Solvents used during extraction process are reported to have an influence on the nature and the amount of secondary metabolites extracted from medicinal plants. Thus, the choice of proper extraction ...solvent is necessary for the desired pharmacological activity of these extracts. In the present study, we extracted six medicinal plants grown in Sudan, namely, Blepharis linariifolia, Cyperus rotundus, Guiera senegalensis, Maerua pseudopetalosa, Tinospora bakis and Dicoma tomentosa with six solvents of different polarity, i.e. water, 50% ethanol (EtOH), 70% EtOH, 95% EtOH, acetone and dichloromethane to obtain total 36 extracts. Quantitative estimation of total phenolic and flavonoid contents was performed. These extracts were further evaluated for their free radical scavenging activities and α-glucosidase, pancreatic lipase and tyrosinase inhibitory activities. 50% EtOH and 70% EtOH extracts of G. senegalensis showed the highest content of phenolic compounds in comparison to other extracts. For total flavonoid contents, higher content was found in acetone extracts of G. senegalensis followed by B. linariifolia and M. pseudopetalosa. Polar extracts showed higher free radical scavenging activity in comparison to dichloromethane extract, with 70% EtOH and 50% EtOH extracts of G. senegalensis being the most active ones. The 50% EtOH and 70% EtOH extracts G. senegalensis also showed the potent inhibitory activity against α-glucosidase. In contrast, acetone and dichloromethane extracts showed potent pancreatic lipase inhibitory activity. Potent tyrosinase inhibitory activity was shown by acetone extract of G. senegalensis. In conclusion, 50% EtOH, 70% EtOH and acetone were found to be the best solvents of choice for the extraction of phenolic compound rich extracts with free radical scavenging and enzyme inhibitory activities. Further studies should focus on the isolation and identification of active secondary metabolites from these extracts.
•Six medicinal plants from Sudan were extracted with solvents of different polarity.•Total phenolic and flavonoid contents of extracts were analyzed.•Extracts were evaluated for their free radical scavenging and enzyme inhibitory activities.•Extraction solvents had variable effect on the content of secondary metabolites and bioactivities.
In this paper, the kinetics of polyphenols extraction from spruce bark (Picea abies) under ultrasounds action was investigated. Studies were performed in order to express the effect of some specific ...parameters (as: ultrasounds, surface contact between solvent and solid, extraction time and temperature) on the total phenolic content (TPC). Experiments were performed in the presence and absence of ultrasounds, using different contact surfaces between solvent and solid, for times from 5 to 75min and temperatures of 318, 323 and 333K. All these factors have a positive influence on the process, enhancing the extraction rate by recovering higher amounts of polyphenols. The process takes place in two stages: a fast one in the first 20–30min (first stage), followed by a slow one approaching to an equilibrium concentration after 40min (second stage). In these conditions, the second-order kinetic model was successfully developed for describing the mechanism of ultrasound-assisted extraction of polyphenols from P. abies bark. Based on this model, values of second-order extraction rate constant (k), initial extraction rate (h), saturation concentration (Cs) and activation energy (Ea) could be predicted. Model validation was done by plotting experimental and predicted values of TPC’s, revealing a very good correlation between the obtained data (R2>0.98).
Current study illustrates the impact assessment of TiO2 nano-particle seed priming on the overall germination, physiology in maize thriving under salinity stress.
Seeds of maize cultivar were soaked ...in 40, 60 and 80 ppm aerated solution of TiO2nano-particle for one day and nano-primed seeds were then exposed to salinity stress, i.e., 200 mM NaCl on paper culture system.
Results indicated that 60 ppm TiO2nano-priming treatment effect positively on the rate of germinate and growth of maize seedling under salinity stress. The experiment was carried out in sand as a growth medium with 60 ppm TiO2 priming. Results exhibited that germination percentage, germination energy, seedling vigor index, lengths of root and shoot, fresh and dry weights of seedling, potassium ion (K+) concentration, relative water content (RWC), total phenolic and proline and contents, superoxide dismutase (SOD), catalase (CAT) and phenylalanine ammonia lyase (PAL) activities were significantly enhanced and mean emergence time (MET), sodium ion (Na+) concentration, membrane electrolyte leakage (MEL) and malondialdehyde (MDA) content were decreased by TiO2 priming as compared to control under salinity stress.
So, nano-priming with TiO2 mitigates the salinity injury in maize and could be a significant alternate strategy to mitigate the deleterious impact of salinity stress in maize.
•A novel intermittent microwave convective drying (IMCD) model was developed.•The model predicted accurately drying process, bioactive compounds and colour changes.•Effects of different IMCD ...conditions on quality changes are discussed.•The model can predict accurately quality indices over a range of IMCD conditions.
