Antioxidant Activity Of Phenolic Compounds Research Articles

Characterization, Bioaccesibility and Antioxidant Activities of Phenolic Compounds Recovered from Yellow pea (Pisum sativum) Flour and Protein Isolate.

This study focused on studying the bioaccesible phenolic compounds (PCs) from yellow pea flour (F) and protein isolate (I). Total phenolic contents (TPC), PCs composition and antioxidant activities were analysed in ethanol 60% extracts obtained by applying ultrasound assisted extraction (UAE, 15min/40% amplitude). The preparation of I under alkaline conditions and the elimination of some soluble components at lower pH produced a change of PCs profile and antioxidant activity. After simulated gastrointestinal digestion (SGID) of both ingredients to obtain the digests FD and ID, notable changes in the PCs concentration and profiles could be demonstrated. FD presented a higher ORAC activity than ID (IC50 = 0.022 and 0.039mg GAE/g dm, respectively), but lower ABTS•+ activity (IC50 = 0.8 and 0.3mg GAE/g dm, respectively). After treatment with cholestyramine of extracts from FD and ID in order to eliminate bile salts and obtain the bioaccesible fractions FDb and IDb, ROS scavenging in H2O2-induced Caco2-TC7 cells was evaluated, registering a greater activity for ID respect to FD (IC50 = 0.042 and 0.017mg GAE/mL, respectively). These activities could be attributed to the major bioaccesible PCs: OH-tyrosol, polydatin, trans-resveratrol, rutin, (-)-epicatechin and (-)-gallocatechin gallate for FD; syringic (the most concentrated) and ellagic acids, trans-resveratrol, and (-)-gallocatechin gallate for ID, but probably other compounds such as peptides or amino acids can also contribute.

Effects of natural deep eutectic solvent on the extraction efficiency and antioxidant activities of Toona sinensis seed polyphenols: Composition and mechanism

This study was designed to investigate the effects of natural deep eutectic solvents (NADESs) on extraction efficiency and antioxidant activities of phenolic compounds from Toona sinensis seeds (TSSs) compared with ethanol and water extraction methods. The single factor experiment was employed to optimize the extraction conditions of TSSs phenolic compounds on NADESs. Results indicate that the NADES of choline chloride-oxalic acid (CC-OA) with a molar ratio of 2:1 (solid/liquid ratio: 1:90 (m/v), extraction time: 30 min) showed the highest total phenolic content (32.58 mg GAE/g DW) and antioxidant activities (DPPH radical scavenging activity: 95.94%) compared with ethanol or water extraction. In addition, 15 main phenolic compounds were identified in the extracts of CC-OA solvent, while only 9 and 6 main compounds were identified in the extracts of ethanol and water solvents, respectively. The molecular dynamic simulation result illustrates that the high extraction efficiency of the NADES mainly attributing to their high compatibility as well as hydrogen interaction between ellagic acid (the main polyphenol in TSSs) and CC-OA solvent. In summary, the NADES (CC-OA at the ratio of 2:1) showed superior extraction efficiency on TSSs phenolic compound compared with ethanol or water extraction which could be an environmentally friendly method for the high-value utilization of TSSs.

Extraction of polyphenols associated with pectin from olive waste (alperujo) with choline chloride.

The main by-product from olive oil extraction (alperujo) was extracted with hot water, citric acid, natural deep eutectic solvent (choline chloride: citric acid), and only choline chloride. The purified extracts were composed of macromolecular complexes constituting polyphenols associated with pectin. The extracts were structurally characterized by FT-IR and solid-NMR spectroscopy and an in vitro test revealed distinct antioxidant and antiproliferative activity, depending on the extracting agents. The choline chloride-extracted complex contained the highest amount of polyphenols among the examined agents, which exhibited a strong antioxidant activity and significant antiproliferative capacity. However, the complex extracted by hot water showed the highest antiproliferative capacity in vitro against the colon carcinoma Caco-2 cell line. In this finding, choline chloride could be used as a novel, green and promising alternative to the conventional extracting agent for the production of complexes that combine the antioxidant activity of phenolic compounds and the physiological effects of pectic polysaccharides.

