05) the FBW, BWG, FI, serum TP, TG, T4, GSH, CAT, and T-AOC levels, and decreased (P < 0.05) the FGR and serum MDA in broilers. There were significant decreases (P < 0.05) in the glutathione peroxidase (GSH-Px), γ-glutamylcysteine synthetase (γ-GCS), and Nrf2, but significant increases (P < 0.05) in the HSP70 of the broiler serum after heat stress treatment. Among the heat-stressed groups, supplementary 200 mg/kg phloretin increased (P < 0.05) the GSH-Px, γ-GCS, and Nrf2 levels, but decreased (P < 0.05) the serum HSP70 level in the heat-stressed broilers. Under high temperature condition, FBW, BWG, FI, FGR, serum TP, TG, T4, MDA, GSH, CAT, T-AOC, GSH-Px, γ-GCS, Nrf2 and HSP70 were linearly affected by inclusion of phloretin. These results indicated that phloretin may improve growth performance, serum parameters, and antioxidant profiles through regulated GSH-related enzymes, Nrf2 and HSP70 in heat-stressed broilers.

Antioxidative Properties and Chemical Changes of Quercetin in Fish Oil: Quercetin Reacts with Free Fatty Acids to Form Its Ester Derivatives

In this research, we studied the antioxidative properties and chemical changes of quercetin in fish oil during accelerated storage at 60 °C for 5 days. Gas chromatography (GC) analysis showed that quercetin inhibited aldehyde formation and unsaturated fatty acid oxidation in fish oil significantly; however, the inhibitory effects decreased gradually with prolonged heating time. Moreover, quercetin was consumed with increasing heating time. Some new phenolic derivatives were discovered in the fish oil with quercetin, with their structures fully elucidated by LC-MS/MS and comparison with newly synthesized ones (characterized by MS and NMR spectroscopy). Based on their chemical structures, we proposed that quercetin reacted with EPA and DHA to form the corresponding quercetin fatty acid esters in fish oil. In addition, the newly formed quercetin-3-O-eicosapentaenoate and quercetin-3-O-docosahexaenoate showed weaker DPPH and ABTS radical cation scavenging activity but much improved lipophilicity, higher cell membrane affinity, and hence enhanced cellular antioxidant activity compared with the parent quercetin. Overall, quercetin could be used as a safe dietary polyphenol to inhibit lipid oxidation. The newly formed quercetin-polyunsaturated fatty acid esters may render improved bioactivity to humans, which needs further investigation.

Hairy Garlic (Allium subhirsutum) from Sicily (Italy): LC-DAD-MSn Analysis of Secondary Metabolites and In Vitro Biological Properties

Allium subhirsutum, known as hairy garlic, is a bulbous plant widespread in the Mediterranean area and locally used as a food and spice. In the present study, the chemical profile of the ethanolic extracts from bulbs (BE) and aerial parts (APE) were analyzed by HPLC-ESI-MSⁿ, and antioxidant properties were evaluated by DPPH, ABTS and TEAC assays. The traditional use in the diet, and the well documented biological activity of Allium species suggest a potential as a new nutraceutical. For this reason, the potential usefulness of this food can be considered in the treatment and prevention of degenerative Alzheimer disease. For this reason, acetylcholinesterase inhibitory property was investigated. Furthermore, due to the observed presence of sulfur-containing and phenolic constituents, the cytotoxicity on tumor cells line was investigated. Results revealed significant AChE inhibitory activity for BE and APE. Both extracts exhibited also moderate antioxidant properties in the in vitro assays. Finally, limited cytotoxic activity was observed towards Human colon carcinoma and adenocarcinoma cell line, with differences between the individual parts tested. HPLC-ESI-MSⁿ analysis showed that hairy garlic is a good source of sulphur compounds, flavonoids and phenylpropanoids derivatives, thus being a valid alternative to the common garlic (A. sativum). This work opens new opportunities for the application of A. subhirsutum as a health-promoting food.

