Extraction Of Bioactive Phenolic Compounds Research Articles

Ohmic heating-based extraction of biocompounds from cocoa bean shell

Cocoa bean shell (CBS), a by-product of the chocolate industry, was employed as substrate for the sustainable recovery of bioactive compounds using ohmic heating (OH). Total phenolic content and antioxidant activity of the treated CBS were optimized by experimental design. Maximum extraction of antioxidant phenolic compounds (23 mg GAE/g CBS) was obtained at 67 °C, 50 min and 44% ethanol (v/v). The antioxidant activity of the extracts obtained under of the central point conditions was 284.5 μM Fe2+/g extract (FRAP) and 36.4 μM TE/g extract (DPPH). The use of OH increased the extraction of bioactive phenolic compounds when compared to the conventional process (CH) (approximately 40%). An increased on the chemical antioxidant activity was also observed, ranging from 4 to 20%. The metabolic activity of the extracts obtained by the two methods (OH and CH) was evaluated in non-tumoral (HEK293T and L929) and tumoral cell lines (Caco-2, HT-29, and HeLa). The CBS extracts presented low toxicity in non-tumoral cells and ROS preventive effects. These characteristics make them ideal to be used in food processing and formulation, as well as nutraceutical products due to their antioxidant protection. The use of OH results in an extract with higher phenolic content and higher antioxidant activity and low environmental impact.

Deep Eutectic Solvents as a Green Tool for the Extraction of Bioactive Phenolic Compounds from Avocado Peels.

Avocado peels are the main agro-industrial residue generated during the avocado processing, being a rich source of bioactive compounds like phenolic compounds. The growing demand for more sustainable processes requires the development of new and effective methods for extracting bioactive compounds from industrial waste. Deep eutectic solvents (DESs) are a new sustainable alternative to toxic organic solvents due to their non-toxicity and biocompatibility. In this study, five selected DESs were applied for the extraction of bioactive phenolic compounds from avocado peels. The extraction efficiency was evaluated by measuring the total phenolics and flavonoids content. The best extraction results were obtained with choline chloride-acetic acid and -lactic acid (92.03 ± 2.11 mg GAE/g DAP in TPC and 186.01 ± 3.27 mg RE/g DAP); however, all tested DESs show better extraction efficiency than ethanol. All the obtained NADES extracts have high antioxidant activity (FRAP: 72.5–121.1 mg TE/g; TAC: 90.0–126.1 mg AAE/g). The synthesized DESs and avocado peels DES extracts had activity against all tested bacteria (Staphylococcus aureus, Streptococcus dysgalactiae, Escherichia coli and Pseudomonas putida), and the extracts prepared with choline chloride-acetic acid and -lactic acid have the highest antibacterial activity against all microorganisms. These results, coupled with the non-toxic, biodegradable, low-cost, and environmentally friendly characteristics of DESs, provide strong evidence that DESs represent an effective alternative to organic solvents for the recovery of phenolic bioactive compounds from agro-industrial wastes.

Subcritical water extraction of bioactive phenolic compounds from distillery stillage.

Distilleries generate huge amounts of by-products that have a negative impact on the environment, so the management of wastes generated by this sector should be improved. Because distillery by-products are a source of bioactive compounds, the recovery of these compounds not only reduces issues with environmental protection but also provides the basis for a waste-to-profit solution. Following the latest trends in the search for so-called green extraction techniques for recovering valuable products, this study investigated the effect of subcritical water extraction (SWE) conditions (temperature (25-260°C), time (5-90min), and solid-to-solvent ratio (1:5-1:50, w:v)) on the efficiency of recovery of bioactive compounds, i.e., polyphenols from distillery stillage, and on the antioxidant activity of the extracts. The highest extraction yield was obtained with 30-min SWE with a solid-to-solvent ratio of 1:15at either 140°C (for total polyphenol content and phenolic acid content) or 200°C (for total flavonoid content), as indicated by the Response Surface Methodology analysis. Phenolic acids in the extracts were present mainly in free forms (up to 88% of the total content). The antioxidant activity, which was measured using several assays, correlated positively with the content of phenolic acids, which confirmed their significant contribution to the bioactive properties of the extracts. The antioxidant effects of the extracts were mostly due to hydroxycinnamic acids (especially ferulic and p-coumaric acids). Principal component analysis showed that the temperature and time of SWE were the factors that can explain the greatest amount of variation in the extraction yield, composition, and bioactive properties of the polyphenols. These results will influence the design of further processes, such as purification and concentration, which are necessary before using the extracted compounds as substrates that are applicable in various industries. Based on the analysis of the elemental composition, the biomass remaining after SWE was evaluated to consider the possibilities of its further utilization.