Myrtaceae leaves grown in Agroforestry: a sustainable alternative to producing natural antioxidants extracts

Myrtaceae species such as uvaia, grumixama, and feijoa have been used in Brazil’s Agroforestry Systems (AFS). In AFS, frequent pruning occurs, and leaves are discarded. However, the leaves contain specific phenolic compounds (PC) that, when appropriately extracted, produce extracts with antioxidant activity (AA). These extracts meet the demand for natural and sustainable food ingredients. Therefore, the drying study (40, 50, and 60 °C) of uvaia, grumixama, and feijoa leaves obtained from AFS was carried out, and the effect of drying on the PC profile (LC-ESI-MS/MS) and AA were evaluated. In the uvaia extracts, the major compounds were EGCG, gallic acid, and isoquercitin, accounting for 94% of their PC, and leaves dried at 50 °C promoted a better phenolic extraction. The gallic acid, 2.5 DHBA and isoqueticitrin represent 79% of the relative composition of PC in grumixama extracts, and leaves dried at 60 °C were the condition that allowed a greater extraction. While, epicatechin, catechin, gallic acid and isoquercitrin correspond to 66% of the PC composition of feijoa leaves. Grumixama had the highest values for AA by the FCRC and DPPH while feijoa had significant values for FRAP in all treatments. Dried leaves at 50 °C showed higher AA for all methods, except for grumixama which showed this behavior at 60 °C. These results indicate that these matrices proved promising sustainable sources of various phenolic compounds. The drying process of the leaves at 50 and 60 °C had a greater extraction of compounds with antioxidant activity, with potential industrial applications.

Antioxidant system of garden cress sprouts for using in bio-monitor of cadmium and lead contamination

Based on garden cress significantly used for phytoremediation, the antioxidant system included antioxidant-phenolic compounds and antioxidant-enzymes of 6-day-garden cress sprouts (GCS) were assessed as potential bio-indicators for cadmium (Cd) and lead (Pb) contamination. Total phenolic and flavonoid contents of GCS germinated under Cd and Pb treatments (25–150 mg kg−1) gradually increased with increasing concentration of metals and peaked by 2.0, 2.6, and 2.5, 2.3 folds at 150 mg kg−1, respectively. By using DPPH, ABTS, and PMC antioxidant assays, the total antioxidant activity of phenolic compounds of GCS increased 6.1, 13.0, and 5.8-fold for Cd and 5.9, 14.6, and 8.2-fold for Pb at 150 mg kg−1, respectively. The antioxidant enzymes of GCS (POD, CAT, GR, and GST) were significantly activated in response to Cd and Pb stress, and two new electrophoretic POD bands were detected. GCS was absorbed 19.0% and 21.3% of Cd and Pb at 150 mg metal kg−1, respectively. In conclusion, the approaches of the antioxidant defense system of GSC could potentially be used as bio-indicator for monitoring Cd and Pb contamination in a short time of germination process.

Nutritional composition, antioxidant activity and gossypol level of Nazilli glandless cottonseed, cottonseed kernel and their cold-pressed meal

