Yield Of Total Phenolic Compounds Research Articles

Optimization of Extraction Method of Bioactive Compounds from Elderberries (Sambucus nigra L.) and Testing Extract Stability

Phenolic compounds from elderberries (Sambucus nigra L.) have attracted attention due to their potential health benefits. This paper examines different extraction methods used to obtain phenolic compounds from these fruits and the stability of the extracts. Several extraction techniques (extraction with continuous agitation, ultrasound-assisted extraction, microwave-assisted extraction, maceration, and enzyme-assisted extraction) were tested and compared to evaluate the yield and the quality of the extracts. The stability of the extracts with various storage parameters (time and temperature) and processing conditions (concentration and lyophilization) was also investigated. The results showed that ultrasound-assisted extraction (UAE) provided the highest yield of total phenolic compounds (74.89 mg GAE/g), of which 71.23% were represented by total anthocyanins and 62.50% by monomeric anthocyanins, with total flavonoids of 8.11–9.41 mg RUE/g. The analysis of individual phenolic compounds reconfirms the efficiency of UAE, obtaining 0.42–0.09 mg/g gallic acid, 0.59–0.01 mg/g chlorogenic acid, 0.17–0.03 mg/g 4-coumaric acid, and 2.43–0.01 mg/g rutin. The optimization of the extraction conditions led to the conclusion that the best solvent is 45% ethanol (v/v), and the optimal parameters are 40 °C for 40 min. It was also found that the stability of the extracts can be high during long periods of time (even after 180 days). These findings contribute to the understanding of the optimization of extraction processes and storage conditions to obtain extracts rich in phenolic compounds from elderberries, with potential uses in pharmaceutical and food applications.

Optimization of Ultrasonic-Assisted Extraction Condition for Total Phenolic Compounds from Citrus Hystrix Peel

This study aims to optimize the extraction conditions of Ultrasonic-Assisted Extraction (UAE) on the extraction of phenolic compound and antioxidant activity of Citrus Hystrix (C. Hystrix) peel. The experimental design was carried out using Face Centered Central Composite Design. A total of 20 sets of different combination experiment designs were generated from 3 parameters; temperature (30-50°C), time (20-40 min), and raw material to the solvent ratio (1:30-1:70). The highest yield of total phenolic compounds was 4.36 mg/g with the optimize extraction condition of , 30 min extraction time and 1:50 raw material to the solvent ratio. The result of this study indicates that the phenolic compounds extracted from C. Hystrix peel could have the potential to be used for pharmaceutical and food applications.

Extraction of phenolic compounds from lucuma (Pouteria lucuma) seeds with natural deep eutectic solvents: modelling using response surface methodology and artificial neural networks

The present study aimed to extract polyphenolic compounds from lucuma (Pouteria lucuma) seeds using natural deep eutectic solvents (NADES) as a green, efficient, and environmentally friendly extraction. This was optimized by using the Response Surface Method (RSM) and comparing its predictive capacity with Artificial Neural Networks (ANN) and Convolutional Neural Networks (CNN). Four NADES were prepared by mixing lactic acid (LA) with each of the following reagents: sodium acetate (SA), urea (U), glucose (G), and ammonium acetate (AA), separately. The yield of total phenolic compounds (TPC) obtained from lucuma seeds with each NADES was measured as an optimization criterion with the Box-Benhken design. The following factors were evaluated: time, temperature, and the lucuma seed flour (LSF): NADES ratio. The response variables were TPC and antioxidant activity. The LA-AA extract was selected because it exhibited the highest TPC value and was analyzed by UHPLC–MS (Ultra-performance Liquid Chromatography-Mass Spectrometry). From the RSM, the optimal extraction parameters were 80 min, 52°C, and LSF: NADES ratio of 8:100 (w/v), obtaining a TPC value of 3601.51 ± 0.51 mg GAE/100 g LFS. UHPLC–MS analysis evidenced the formation of epigallocatechin isomers from epigallocatechin gallate. The predictive ability of ANNs compared to RSM was demonstrated.

Optimization of Aqueous Extraction of Polyphenols from Cuminum cyminum Seeds Using Response Surface Methodology and Assessment of Biological Activity.

