Abstract: Gallic acid (3,4,5 trihydroxybenzoic acid) is a secondary metabolite present in most plants. This metabolite is known to exhibit a range of bioactivities including antioxidant, antimicrobial, anti-inflammatory, and anticancer. There are various methods to analyze gallic acid including spectrometry, chromatography, and capillary electrophoresis, among others. They have been developed to identify and quantify this active ingredient in most biological matrices. The aim of this article is to review the available information on analytical methods for gallic acid, as well as presenting the advantages and limitations of each technique.

Abstract: The use of pomegranate peel is highly associated with its rich phenolic concentration. Series of drying methods are recommended since bioactive compounds are highly sensitive to thermal degradation. The study was conducted to evaluate the effects of drying on the bioactive compounds, antioxidant as well as antibacterial and antityrosinase activities of pomegranate peel. Dried pomegranate peels with the initial moisture content of 70.30 % wet basis were prepared by freeze and oven drying at 40, 50 and 60 °C. Difference in CIE-LAB, chroma (C*) and hue angle (h°) were determined using colorimeter. Individual polyphenol retention was determined using LC-MS and LC-MSE while total phenolics concentration (TPC), total flavonoid concentration (TFC), total tannins concentration (TTC) and vitamin C concentration were measured using colorimetric methods. The antioxidant activity was measured by radical scavenging activity (RSA) and ferric reducing antioxidant power (FRAP). Furthermore, the antibacterial activity of methanolic peel extracts were tested on Gram negative (Escherichia coli and Klebsiella pneumonia) and Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) using the in vitro microdilution assays. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin as positive controls. Oven drying at 60 °C resulted in high punicalin concentration (888.04 ± 141.03 mg CE/kg dried matter) along with poor red coloration (high hue angle). Freeze dried peel contained higher catechin concentration (674.51 mg/kg drying matter) + catechin and –epicatechin (70.56 mg/kg drying matter) compared to oven dried peel. Furthermore, freeze dried peel had the highest total phenolic, tannin and flavonoid concentrations compared to oven dried peel over the temperature range studied. High concentration of vitamin C (31.19 μg AAE/g dried matter) was observed in the oven dried (40 °C) pomegranate peel. Drying at 50 °C showed the highest inhibitory activity with the MIC values of 0.10 mg/ml against Gram positive (Staphylococcus aureus and Bacillus subtili. Likewise, the extracts dried at 50 °C showed potent inhibitory activity concentration (22.95 mg/ml) against monophenolase. Principal component analysis showed that the peel colour characteristics and bioactive compounds isolated the investigated drying method. The freeze and oven dried peel extracts exhibited a significant antibacterial and antioxidant activities. The freeze drying method had higher total phenolic, tannin and flavonoid concentration therefore can be explored as a feasible method for processing pomegranate peel to ensure retention of the maximum amount of their naturally occurring bioactive compounds. Not relevant for this study.

Abstract: Total polyphenols and flavonoids contents, as well as ferric reducing antioxidant power (FRAP), metal ions chelating activity, reducing power assay and scavenging activity of DPPH and ABTS radicals in aqueous and methanolic extracts obtained from mycelium, primordium and fruiting body of Pleurotus ostreatus in both fresh as dry, were evaluated. The total polyphenol content of dried samples was higher in aqueous extracts obtained both in room temperature and boiling. The total polyphenol content of the fresh samples obtained at room temperature and boiling was higher in aqueous extract of mycelium and in the methanolic extract of the fruiting body. In general, flavonoids represented a very small percentage of the total polyphenol content. The antioxidant activity measured by the FRAP method of extracts from fresh samples were higher with respect to the dried samples. The results of the metal ion chelating activity indicate that all extracts tested had acted. Reducing the power of all samples was concentration dependent. In general, the extracts of dried samples showed higher reducing power than the extracts of fresh samples and tend to show greater reducing power by aqueous than methanolic extracts. It was observed that the DPPH and ABTS radical scavenging activities were positively correlated to the concentration of the extract. The results suggested that antioxidant activity could be due to polyphenols, but mainly by different molecules or substances present in the extracts. Overall, the fruiting body of Pleurotus ostreatus showed the best results and the possibility of continuing to investigate its functional properties of this fungus is opened. This is the first report where the antioxidant activity of Pleurotus ostreatus in different growth stage was reported.