BackgroundThe study was conducted to determine the nutrient composition and gossypol levels of glandless cottonseed (GCS), glandless cottonseed kernel (GCSK) glandless cottonseed meal (GCSM) and cottonseed kernel meal (GCSKM) obtained by cold pressing of cotton seeds and kernels (Glandless Nazilli variety) as a raw material of compound feed industry.ResultFeed and dry matter (DM)-based nutrient analyses showed significant differences (p < 0.05) in DM, OM (organic matter), CP (crude protein), EE (ether extract), ash and NFE (nitrogen-free extract) contents between GCS and GCSK. The DM-based K, P, S, Mg, Ca, Na, Fe, Cu, Zn and Al contents were significantly different (p < 0.05) between GCS and GCSK. The concentrations of nonessential heavy metals (Cd, Pb, Ni and Al) in GCS, GCSK, GCSM and GCSKM samples were below the permissible limits. The linoleic acid (C18:2; ω6) was the main component (55.55%) among the 20 fatty acids identified in GCS oil. The level of unsaturated fatty acids (70.78%) was higher than that of saturated fatty acids (29.22%). Total phenolics concentrations of GCS, GCSK, GCSM and GCSKM samples were 7.87, 2.18, 5.86 and 1.91 mg gallic acid equivalents (GAE)/g, respectively. Free and total gossypol levels of GCS and GCSK were 294 and 440, and 521 and 706 mg/kg, respectively.ConclusionThe results revealed that nutritional properties of Nazilli GCS with low gossypol and high linoleic acid content were relatively higher compared to the other meals investigated. The antioxidant activity of phenolic compounds, albeit at low levels in Nazilli GCS and GCSM, may contribute to animal health and production efficiency when used in animal rations.

Gastrointestinal digestion assays for evaluating the bioaccessibility of phenolic compounds in fruits and their derivates: an overview

Fruits and their derivatives are sources of phenolic compounds, which contribute to the maintenance of health benefits. In order to exert such properties, these compounds must be exposed to gastrointestinal conditions during digestion. In vitro methods of gastrointestinal digestion have been developed to simulate and evaluate the changes that compounds undergo after being exposed to various conditions. We present, in this review, the major in vitro methods for evaluating the effects of gastrointestinal digestion of phenolic compounds in fruits and their derivatives. We discuss the concept of bioaccessibility, bioactivity, and bioavailability, as well as the conceptual differences and calculations among studies. Finally, the main changes caused by in vitro gastrointestinal digestion in phenolic compounds are also discussed. The significant variation of parameters and concepts observed hinders a better evaluation of the real effects on the antioxidant activity of phenolic compounds, thus, the use of standardized methods in research would contribute for a better understanding of these changes.

Dietary Phenolic Compounds: Their Health Benefits and Association with the Gut Microbiota.

Oxidative stress causes various diseases, such as type II diabetes and dyslipidemia, while antioxidants in foods may prevent a number of diseases and delay aging by exerting their effects in vivo. Phenolic compounds are phytochemicals such as flavonoids which consist of flavonols, flavones, flavanonols, flavanones, anthocyanidins, isoflavones, lignans, stilbenoids, curcuminoids, phenolic acids, and tannins. They have phenolic hydroxyl groups in their molecular structures. These compounds are present in most plants, are abundant in nature, and contribute to the bitterness and color of various foods. Dietary phenolic compounds, such as quercetin in onions and sesamin in sesame, exhibit antioxidant activity and help prevent cell aging and diseases. In addition, other kinds of compounds, such as tannins, have larger molecular weights, and many unexplained aspects still exist. The antioxidant activities of phenolic compounds may be beneficial for human health. On the other hand, metabolism by intestinal bacteria changes the structures of these compounds with antioxidant properties, and the resulting metabolites exert their effects in vivo. In recent years, it has become possible to analyze the composition of the intestinal microbiota. The augmentation of the intestinal microbiota by the intake of phenolic compounds has been implicated in disease prevention and symptom recovery. Furthermore, the "brain-gut axis", which is a communication system between the gut microbiome and brain, is attracting increasing attention, and research has revealed that the gut microbiota and dietary phenolic compounds affect brain homeostasis. In this review, we discuss the usefulness of dietary phenolic compounds with antioxidant activities against some diseases, their biotransformation by the gut microbiota, the augmentation of the intestinal microflora, and their effects on the brain-gut axis.

The Effect of Probiotic on Antioxidant Activity of Phenolic Compounds in Functional Yogurt Fortified by Plum Juice

The Effect of Probiotic on Antioxidant Activity of Phenolic Compounds in Functional Yogurt Fortified by Plum Juice

Chemoinformatic modelling of the antioxidant activity of phenolic compounds.

