Plant Phenolics: Extraction, Analysis and Their Antioxidant and Anticancer Properties

The inhibition of enzymatic browning and oxidation is still an important challenge in food processing. This study was designed to examine in vitro the inhibition of enzymatic browning in apple and the antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferrous ion chelating activity by Mentha suaveolens phenol, methanol and aqueous extracts. The use of various extracts in the prevention of the enzymatic browning, catalysed by polyphenol oxidases (PPO) and peroxidases (POD) showed that the phenol extract had a high effect on PPO more than synthetic inhibitor (potassium sorbate), whereas all extracts of M. suaveolens presented only a minor effect on POD of apple. The radical scavenging activity of various extracts of M. suaveolens using DPPH showed that the phenol extract had same activity as butyl hydroxyl toluene (BHT) which is a known inhibitor for its antioxidant activity. The highest ferrous ion chelating activity was found in phenol and methanol extracts. The chemical analysis of the phenol extract using the high performance liquid chromatography (HPLC) suggests that the rosmarinic acid could explain the observed inhibition. In conclusion, these data suggest that the M. suaveolens compounds can act as preservatives of food against oxidation and enzymatic browning. Keywords: Mentha suaveolens , phenolic compounds, enzymatic browning, antioxidant activity

Fruiting body, spores and in vitro produced mycelium of Ganoderma lucidum from Northeast Portugal: A comparative study of the antioxidant potential of phenolic and polysaccharidic extracts

In vitro antioxidant potential of Nephelium lappaceum L. rind extracts and geraniin on human epidermal keratinocytes

The purpose of this study was to evaluate the total phenolic extracts and antioxidant activity and anthocyanins of varieties of the investigated plants. These plants include oregano, thyme, terebinth, and pomegranate. The optimum extraction conditions including temperature and solvent of the extraction process itself were investigated. Total phenolic and anthocyanin extracts were examined according to Folin-Ciocalteu assay and Rabino and Mancinelli method, respectively. The effect of different extracting solvents and temperatures on extracts of phenolic compounds and anthocyanins were studied. Plant samples were evaluated for their antioxidant chemical activity by 2, 2-diphenyl-1-picrylhydrazl assay, to determine their potential as a source of natural antioxidant. Results showed that all tested plants exhibited appreciable amounts of phenolic compounds. The methanolic extract (60 °C) of sour pomegranate peel contained the highest phenolic extract (4952.4 mg/100 g of dry weight). Terebinth green seed had the lowest phenolic extract (599.4 mg/100 g of dry weight). Anthocyanins ranged between 3.5 (terebinth red seed) and 0.2 mg/100 g of dry material (thyme). Significant effect of different extracting solvents and temperatures on total phenolics and anthocyanin extracts were found. The methanol and 60 °C of extraction conditions found to be the best for extracting phenolic compounds. The distilled water and 60 °C extraction conditions found to be the best for extracting anthocyanin.

Methods for determining primary antioxidant activity were evaluated. A beta-carotene bleaching method and a free radical method using 2, 2-diphenyl-1-picrylhydrazyl (DPPH(*)) were modified to rapidly test samples for potential antioxidant activity. Malonaldehyde production in a linoleic acid emulsion system assayed by an HPLC method was also used to determine antioxidant and prooxidant activities initiated by a metal catalyst (Cu(2+)). All methods were used to assess activity of selected phenolic compounds including several anthocyanidins/anthocyanins and selected berry extracts. Most phenolic compounds had prooxidant activity at low concentrations, unlike synthetic antioxidants (BHA and BHT). Compounds with similar structures exhibited comparable trends in antioxidant activity. Antioxidant activity usually increased with an increase in the number of hydroxyl groups and a decrease in glycosylation. The antioxidant activity of many phenolic compounds and extracts was comparable to those of synthetic antioxidants using the beta-carotene bleaching and HPLC methods.

