Protection of deoxyribose and DNA from degradation by using aqueous extracts of several wild plants

BACKGROUND: Aqueous extracts of 48 herbal plants were obtained via alternative extraction protocols, and were assayed for their capacity to protect deoxyribose and DNA itself from degradation (or, conversely, for their capacity to promote DNA degradation), using electrophoresis as analytical tool. RESULTS: For a given (constant) volume of extract, deoxyribose protection ranged from 14.13 ± 1.35% (mean ± SD) inhibition by dwarf mallow powder infusion, up to 106.51 ± 15.93% inhibition by avocado powder infusion. DNA protection was tested at two extract concentrations, and was slightly greater at the higher concentration. Pro-oxidant effects were essentially absent. CONCLUSION: The anti-oxidative roles of plants upon deoxyribose and DNA displayed by our experimental results were rather promising with regards to practical applications of those plants, viz. as ingredients in the formulation of nutraceutical beverages and/or foods

Understanding the effects of roasting on antioxidant components of coffee brews by coupling on-line ABTS assay to high performance size exclusion chromatography

INTRODUCTION: Coffee is a widely consumed beverage containing antioxidant active compounds. During roasting the phytochemical composition of the coffee bean changes dramatically and highly polymeric substances are produced. Besides chlorogenic acids that are already present in green coffee beans, melanoidins show antioxidant capacity as well. OBJECTIVE: To employ post‐column derivatisation by coupling high performance size exclusion chromatography (HPSEC) to an antioxidant assay to investigate the effect of roasting on the properties of antioxidant active compounds in coffee brews. METHODOLOGY: We have investigated the antioxidant capacity of Coffea arabica (Arabica) and C. canephora (Robusta) beans that were roasted over the full spectrum of roast conditions (four roasting speeds to three roast degrees) by comparing the results from HPSEC coupled on‐line to the ABTS assay with those from two batch assays, Folin Ciocalteu (FC) and oxygen radical absorbance capacity (ORAC) assay. RESULTS: The antioxidant capacity showed a general decrease towards slower and darker roasted coffee for all three assays, indicative of heat degradation of active compounds. Hence, low molecular weight (LMW) compounds such as chlorogenic acids (CGAs) decreased progressively already from relatively mild roasting conditions. In contrast, high molecular weight (HMW) compounds (e.g. melanoidins) increased from light to dark roast degrees with lowering magnitude towards slower roasting profiles. CONCLUSION: By coupling HPSEC on‐line to the ABTS assay we were able to separately quantify the contribution of HMW and LMW compounds to the total antioxidant capacity, increasing our understanding of the roast process. © 2016 The Authors. Phytochemical Analysis Published by John Wiley & Sons Ltd

Effect of thermal treatment and storage on bioactive compounds, organic acids and antioxidant activity of baobab fruit (Adansonia digitata) pulp from Malawi

Bioactive compounds of baobab (Adansonia digitata) pulp from Malawi were investigated. The effect of thermal treatment and storage on selected quality attributes of the juice was also evaluated. Organic compounds were analysed by HPLC; total phenol content (TPC) and total antioxidant activity (FRAP, ABTS and DPPH) were measured by spectrophotometry. Malawi baobab pulp contains high levels of procyanidin B2 (533 ± 22.6 mg/100 g FW), vitamin C (AA + DHA) (466 ± 2.5 mg/100 g FW), gallic acid (68.5 ± 12.4 mg/100 g FW) and (−)-epicatechin (43.0 ± 3.0 mg/100 g FW) and showed a maximum TPC of 1.89 × 103 ± 1.61 mg GAE/100 g FW. The maximum antioxidant activity was 2.81 × 103 ± 92.8 mg TEAC/100 g FW for FRAP, 1.52 × 103 ± 17.1 mg TEAC/100 g FW for ABTS and 50.9 ± 0.43% DPPH for DPPH. Thermal pasteurisation (72 °C, 15 s) retained vitamin C which further showed extended half-life under refrigeration temperature (6 °C). Procyanidin B2, (−)-epicatechin, TPC and antioxidant activity fluctuated during storage. Antioxidant activity was significantly correlated (p ≤ 0.05) with bioactive compounds and TPC

Bio-augmentation of antioxidants and phenolic content of Lablab purpureus by solid state fermentation with GRAS filamentous fungi

The present study was conducted to find out the effect of solid state fermentation on release of phenolics and subsequently on improvement of antioxidant activity of fermented seed and flour of Lablab purpureus (seim), using GRAS filamentous fungi i.e. Aspergillus awamori and Aspergillus oryzae. Significant increase in TPC level was observed on 5th day of fermentation of seed and flour with A. awamori and A. oryzae as compared to non-fermented ones. In DPPH and ABTS antioxidant assay, maximum activity was noticed in fermented ethanolic extract of seim seed with A. awamori and A. oryzae on 3rd and 4th day of incubation, respectively. The findings showed higher antioxidant activity formation in fermented seim seed than flour. Significant increase in enzyme activity of α-amylase was also contributed by SSF. This study demonstrated that fermented seed and flour of seim are better source of phytochemicals compared to the non-fermented ones

Polyphenolic content and antioxidant capacity in fruits of plum (prunus domestica l.) Cultivars "valjevka" and "mildora" as influenced by air drying

