scholarly journals Comparison of antioxidant activity of extracts of hop leaves harvested in different years

2019 ◽  
Vol 65 (3) ◽  
pp. 1-9 ◽  
Author(s):  
Anna Muzykiewicz ◽  
Anna Nowak ◽  
Joanna Zielonka-Brzezicka ◽  
Katarzyna Florkowska ◽  
Wiktoria Duchnik ◽  
...  

Summary Introduction: Hop (Humulus lupulus L.) is a common plant in Europe, with many beneficial health effects. In addition to the use in brewing, hops are a valuable source of active substances used in conventional and folk medicine, such as humulones and lupulones, as well as antioxidants, including phenolic compounds. Objective: The aim of the study was to evaluate and compare the antioxidant activity of alcoholic extracts of fresh hop leaves collected in 2017 and 2018. Material and methods: The raw material consisting of fresh hop leaves was extracted using ultrasound-assisted extraction. Methyl, ethyl and isopropyl alcohol at three concentrations were used as extractants. The antioxidant activity of extracts was determined using DPPH and FRAP methods. Total phenolic content was evaluated using the Folin-Ciocalteu technique. Results: All the extracts showed antioxidant potential as well as the phenolic content. Regardless of the harvesting year and methods of evaluation, the highest antioxidant activity and the total polyphenol content were observed for extracts prepared in undiluted methanol, obtained during one hour lasting extraction. Conclusion: The results of the studies have suggested that hop leaves can be a potential source of health-promoting antioxidants.

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 582
Author(s):  
Inês Mansinhos ◽  
Sandra Gonçalves ◽  
Raquel Rodríguez-Solana ◽  
José Luis Ordóñez-Díaz ◽  
José Manuel Moreno-Rojas ◽  
...  

The present study aimed at evaluating the effectiveness of different natural deep eutectic solvents (NADES) on the extraction of phenolic compounds from Lavandula pedunculata subsp. lusitanica (Chaytor) Franco, on the antioxidant activity, and acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and tyrosinase (Tyr) inhibitory capacities. Ten different NADES were used in this research and compared with conventional solvents. Ultrasound-assisted extraction (UAE) for 60 min proved to be the best extraction condition, and proline:lactic acid (1:1) and choline chloride:urea (1:2) extracts showed the highest total phenolic contents (56.00 ± 0.77 mgGAE/gdw) and antioxidant activity [64.35 ± 1.74 mgTE/gdw and 72.13 ± 0.97 mgTE/gdw in 2.2-diphenyl-1-picrylhydrazyl (DPPH) and 2.2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods, respectively]. These extracts also exhibited enzymes inhibitory capacity particularly against Tyr and AChE. Even so, organic acid-based NADES showed to be the best extractants producing extracts with considerable ability to inhibit enzymes. Twenty-four phenolic compounds were identified by HPLC-HRMS, being rosmarinic acid, ferulic acid and salvianolic acid B the major compounds. The results confirmed that the combination of UAE and NADES provide an excellent alternative to organic solvents for sustainable and green extraction, and have huge potential for use in industrial applications involving the extraction of bioactive compounds from plants.


2020 ◽  
Vol 16 (1-2) ◽  
Author(s):  
Cassiano Brown da Rocha ◽  
Caciano Pelayo Zapata Noreña

AbstractThe grape pomace is a by-product from the industrial processing of grape juice, which can be used as a source of bioactive compounds. The aim of this study was to separate the phenolic compounds from grape pomace using an acidic aqueous solution with 2 % citric acid as a solvent, using both ultrasound-assisted extraction, with powers of 250, 350 and 450 W and times of 5, 10 and 15 min, and microwave-assisted extraction using powers of 600, 800 and 1,000 W and times of 5, 7 and 10 min. The results showed that for both methods of extraction, the contents of total phenolic compounds and antioxidant activity by ABTS and DPPH increased with time, and microwave at 1,000 W for 10 min corresponded to the best extraction condition. However, the contents of phenolic compounds and antioxidant activity were lower than exhaustive extraction using acidified methanol solution.


Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1120
Author(s):  
María del Carmen Razola-Diaz ◽  
Eduardo Jesús Guerra-Hernández ◽  
Celia Rodríguez-Pérez ◽  
Ana María Gómez-Caravaca ◽  
Belén García-Villanova ◽  
...  