The utilisation solutions of olive mill by‐products in the terms of sustainable olive oil production: a review

SummaryDespite the high economic and nutritional value as major positive aspects, olive oil production has an unfavourable side, which is the negative environmental impact caused by the generation of significant amounts of liquid and solid wastes. Therefore, the implementation of sustainable technologies to add value to the olive oil production process is a matter of great interest. This study aimed to review novel solutions dealing with the utilisation of olive oil production by‐products while taking into account sustainable waste management options. The most promising technologies for the production of high‐added value products from olive oil production by‐products have been described with a special attention to the sustainable nonthermal technologies for the extraction of bioactive phenolic compounds, and the key findings of such investigations were reviewed. All described technologies are environmentally friendly and show great potential. Nevertheless, further researches are required to optimise and increase their applicability.

Extraction optimization of bioactive compounds from ora-pro-nobis (Pereskia aculeata Miller) leaves and their in vitro antioxidant and antihemolytic activities

Ora-pro-nobis (Pereskia aculeata Miller) is a non-conventional food plant common in Brazil. The objective of this study was to optimize the extraction of bioactive phenolic compounds from ora-pro-nobis leaves by employing solvent mixtures. Ten extracts were obtained with water, ethanol, acetone, and their binary and ternary mixtures, evaluating the chemical composition, antioxidant activity and bioactivities in vitro. The response surface methodology was applied to model the results and calculate the optimal solvent composition, which is 60% water, 40% ethanol and 0% acetone. The optimized extract is rich in phenolic compounds (64 mg GAE/g) and proteins (823 mg/g) and presents antioxidant activity (in intracellular media as well) and inhibits lipid peroxidation (32%) along with hypotonic hemolysis (H50 = 0.339%), it does not present toxicity in vitro against cancer and normal cells. This is the first report of chicoric, caffeoyl-hexaric and coumaroyl-hexaric acids and some glycosylate derivatives of flavonols in ora-pro-nobis leaves.

Greener ultrasound-assisted extraction of bioactive phenolic compounds in Croton heliotropiifolius Kunth leaves

In this present work, an ultrasound-assisted extraction was developed and optimized to the extraction of bioactive phenolic compounds in leaves of Croton heliotropiifolius plants. A factorial design (24) was performed to screen the most significant variables. Subsequently, the Doehlert matrix was used to optimize the percentage of the solvent, extractor volume, temperature, and extraction time. Through HPLC DAD, phenolic compounds were determined in the samples of the C. heliotropiifolius extract, catechin, gallic acid, quercetin, vanillic acid, ellagic acid, trans-cinnamic acid, p-coumaric acid, syringic acid, acid ferulic and chlorogenic acid. The accuracy of the analytical method used was assessed, the results of the recovery ranged from 88 to 94%. The optimum conditions found were 11.4 mL of 37.5% v/v ethanol at a temperature of 54.8 °C for 39.5 min in an ultrasonic bath. The procedure developed for the extraction of bioactive compounds is efficient, fast, simple, and following the principles of green chemistry.

Sustainable Micro-Scale Extraction of Bioactive Phenolic Compounds from Vitis vinifera Leaves with Ionic Liquid-Based Surfactants.

