Composition of Flavonoids and Phenolic Acids in Lychee (Litchi Chinensis Sonn.) Flower Extracts and Their Antioxidant Capacities Estimated with Human LDL, Erythrocyte, and Blood Models

Caesalpinia palmeri: First Report on the Phenolic Compounds Profile, Antioxidant and Cytotoxicity Effect

This study aimed to determine the phenolic compounds profile, antioxidant potential and cytotoxicity of extracts and fractions of Caesalpinia palmeri. Methanolic extracts were generated from C. palmeri berries, stems and flowers. The latter was subjected to liquid-liquid partition, obtaining hexane, ethyl acetate and residues fractions. Results showed that the flower extract and ethyl acetate fraction had a larger concentration of phenolic compounds (148.9 and 307.9 mg GAE/g, respectively), being ellagic acid (6233.57 and 19550.08 μg/g, respectively), quercetin-3-β-glycoside (3023.85 and 8952.55 μg/g, respectively) and gallic acid (2212.98 and 8422.34 μg/g, respectively) the most abundant compounds. Flower extract and ethyl acetate fraction also presented the highest antioxidant capacity on all tested methods (DPPH, ABTS, ORAC and FRAP) and low cytotoxicity against ARPE-19 cells (IC₅₀ >170 μg/mL). C. palmeri possessed high antioxidant potential, associated with the presence of phenolic compounds and low cytotoxicity, suggesting that they could represent an option to counter oxidative stress.

Mass spectrometry characterization, antioxidant activity, and cytotoxicity of the peel and pulp extracts of Pitomba

The fruit of the Talisia esculenta tree, is largely consumed and appreciated for its bittersweet taste; however, detailed information on its constituent bioactive compounds is still scarce. Therefore, this study aims to screen the antioxidant activity by six methods and determine the chemical profile of the pitomba fruit peel and pulp by electrospray ionization-Fourier transform-mass spectrometry. This is the first study attempting to identify the bioactive compounds in the pitomba fruit peel. Consequently, 19 and 14 compounds were identified in the ethanolic and hexanic peel extracts, while 7 and 10 compounds were detected in the ethanolic and hexanic pulp extracts, respectively. The common compounds across the board were citric acid, ascorbic acid, and shikimic acid. In addition, the ethanolic peel extract exhibited a high 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (54.21-81.41%). The obtained results highlight the importance the pitomba fruit as a promising source of natural compounds with high antioxidant activities.

Protection of natural antioxidants against low-density lipoprotein oxidation

This chapter reports essential information about the protective action of antioxidants against LDL oxidation. The activity of individual compounds (tocopherols, vitamin C, phenolic compounds) as well as extracts obtained from plant material (cereals, fruits, legumes, nuts, mushrooms, by-products of food industry) is reported. The structure-antioxidant activity relationship of phenolic compounds is discussed. This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. This chapter summarizes also the reportings to date of in vivo studies using foods or beverages at inhibiting the incidence of LDL oxidation.

Litchi (Litchi chinensis Sonn.) flower proanthocyanidin fraction exhibited protective efficacy to suppress nickel-induced expression for vascular endothelial growth factor in HepG2 cells

The protective efficacy of litchi (Litchi chinensis Sonn.) flower proanthocyanidin fraction (LFPF) composed of (-)-epicatechin and proanthocyanidin A2 against vascular endothelial growth factor (VEGF) generation induced by nickel (Ni) in hepatocellular carcinoma (Hep G2) cells was studied. VEGF is an angiogenic inducer, which promotes tumor angiogenesis, leading to rapid tumor growth and metastasis. VEGF could be substantially induced in the Ni-mediated Hep G2 cells. Through LFPF treatment, the Ni-induced VEGF generation could be suppressed significantly. The inhibition of HIF-1α expression by blocking phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathways, and the suppression of Janus kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT 3), and Raf-1 proto-oncogene, serine/threonine kinase (RAF1)/mitogen-activated protein kinase (MEK1/2)/extracellular-signal-regulated kinase (ERK1/2) pathways are important molecular mechanisms for the LFPF action. LFPF should probably reduce the risk of liver cancer in Ni-contaminated environments by inhibiting VEGF expression. PRACTICAL APPLICATIONS: LFPF mainly contained (-)-epicatechin and proanthocyanidin A2. Our results demonstrated that LFPF considerably suppressed the Ni-induced VEGF expression through inhibition of JAK2/STAT 3 and RAF1/MEK1/2/ERK1/2 pathways and prohibited HIF-1α expression through blocking PI3K/AKT/mTOR pathway. Litchi flowers might have the potential to diminish the liver cancer risk in a Ni-contaminated environment through suitable treatment.

