Determination of Major Phytohormones in Fourteen Different Seaweeds Utilizing SPE-LC-MS/MS

Analysis of plant growth regulators (PGRs) should be approached by considering their extremely low concentrations and serious interfering effects that result from the matrix of various plant tissues. In the current research, the separation and simultaneous determination of different classes of phytohormones in 14 seaweeds collected from Turkey seashores were achieved by using solid-phase extraction (SPE) followed by a rapid and sensitive liquid chromatography tandem mass detection method. OASIS HLB (Hydrophilic-Lipophilic Balance) cartridges were successfully used for SPE process to eliminate the matrix effect and enhance the PGRs including zeatin, benzyl amino purine, indole-3-acetic acid, abscisic acid and gibberellic acid within partially different polarities. Based on the optimized experimental conditions, the method presented excellent performance related to linearity (r, 0.9996-0.9999) within the ranges of 0.5-500 ng/mL, relative standard deviation values ((1.43-2.01) for intraday and (2.36-3.50) for interday)), the limit of detection (0.01-0.84 mu g/L) and the limit of quantification (0.02-2.76 mu g/L). The obtained results confirm that the SPE-liquid chromatography/tandem mass spectrometry method performed is highly effective and convenient for routine analyses of trace amounts of the tested phytohormones in seaweeds and any other plant samples as well

Chemical composition and biological activities of propolis samples from different geographical regions of Turkey

Propolis is a natural product with many biological activities, and it has been used in many industrial areas, such as pharmaceuticals, food and cosmetics. Thus, in this study, we aim to evaluate the chemical content, antioxidant, antiviral activities, cytotoxicity and the iNOS of propolis samples collected from 39 different regions in Turkey. Phenolic, flavonoid and triterpene profiles were determined using the LC-HRMS method. The main phenolic compounds identified were flavonoids, including diosmetin, rhamnocitrin, isosakuranetin, naringenin, chrysin, 3-O-methyl-quercetin and acacetin, the main phenolic acid was found as caffeic acid. The major triterpene compounds were also detected as oleanolic acid and hederagenin. The composition of volatile compounds in the propolis samples was examined using GC-MS. alpha-Pinene, beta-pinene and limonene were found as the main compounds in most of the samples. Cytotoxic activities against MDA-MB-231, PC-3, A549, HeLa and a nontumor cell line HEK293 were performed using the MIT method. The iNOS was also determined using LPS induced RAW 264.7 macrophage cells. Pmpolis samples exhibited significant cytotoxic and nitric oxide inhibition activities with a significant range of IC50 values. The total antioxidant/phenolic capacities in TR equivalents of pmpolis samples were assayed by DPPH, CUPRAC, FRAP, and Folin methods. The total phenolics content in the studied pmpolis extracts were found as between 0.96 and 13.53 mmol TR/g. TAC of propolis samples range with respect to the CUPRAC and FRAP methods were found from 0.71 to 8.24 and 0.21 to 2.27 mmol TR/g, respectively. Most of the propolis extracts exhibited more than 80 % DPPH scavenging activities, almost similar or higher than the positive controls. Antiviral activities of the samples were measured as virucidal activity by in ovo. All propolis samples promise for the significant inhibition of avian coronavirus. To our knowledge, this study is the first detailed study in the literature that includes the chemical content and biological activities of Turkish pmpolis collected from different geographical regions

Novel Spectroscopic and Electrochemical Sensors and Nanoprobes for the Characterization of Food and Biological Antioxidants

Since an unbalanced excess of reactive oxygen/nitrogen species (ROS/RNS) causes various diseases, determination of antioxidants that can counter oxidative stress is important in food and biological analyses. Optical/electrochemical nanosensors have attracted attention in antioxidant activity (AOA) assessment because of their increased sensitivity and selectivity. Optical sensors offer advantages such as low cost, flexibility, remote control, speed, miniaturization and on-site/in situ analysis. Electrochemical sensors using noble metal nanoparticles on modified electrodes better catalyze bioelectrochemical reactions. We summarize the design principles of colorimetric sensors and nanoprobes for food antioxidants (including electron-transfer based and ROS/RNS scavenging assays) and important milestones contributed by our laboratory. We present novel sensors and nanoprobes together with their mechanisms and analytical performances. Our colorimetric sensors for AOA measurement made use of cupric-neocuproine and ferric-phenanthroline complexes immobilized on a Nafion membrane. We recently designed an optical oxidant/antioxidant sensor using N,N-dimethyl-p-phenylene diamine (DMPD) as probe, from which ROS produced colored DMPD-quinone cationic radicals electrostatically retained on a Nafion membrane. The attenuation of initial color by antioxidants enabled indirect AOA estimation. The surface plasmon resonance absorption of silver nanoparticles as a result of enlargement of citrate-reduced seed particles by antioxidant addition enabled a linear response of AOA. We determined biothiols with Ellman reagent−derivatized gold nanoparticles

Microwave-assisted extraction of antioxidant compounds from by-products of Turkish hazelnut (Corylus avellana L.) using natural deep eutectic solvents: Modeling, optimization and phenolic characterization

© 2022 Elsevier LtdAn environmentally friendly method using natural deep eutectic solvents (NADES) and microwave-assisted extraction (MAE) for the recovery of bioactive compounds from hazelnut pomace (a hazelnut oil process by-product) was developed to contribute to their sustainable valorization. Eight different NADES were prepared for the extraction of antioxidant constituents from hazelnut pomace, and choline chloride:1,2-propylene glycol (CC-PG) was determined as the most suitable NADES, considering their extraction efficiency and physicochemical properties. After selecting suitable NADES, operational parameters for the MAE process of antioxidants from hazelnut pomace were optimized and modeled using response surface methodology. For the highest recovery of antioxidants, the operational parameters of the MAE process were found to be 24% water, 38 min, 92 °C and 18 mL/0.1 g-DS. Under optimized conditions, extracts of both pomace as a by-product and unprocessed hazelnut flours of three different hazelnut samples (Tombul, Çakıldak, and Palaz) were prepared, and their antioxidant capacities were evaluated by spectrophotometric methods. Antioxidant capacities of CC-PG extracts of all hazelnut samples were 2–3 times higher than those of ethanolic extracts. In addition, phenolic characterization of the prepared extracts was carried out using the UPLC-PDA-ESI-MS/MS system. The results of this study suggest that hazelnut by-products can potentially be considered an important and readily available source of natural antioxidants. Furthermore, the modeled MAE procedure has the potential to create an effective and sustainable alternative for pharmaceutical and food industries