This paper proposes a new sustainable and simple strategy for the micro-scale extraction of phenolic compounds from grapevine leaves with analytical purpose. The method is based on a microwave-assisted solid-liquid extraction approach (MA-SLE), using an aqueous solution of an ionic liquid (IL)-based surfactant as extraction phase. The method does not require organic solvents, nor any clean-up step, apart from filtration prior to the injection in the analytical system. Two IL-based surfactants were evaluated, and the method was optimized by using experimental designs, resulting in the use of small amounts of sample (100 mg) and extraction phase (2.25 mL), low concentrations of the selected 1-hexadecyl-3-butyl imidazolium bromide IL (0.1 mM), and 30 min of extraction time. The proposed methodology was applied for the determination of the polyphenolic pattern of six different varieties of Vitis vinifera leaves from the Canary Islands, using high-performance liquid chromatography and photodiode array detection for the quantification of the compounds. The proposed MA-SLE approach was greener, simpler, and more effective than other methods, while the results from the analysis of the leaves samples demonstrate that these by-products can be exploited as a source of natural compounds for many applications.

Integrated Process for Sequential Extraction of Bioactive Phenolic Compounds and Proteins from Mill and Field Olive Leaves and Effects on the Lignocellulosic Profile.

The extraction of bioactive compounds in a biorefinery context could be a way to valorize agri-food byproducts, but there is a remaining part that also requires attention. Therefore, in this work the integrated extraction of phenolic compounds, including the bioactive oleuropein, and proteins from olive mill leaves was addressed following three schemes, including the use of ultrasound. This affected the total phenolic content (4475.5–6166.9 mg gallic acid equivalents/100 g), oleuropein content (675.3–1790.0 mg/100 g), and antioxidant activity (18,234.3–25,459.0 µmol trolox equivalents/100 g). No effect was observed on either the protein recovery or the content of sugars and lignin in the extraction residues. Concerning the recovery of proteins, three operational parameters were evaluated by response surface methodology. The optimum (63.1%) was achieved using NaOH 0.7 M at 100 °C for 240 min. Then, the selected scheme was applied to olive leaves from the field, observing differences in the content of some of the studied components. It also changed the lignocellulosic profile of the extraction residues of both leaf types, which were enriched in cellulose. Overall, these results could be useful to diversify the valorization chain in the olive sector.

Microwave-assisted deep eutectic solvent extraction of phenolic antioxidants from onion (Allium cepa L.) peel: a Box-Behnken design approach for optimization.

Valorization of onion peel waste, considered to be a rich source of polyphenolic compounds, by employing green extraction techniques is the need of the hour. The aim of the present study was to optimize the microwave-assisted extraction of bioactive phenolic compounds from onion peel wastes employing ChCl:Urea:H2O deep eutectic solvent. Microwave power (100-200-300W), time (5-15-25min) and liquid to solid ratio (40:1-50:1-60:1) were studied as the major parameters affecting the extraction efficiency. A Box-Behnken design was adopted including 17 experiments with five centre points. The optimum conditions determined were 100W microwave power, 15.03min irradiation time and 54.97mLg-1 liquid to solid ratio. Under the MAE optimized conditions, the recovery of TPC and FRAP were 80.45 (mgGAEg-1dw) and 636.18 (µmolAAEg-1dw), respectively. Morphology of onion peels before and after DES extraction were also studied to gain an insight in the effect of microwave irradiations on the biomass.

A techno-economic comparison of subcritical water, supercritical CO2 and organic solvent extraction of bioactives from grape marc

Subcritical water extraction (SWE) is a modern extraction technique that posits a number of advantages to traditional solvent extraction. This is especially so in the extraction of medically and commercially important phenolic compounds from food and food by-products. SWE uses water at elevated pressures and temperatures to extract compounds of different polarities, adjusting the water polarity by changing the system temperature. A techno-economic analysis of the extraction of bioactive phenolic compounds from New Zealand grape marc showed that the cost of manufacture (COM) by SWE (NZ$89.60/kg product) approached that of current solvent extraction techniques (NZ$87.0/kg) although was less profitable overall. These were both far below the COM of supercritical CO2 extraction (NZ$123.40/kg). High energy consumption also meant that SWE had higher Potential Environmental Impacts (PEI) than solvent extraction, and higher greenhouse emissions, but outperformed supercritical CO2 extraction in these domains as well.