(1) Background: Cumin seeds, extracted from the plant Cuminum cyminum, are abundant in phenolic compounds and have been extensively researched for their chemical makeup and biological effects. The objective of this research is to enhance the water extraction of polyphenols through the water bath (WB) technique and to evaluate the antiradical, antibacterial, and anticancer effects of the extract. (2) Methods: Response Surface Methodology was used to find the best parameters to extract polyphenols. Three experimental parameters, time, temperature, and solid-liquid ratio, were tested. The disc diffusion method has been used to determine the antimicrobial activities against Salmonella Typhimurium, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans. The antiradical activity was performed using the DPPH method, while total phenolic content was performed using Folin-Ciocalteu. High-Performance Liquid Chromatography (HPLC) was conducted to analyze the phytochemical profile of WB extracts. The anticancer activity of the lyophilized extract was assessed against three cancer cell lines (colon (HT29), lung (A549), and breast (MCF7) cancer cell lines).; (3) Results: The optimal conditions for water extraction were 130 min at 72 °C. The total phenolic compounds yield (14.7 mg GAE/g DM) and antioxidant activity (0.52 mg trolox eq./mL) were obtained using a 1:40 solid-liquid ratio. The primary polyphenols identified were the flavonoids rutin (0.1 ppm) and ellagic acid (3.78 ppm). The extract had no antibacterial or antifungal activities against the microorganisms tested. The extract showed anticancer activity of about 98% against MCF7 (breast cancer cell line), about 81% against HT29 (colon cancer cell line), and 85% against A549 (lung cancer cell line) at high doses. (4) Conclusions: Extraction time and a high solid-liquid ratio had a positive impact on polyphenol recovery and in maintaining their quantity and quality. Furthermore, the optimal aqueous extract exhibited strong antiradical activity reflected by the inhibition of free radicals in addition to a significant specificity against the tested cancer cell lines.

Ultrasound-assisted extraction of shikimic acid and determination of total phenolic compounds in water hyacinth: Grey-based Taguchi optimization

Shikimic acid (SA) is a precursor for formulating the antiviral drug oseltamivir phosphate (Tamiflu®). Ultrasound-assisted extraction was employed to extract shikimic acid using water as a solvent and to determine total phenolic compounds (TPC) from water hyacinth. Grey-based Taguchi optimization was used to optimize the yield of shikimic acid and TPC by varying four distinct parameters. The best results for the yield of SA, i.e., 3.3 % (20 min time, 20 mL water volume, 60 % amplitude, and 40 % pulse ratio) and 3.2 % (30 min time, 20 mL solvent volume, 40 % amplitude, and 40 % pulse ratio) were observed using single and multi-response optimization, respectively for the stem. The best results for TPC, i.e., 12.24 mg GAE/ g biomass (20 min time, 40 mL solvent volume, 40 % amplitude, and 30 % pulse ratio) and 10.53 mg GAE/ g biomass (20 min time, 20 mL solvent volume, 50 % amplitude, 40 % pulse ratio) were obtained using single and multi-response optimization, respectively for leaves. The extraction was also performed for a whole plant (without segregation), and 1.66 % yield of SA (20 min time, 20 mL solvent volume, 50 % amplitude, 40 % pulse ratio) and TPC value of 8.84 mg GAE/ g biomass (40 min time, 30 mL solvent volume, 40 % amplitude, 40 % pulse ratio) were obtained.

Content and Yield of L-DOPA and Bioactive Compounds of Broad Bean Plants: Antioxidant and Anti-Inflammatory Activity In Vitro

The broad bean plant contains L-DOPA, a compound that is essential for patients with Parkinson’s disease. However, little has been reported on other broad bean compounds that have beneficial effects on health. The objective was to evaluate plants of four Mexican broad bean varieties to determine the content and yield of total phenolic compounds (TPC), total flavonoids (TF), and L-DOPA, as well as to analyze the flavonoid profile and antioxidant (AA) and anti-inflammatory (AANTI) activity in vitro. Broad bean seeds were sown in the field and plants were harvested 20 days after emergence. The analyses were performed with visible UV spectrophotometry and HPLC. The variety José María produced the highest yield of TPC (9.30 g m−2), TF (8.08 g m−2), and L-DOPA (5.64 g m−2) per unit of area. The highest yields per plant were obtained with the Rojita variety: TPC (0.25 g plant−1), TF (0.21 g plant−1), and L-DOPA (0.17 g plant−1). This variety also had the highest antioxidant (IC50 = 87.68 µg mL−1) and anti-inflammatory (IC50 = 74.40 mg mL−1) activity, which was attributed to the L-DOPA compounds and to rutin and isoorientins, respectively. The flavonoid profile revealed the presence of rutin and isoorientins, which had not been previously detected in the broad bean plant.