Isorhamnetin: A Nematocidal Flavonoid from Prosopis Laevigata Leaves Against Haemonchus Contortus Eggs and Larvae

Haemonchus contortus affect small ruminants all over the world. Anthelmintics cause resistance, contamination, and a risk of public health. Prosopis laevigata is a plant used as a home remedy against many diseases in Mexico. This study arose from a preliminary study where a P. laevigata hydroalcoholic extract (Pl-hae) showed anthelmintic activity (aa) against H. contortus. Searching for bioactive compounds (bac) with high aa, the Pl-hae was fractioned obtaining an aqueous (Aq-F) and an ethyl acetate fraction (EtAc-F), and a flavonoid with aa identified as isorhamnetin was obtained from EtAc-F. Both fractions were in vitro assessed by the egg hatch test (eht) and larval mortality (lm) assays. The bac obtained from EtAc-F were characterised by NMR analysis. The highest aa were recorded with EtAc-F, resulting in 100% eht and 80.45% lm at 0.75 and 30 mg/mL, respectively. Alterations in eggs and larvae attributed to isorhamnetin were recorded by environmental scanning electron microscopy, confocal laser scanning and by high-resolution digital-coupled camera. This flavonoid caused 100% eht at 0.07 mg/mL after 48 h and 100% lm at 7.5 mg/mL after 72 h exposure. Isorhamnetin has promising potential as an anthelmintic against sheep haemonchosis.

Effects of Lactobacillus plantarum CQPC01-fermented soybean milk on activated carbon-induced constipation through its antioxidant activity in mice

A newly found strain, Lactobacillus plantarum CQPC01 (LP-CQPC01), was used for soybean milk fermentation, and its effects against constipation were determined. LP-CQPC01-FSM (LP-CQPC01-fermented soybean milk) was found to have six kinds of soybean isoflavones; the isoflavones of LP-CQPC01-FSM were more than those of Lactobacillus bulgaricus-fermented soybean milk (LB-FSM) and unfermented soybean milk (U-FSM). Animal experiment showed that the MTL, Gas, ET, AchE, SP, VIP, and GSH levels in the constipated mice were increased; however, the SS, MPO, NO, and MDA levels in the constipated mice were reduced by soybean milk treatment. Further, LP-CQPC01-FSM increased the mRNA and protein expression of Cu/Zn-SOD, Mn-SOD, CAT, c-Kit, SCF, and GDNF and reduced the expression of TRPV1 and NOS relative to those of the mice with untreated constipation. LP-CQPC01 could be used as a new starter to produce high-quality soybean milk, which might be used as a functional drink.

The antityrosinase and antioxidant activities of flavonoids dominated by the number and location of phenolic hydroxyl groups

Background

Compounds with the ability to scavenge reactive oxygen species (ROS) and inhibit tyrosinase may be useful for the treatment and prevention from ROS-related diseases. The number and location of phenolic hydroxyl of the flavonoids will significantly influence the inhibition of tyrosinase activity. Phenolic hydroxyl is indispensable to the antioxidant activity of flavonoids. Isoeugenol, shikonin, baicalein, rosmarinic acid, and dihydromyricetin have respectively one, two, three, four, or five phenolic hydroxyls. The different molecular structures with the similar structure to l-3,4-dihydroxyphenylalanine (l-DOPA) were expected to the different antityrosinase and antioxidant activities.

Methods

This investigation tested the antityrosinase activity, the inhibition constant, and inhibition type of isoeugenol, shikonin, baicalein, rosmarinic acid, and dihydromyricetin. Molecular docking was examined by the Discovery Studio 2.5 (CDOCKER Dock, Dassault Systemes BIOVIA, USA). This experiment also examined the antioxidant effects of the five compounds on supercoiled pBR322 plasmid DNA, lipid peroxidation in rat liver mitochondria in vitro, and DPPH, ABTS, hydroxyl, or superoxide free radical scavenging activity in vitro.

Results

The compounds exhibited good antityrosinase activities. Molecular docking results implied that the compounds could interact with the amino acid residues in the active site center of antityrosinase. These compounds also exhibited antioxidant effects on DPPH, ABTS, hydroxyl, or superoxide free radical scavenging activity in vitro, lipid peroxidation in rat liver mitochondria induced by Fe²⁺/vitamin C system in vitro, and supercoiled pBR322 plasmid DNA. The activity order is isoeugenol < shikonin < baicalein < rosmarinic acid < dihydromyricetin. The results showed the compounds with more phenolic hydroxyls have more antioxidant and antityrosinase activities.

Conclusion

This was the first study of molecular docking for modeling the antityrosinase activity of compounds. This was also the first study of the protective effects of compounds on supercoiled pBR322 plasmid DNA, the lipid peroxidation inhibition activity in liver mitochondria. These results suggest that the compounds exhibited antityrosinase and antioxidant activities may be useful in skin pigmentation and food additives.

Electronic supplementary material

The online version of this article (10.1186/s13020-018-0206-9) contains supplementary material, which is available to authorized users.