Influence of High-Pressure/High-Temperature Extraction on the Recovery of Phenolic Compounds from Barley Grains

The influence of extraction temperature (90–180C), solvent concentration (36–90% ethanol) and time (30–90 min) on extractability of phenolic compounds from barley grains and on antiradical power of extracts was examined. RSM was used to design and optimize the processing parameters. Experimental results of total phenolic contents, total flavonoids and antiradical power of barley extracts were in the range from 3.27 to 26.60 mgGAE/gdb, 0.91 to 6.09 mgCE/gdb and 0.33 to 4.05 gDPPH/mLext, respectively. HPLC analysis of extracts showed epigallocatechin gallate to be the predominant phenolic compound, representing up to 93% of all phenolic compounds determined. Based on RSM analysis, temperature was the most significant factor affecting the observed responses (P < 0.05) and optimal extraction conditions were achieved at 180C, 36% ethanol and 90 min. Additionally, strong correlation between protein content and phenolic compounds of extracts was observed (R = 0.925), indicating the influence of total proteins on possible overestimation of polyphenol content. Practical Applications Barley is a cereal crop with potential health benefits related to its content of phenolic compounds. Extraction is one of the essential steps in the isolation of bioactive compounds from natural sources and it is well known that it depends on numerous parameters. The search for nonconventional method of extraction that can overcome drawbacks of conventional (solid-liquid) extraction was the motivation of this research. Thus, the current study employed high-pressure/high-temperature stirred reactor for extraction process, and RSM for modeling the possible relationship between different extraction parameters and yield of phenolic compounds extracted from barley as well as their antioxidant activities. The data shown would provide the scientific rationale for better understanding of extraction of bioactive phenolic compounds from barley at high-pressure/high-temperature regime and as a contribution to the development of this technique in spite of the high cost of equipment.

Supercritical, ultrasound and conventional extracts from carob (Ceratonia siliqua L.) biomass: Effect on the phenolic profile and antiproliferative activity

A new approach to the extraction of bioactive phenolic compounds from carob kibbles has been proposed. Carob pulp kibbles, a by-product of the carob bean gum production, were subject to supercritical fluid extraction (SFE) and to ultrasound assisted (UAE) and conventional solid–liquid extractions with two different solvent systems (100% H2O and 70% acetone), in order to obtain phenolic rich extracts with biological activities. These extracts were characterized for total phenolics content, antioxidant activity and their phenolic profile was qualitatively evaluated by HPLC-DAD. Chromatographic profile of SFE extract showed a diversity of phenolic compounds while ultrasound and conventional extracts contained mainly gallic acid. The highest phenolics concentration and antioxidant capacity was also found in the SFE extract. Preliminary screening of the extracts antiproliferative activity on rat N1E-115 neuroblastoma cells, and on human HeLa cervical and MCF-7 breast cancer cell lines revealed that carob SFE extract exhibited a much higher antiproliferative effect in the studied tumor cells, indicating its greater potential as a source of natural antitumor compounds. Supercritical fluid extraction revealed to be a more selective and efficient method of extraction. Thus, the potential association of two environmentally clean processes (UAE and SFE) for obtaining polyphenols from carob kibbles will enable bioactive compounds within an integrated and sustainable recovery process. Also, the solid residue after extractions could be used as dietary fiber.

Biosynthesis of phenolic compounds and its regulation in apple

This paper summarises the information on the occurrence of phenolic compounds in apple Malus domestica leaves and fruits with special reference to their developmental changes and regulation of biosynthesis. Besides the ontogenetic variation in biosynthesis and accumulation, the stress-induced and pathogenesis-related changes are emphasised. Aspects of commercial importance are addressed, ranging from fruit colouration, through disease resistance, to the direct use of apple tissues, as raw material for the extraction of bioactive phenolic compounds.