Polyphenolic content and antioxidant capacity of freshly harvested plums cvs. "Valjevka" and "Mildora," and changes caused by drying were analyzed. Plum drying at 90C resulted in significant changes in anthocyanins, flavonoids and phenolics content, and antioxidant capacity in both cultivars examined. Statistical analysis showed that antioxidant capacity of both fresh plums and prunes of "Valjevka" and "Mildora" is strongly influenced by the phenolic constituents of the fruit. The major phenolic compound in fresh plums and prunes is neochlorogenic acid, followed by caffeic acid and chlorogenic acid. After drying, a significant decrease in neochlorogenic acid and an increase in caffeic acid was observed, while chlorogenic acid content decreased in prunes of "Valjevka," and increased in prunes of "Mildora." Rutin and protocatechuic acid contents were slightly decreased after drying, while gallic acid content was dramatically increased. A complete degradation of cyanidin was induced by drying

Screening of antioxidant properties of the apple juice using the front-face synchronous fluorescence and chemometrics

Fluorescence spectroscopy is gaining increasing attention in food analysis due to its higher sensitivity and selectivity as compared to other spectroscopic techniques. Synchronous scanning fluorescence technique is particularly useful in studies of multi-fluorophoric food samples, providing a further improvement of selectivity by reduction in the spectral overlapping and suppressing light-scattering interferences. Presently, we study the feasibility of the prediction of the total phenolics, flavonoids, and antioxidant capacity using front-face synchronous fluorescence spectra of apple juices. Commercial apple juices from different product ranges were studied. Principal component analysis (PCA) applied to the unfolded synchronous fluorescence spectra was used to compare the fluorescence of the entire sample set. The regression analysis was performed using partial least squares (PLS1 and PLS2) methods on the unfolded total synchronous and on the single-offset synchronous fluorescence spectra. The best calibration models for all of the studied parameters were obtained using the PLS1 method for the single-offset synchronous spectra. The models for the prediction of the total flavonoid content had the best performance; the optimal model was obtained for the analysis of the synchronous fluorescence spectra at Delta lambda = 110 nm (R (2) = 0.870, residual predictive deviation (RPD) = 2.7). The optimal calibration models for the prediction of the total phenolic content (Delta lambda = 80 nm, R (2) = 0.766, RPD = 2.0) and the total antioxidant capacity (Delta lambda = 70 nm, R (2) = 0.787, RPD = 2.1) had only an approximate predictive ability. These results demonstrate that synchronous fluorescence could be a useful tool in fast semi-quantitative screening for the antioxidant properties of the apple juices.info:eu-repo/semantics/publishedVersio

Total Phenolic Contents and Antioxidant Capacities of Selected Chinese Medicinal Plants

Antioxidant capacities of 56 selected Chinese medicinal plants were evaluated using the Trolox equivalent antioxidant capacity (TEAC) and ferric reducing antioxidant power (FRAP) assays, and their total phenolic content was measured by the Folin-Ciocalteu method. The strong correlation between TEAC value and FRAP value suggested that the antioxidants in these plants possess free radical scavenging activity and oxidant reducing power, and the high positive correlation between antioxidant capacities and total phenolic content implied that phenolic compounds are a major contributor to the antioxidant activity of these plants. The results showed that Dioscorea bulbifera, Eriobotrya japonica, Tussilago farfara and Ephedra sinica could be potential rich sources of natural antioxidants

Total Phenolic Contents and Antioxidant Capacities of Herbal and Tea Infusions

In order to supply new information on the antioxidant function of selected beverages for nutritionists and the general public, total phenolic contents of 51 kinds of herbal and tea infusions made in China were measured by the Folin-Ciocalteu method, and their antioxidant capacities were evaluated using ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays. A significant correlation between FRAP and TEAC values suggested that antioxidant components in these beverages were capable of reducing oxidants and scavenging free radicals. The high correlation between antioxidant capacities and total phenolic contents indicated that phenolic compounds could be one of the main components responsible for antioxidant activities of these beverages. Generally, these beverages had high antioxidant capacities and total phenolic contents, and could be important dietary sources of antioxidant phenolics for prevention of diseases caused by oxidative stress

Structural basis for CRISPR RNA-guided DNA recognition by Cascade

The CRISPR (clustered regularly interspaced short palindromic repeats) immune system in prokaryotes uses small guide RNAs to neutralize invading viruses and plasmids. In Escherichia coli, immunity depends on a ribonucleoprotein complex called Cascade. Here we present the composition and low-resolution structure of Cascade and show how it recognizes double-stranded DNA (dsDNA) targets in a sequence-specific manner. Cascade is a 405-kDa complex comprising five functionally essential CRISPR-associated (Cas) proteins (CasA1B2C6D1E1) and a 61-nucleotide CRISPR RNA (crRNA) with 5′-hydroxyl and 2′,3′-cyclic phosphate termini. The crRNA guides Cascade to dsDNA target sequences by forming base pairs with the complementary DNA strand while displacing the noncomplementary strand to form an R-loop. Cascade recognizes target DNA without consuming ATP, which suggests that continuous invader DNA surveillance takes place without energy investment. The structure of Cascade shows an unusual seahorse shape that undergoes conformational changes when it binds target DNA.