Protein-precipitating capacity of bearberry-leaf (Arctostaphylos uva-ursi L. Sprengel) polyphenolics

Molecular and technical aspects on the interaction of bovine serum albumin with pyrazine derivatives: From molecular docking to spectroscopy study

In order to better understand the transport and action mechanism of flavor substance and proteins in human body, the interaction mechanism between pyrazine derivatives and bovine serum albumin (BSA) was studied by molecular dynamics simulation and a series of spectroscopic methods. In molecular docking, it was observed that the small molecules were surrounded by hydrophobic amino acid residues of the protein, and the main amino acid residues formed π-π interaction and hydrogen bond interaction with BSA. The results of fluorescence emission spectroscopy combined with thermodynamic analysis showed that static quenching was the main mechanism of the interaction between three pyrazine derivatives and BSA, which was dominated by hydrophobic interaction. Synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy combined with molecular dynamics simulation proved that the pyrazine derivatives changed the conformation of BSA. In summary, pyrazine derivatives can interact with BSA, and the complexation of the complex changes its spatial conformation. The research in this paper has positive significance for understanding the binding, transport, and metabolism of pyrazine compounds in the process of blood circulation and provides key data for the metabolism of pyrazine compounds in vivo. PRACTICAL APPLICATION: The interaction of pyrazine derivatives-BSA is studied by multi-spectra and MD. The fluorescence quenching of pyrazine derivatives-BSA is static quenching. The main force between pyrazine derivatives and BSA is hydrophobic force. There is only one site of association between pyrazine derivatives and BSA. Pyrazine derivatives have effects on conformation of BSA.

Modulatory Effects of Arctostaphylos uva-urs Extract In Ovo Injected into Broiler Embryos Contaminated by Aflatoxin B1

In ovo injection of nutrients can modulate the embryo’s physiological responses against aflatoxin B1 (AFB1) embryotoxicity. This hypothesis was tested using in ovo injection of Arctostaphylos uva-ursi (Ar. uu.) methanolic extract. The total polyphenols, total flavonoids, total antioxidant capacity, and GC-MS analysis were all assessed in the Ar. uu. methanolic extract. A total of 180 ten-day-old embryonated eggs were distributed into six groups of 30 replicates each. The first group was used as a control (non-injected), and the second, third, fourth, fifth, and sixth groups were injected with 10 µ double-distilled water (DDW), 500 µL methanol, 0.01 g Ar. uu./500 µL methanol, 50 ng AFB1/10 µL DDW, and 50 ng AFB1 in 10 µ DDW + 0.01 g Ar. uu./500 µL methanol, respectively. The relative embryo weight, residual yolk sac weight, tibia length and weight, and survival were recorded. Total and differential leukocytes, oxidative stress, and humoral immune responses were observed. The residual yolk sac was lower (p < 0.05) in the Ar. uu. group than other groups. The embryonic growth (tibia weight and length) was enhanced in AFB1 + Ar. uu.-injected embryos compared with those injected with AFB1 alone. In conclusion, in ovo injection of Arctostaphylos uva-ursi could modulate AFB1-induced toxicity in chicken embryos.

Variation in Population and Solvents as Factors Determining the Chemical Composition and Antioxidant Potential of Arctostaphylos uva-ursi (L.) Spreng. Leaf Extracts

The bearberry Arctostaphylos uva-ursi (L.) Spreng. has a long history of ethnopharmacological use. This species has been used in folk medicine for centuries as a rich source of raw material abundant in secondary metabolites and is important for medicinal and pharmacological purposes. The plant is a source of herbal material—Uvae ursi folium, which is highly valued and sought by pharmaceutical and cosmetic industries. The studied bearberry leaves can be classified as a suitable herbal material for use in pharmacy; therefore, the investigated populations can be a potentially valuable source of plant material for cultivation and can be used in in vitro cultures and in biotechnological processes. The objective of this study was to characterize the variability of the phytochemical composition and antioxidant activity of water and ethanol bearberry extracts from raw material collected from different natural populations. In each of the twelve A. uva-ursi sites, three leaf samples were collected and analyzed. The water extracts from bearberry leaves were characterized by similar concentration of arbutin (77.64–105.56 mg g⁻¹) and a significantly higher concentration of hydroquinone (6.96–13.08 mg g⁻¹) and corilagin (0.83–2.12 mg g⁻¹) in comparison with the ethanol extracts −77.21–103.38 mg g⁻¹, 10.55–16.72 mg g⁻¹, 0.20–1.54 mg g⁻¹, respectively. The concentration of other metabolites in the water extracts was significantly lower in comparison with the ethanol extracts. In the case of the water extracts, a significant effect of not only total phenolic compounds, but also hydroquinone on the antioxidant parameters, was observed, which indicates the solvent-related activity of these metabolites. Therefore, it is suggested that special attention should be paid to the concentration of not only arbutin, but also hydroquinone in Uvae ursi folium. The latter metabolite serving a very important function as an active bearberry ingredient should be controlled not only in alcoholic extracts but also in water extracts, since bearberry leaves are applied as infusions and decoctions. The results presented in this paper can contribute to appropriate selection of plant material for pharmaceutical, cosmetic, and food industries, with special emphasis on the antioxidant activity of different types of extracts.