Intermittent microwave convective drying (IMCD) is an advanced drying method where volumetric heating of samples drives the drying process. Understanding of the physical effects of IMCD on simultaneous heating and mass transfer as well as quality changes during IMCD is essential to predict accurately drying processes and quality attributes of end products. However, there is a lack of studies in this particular interest area. The aim of this research was to develop an IMCD model coupled with quality degradation kinetics by integrating a simultaneous heat and mass transfer model with Maxwell’s equations for microwave heating and the chemical reaction kinetics model. The simulated results were compared with experimental results and a good agreement was observed. As it was found that power ratio (PR) had a vital role in altering quality attributes, different PR and drying conditions were considered to investigate the effects of IMCD on the drying kinetics. The simulated results showed that the model was capable of predicting accurately moisture and temperature distributions along with heath beneficial compounds, such as total phenolic content (TPC) and ascorbic acid (AA) as well as colour changes during IMCD processing. About 70% of AA was degraded during IMCD drying using PR of 1/3. However, losses were reduced when PR was reduced to 1/4 or 1/5. Likewise, TPC degraded significantly during the early stages (first 60 min) of IMCD processing but stabilised at later stages.
Hydration, a crucial preliminary stage of dried bean processing is mostly performed as a slow, batch-wise process. Here we investigated the effect of thermal and pulsed electric field (PEF)-assisted ...hydration of two common beans (Phaseolus vulgaris) on hydration behaviour, mass loss and leaching of bioactive components. Beans were hydrated in media either using a thermal process (30–80 °C, 10 °C intervals) until equilibrium moisture content (EMC) was reached or were hydrated to 40 g/100 g dry basis moisture at 45 °C, then PEF-treated at an electric field intensity of 4 kV/cm, f = 2 Hz, pulse width 15 μs, pulse numbers from 200 to 1000 (specific energy from 91 kJ/kg to 455 kJ/kg) and further hydrated until EMC. PEF-assisted hydration reached higher equilibrium moisture values and reduced the hydration time by 3-fold for small red beans (1000 pulses, 455 kJ/kg specific energy) compared to 45 °C soak, however, it also leached higher amounts of bioactive polyphenols into the media. Comparable losses of prebiotic oligosaccharides from beans into the media were found in the two hydration approaches. PEF-assisted hydration is a promising alternative to soaking to reduce process time for slow hydrating beans and leaching of bioactive components could be minimised through process optimization.
•PEF-assisted hydration gave higher final moisture contents compared with thermal soaking.•PEF reduced bean hydration time by 3-fold compared with 45 °C soaking.•More bioactive polyphenols were leached from beans during PEF-hydration.•Prebiotic oligosaccharide leaching was similar during thermal and PEF assisted hydration.
This study aimed to evaluate the physical properties and antioxidant activity of buuz wrappers and to determine the appropriate ratio for replacement of wheat flour (WF) with buckwheat flour (BF). ...Wrappers were prepared with four ratios of BF and WF: 0:100 (BF0), 25:75 (BF25), 50:50 (BF50), and 75:25 (BF75). The total phenolic content (TPC) and DPPH free-radical-scavenging activity were highest in BF75 wrappers and lowest in BF0 wrappers, while the opposite trend was observed for toughness and extension. Steamed BF50 wrappers could be prepared without cracks and had similar toughness and 2.43- and 4.79-fold higher TPC and DPPH free-radical-scavenging activity than BF0 wrappers. In conclusion, the optimal substitution ratio for replacement of WF with BF in buuz wrappers was 50:50.
This work aims to explore chemometric methods for determining the total phenolic content in Brazilian standard American lager beers using synchronous fluorescence spectroscopy fused data. Two hundred ...and sixteen (216) beer samples were diluted at a ratio of 1:5 (v/v), sonicated for 15 min in a water bath, and buffered using an acetic acid/acetate buffer of pH 4.5. The synchronous fluorescence spectra were obtained from 200 to 600 nm with a resolution of 1 nm. However, different offsets were tested for synchronous fluorescence (Δλ = 20, 50, and 80). All measurements were carried out in triplicate, and the Folin-Ciocalteu method was used as the reference method for the total phenolic content. All chemometric methods were explored using R software and its graphic interface, RStudio. First, the spectral data with different offsets were normalized and fused. After this, the fused data were smoothed with the Savitzky-Golay algorithm with a window of length 11 and a quadratic polynomial, followed by data mean centering. Robust principal component analysis (ROBPCA) was used to identify anomalous data. The Kennard-Stone algorithm was used to split the dataset into 75% for the training set and 25% for the test set. The prediction models used were partial least squares (PLS), orthogonal partial least squares (O-PLS), and elastic net regressions with cross-validation (CV). Ensemble PLS and ensemble sparse PLS with bootstrap resampling were also used. Other PLS regression methods based on the selection of variables were tested, such as significance multivariate regression (sMC – PLS), uninformative variable elimination (UVE – PLS), and interval PLS (iPLS) global and optimized models with cross-validation. All the regression models were built with the training set. The validation was carried out with the application of the regression models to the test set. Within this context, two multivariate regression were highlighted, the CV elastic net and iPLS optimized models, with the root mean square error of prediction (RMSEP) equaling 1.0 and 1.1 mg GAE L−1, respectively.