The use of 1 H-NMR Metabolomics to Optimise the Extraction and Preliminary Identification of Anthelmintic Products from the Leaves of Lysiloma latisiliquum

INTRODUCTION

Tannin-rich forages are recognised as an important alternative for the control of gastrointestinal nematodes in small ruminants. Lysiloma latisiliquum, a forage commonly consumed by goats and sheep, has shown anthelmintic activity when tested against Haemonchus contortus. However, to date, the metabolites responsible for the activity are not known.

OBJECTIVE

To use ¹ H-NMR metabolomics in the extraction and identification of anthelmintic metabolites from L. latisiliquum.

METHODOLOGY

Eight different solvent systems were compared for the optimum extraction of anthelmintic metabolites from L. latisiliquum. ¹ H-NMR spectra of the tannin-free extracts were measured in methanol-d₄ using trimethylsilylpropanoic acid (TSP) as internal standard. Extracts were also evaluated for their anthelmintic activity using the larval exsheathment inhibition assay against H. contortus. These data were correlated by multivariate analysis [principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA)] and analysed. To validate the results obtained after the OPLS-DA, a bioassay-guided isolation of bioactive metabolites was conducted.

RESULTS

The PCA of the ¹ H-NMR data allowed the identification of hydrophilic solvents as those best suited for the extraction of anthelmintics from L. latisiliquum and indicated that the bioactive metabolites are high-polarity, glycosylated products. Similarly, OPLS-DA of the data enabled the detection of activity-related signals, assigned to the glycosylated metabolites quercitrin and arbutin obtained from the bioassay-guided purification of the extract.

CONCLUSION

The results of this investigation confirm metabolomics as a useful tool in the detection of bioactive metabolites in plants without previous phytochemical studies. Copyright © 2017 John Wiley & Sons, Ltd.

The Potential Protective Effects of Phenolic Compounds against Low-density Lipoprotein Oxidation

BACKGROUND

The exact mechanism(s) of atherosclerosis in humans remains elusive, but one theory hypothesizes that this deleterious process results from the oxidative modification of low-density lipoprotein (LDL). Research suggests that foods rich in dietary phenolic compounds with antioxidant activity can mitigate the extent of LDL oxidation in vivo. With regard to the different classes of flavonoids, there appears to be a structurefunction relationship between the various moieties/constituents attached to the flavonoids' three ring system and their impact at retarding LDL oxidation.

METHODS

This article summarizes the findings to date of both in vitro and in vivo studies using foods or phenolic extracts isolated from foodstuffs at inhibiting the incidence of LDL oxidation. Three bases: SCOPUS, Web Science, and PubMed were used for search.

RESULTS

An often used method for the determination of antioxidant properties of natural phenolic compounds is the LDL oxidation assay. LDLs are isolated from human plasma and their oxidation is induced by Cu2+ ions or 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). The sample is incubated with a phenolic extract or individual/isolated phenolic compounds. LDL oxidation is then monitored by various chemical methods (e.g., measurement of the generation of conjugated dienes and trienes). This technique confirmed the antioxidant properties of several extracts as obtained from plant material (e.g., grapes, berries, orange, grapefruit, coffee, tea, chocolate, olives, nuts) as well as the individual phenolic compounds (e.g., luteolinidin, apigenidin, caffeic acid, chlorogenic acid, catechin, quercetin, rutin). Several studies in vivo confirmed protective effects of phenolic compounds against LDL oxidation. They covered the healthy subjects with hyperlipidaemia, overweight, obesity, metabolic syndrome, heavy smokers, patients receiving haemodialysis, patients with peripheral vascular disease, and subjects at high cardiovascular risk. The studies comprise individuals of all ages, and the number of participants in the different experiments varied widely.

CONCLUSION

Properly designed double-blind, placebo-controlled randomised clinical trials offer stronger evidence as to the impact of dietary phenolics consumption at retarding LDL oxidation. More such clinical trials are needed to strengthen the hypothesis that foods rich in dietary phenolic compounds with antioxidant activity can mitigate the extent of LDL oxidation in vivo.