Abstract: The present work was undertaken to evaluate the chemical composition (proximate, minerals and dietary fibre), colour parameters, antioxidant activity and polyphenol profiles of different fruits (pomegranate, kinnow, mango, banana, jambolan, grapes and sapodilla) and vegetables (beetroot, brinjal, orange carrot, bitter gourd, mentha and spinach). The amount of insoluble dietary fibre was higher than soluble dietary fibre for all fruits and vegetables. Vegetables showed superior mineral composition (higher amounts of K, Ca and Fe) as compared to fruits. Total phenolic content (TPC) and antioxidant activity (ABTS and DPPH) ranged from 354.9 to 1639.7 mg GAE/100 g, 2.6 to 5.5 and 3.0 to 6.3 mM TE/g, respectively for different fruits, while it ranged from 179.3 to 1028.6 mg GAE/100 g, 2.1 to 4.7 and 2.0 to 5.0 mM TE/g, respectively for different vegetables. Gallic acid, protocatechuic acid, catechin, caffeic acid, ferulic acid, sinapic acid, quercetin, resveratrol and kaempferol were detected and quantified in different fruits and vegetables. The results highlighted that fruit peels could be used as valuable sources of minerals and polyphenols having high antioxidant activity.

Abstract: Background This study explored the bioactivities and nutrient compositions of coffee ( Coffea Arabica L.) pulp which was prepared in three different ways [Coffee Pulp Extracts (CPE) 1–3]. Methods The coffee pulp was prepared in three different ways by distinct selecting and freezing processes. The nutritional values, polyphenol contents, antioxidant activity, and antibacterial properties of the coffee pulp as well as the characterization of the active ingredients by liquid chromatography-electrospray ionization-quadrupole-time-of-flight mass spectrometry (LC-ESI-Q-TOF-MS) were evaluated. Results The chemical profiles of three aqueous extracts were compared and characterized using LC-ESI-QTOF-MS. They showed slightly different nutrient compositions. The total phenolic content was highest in CPE1, and decreased in the following order: CPE1>CPE2 > CPE3. Among the CPEs tested, CPE1 showed the most potent antioxidant activity with IC 50 18μg/mL and 82μg/mL by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and 1,1-diphenyl-2-picryl-hydrazyl assay, respectively. Chlorogenic acid and caffeine were the most prominent in CPE1 and it contained more compounds than the others. Moreover, CPE1 demonstrated antibacterial activity against both gram-positive ( Staphylococcus aureus and Staphylococcus epidermidis ) and gram-negative bacteria ( Pseudomonas aeruginosa and Escherichia coli ). Conclusion These findings indicated that CPE1 has powerful nutrients with antioxidant and antibacterial properties—the potency of which is impacted by the preparation process.

Abstract: The aim of this study was to evaluate the production of dried fruits and juices from chokeberry as potential sources of bioactive compounds with beneficial effects on human health. Dry powders and juices from chokeberry were analyzed for the contents of sugars with high-performance liquid chromatography coupled with an evaporative light scattering detector (HPLC-ELSD method), and the antioxidant capacity was analyzed by the FRAP (ferric-reducing ability of plasma) and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) tests. Polyphenols were identified by high performance liquid chromatography (HPLC) coupled with a tandem mass spectrometer and a photodiode-array detector (LC-PDA-ESI-MS/MS), and their quantitative analysis was carried out by UPLC-MS/MS (using a Q/TOF detector and a PDA detector). A total of 27 polyphenolic compounds was identified in chokeberry products, including 7 anthocyanins, 11 flavonols, 5 phenolic acids, 3 flavan-3-ols and 1 flavanone. Three anthocyanin derivatives were reported for the first time from chokeberry fruit. A higher activity of the bioactive compounds was determined in dried fruit pomace and in juice obtained from crushed fruits than in those from the whole fruits. In addition, the pomace was found to be a better material for the production of dry powders, compared to chokeberry fruits.

Abstract: Terminalia arjuna is a medicinal plant used in ethnomedicine and the codified traditional medicine. A number of active constituents are reported, but there is no information on the whole range of gallic and ellagic acid derivatives present in this plant A rapid and sensitive analytical method was developed using reverse phase high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) for qualitative analysis to determine the array of bioactive phytochemicals and their variations in different plant parts viz. bark, unripe fruit, ripe fruit, leaf, root and stem. Separation was performed on a Thermo Betasil C8 column (250 mm x 4.5 mm, 5 µm) with a mobile phase consisted of 0.1% formic acid aqueous solution and acetonitrile at a flow rate of 0.5 mL/min in 55 min. A wide range of constituents of T. arjuna were characterized and broadly grouped as 27 gallic acid and 52 ellagic acid derivatives.