Application of Untargeted Metabolomics to Determine Volatile Compounds from the Spanish Plant Arctostaphylos uva-ursi Used as Tea

One-hundred and seven different volatile compounds were identified in the samples of Arctostaphylos uva-ursi collected from nine locations in Spain. This plant is commonly brewed and used as tea. Volatile compounds profile was detected using solid-phase microextraction gas chromatography-mass spectrometry. The most interesting compounds detected from an antioxidant capacity point of view were esters, phenols, and aromatics compounds. All samples were discriminated by principal component analysis. The insolation and altitude of harvest areas, and latent structures were considered for interpretation of results. Discriminant analysis was applied to control the type and concentration of metabolites and determine the best plant antioxidant profiles of volatile compounds from plant origin. Moreover, a heatmap displayed correlations between detected compounds. The discriminant analysis led to 20 quality markers being identified for the analysed plants. The strongest antioxidant capacity was obtained in the samples from Pina de Montalgrao and Loarre (collected in September) for ORAC (33.11 ± 0.61 g Trolox/g sample) and DPPH (IC50 = 711 ± 12 µg/g) methods, respectively. The plant with the highest total phenolic content was Loarre collected in September (171.9 ± 19.4 mg GAE/g DW) and November (177.1 ± 11.0 mg GAE/g DW).

Discovery and Characterization of Phenolic Compounds in Bearberry (Arctostaphylos uva-ursi) Leaves Using Liquid Chromatography-Ion Mobility-High-Resolution Mass Spectrometry

The characterization and quantification of phenolic compounds in bearberry leaves were performed using hyphenated ion mobility spectroscopy (IMS) and a quadrupole time-of-flight mass spectrometer. A higher identification confidence level was obtained by comparing the measured collision cross section (^TWCCS_N2) with predicted values using a machine learning algorithm. A total of 88 compounds were identified, including 14 arbutin derivatives, 33 hydrolyzable tannins, 6 flavanols, 26 flavonols, 9 saccharide derivatives, and glycosidic compounds. Those most reliably reproduced in all samples were quantified against respective standards. Arbutin (47-107 mg/g), 1,2,3,4,6-pentagalloylglucose (6.6-12.9 mg/g), and quercetin 3-galactoside/quercetin 3-glucoside (2.7-5.7 mg/g) were the most abundant phenolic components in the leaves. Quinic acid and ellagic acid were also detected at relatively high concentrations. The antioxidant activity of the most abundant compounds was evaluated. A critical view of the advantages and limitations of traveling wave IMS and CCS for the discovery of natural products is given.

Antioxidant and antimicrobial markers by UPLC®-ESI-Q-TOF-MSE of a new multilayer active packaging based on Arctostaphylos uva-ursi

49 different non-volatile compounds were determined in Spanish Arctostaphylos uva-ursi leaves using UPLC^®-ESI-Q-TOF with MS^E technology. Both positive and negative electrospray ionization were applied. MarkerLynx^® was proposed as a powerful tool to distinguish samples from eight wild populations of Spain by determining their non-volatile markers. Development of HRMS methods let to analysis of metabolites in plants. Antioxidant and antimicrobial capacities of different extracts were evaluated. Plant extract with the strongest antioxidant and simultaneous good antimicrobial capacity (Lierta) was chosen and incorporated in a multilayer packaging. Then, antioxidant capacity of the new packaging was evaluated and the efficient free radical scavenging properties were demonstrated.

Study of the Properties of Bearberry Leaf Extract as a Natural Antioxidant in Model Foods

The common bearberry (Arctostaphylos uva-ursi L. Sprengel) is a ubiquitous procumbent evergreen shrub located throughout North America, Asia, and Europe. The fruits are almost tasteless but the plant contains a high concentration of active ingredients. The antioxidant activity of bearberry leaf extract in the 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation assay was 90.42 mmol Trolox equivalents/g dry weight (DW). The scavenging ability of the methanol extract of bearberry leaves against methoxy radicals generated in the Fenton reaction was measured via electron paramagnetic resonance. Lipid oxidation was retarded in an oil–water emulsion by adding 1 g/kg lyophilised bearberry leaf extract. Also, 1 g/kg of lyophilised bearberry leaf extract incorporated into a gelatin-based film displayed high antioxidant activity to retard the degradation of lipids in muscle foods. The present results indicate the potential of bearberry leaf extract for use as a natural food antioxidant.