Antioxidants are chemicals used to protect foods from deterioration by neutralizing free radicals and inhibiting the oxidative process. One approach to investigate the antioxidant activity is to develop quantitative structure-activity relationships (QSARs). A curated database of 165 structurally heterogenous phenolic compounds with the Trolox equivalent antioxidant capacity (TEAC) was developed. Molecular geometries were optimized by means of the GFN2-xTB semiempirical method and diverse molecular descriptors were obtained afterwards. For model development, V-WSP unsupervised variable reduction was used before performing the genetic algorithms-variable subset selection (GAs-VSS) to construct the best five-descriptor multiple linear regression model. The coefficient of determination and the root-mean-square error were used to measure the performance in calibration (R2 = 0.789 and RMSEC = 0.381), and test set prediction (Q2 = 0.748 and RMSEP = 0.416), along several cross-validation criteria. To thoroughly understand the TEAC prediction, a fully explained mechanism of action of the descriptors is provided. In addition, the applicability domain of the model defined a theoretical chemical space for reliable predictions of new phenolic compounds. This in silico model conforms to the five principles stated by the Organization for Economic Co-operation and Development (OECD). The model may be useful for virtual screening of the antioxidant chemical space, and for identifying the most potent molecules related to an experimental measurement of TEAC activity. In addition, the model could assist chemists working on computer-aided drug design (CADD) for the synthesis of new targets with improved activity and potential uses in food science. This article is protected by copyright. All rights reserved.

Molecular Geometry, Homo-Lumo Analysis and Mulliken Charge Distribution of 2,6-Dichloro-4-Fluoro Phenol Using DFT and HF Method

&#x0D; Phenolic compounds are used in human diet, commonly present in plants. Foremost polyphenolic compounds found in plants are flavanols, flavonoids, flavonones, iso-flavones, phenolic acids, flavonoids, chalcones, lignans etc. These compounds possess antimicrobial, antiviral and anti-inflammatory properties along with high antioxidative activity. The antioxidative activity of phenolic compounds depends on their structure. The polyphenols are very useful for the treatment of inflammation, cancer, anti-ageing purposes in cosmetic formulations, and nutraceutical applications. This article focused on substituted phenol, taking into concern their potential health benefits. The recent rise in machine-learning methods has engendered many advances in the molecular sciences. Using desired level of electronic structure theory from density functional theory, we can calculate the properties (electronic structure, force field, energy) of atomistic systems. The full electron density carries with it a considerable computational cost. While the DFT calculation loses accuracy when the molecule is either extended or compressed, Δ-DFT corrects these errors. Here, molecular point group symmetries are used to obtain chemical accuracy. The optimal 2,6-dichloro-4-fluoro phenol molecular geometry was derived using the 6-311+G (d, p) basis set and DFT/B3LYP (density functional theory) and Hartree-Fock (HF) techniques. A detailed interpretation of Homo-Lumo analysis of 2,6-dichloro-4-fluoro phenol is also listed. Using the 6-311+G (d, p) basis set and the Hartree-Fock (HF) method, the Mulliken charge distribution of this molecule has also been computed.

Stability and antioxidant activity of phenolic compounds during in vitro digestion.

The impact of phenolic compounds on the human body depended on the type, content, bioavailability, and antioxidant activity. After digestion, different phenolic compounds had different changes of bioavailability and antioxidant activity, which needed to be considered in the application. In this experiment, the structural stability and antioxidant activity of 27 phenolic compounds (phenolic acids, flavonols, flavonoids, and flavanones) were investigated during the in vitro simulated digestion. This experiment eliminated the influence of food matrix, provide a basis for regularity for the changes of phenolic substances in different materials. Results showed that the bioaccessibility of phenolic compounds with different structures varied, and there was a conformational relationship between the structure and stability. After oral digestion, most of the phenolic compounds underwent degradation and the cellular antioxidant activity (CAA) values decreased to a large extent (p<0.05). After gastric digestion, the content (p>0.05) and CAA values (p<0.05) of most phenolic compounds increased. However, after intestinal digestion, the phenolic compounds were degraded to a greater extent, and different structures of phenolic compounds had different changes in CAA values (p<0.05). In general, the CAA values of most phenolic compounds after in vitro digestion were lower than the initial value. The 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ehylbenzthiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) values of phenolic acids and flavonols decreased after in vitro simulated digestion (p<0.05), while the values of DPPH, ABTS, and FRAP of most flavonoids (p<0.05) increased. The increased oxygen radical absorption capacity (ORAC) values were found in most phenolic acids, flavonols, and flavonoids (p<0.05), and most flavanones showed unremarkable changes in ORAC values (p>0.05). In general, the changing trend of chemical-based antioxidant activity was consistent with the content of phenolic compounds.