Microwave-assisted extraction optimization and conventional extraction of phenolic compounds from coriander leaves: UHPLC characterization and antioxidant activity

Background: Qualitative and quantitative investigations of bioactive compounds in plant materials are heavily based on the selection of an accurate extraction method. Aims: That’s why; this work consists of a comparative study between Microwave Assisted Extraction (MAE) and Conventional Extraction (CE), based on the total phenolic compounds (TPC) yield, phenolic profile, and antioxidant activity of coriander leaves powder (Coriandrum sativum L.). Material and Methods: MAE was optimized and performed using the Response Surface Methodology (RSM), and was modeled by using a second-order regression equation. While CE was done using the classic water bath method. Results: Under the optimal conditions, the recovery of TPC yield obtained was 37.94 ± 2.06 mg (MAE) vs 44.47 ± 0.57 mg GAE/g DW (CE). The UHPLC characterization showed a close phenolic composition of the two extracts, mainly represented by quercetin glucosides and by dimethoxycinnamoyl hexoside. No significant difference (p>0.05) was recorded in terms of the antioxidant activity of both extracts, as estimated by Ferric reducing antioxidant power (FRAP), Nitric oxide (NO•), and superoxide anion (O2•-) scavenging tests. Conclusions: Hence, the exploitation of MAE has many valuable advantages, as the processing time is brief and the antioxidant activities and phenolic composition were not affected by the extraction process.

Screening of anticandidal activity of Vaccinium corymbosum shoots’ extracts and content of polyphenolic compounds during seasonal variation

Background. A comprehensive analysis of polyphenols (flavonoids and proanthocyanidins) content of aqueous and hydroethanolic shoots’ extracts of Vaccinium corymbosum L. (highbush blueberry) (HB) cv. Elliott was performed. Materials and Methods. In this study, water and various concentrations of aqueous-ethanol (AE) were used as extragents, and plant material – the shoots of V. corymbosum harvested at stages of flowering (I), fruiting (II), after fruiting (III), and at the beginning of winter dormancy (IV). The anticandidal activity of aqueous (A) and AE extracts was studied with five strains of fungi: Candida pseudotropicalis (Kluyveromyces marxianus ATCC 4922=VKM Y-922), C. curvata (Cutaneotrichosporon curvatus ATCC 10567=VKM Y-2230), C. kefyr (Kluyveromyces marxianus VKM Y-459), C. parapsilosis ATCC 22019=UKM Y-73т=VKM Y-58 and C. tenuis ATCC 10573=UKM Y-1525т (Yamadazyma tenuis ATCC 10573=VKM Y-70). These strains were treated with extracts to investigate their effect on the growth of these microorganisms in vitro and compare with commercially available herbal medicinal extracts and antiseptic drugs. Anticandidal activity has been compared with the content of total phenolic compounds (flavonoids and proanthocyanidins). Results. Our results reveal that phenolic compounds concentration of V. corymbosum shoots’ extracts were significantly dependent on extragents and the stage of growth. The total content of phenolic compounds in aqueous-ethanol extracts was generally higher than aqueous and depended on the concentration of aqueous-ethanol. The highest extraction yield of total phenolic compounds was obtained using 40–80%-AE at all investigated stages. The highest content of flavonoids (105–123 mg·g-1 DW in quercetin equivalent) was observed at the stage of winter dormancy (IV). The content of proanthocyanidins was the highest at stages II and IV, and with 40–96% AEs as solvents; their contents varied within 178–239 mg·g-1 DW in catechin equivalent. Extracts prepared with 40–80% AE have pronounced inhibitory activities against all investigated Candida spp., but the maximum inhibition zone of a single strain may vary. High correlations indicate the determining effect of proanthocyanidins on the anticandidal activity of the extract. Conclusions. The study results indicate that V. corymbosum shoots may have promising properties in supporting therapy as anticandidal drugs.