Antiobesity Efficacy of Quercetin-Rich Supplement on Diet-Induced Obese Rats: Effects on Body Composition, Serum Lipid Profile, and Gene Expression

The antiobesity effects of quercetin-rich supplement (QRS), which contain quercetin, lycopene, taurine, and litchi flower extract, on a high-fat diet (HFD)-induced obese rats were investigated. The rats that consume HFD with QRS (185 mg/kg rat) have significantly modulated the final body weights [490 ± 11 (HFD) → 441 ± 11 (HFD+QRS) g], total body fat [112.9 ± 4.5 (HFD) → 86.6 ± 5.7 (HFD+QRS) g], liver weights [14.8 ± 0.4 (HFD) → 12.6 ± 0.4 (HFD+QRS) g/rat], and the serum TG [102.5 ± 7.3 (HFD) → 90.7 ± 6.5 (HFD+QRS) mg/dL] to a level that resembled the regular diet-consumed rats (p < 0.05). The excretion of lipid in the faeces augmented in QRS groups as compared with the nonsupplemented HFD group [faecal total lipid: 62.43 ± 2.80 (HFD) → 73.15 ± 0.88 (HFD+QRS) mg/g dried faeces, p < 0.05]. In the histological analysis, quercetin-rich formulation supplemented groups presented a much less lipid accumulation and smaller size of adipocytes. Moreover, a decreased serum thiobarbituric acid reactive substances [1.55 ± 0.17 (HFD) → 0.78 ± 0.04 (HFD+QRS) nmol MDA eq/mL serum] increased levels of serum Trolox equivalent antioxidant capacity [3.89 ± 0.08 (HFD) → 6.46 ± 0.20 (HFD+QRS) μmol/mL serum], and more active hepatic antioxidant enzymes were observed in the supplemented groups (p < 0.05). The result of this work is a good demonstration of how a combination of bioactive compounds could work synergistically and become very effective in disease prevention.

Composition of phenolic compounds and antioxidant attributes of Cyclea gracillima Diels extracts

Cyclea gracillima Diels is a Taiwanese native medicinal herb. However, there are currently few relevant reports on its biochemical activity. In this study, the antioxidant attributes of the ethanol and hot water extracts of this herb were assayed using in vitro models, including the following: 2,2-diphenyl-1-(2,4,6-trinitrophenyl)-hydrazyl radical scavenging, Trolox equivalent antioxidant capacity, reducing power, and chelating ferrous ions. The following biochemical models were also assayed: inhibition of human low density lipoprotein oxidation, inhibition of human erythrocyte hemolysis, and scavenging oxygen radicals in human blood. The composition and content of flavonoids and phenolic acids in these extracts were also analyzed. The results showed that these extracts with high polyphenol levels presented remarkable antioxidant effects in all assays, especially when extracted with ethanol. Six phenolic acids (mainly ferulic acid, sinapic acid, and syringic acid) and 12 flavonoids (mainly narigenin, myricetin, naringin, and apigenin) were found in these extracts.

Systemic Perturbations of Key Metabolites in Type 2 Diabetic Rats Treated by Polyphenol Extracts from Litchi chinensis Seeds

Our previous research obtained Litchi chinensis Sonn. seeds extract (LSE) which showed hypoglycaemic effects on type 2 diabetes (T2D) rats. In order to understand the detailed pathogenesis of diabetes intervened by LSE, the metabonomics strategy was used. As a result, LSE decreased the insulin resistance index and the levels of glucose in urine through elevating the mRNA level of insulin, while decreasing the expression of glucagon to enhance the function of the pancreas. Meanwhile, LSE regulated the glucose and fatty acid metabolisms via increasing the expression of glucose transporter (Glu) 2, Glu4, insulin receptor (IR), and IR substrate-2 (IRS2). LSE effectively restored the impairment of the IRS2/PI3K/Akt/mTOR insulin signaling in the livers. All in all, LSE played a pivotal role in the treatment of T2D through regulation of broad-spectrum metabolic changes and inhibition of the glycogenesis, proteolysis, and lipogenesis in T2D rats.

Effective compounds in the fruit of Muntingia calabura Linn. cultivated in Taiwan evaluated with scavenging free radicals and suppressing LDL oxidation

The effective antioxidant compounds ofM. calaburaLinn. fruit.