Metabolomic Profiling and Assessment of Phenolic Compounds Derived from Vitis davidii Foex Cane and Stem Extracts

Phenolic extracts from berry seeds have been extensively studied for their health benefits. However, few studies have been conducted on the effects of phenolic extracts from Vitis L. canes and berry stems. The Chinese spine grape (V. davidii Foex) is an important and widely distributed wild species of Vitis L. The present study explored the metabolomic profile and evaluated the antioxidant activity of phenolic compounds in extracts from V. davidii Foex. canes and stems, with a focus on their role in preventing DNA damage caused by free radicals and inhibiting the growth of breast (MCF-7) and cervical (HeLa) cancer cells. Total phenolic compounds in the dried berry stems of spine grapes were higher than that in vine canes. Analysis of the extracts showed that proanthocyanins, epicatechin, catechin, and phenolic acid were the main phenolic compounds in V. davidii Foex, but in higher quantities in berry stems than in vine canes. However, trans-resveratrol and kaempferol 3-O-glucoside were present in the vine canes but not in the berry stems. Antioxidant analysis by FRAP and ABTS showed that extracts from berry stems and vine canes had a higher antioxidant activity than thinned young fruit shoots before flowering, leaves, peel, pulp, and seeds in V. davidii Foex. Moreover, the antioxidant activity of extracts from berry stems was higher than that in other grape species, except for muscadine. In vitro analyses further showed that the extracts significantly increased H2O2 scavenging ability and conferred a protective effect against DNA damage. Furthermore, a low concentration of phenolic compounds in extracts from the vine canes and berry stems of spine grapes inhibited the proliferation of the MCF-7 and Hela cancer cells. These research results provided some important useful information for the exploitation of V. davidii Foex canes and berry stems and indicated that canes and stems of V. davidii Foex had good antioxidant properties, anticancer activity and prevented DNA damage, providing evidence for medical utilization of V. davidii Foex.

Phenolic features and anthocyanin profiles in winemaking pomace and fresh berries of grapes with different pedigrees.

The total contents and antioxidant activities of phenolic compounds as well as anthocyanin profiles were analyzed and compared in fresh berries and fermented pomace of three grape cultivars with different pedigrees. The phenolic contents and antioxidant activities decreased significantly in skins (p < 0.05), while relatively large amounts of them were retained in seeds after fermentative maceration. Fermentative maceration also had a significant impact on the anthocyanin compositions. The proportions of anthocyanins with more stable structures, such as malvidin derivatives, methylated, diglucosides and nonacylated anthocyanins, increased significantly in the pomace skins (p < 0.05). There were obvious differences in phenolic features and anthocyanin profiles among the three cultivars. 'NW196', a wine hybrid of Vitis vinifera and V. quinquangularis, was characterized by the highest total anthocyanin contents and degree of diglucosylation. The results obtained in this study could contribute to the primary data for the development and utilization of winemaking pomace, especially from local non-Vitis vinifera grapes.

In Vitro Bioaccessibility and Antioxidant Activity of Phenolic Compounds in Coffee-Fortified Yogurt.