Optimization of total polyphenol extraction and flavonoid screening by mass spectrometry in mango (Mangifera indica L.) waste from Peru

This research aims to optimize the extraction yield of total phenolic compounds (TPC) and quantify flavonoids by mass spectrometry in peel and kernel of mango (Mangifera indica L.), varieties: Edward, Kent, Haden, and Criollo from the department of Lambayeque, Peru, which resulted in eight samples. Mango peels and kernels were manually separated, frozen at -20 °C, freeze-dried, and ground (300 μm). For the extraction, the Central Composite Design was applied with the factors of ethanolic solution, time, and sample/volume ratio. The extracts determined TPCs by Folin-Ciocalteu and UV-Vis spectrophotometry expressed as gallic acid equivalent. Optimization was performed by the desirability function; Quercetin was also quantified by liquid chromatography-mass spectrometry (m/z). The highest yield of TPC content for Criollo mango kernel was obtained with 67.99% ethanolic solution, 89.94 min, and 0.343 g sample/10 mL ethanolic solution with R2 of 0.8966, and for Edward mango peel with 73.996% ethanolic solution, 58.5 min, and 0.432 g sample/10 mL ethanolic solution with R2 of 0.8020. For peel, the methanolic extract from Criollo mango peel had the highest Quercetin value at (23.28 ± 2.35 mg QE/100 g) (p < 0.05), and for kernels, in both extractions (ethanolic and methanolic), the four varieties did not present differences (p > 0.05).

Effect of Extraction Type on Bioactive Compounds and Antioxidant Activity of Moringa oleifera Lam. Leaves

The objective of this study was to determine the extraction yield, the content of bioactive compounds and in vitro antioxidant activity of different extracts from Moringa oleifera (MO) leaves, and their potential use as a natural feed additive for ruminant diets. For the preparation of MO extracts, three treatments were used: (1) MO extract in distilled water (MOEW, 0%), (2) ethanol-water (MOEEW, 50%) and (3) absolute ethanol (MOEE, 100%). The extraction yield and the antioxidant activity measured with the DPPH assay in the MO extracts were higher for MOEW and MOEEW. From all treatments, MOEEW had the highest antioxidant activity evaluated with the ABTS assay and showed a higher content of bioactive compounds. On the other hand, the principal component analysis showed that the first two principal components explained 96.5% of the variability of the data. The variables that contributed to the greatest variation were condensed tannins (CT), total phenolic compounds (TPC), total flavonoids (TF), and extraction yield. A high correlation (p ≤ 0.001) was observed between TPC and extraction yield with r2 = 0.989. The content of bioactive compounds and antioxidant activity was higher in the MOEEW extract; therefore, its inclusion in ruminant diets can be suggested to potentially improve their productivity and product quality.

Intensification of total phenolic compounds extraction from Azadirachta indica (Neem) leaves by ultrasound

The current work deals with ultrasound-assisted extraction (UAE) of the total phenolic compounds (TPC) from A. indica (Neem) leaves powder. Various process parameters have been optimized, including solvent screening, solid/solvent ratio, extraction temperature, particle size, power input, duty cycle, and sound wave frequency. The highest TPC yield of 11.87 mg of GA/g of powder was obtained at a time of 14 min, 70% ethanol as solvent, solid to solvent ratio of 1:30, particle size of 0.2–0.3 mm, extraction temperature of 40ºC, power input of 90 W, and duty cycle of 50%. The experimental outcomes obtained from the UAE have been matched with stirred batch and Soxhlet extraction of TPC, which shows that ultrasound, was relatively better than the traditional method. The UAE method has efficiently decreased the extraction time (14 min) and marginally improved the TPC yield from A. indica leaves. Further, Peleg's mathematical model was studied for the extraction kinetics and to calculate the predicted extraction values of the rate constant, initial rate, and equilibrium concentration for all investigational circumstances. The predicted values obtained from Peleg's mathematical model show a good fit with experimental outcomes.

Simultaneous extraction of proteins and carbohydrates, including phenolics, antioxidants, and macamide B from Peruvian maca (Lepidium meyenii Walp.)