Molecular mechanisms of the effects of the ethanolic extract of Muntingia calabura Linn. fruit on lipopolysaccharide-induced pro-inflammatory mediators in macrophages

The anti-inflammatory effect and mechanisms ofM. calaburaLinn. fruit.

Inhibitory effect of litchi (Litchi chinensis Sonn.) flower on lipopolysaccharide-induced expression of proinflammatory mediators in RAW264.7 cells through NF-κB, ERK, and JAK2/STAT3 inactivation

Litchi (Litchi chinensis Sonn.) flower ethanolic extract (LFEE) was found to contain five flavanoids [total amount, 102.73 ± 5.50 mg/g of dried extract (gDE)], nine phenolic acids (total amount, 60.31 ± 4.52 mg/gDE), and proanthocyanidin A2 (79.31 ± 2.95 mg/gDE). LFEE was used to evaluate the inhibitory effects on lipopolysaccharide- (LPS-) induced pro-inflammatory mediators in RAW264.7 cells. The results showed that LFEE treatment could suppress the expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the productions of nitric oxide (NO) and prostaglandin E2 (PGE2), and the secretions of pro-inflammatory cytokines [interleukin-1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α)] in the LPS-mediated RAW264.7 cells. The attenuation of LPS-induced inflammatory responses by LFEE was found to be closely related to the inhibition of the translocation of nuclear factor κB (NF-κB) p50/p65 subunits correlated with suppression of the activation of the inhibitor of κB kinase (IKK) α/β and downregulation of activation of extracellular signal-regulated kinase (ERK) and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3).

Erythrocytes and cell line-based assays to evaluate the cytoprotective activity of antioxidant components obtained from natural sources

Oxidative stress can damage cellular components including DNA, proteins or lipids, and may cause several skin diseases. To protect from this damage and addressing consumer's appeal to natural products, antioxidants obtained from algal and vegetal extracts are being proposed as antioxidants to be incorporated into formulations. Thus, the development of reliable, quick and economic in vitro methods to study the cytoactivity of these products is a meaningful requirement. A combination of erythrocyte and cell line-based assays was performed on two extracts from Sargassum muticum, one from Ulva lactuca, and one from Castanea sativa. Antioxidant properties were assessed in erythrocytes by the TBARS and AAPH assays, and cytotoxicity and antioxidant cytoprotection were assessed in HaCaT and 3T3 cells by the MTT assay. The extracts showed no antioxidant activity on the TBARS assay, whereas their antioxidant capacity in the AAPH assay was demonstrated. On the cytotoxicity assays, extracts showed low toxicity, with IC50 values higher than 200μg/mL. C. sativa extract showed the most favourable antioxidant properties on the antioxidant cytoprotection assays; while S. muticum and U. lactuca extracts showed a slight antioxidant activity. This battery of methods was useful to characterise the biological antioxidant properties of these natural extracts.

Brewers' spent grain; bioactivity of phenolic component, its role in animal nutrition and potential for incorporation in functional foods: a review

Brewers' spent grain (BSG) is a low-value co-product of the brewing industry produced in large quantities annually. This paper reviews the existing evidence regarding the phenolic component of BSG, focusing on composition, extraction and biofunctions such as antioxidant, anti-atherogenic, anti-inflammatory and anti-carcinogenic activities. Furthermore, the incorporation of BSG in foodstuffs will be discussed, including the use of BSG as an animal feed supplement and the potential of BSG to be incorporated into foods for human consumption. BSG contains hydroxycinnamic acids including ferulic acid, p-coumaric acid and caffeic acid; which have shown bioactivity in the pure form (antioxidant, anti-inflammatory, anti-atherogenic and anti-cancer). Phenolic extracts from BSG have also shown antioxidant potential, by protecting against oxidant-induced DNA damage, possibly by Fe chelation. Studies show that BSG has many benefits when used as a supplement in animal feed, such as increasing milk yield, milkfat content and in providing essential dietary amino acids. The incorporation of BSG in human foods such as cookies and ready-to-eat snacks has resulted in increased protein and fibre contents of the products, where the changes in organoleptic properties are controllable. It can be concluded that the phenolic component of BSG has potential bioactive effects, which are worth pursuing given that the inclusion of BSG into human foodstuffs is viable and beneficial.