Yogurt is considered one of the most popular and healthy dairy products, and has been exploited as a delivery matrix for phenolic compounds. In this study, coffee powder was added to yogurt as a functional ingredient to produce coffee-fortified yogurt. Total phenolic compounds, antioxidant activity and individual hydroxycinnamic acids have been identified and quantified through mass spectrometry. The results from coffee-fortified yogurt were compared with fermented coffee and plain yogurt. Coffee-fortified yogurt had higher total phenolic content and antioxidant activity compared to plain yogurt. However, the total phenolic compounds found in coffee-fortified yogurt represented only 38.9% of the original content in coffee. Caffeoylquinic acids were the most abundant phenolic compounds in coffee. Fermented coffee and coffee-fortified yogurt displayed lower amounts of individual phenolic compounds with respect to coffee (69.8% and 52.4% of recovery, respectively). A protective effect of the yogurt matrix on total and individual coffee phenolic compounds has been observed after in vitro digestion, resulting in a higher bioaccessibility in comparison with digested fermented coffee. Moreover, coffee-fortified yogurt showed the highest antioxidant values after digestion. These findings clearly demonstrate that coffee-fortified yogurt can be considered a significant source of bioaccessible hydroxycinnamic acids, besides its health benefits as a fermented dairy product.

Microencapsulation by Spray Drying and Antioxidant Activity of Phenolic Compounds from Tucuma Coproduct (Astrocaryum vulgare Mart.) Almonds.

The industrial processing of fruits in the Amazon region, such as tucuma, generates a large amount of coproducts with great nutritional potential. In this work, phenolic compounds from tucuma coproduct almonds were extracted and microencapsulated by spray drying using maltodextrin as the encapsulating agent and verified its antioxidant activity. Phenolic compounds were determined by UV spectroscopy and identified by Ultraefficiency Liquid Chromatography. Antioxidant activity was measured by ABTS and DPPH assay. Thermogravimetric techniques, infrared spectroscopy, scanning electron microscopy, moisture content and water activity were applied to characterize the microparticle. The crude extract and microparticle had total polyphenols of 135.1 mg/g ± 0.078 and 130.5 mg/g ± 0.024, respectively. Caffeic and gallic acids were identified. The crude extract and the microparticle showed good antioxidant activity by ABTS and DPPH assay, justified by the presence of the phenolic compounds found. The microparticle showed spherical and heterogeneous structures and good encapsulation efficiency from the spray drying process using maltodextrin. The results show that the extract of the tucuma almond coproduct can be used as a phenolic compound-rich source and microencapsulated with possible application for functional food production.

QSAR study of phenolic compounds and their anti-DPPH radical activity by discriminant analysis

Phenolic compounds (PCs) could be applied to reduce reactive oxygen species (ROS) levels, and are used to prevent and treat diseases related to oxidative stress. QSAR study was applied to elucidate the relationship between the molecular descriptors and physicochemical properties of polyphenol analogues and their DPPH radical scavenging capability, to guide the design and discovery of highly-potent antioxidant substances more efficiently. PubMed database was used to collect 99 PCs with antioxidant activity, whereas, 105 negative PCs were found in ChEMBL database; their molecular descriptors were generated with Python's Rdkit package. While the molecular descriptors significantly related to the antioxidant activity of PCs were filtered by t-test. The prediction QSAR model was then established by discriminant analysis, and the obtained model was verified by the back-substitution and Leave-One-Out cross-validation methods along with heat map. It was revealed that the anti-DPPH radical activity of PCs was correlated with the drug-likeness and molecular fingerprints, physicochemical, topological, constitutional and electronic property. The established QSAR model could explicitly predict the antioxidant activity of polyphenols, thus were applicable to evaluate the potential of candidates as antioxidants.