Maca (Lepidium meyenii Walp.) has been used for nutritional and traditional purposes, owing to its chemical composition and the presence of bioactive compounds. This study aimed to develop and optimize a maceration-based method for the simultaneous extraction of total phenolic compounds (TPCs), total flavonoids (TFs), radical-scavenging activity (RSA), soluble proteins (SPs), total sugars (TSs), reducing sugars (RSs), and macamide B from maca using 95% ethanol and acidified ethanol. The effects of extraction parameters, including temperature, solvent-to-solid ratio, time, and acid concentration, on the extraction yield of TPCs, TFs, RSA, SPs, TSs, RSs, and macamide B were investigated. Optimal extraction was achieved at 40-60°C for 5-7.5 h with the solvent-to-solid ratio of 100:10. The addition of hydrochloric acid (HCl) to ethanol significantly improved the extraction yield, and maximum extraction was achieved using 1 N HCl in ethanol. The RSA of the ethanolic extracts showed a significant linear correlation (p&lt;0.001) with total extraction yield, TPCs, SPs, and TSs. These results imply that polyphenolic compounds, SPs/peptides, and polysaccharides are important determinants for the antioxidant function of maca. The optimized condition may be employed in nutraceutical industries to extract bioactive compounds from maca.

Exploring different strategies of separation of antioxidant compounds from winery by-products via surfactant-assisted processes for process intensification and integration

The impact of Tween20 surfactant, applied in native form or as colloidal gas aphrons (CGAs), on the extractability/purification enhancement of antioxidant compounds from grape skins (GS), compared to conventional solid–liquid extraction (SLE), was evaluated.Three strategies were developed (S1: partial ethanol replacement during SLE with aqueous Tween20 solutions; S2: CGAs application to GS-extract suspension from SLE; S3: Tween20 addition to extracts before spray-drying). The effect of surfactant/solvent concentration (S1), extract/CGAs volumetric ratio (S2), and surfactant addition (S3) on total phenolic compounds (TPC), total anthocyanin compounds (TAC), and antioxidant power of recovered phases, was investigated.In S1, using surfactants could not significantly reduce ethanol percentage in solvent to achieve a given TPC yield, but similar TAC yields than those from SLE were obtained when partially replacing ethanol with Tween20. In S2, CGAs allowed an averaged 40% recovery of TPC, and TAC contained in crude extract, with only a slight detected additional TAC recovery from exhausted GS. Adding surfactants within spray-drying processes (S3) enhanced the water solubility of powdered extracts, despite reducing the powder/phenolics yield due to increased sample stickiness.Results demonstrated the potential of employing food-grade surfactants at different stages of grape pomace valorization process for the recovery of antioxidant extracts.

Effect of ohmic heating on ultrasound extraction of phenolic compounds from cornelian cherry (Cornus mas)

In this study, total phenolic compounds (TPCs) from cornelian cherry were extracted by using maceration (ME), ultrasound extraction (UE), and ohmic heating-assisted ultrasound extraction (OAUE) methods. ME was used as a control group. It was observed that the ultrasound was effective on the yield of TPC in extraction and the effect was increased when this method was supported with ohmic heating (OH). The maximum TPC extracted was found to be 7.52 mg GAE/g dry matter (by using OAUE) which was 13% and 37% higher compared with that of obtained by UE and ME, respectively. It was also observed that the ohmic heating application decreased the extraction time by about 34% compared with UE. Moreover, the extracts obtained by OAUE had the highest total monomeric anthocyanin concentration and antioxidant activity. Consequently, the OH application prior to extraction played an active role in both obtaining the valuable compounds and decreasing the extraction time. Practical applications Cornelian cherry (Cornus mas), which is a natural antioxidant source, contains a significant number of valuable compounds (polyphenols, vitamins, minerals, etc.). Therefore, new extraction methods were used as an alternative to conventional methods (such as maceration) to extract the valuable compounds. It was observed that novel methods such as ultrasound and ohmic heating-assisted extraction had a positive effect to increase extraction yield and saving time. Highly efficient applications (such as ohmic heating) on the extraction of bioactive compounds from food materials open up a new horizon in the food industry.