Abstract: Sweet potato ( Ipomoea batatas L.) leaves are under utilized vegetables with abundant polyphenols. In this study, ten different solvents, including water, aqueous methanol, aqueous ethanol and aqueous acetone were used to investigate the effect of solvents on the recovery and antioxidant activities of polyphenols from sweet potato leaves. Results indicated that the total phenolic content in extracts ranged from 23.3 to 43.8 mg CAE/g DM, and 70% ethanol extract had the highest total flavonoid (3.4 mg QE/g DM) and total anthocyanin (36.5 mg c-3-gE/100 g DM) content. While, 50% acetone extract exhibited the highest crude extract yield (33.4% in dry materials), total phenolic content (43.8 mg CAE/g DM), as well as the strongest in vitro antioxidant activities. The best correlation with antioxidant activities was observed on total phenolics. Totally 14 phenolics were identified or tentatively identified in 50% acetone extract, caffeoylquinic acid (CQA) and quercetin derivatives were indicated as the most abundant phenolics. HPLC analysis also revealed that the extraction efficiency of 3-CQA, caffeic acid, 3,4-, 3,5- and 4,5-diCQA varied with the polarity of tested solvent, and 70% acetone showed the highest extraction capacity for 3,4-, 3,5- and 4,5-diCQA. All these data demonstrated that the types of extracting solvents impact the recovery and antioxidant activities of sweet potato leaf polyphenols greatly, and 50% (v/v) acetone is quite an efficient solvent to recover polyphenols and antioxidants from sweet potato leaves.

Abstract: This study is focused on optimizing, by surface response methodology, the mixture of natural additives: nisin (an antimicrobial peptide) in combination with avocado seed or avocado peel extracts (both with antioxidant capacities) in order to maximize the antioxidant activity and antimicrobial response against some food-borne bacteria such as Listeria . The peel or seed extracts used in the mixture showed radical scavenging capacity and antioxidant activity due to their polyphenol composition, including kaempferide, epicatechin, chlorogenic acid, epicatechin gallate, among others. During optimization, the results showed that the major antioxidant response in the mixture was mainly provided by the peel extract compared with nisin, seed and their combinations in different proportions. In the antimicrobial response, a synergic effect was observed in the mixtures of each avocado byproduct extract with nisin. Maximum antioxidant and antimicrobial response were obtained with the mixture of 61% of peel extract with 39% of nisin ( p

Abstract: Catechin is a plant polyphenol composed of epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG) as diastereoisomers. Among the various classes of flavonoids, catechin was found to be the most powerful free radical scavenger, scavenging the reactive oxygen species (ROS) generated due to oxidative damage with antibacterial and anti-inflammatory activity. The toxicity of catechin towards bacteria was studied using gram-positive bacteria (B. subtilis) and gram-negative bacteria (E. coli) as model organisms and was found to be more toxic towards gram-positive bacteria. From the results, catechin was found to be beneficial as well as toxic (inhibitory) to the bacteria at a selective concentration behaving as double-edged swords with an IC50 value of 9 ppm for both the bacteria. The inhibitory mechanism of catechin was by oxidative damage through membrane permeabilization which was confirmed by the formation and treatment of bacterial liposomes. SEM images of the control and treated bacteria reveals membrane damage with morphological changes.

Abstract: Polyphenols in whole grain wheat have potential health benefits, but little is known about the expression patterns of phenolic acid biosynthesis genes and the accumulation of phenolic acid compounds in different-colored wheat grains. We found that purple wheat varieties had the highest total phenolic content (TPC) and antioxidant activity. Among phenolic acid compounds, bound ferulic acid, vanillic, and caffeic acid levels were significantly higher in purple wheat than in white and red wheat, while total soluble phenolic acid, soluble ferulic acid, and vanillic acid levels were significantly higher in purple and red wheat than in white wheat. Ferulic acid and syringic acid levels peaked at 14 days after anthesis (DAA), whereas p-coumaric acid and caffeic acid levels peaked at 7 DAA, and vanillic acid levels gradually increased during grain filling and peaked near ripeness (35 DAA). Nine phenolic acid biosynthesis pathway genes (TaPAL1, TaPAL2, TaC3H1, TaC3H2, TaC4H, Ta4CL1, Ta4CL2, TaCOMT1, and TaCOMT2) exhibited three distinct expression patterns during grain filling, which may be related to the different phenolic acids levels. White wheat had higher phenolic acid contents and relatively high gene expression at the early stage, while purple wheat had the highest phenolic acid contents and gene expression levels at later stages. These results suggest that the expression of phenolic acid biosynthesis genes may be closely related to phenolic acids accumulation.