Evaluation of Antioxidant, Antidiabetic and Anticholinesterase Activities of Smallanthus sonchifolius Landraces and Correlation with Their Phytochemical Profiles

The present study aimed to investigate the phytochemical profile of leaf methanol extracts of fourteen Smallanthus sonchifolius (yacon) landraces and their antioxidant, anticholinesterase and antidiabetic activities that could lead to the finding of more effective agents for the treatment and management of Alzheimer's disease and diabetes. For this purpose, antioxidant activity was assessed using different tests: ferric reducing ability power (FRAP), 2,2-diphenyl-1-picryl hydrazyl (DPPH), nitric oxide (˙NO) and superoxide (O2˙-) scavenging and lipid peroxidation inhibition assays. Anticholinesterase activity was investigated by quantifying the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, whereas antidiabetic activity was investigated by α-amylase and α-glucosidase inhibition tests. To understand the contribution of metabolites, phytochemical screening was also performed by high performance liquid chromatography-diode array detector (HPLC-DAD) system. Among all, methanol extract of PER09, PER04 and ECU44 landraces exhibited the highest relative antioxidant capacity index (RACI). ECU44 was found to be rich in 4,5-di-O-caffeoylquinic acid (CQA) and 3,5-di-O-CQA and displayed a good α-amylase and α-glucosidase inhibition, showing the lowest IC50 values. Flavonoids, instead, seem to be involved in the AChE and BChE inhibition. The results of this study revealed that the bioactive compound content differences could be determinant for the medicinal properties of this plant especially for antioxidant and antidiabetic activities.

UHPLC-PDA-ESI-TOF/MS metabolic profiling of Arctostaphylos pungens and Arctostaphylos uva-ursi. A comparative study of phenolic compounds from leaf methanolic extracts

The aim of this study was to get a rapid metabolic fingerprinting and to gain insight into the metabolic profiling of Arctostaphylos pungens H. B. K., a plant morphologically similar to Arctostaphylos uva-ursi (L.) Spreng. (bearberry) but with a lower arbutin (Arb) content. According to the European Pharmacopoeia the Arb content in the dried leaf of A. uva-ursi (L.) Spreng. must be at least 7% (wt/wt) but other species, like A. pungens, are unintentionally or fraudulently marketed instead of it. Therefore, methanolic leaf extracts of nine A. uva-ursi and six A. pungens samples labeled and marketed as "bearberry leaf" have been analyzed. A five-minute gradient with a UHPLC-PDA-ESI-TOF/MS on an Acquity BEH C18 (50×2.1 mm i.d.) 1.7 μm analytical column has been used for the purpose. A comprehensive assignment of secondary metabolites has been carried out in a comparative study of the two species. Among twenty-nine standards of natural compounds analyzed, fourteen have been identified, while other fifty-five metabolites have been tentatively assigned. Moreover, differences in both metabolic fingerprinting and profiling have been evidenced by statistical multivariate analysis. Specifically, main variations have been observed in the relative content for Arb, as expected, and for some galloyl derivative like tetra- and pentagalloylglucose more abundant in A. uva-ursi than in A. pungens. Furthermore, differences in flavonols profile, especially in myricetin and quercetin glycosilated derivatives, were observed. Based on principal component analysis myricetrin, together with a galloyl arbutin isomer and a disaccharide are herein proposed as distinctive metabolites for A. pungens.

Improving antioxidant status in aged mice by 50% ethanol extract from red bean fermented by Bacillus subtilis

BACKGROUND

The purpose of this study was to investigate the effects of 50% ethanol extracts from red bean non-fermented (RBE) and fermented by Bacillus subtilis (RBNE) on the antioxidant status of aged ICR mouse.

RESULTS

Compared to 2-month-old ICR mouse, the plasma total antioxidant status (TAS) in 12-month-old ICR mouse decreased about 57%, while malondialdehyde (MDA) levels in the liver and brain of 12-month-old ICR mouse increased 56% and 30%, respectively. Orally administration of RBE or RBNE could completely recover the changes of MDA and plasma TAS levels due to the aging process. Vitamin E contents declined 88% in the liver and 74% in the brain of aged ICR mouse. At a level of 0.3 or 0.6 g kg(-1) body weight, RBNE raised vitamin E content in the liver and brain; however, RBE showed no significant influence. All antioxidant enzymes activities in the liver and brain of aged ICR mouse decreased compared to those activities in 2-month-old ICR mouse. RBNE could significantly enhance the superoxide dismutase activity in the brain of aged ICR mouse.

CONCLUSION

Oral administration of RBE or RBNE could improve antioxidant status in aged ICR mouse. Fermentation by Bacillus subtilis could enhance the antioxidant properties of red bean.