Phenolic compounds, antimicrobial activity, cytotoxicity, and identification of phytochemicals present in Inga marginata Willd seeds

Brazil has an invaluable source of plants and fruits rich in phenolic compounds important to health, some of which have yet to be discovered. Inga marginata Willd is a fruit that can be found throughout Brazil, and its seeds are rich in phenolic compounds and antimicrobial activity, thus making their extraction and characterization highly relevant. This study aimed to determine the total phenolic compounds, antioxidant capacity, antibacterial and antifungal activities, cytotoxicity evaluation, and characterize the phytochemical compounds present in the extract. The results indicated that extraction by agitation at 30 ºC obtained the highest yield of total phenolic compounds (48.23 mg GAE g-1), antioxidant capacity (40.34 mg TEAC g-1), and IC50 (2.60 mg mL-1). The extracts at 30 and 60 ºC inhibited all microorganisms tested, and the temperature of 30 ºC acted as a bactericide and fungicide at low concentrations. Ten phytochemical compounds were found, mainly being antioxidants and antimicrobials. The cytotoxicity assays showed that Inga marginata seeds do not present cellular cytotoxicity up to the concentration of 250 µg mL-1, maintaining cell viability above 90%.

Optimization of Ultrasonic-assisted Extraction of Total Phenolic Compound from Leaves of Chromolaena Odorata L. Using Response Surface Methodology

Chromolaena odorata L. or C. odorata is a weed that found in tropical continents . Leaves, roots and flowers of C. odorata have been used as medicinal plants for centuries. Preliminary phytochemical screening showed the chemical composition of its extracts having phenolic compounds such as flavonoids, saponins, tannins and steroids. The total phenolic compounds (TPC) in medicinal plants are acknowledged as biochemical activities such as antiinflammatory, antiviral, antimicrobial, antioxidant agents and etc. This work is interested in antioxidant and antimicrobial activity of an ethanolic extract of C. odorata leaves. Though, many solvents can be used to extract TPC from plants. Ethanol with ultrasound assisted extraction was selected. The response surface methodology coupled with the nonlinear solver were used to find the optimal extraction variables. The Central Composite Design (CCD) was employed as the sampling technique. Three variables are the ratio of ethanol to the dried leaves of C. odorata (X1), aqueous ethanol concentration (X2), and the extraction time (X3). The extraction conditions were fixed at 40 kHz and 60 ˚C. The maximum yield of TPC was 111.77 mg GAE/g dry extract at 57 % v/v of aqueous ethanol concentration, 43 mL of solvent/g of dried sample and 35 minutes extraction time.

Evaluation of Direct Ultrasound-Assisted Extraction of Phenolic Compounds from Potato Peels

Potato peels (PPs) are generally considered as agriculture waste. The United States alone generates over one million tons of PPs a year. However, PPs contain valuable phenolic compounds with antioxidant activities. In this study, we evaluated the efficiency of ultrasound-assisted extraction techniques in recovering antioxidants from PPs. These techniques included a direct ultrasound-assisted extraction (DUAE), an indirect ultrasound-assisted extraction (IUAE), and a conventional shaking extraction (CSE). Results of this study showed that DUAE was more effective in extracting phenolic compounds than IUAE and CSE. We also evaluated the factors affecting the yield of total phenolic compounds (TPC) in DUAE, including the temperature, time, acoustic power, ratio of solvent to solids, and size of PPs particles. TPC yield of DUAE was higher, and the extraction rate was faster than IUAE and CSE. Furthermore, TPC yield was strongly correlated to the temperature of the mixture of PPs suspension. SEM images revealed that the irradiation of ultrasound energy from DUAE caused micro-fractures and the opening of PPs cells. The extract obtained from DUAE was found to have antioxidant activity comparable to commercial synthetic antioxidants. Results of this preliminary study suggest that DUAE has the potential to transform PPs from agricultural waste to a valuable ingredient. A future systematic research study is proposed to advance the knowledge of the impact of processing parameters in the kinetics of phenolic compounds extraction from potato peels using various extraction methods.