Bioassay-guided isolation of human carboxylesterase 2 inhibitory and antioxidant constituents from Laportea bulbifera: Inhibition interactions and molecular mechanism

Laportea bulbifera (Sieb. et. Zucc.) Wedd has long been utilized in Traditional Chinese Medicines (TCM) for the treatment of rheumatoid arthritis. However, the study of systematic anti-inflammatory chemical constituents in L. bulbifera has never been reported. Thus, bioassay-guided isolation for its roots part led to 46 compounds, including 38 phenolic derivatives. Their structures were determined on the basis of 1H and 13C NMR and MS spectra. All compounds were isolated from L. bulbifera for the first time except for 13 compounds. Most of the compounds showed good COX-2 inhibitory activity (IC50: 0.13–3.94 μM) and DPPH radical-scavenging activity (IC50: 1.57–9.55 μM). Four compounds (4, 17, 35, and 43) with different skeletons showed preferential COX-2 over COX-1 inhibition with selective indices ranging from 12 to 171. High content active compounds are important for elucidating the basis of the active substance of TCM. Compound 4 (COX-2, IC50 0.24 μM), a high content compound, represented one of the best selective COX-2 inhibitors. Another high content active compound (35) with a different skeleton might have different mechanism. Further study for the inhibition kinetics against COX-2 indicated compounds 4 and 35 were noncompetitive and competitive COX-2 inhibitors, respectively. Moreover, molecular docking and molecular dynamics simulation data further indicated that compound 4 could bind in the cavity of COX-2 and interacted with key residues VAL-538, PHE-142, and GLY-225 of COX-2 through hydrogen bonds. The results indicated that L. bulbifera roots could be applied as antioxidant and anti-inflammatory agents due to their potent selective COX-2 inhibitory and antioxidant activity of phenolic compounds.

Extraction, Chemical Composition and Antioxidant Activity of Phenolic Compounds from Moroccan Satureja nepeta L.

Satureja nepeta is an aromatic medicinal plant, widely used by the Moroccan population. The objective of this study is to evaluate the influence of extraction methods on total phenolic compounds (TPC) and total flavonoid compounds (TFC). The phytochemical characteristics are subsequently analyzed to determine the components constitution as well as the evaluation of antioxidant activity. The extraction optimization and the extraction of total polyphenols was carried out using three methods (decoction, infusion and hydroethanolic). The antioxidant capacity was evaluated using the DPPH free radical trapping method, reducing power assay and the ABTS radical reduction test. Polyphenols were identified by the HPLCUV method. The optimal hydro-ethanol extraction conditions defined from the experimental design are: ethanol/water, 60/40 (v/v), 15 hours, 42.5 °C TPC and TFC of the infused extract were the highest. The evaluation of the antioxidant capacity showed that the infused extract had a good antioxidant efficacy. HPLC-UV and GC-MS has been used to identify some phenolic compounds in various extracts. In conclusion, optimizing the extraction of S. nepeta seems to be an efficient and quick method to establish the best extraction conditions. Also, Satureja. Key words: Moroccan Satureja nepeta, Antioxidant activity, Total polyphenol, Total flavonoids, Total tannins.

Microbial Bioconversion of Phenolic Compounds in Agro-industrial Wastes: A Review of Mechanisms and Effective Factors.

Agro-industrial wastes have gained great attention as a possible source of bioactive compounds, which may be utilized in various industries including pharmaceutics, cosmetics, and food. The food processing industry creates a vast amount of waste which contains valuable compounds such as phenolics. Polyphenols can be found in soluble (extractable or free), conjugated, and insoluble-bound forms in various plant-based foods including fruits, vegetables, grains, nuts, and legumes. A substantial portion of phenolic compounds in agro-industrial wastes is present in the insoluble-bound form attached to the cell wall structural components and conjugated form which is covalently bound to sugar moieties. These bound phenolic compounds can be released from wastes by hydrolysis of the cell wall and glycosides by microbial enzymes. In addition, they can be converted into unique metabolites by methylation, carboxylation, sulfate conjugation, hydroxylation, and oxidation ability of microorganisms during fermentation. Enhancement of concentration and antioxidant activity of phenolic compounds and production of new metabolites from food wastes by microbial fermentation might be a promising way for better utilization of natural resources. This review provides an overview of mechanisms and factors affecting release and bioconversion of phenolic compounds in agro-industrial wastes by microbial fermentation.