•The phenolic content in beers was determined by synchronous fluorescence spectroscopy.•The model using fused spectra produced a better result than spectra with one offset.•Cross-validation Elastic Net gave the lowest RMSEP and equal to 1.0 mg GAE.L−1.•iPLS optimized model produced a better performance with QF32 > 0.65
Recently, discovering natural antioxidants have gained more interest due to the fact that most infectious ailment, namely cardiovascular disorder, diabetes and cancer are associated with free radical ...cells. Thus, the extraction of phenolic compounds from Vernonia cinerea leaves through Soxhlet extraction method was studied. The effects of extraction time (1–4 h), feed-to-solvent (1:10–1:25 g/mL) and ethanol concentration (20–80% v/v) on the yield of extract, total phenolic content (TPC) and total flavonoid content (TFC) were examined. Moreover, the phenolic compounds and functional groups in the extract at maximum conditions were identified using Liquid Chromatography-Mass Spectrometry Quadrupole Time of Flight (LC–Q–TOF–MS) and Fourier Transform Infrared Spectrometry (FTIR), respectively. The antioxidant activity of the extract was as well investigated. The experimental results showed that the highest yield of extract (10.01 ± 0.85% w/w), TPC (53.96 ± 1.45 mg GAE/g d.w.) and TFC (30.09 ± 0.44 mg QE/g d.w.) were achieved using extraction time of 2 h, feed-to-solvent of 1:20 g/mL and ethanol concentration of 60% v/v. However, the extract reflected good antioxidant activity.
This study purpose was to investigate the effect of radiofrequency low pressure cold plasma (LPCP) process by using dried peppermint (Mentha piperita) on the reduction in microbial load, antioxidant ...activity, total phenolic content, and color. The microbial load of the sample was investigated by infecting it with 106 CFU/g of Escherichia coli O157:H7, and after treatment with LPCP at 20, 50, and 60 W for 20 min. It was found that LPCP process had a significant effect on the removal of E. coli O157:H7 at 50 and 60 W, but at 20 W revealed no significant effect on this bacterium removal (p > 0.05). The LPCP significantly increased the total phenolic content (p < 0.05); consequently, antioxidant activity increased after studying the antioxidant properties by two methods of FRAP and DPPH in all 3 powers. The results also indicated that the LPCP darkened the treated sample's color.
•Dry peppermint was treated by RF low pressure cold plasma.•Escherichia coli O157:H7 removed after treatment for 20 min at 50 and 60 W.•50 W significantly increased total phenolic content and antioxidant activity.•Low pressure cold plasma significantly darkened the treated sample's color.
Propolis is considered to contain a variety of polyphenols (flavonoids, phenolic acids and their esters), waxes, steroids and terpenoids and its contents may be influenced by the vegetation at the ...site of collection as well as the species of stingless bees. The purpose of this study is to investigate the total phenolic and flavonoid content and the correlation that may exist between the mentioned class of compounds and the antioxidant properties. The ethanolic extract of propolis samples were prepared from three different stingless bee species namely Tetrigona apicalis, Heterotrigona itama and Geniotrigona thoracica, collected from one of the bee farms located in Perak, Malaysia. Antioxidant activity of the propolis samples was examined by three different methods which were DPPH, ABTS and FRAP assay. Total phenolic and total flavonoid content were determined by using Folin-Ciocalteu and aluminium chloride colorimetric method, respectively. The result shows that all propolis samples exhibited positive antioxidant activity. Propolis of G. thoracica was found to be the most potent sample in all antioxidant tests. The analysis between total phenolic and flavonoid content of propolis and its antioxidant properties were found to have a strong correlation. These results signify that the potency of propolis derived from different species is variable, depending on the phytochemical contents, thus further study on the specific bioactive compounds would be the area of interest in the near future.
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