Density functional theory study of the role of benzylic hydrogen atoms in the antioxidant properties of lignans

Antioxidants are a diverse group of chemicals with proven health benefits and thus potential preventive medicine and therapeutic applications. While most of these compounds are natural products, determining their mechanism of radical scavenging and common motifs that contribute to antioxidant activity would allow the rational design of novel antioxidants. Here the origins of the antioxidant properties of ten natural products of the lignan family were studied in silico by calculating their thermochemical properties by using ROB3LYP/6-311++G(2df,2p)//B3LYP/6-311G(d,p) model chemistry. Three conditions were modelled: gas phase, ethanol and water solvents. The results allowed assigning the antioxidant activity to specific moieties and structural features of these compounds. It was found that the benzylic hydrogen atoms are the most likely to be abstracted to form radicals and hence define antioxidant properties in most of the studied compounds. The results also suggested that the most likely mechanism of HOO^• radical scavenging differs by the key moiety: it is hydrogen atom transfer in case the benzylic C-H bonds, however it is proton coupled electron transfer in case of the compounds where O-H bonds are responsible for radical scavenging.

A novel electrochemical biosensor for antioxidant evaluation of phloretin based on cell-alginate/ʟ-cysteine/gold nanoparticle-modified glassy carbon electrode

Antioxidant evaluation of bioactive compounds is limited, since many methods lack a real physiological environment that can be used conveniently and intuitively. In this study, a simple, label-free and effective electrochemical biosensor method has been developed to evaluate the antioxidant effect of phloretin (Ph) by 3D cell modification on a glassy carbon electrode (GCE). In response to this, A549 cells were immobilized onto a self-assembled ʟ-cysteine/gold nanoparticle (AuNPs/ʟ-Cys)-modified GCE surface by a simple drop casting after encapsulated in alginate. The electrochemical impedance spectroscopy (EIS) results showed that the impedance value (R_et) increased with the concentration of H₂O₂ in the range of 0-60 μmol/L with the correlation of 0.990 which acted as an oxidative stress model inducer. However, the EIS value decreased with the co-incubation of Ph ranging from 10 to 100 μmol/L, showing a dose-dependent manner and time effect, indicating that the variation of R_et was responded to the antioxidant effect. The response impedance of the biosensor is linear to Ph concentrations from 20 μmol/L to 100 μmol/L with the detection limit (LOD) as 1.96 μmol/L. A significant correlation was observed between reactive oxygen species (ROS) values and R_et values following the concentrations of Ph, thus demonstrating the good biological relevance of cell-based electrochemical method. The strategy has been used to evaluate Ph antioxidant capacity in real cells with satisfactory results, indicating the feasibility of biosensor analysis for antioxidant evaluation.

In Vitro and In Vivo Antioxidant Activities of the Flowers and Leaves from Paeonia rockii and Identification of Their Antioxidant Constituents by UHPLC-ESI-HRMSn via Pre-Column DPPH Reaction

The genus Paeonia, also known as the “King of Flowers” in China, is an important source of traditional Chinese medicine (TCM). Plants of this genus have been used to treat a range of cardiovascular and gynecological diseases. However, the potential pharmacological activity of one particular species, Paeonia rockii, has not been fully investigated. In the first part of the present study, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS), reducing power assays, and metal ion chelating assays were used to investigate the in vitro antioxidant activities of Paeonia rockii. In the second portion of the study, a mouse model of d-galactose-induced aging was used to validate the antioxidant effects of the flowers from Paeonia rockii in vivo. Lastly, potential antioxidant constituents were screened and identified by ultra-high pressure liquid chromatography and electrospray ionization coupled with high-resolution mass spectrometry (UHPLC-ESI-HRMSⁿ) combined with the DPPH assay. Results indicated that the flowers and leaves exhibited stronger antioxidant activity than ascorbic acid in vitro. The therapeutic effect of Paeoniarockii was determined in relation to the levels of biochemical indicators, such as 8-iso-prostaglandin F_2α (8-iso PGF_2α) in the serum, superoxide dismutase (SOD), protein carbonyl, malondialdehyde (MDA), and glutathione (GSH) in the liver and brain, after daily intra-gastric administration of different concentrations of extracts (100, 200 and 400 mg/kg) for three weeks. The levels of 8-iso PGF_2α (p < 0.01) and protein carbonyl groups (p < 0.01) were significantly reduced, whereas those of SOD (p < 0.05) had significantly increased, indicating that components of the flowers of Paeonia rockii had favorable antioxidant activities in vivo. Furthermore, UHPLC-ESI-HRMSⁿ, combined with pre-column DPPH reaction, detected 25 potential antioxidant compounds. Of these, 18 compounds were tentatively identified, including 11 flavonoids, four phenolic acids, two tannins, and one monoterpene glycoside. This study concluded that the leaves and flowers from Paeonia rockii possess excellent antioxidant properties, highlighting their candidacy as “new” antioxidants, which can be utilized therapeutically to protect the body from diseases caused by oxidative stress.