Orange peel is the main by-product from orange juice industry. It is a known source of bioactive compounds, mostly phenolic compounds, and it has been widely studied for its healthy activities. Thus, this research focuses on the establishment of ultrasound-assisted extraction of phenolic compounds in orange peel using a sonotrode. For this purpose, a Box–Behnken design of 27 experiments was carried out with four independent factors—ratio ethanol/water (v/v), time (min), amplitude (%), and pulse (%). Quantitative analyses of phenolic compounds were performed and the antioxidant activity was measured by ABTS and DPPH methods. The validity of the experimental design was confirmed by ANOVA and the optimal sonotrode extraction conditions were obtained by response surface methodology (RSM). The extracts obtained in the established conditions were analyzed by High Performance Liquid Chromatography (HPLC) coupled to mass spectrometer detector and 74 polar compounds were identified. The highest phenolic content and antioxidant activity were obtained using 45/55 ethanol/water (v/v), 35 min, amplitude 90% (110 W), and pulse 100%. The established method allows an increment of phenolics recovery up to 60% higher than a conventional extraction. Moreover, the effect of drying on phenolic content was also evaluated.


Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3104 ◽  
Author(s):  
Alessandra Braca ◽  
Chiara Sinisgalli ◽  
Marinella De Leo ◽  
Beatrice Muscatello ◽  
Pier Luigi Cioni ◽  
...  

Background: Adansonia digitata L. (Malvaceae), also known as baobab, is a tree attracting recent interest especially due to the high nutritional value of the fruit pulp. However, few studies are reported on the secondary metabolite content, showing high variability depending on the geographic region. Methods: In this study, the chemical profiles of Malian commercial baobab fruits and leaves, focused on phenolic content, were investigated by HPLC coupled with a photodiode array (PDA)/UV and an electrospray ionization (ESI) mass spectrometer (MS) and gas chromatography (GC)/MS. In addition, the extracts of fruit pulps obtained from three different markets (Fruits 1, 2, and 3) were evaluated for their total phenolic content (TPC), antioxidant activity and α-glucosidase inhibition. Results: Baobab fruit pulps were found to be rich in procyanidins and flavonol glycosides, with tiliroside as the major constituent. The baobab leaves showed a similar profile respect to the fruits, but with more detected phenolics. All fruit pulp extracts exerted antioxidant activity (highest for Fruit 3) and higher α-glucosidase inhibition than acarbose used as standard. Conclusions: This study confirmed the variability of baobab with different origins and indicated Malian species baobab as a promising source of health-promoting substances.


The pomelo peel occupies 50% of the fruit mass in pomelo juice processing. It contains large amounts of phenolic compounds, which may provide benefits to human health. These components should be isolated. In this study, the effects of ethanol concentrations, material-to-solvent ratios (g/mL), temperatures and sonication time on total phenolic content (TPC), naringin content and antioxidant capacity (using DPPH assay) of extract solution was evaluated. The results showed that all experimental factors significantly influenced the extraction of total polyphenol content, naringin content, and antioxidant capacity of the extract. The extraction condition was ethanol 80%, material-to-solvent ratio of 1:25 (w/v) at 60oC, and sonication time of 7.5 min, gave the extract had total phenolic content of 9.05 ± 0.08 mg GAE/g DM, naringin content of 4.65 ± 0.08 mg NE/ g DM, and antioxidant capacity of 4.76 ± 0.03 mg AAE/g DM. The ultrasound treatment was a useful method for improving the extraction of phenolic acid compounds from pomelo peel.


2014 ◽  
Vol 4 (2) ◽  
pp. 68 ◽  
Author(s):  
Umesh C. Lohani ◽  
Kasiviswanathan Muthukumarappan

Although extrusion is a promising process to develop ready to eat cereals and snacks, thermal treatment to raw material during extrusion results in degradation of phenolic compounds. Therefore, an approach was made to enhance the total phenolic content (TPC) and antioxidant activity (AA) of apple pomace (AP) prior to extrusion process. In this study, AP powder was naturally fermented (F) for 12 h and then was subjected to ultrasonication (U) at various conditions [25, 37, and 50 µm ultrasonication amplitude (UA) for 1, 2, and 3 min of ultrasonication time (UT)]. AP was then dried in oven (O) and microwave (MW), separately and thus four drying methods, i.e. O<sub>F</sub>-O<sub>U</sub>, O<sub>F</sub>-MW<sub>U</sub>, MW<sub>F</sub>-O<sub>U</sub>, MW<sub>F</sub>-MW<sub>U</sub> were used in combinations. Full factorial design was used for experimental plan and results were analyzed using statistical software. It was observed that drying method significantly affected the TPC and AA of AP powder followed by UA. UT did not have any significant effect on TPC, and AA. Maximum TPC, and AA observed for the AP powder dried in MW after fermentation and ultrasonication (MW<sub>F</sub>-MW<sub>U</sub>) at 50 µm UA for 3 min UT were 372.98 mg GAE/100g DW, and 729.67 µmol TE/100 g DW, respectively. MW<sub>F</sub>-MW<sub>U</sub> drying exhibited a more prominent disrupted and porous structure of AP powder compared with that of O<sub>F</sub>-O<sub>U</sub> drying.


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