Comparison of the Effect of Acids in Solvent Mixtures for Extraction of Phenolic Compounds From Aronia melanocarpa

Thirty-two different solvent mixtures containing methanol and acid (acetic, formic, and hydrochloric); methanol, water, and acid; and pure methanol were tested for their efficiency for extraction of phenolic compounds from aronia ( Aronia melanocarpa) belonging to the groups of anthocyanins, flavonols, and hydroxycinnamic acid derivatives. Thirteen compounds were detected and quantified in the extracts using HPLC/DAD/ESI-MS n. The yield of each compound and group was evaluated with regard to the extraction solvent composition. Extraction mixtures containing HCl were superior to the ones containing acetic or formic acid for the extraction yield of total phenolic compounds, which was especially pronounced for anthocyanins. The solvent mixture containing methanol/water/HCl (90:8:2, v/v/v) gave best results for the qualitative and quantitative assay of anthocyanins. However, this solvent mixture caused O-methylation of 3- and 5-caffeoylquinic acids transforming them to 3- and 5-feruloylquinic acids, respectively, during extraction. This peculiar finding must be taken into account during sample preparation for the analysis of polyphenols in any sample. It was observed that this O-methylation is specific for dihydroxycinnamic acid compounds containing neighboring hydroxyl groups. These results suggest the need for a detailed study of the behavior of various polyphenolic compounds during extraction with solvent mixtures containing methanol/HCl since it is very often used for the analysis of anthocyanins.

Catalytic fast pyrolysis of walnut shell with K/AC catalyst for the production of phenolic-rich bio-oil

Potassium supported on commercial activated carbon (K/AC) catalysts were prepared and used for catalytic fast pyrolysis (CFP) of walnut shell to produce phenolic-rich bio-oil. Pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and fixed-bed CFP tests were performed to reveal the influences of pyrolytic temperature, potassium loading and catalyst-to-biomass (C-to-B) ratio on the product distribution. The Py–GC/MS results showed that the K5.79/AC catalyst in which the potassium loading was 5.79% exhibited the maximal improvement on the yield of phenolic compounds. Pyrolytic temperature significantly affected the total phenolic yield, which achieved the maximum value at 450 °C whether with or without catalysts. Moreover, the C-to-B ratio also dramatically affected the yield of phenolic compounds. The total phenolic yield raised with increasing C-to-B ratio, whereas the excessive C-to-B ratio (higher than 3:1) would lead to an obvious decrease in total phenolic yield. Overall, the yield of total phenolic compounds achieved the maximum value of 145.65 mg/g (14.57 wt%) at 450 °C under C-to-B ratio of 3:1 in Py–GC/MS runs. Meanwhile, the lab-scale experiments obtained the maximal total phenolic yield of 135.13 mg/g (13.51 wt%) at 450 °C under C-to-B ratio of 1:3.

High-Voltage Electrical Discharges in Green Extractions of Bioactives from Oregano Leaves (Origanum vulgare L.) Using Water and Ethanol as Green Solvents Assessed by Theoretical and Experimental Procedures

Development of green extractions of natural compounds is an ongoing challenge for researches. The aim of the study was to evaluate the extraction of bioactive compounds (BACs) from oregano combining an experimental procedure with a theoretical approach using two computational simulation methods, Hansen solubility parameters (HSP) and conductor-like screening model for real solvents (COSMO-RS) software. In this study, the high-voltage electrical discharge-plasma (HVED) was used as one of new promising green extraction techniques. Optimization of processing extraction parameters (argon and nitrogen for generation of plasma, voltage―15 kV, 20 kV, and/or 25 kV), frequency (100 Hz), pulse duration (400 ns), and treatment time (3 and 9 min) was done using software STATGRAPHICS. Oregano extracts were prepared by pharmacopoeia, 1 g per 50 mL of solvents (water or aqueous ethanol (25 and 50% v/v) treated by HVED. Extraction process was controlled by analytical methods (determination of total phenolic compounds (TPC); antioxidant properties by electronic paramagnetic resonance (EPR), 2,2-diphenyl-2-picrylhydrazyl (DPPH) free radical assay; near-infrared (NIR) spectroscopy; and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) characterization of phenolic compounds, and changes during and after extraction process were investigated. Process follows six principles of green extractions. Theoretical results were in line with experimental for solvent selection; ethanol had higher potential of solubility of BACs than water. Results showed that HVED, as a green extraction method, confirmed high potential for extraction of BACs from oregano with increased yield of individual BACs and TPC in obtained extracts and increased antioxidant activity, compared with untreated samples.