Characterization of Polyphenolic Content in the Aquatic Plants Ruppia cirrhosa and Ruppia maritima -A Source of Nutritional Natural Products

Herein, the polyphenolic content in extracts of Ruppia cirrhosa (Petagna) Grande and Ruppia maritima L.was fully characterized for the first time. High amounts of the main compound chicoric acid (CA) (≤30.2 ± 4.3 mg/g) were found in both Ruppia species. In addition, eight flavonoids, namely the 3-O-glucopyranosides and 3-O-galactopyranosides, as well as malonylated 3-O-glycosides of quercetin and isorhamnetin, were isolated and identified. The antioxidant activity of Ruppia cirrhosa extracts and isolated compounds was investigated spectrophotometrically by a 1,1-diphenyl-2-picrylhydrazyl (DPPH·) radical scavenging assay. IC50 values were 31.8-175.7 μg/mL for Ruppia cirrhosa extracts and 12.1-88.4 μg/mL for isolated flavonoids. Both individual and total phenolic and flavonoid content were quantified in crude extracts using analytical HPLC. The relative high amount of total flavonoids ranged from 5.9 to 14.7 mg/g in both species, with concentrations of individual flavonoids ranging from 0.4 to 2.9 mg/g dry weight. The content of chicoric acid was twofold more in Ruppia maritima than in Ruppia cirrhosa. Seasonal variation of the quantitative content in Ruppia cirrhosa was examined. Total flavonoid content ranged from 8.4 mg/g in October to 14.7 mg/g in August, whereas the highest concentration of chicoric acid was observed in March (29.2 mg/g).

Spectroscopic studies on the antioxidant activity of ellagic acid

Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTS+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

Effect of methyl jasmonate, sodium selenate and chitosan as exogenous elicitors on the phenolic compounds profile of broccoli sprouts

BACKGROUND

Broccoli sprouts are a good source of secondary metabolites, exhibiting biological activity, such as polyphenols, whose concentration is affected by the exposure to exogenous elicitors. The aim of this work was to investigate the effect of sodium selenate, chitosan and methyl jasmonate, applied directly to the seeds or through irrigation, on the content and profile of phenolic compounds in broccoli sprouts. The effect on antioxidant activity was also investigated.

RESULTS

Methyl jasmonate and chitosan decreased antioxidant capacity. Methyl jasmonate significantly decreased total polyphenols content in comparison with control sprouts, while chitosan significantly increased it. Sodium selenate had no statistical effect on antioxidant capacity and total polyphenols concentration. The polyphenols profile in sprouts was composed by quercetin, morine, genisteine, luteoline and sinapic acid. Elicitor type and concentration affected the synthesis of these compounds. Chitosan stimulated the synthesis of quercetin, sinapic acid and morine, whereas methyl jasmonate stimulated the synthesis of luteoline. Sodium selenate had no effect on polyphenols synthesis.

CONCLUSION

The exposure of broccoli to the elicitors produced changes in the phenolic compounds profile of broccoli sprouts. Besides, the stimulation of phenolic compounds synthesis was elicitor-specific, thus opening the possibility of managing culture conditions to increase the content of a specific phenolic compound.

Spectroscopic studies on the antioxidant activity of p-coumaric acid

p-coumaric acid (4-hydroxycinnamic acid), a phenolic acid, is a hydroxyl derivative of cinnamic acid. It decreases low density lipoprotein (LDL) peroxidation and reduces the risk of stomach cancer. In vitro radical scavenging and antioxidant capacity of p-coumaric acid were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe(2+)) chelating activity and ferric ions (Fe(3+)) reducing ability. p-Coumaric acid inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45μg/mL concentration. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and ascorbic acid displayed 66.8%, 69.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, p-coumaric acid had an effective DPPH scavenging, ABTS(+) scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe(3+)) reducing power and ferrous ions (Fe(2+)) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that p-coumaric acid can be used in the pharmacological and food industry because of these properties.