The academia and chemical industry are actively searching for alternative solvents to meet technology requirements since the most widely used solvents are harmful and volatile. For ionic liquids, there are several advantages over conventionally using organic membrane solvents, including high thermal stability, negligible vapour pressure, low volatility, etc. Here in this study, we have analyzed the abilities of ionic liquids as pure solvents as well as their binary mixtures, to recover phenolic compounds from the industrial wastewater. The field of phenol extraction from wastewater using ionic liquids remains less exposed, and we presume that the work of this kind would open up more and more opportunities for the scientific community as well as industrial people. Based on all these assumptions, the present work includes experimental data of a work which explains the possibilities of room temperature ionic liquids (RTILs) as potential bulk liquid membranes (BLM) for extracting phenol and other phenolic compounds from the industrial affluents. Four high hydrophobicity ionic liquids namely: 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF6], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [Bmim][NTf2], 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim] [PF6] and 1-ethyl-3-methyimidazolium bis(trifluoromethanesulfonyl) imide [Emim][NTf2] were used for investigating the Phenol extraction efficiency and stripping efficiency. To provide a best comprehension of the influence of the phenolic structure as well as the nature of cation on the extraction ability of the ILs, we tried to understand the molecular interactions between the phenolic compounds and the solvents. The influence of hydrophobicity of ionic liquids and different kinds of anions on the extraction of phenol and efficiencies of stripping were investigated. All the experimental investigations performed here indicated that the only cation part of the ionic liquid is not an important aspect directly in this extraction, but the hydrogen bonding and the solute-solvent interactions play a significant role in the phenol removal process from aqueous phase to IL phase. First, the optimal conditions of operating (settling time and stirring) were analyzed for the clarity of the experiments performed. Concentration of NaOH in enhancing the performance of ionic liquids was also inspected here in this study. A binary mixture of ionic liquids (BMILs) membrane was examined for the optimized parameters, and the efficiency of phenol extraction was analyzed with the efficiency obtained for the single ionic liquid (SIL) membranes. The phenol concentration was determined by UV/visible spectrophotometer absorbance measurements. The highest phenol extraction efficiencies of 91% and 98.5%, were achieved by using [Bmim][NTf2] and [Bmim][NTf2+PF6] respectively, and the higher stripping efficiencies came up with 79% and 84% respectively, for [Emim][NTf2] and [Bmim + Emim][NTf2]. The results show that the binary mixture ionic liquid (BMIL) membrane is a better choice than single ionic liquid (SIL) membrane solvents. Hence, [Bmim] [(NTf2+PF6)] is an excellent selection as it provides high phenol stripping and extraction efficiencies with a minimal solvent loss and better stability in transport process.

Baccharis trimera is a plant popularly used as a tea and to treat gastrointestinal diseases and inflammatory processes as well. The total phenolic content was determined and the antioxidant and anti-inflammatory activities of six extracts (dichloromethane, ethyl acetate, butanol, aqueous, saponin and phenolic) from B. trimera were evaluated. Using carrageenan-induced pleurisy as a model of acute inflammation, the phenolic extract at 15 mg/kg decreased significantly the analyzed parameters when compared to the carrageenan group (p < 0.05), thus showing potential anti-inflammatory activity. The total phenolic content and antioxidant activity were evaluated by the Folin-Ciocalteau and DPPH methods, respectively. Phenolic and ethyl acetate extracts presented higher antioxidant activity (p < 0.05) than ascorbic acid. The phenolic extract also showed the highest antioxidant potential in relation to the other extracts, thus suggesting that the antioxidant and anti-inflammatory activities were due to the presence of phenolic compounds.

Impact of extraction parameters and concentration by nanofiltration on the recovery of phenolic compounds from Cynara cardunculus var. altilis: Assessment of antioxidant activity

Extraction of phenolic compounds has been always conditioned to the use of organic solvents. An alternative to reduce the use of organic solvents in phenolic compounds extraction can be the cyclodextrins (CD). This work aims to determine the effect of cyclodextrins and extraction method on the extraction of phenolic compounds and antioxidant capacity of extracts. Phenolic extractions were made from Monastrel red variety pomace. Extractions were made by ultrasound and microwave at 50oC during 10’ with aqueous solutions of a-, b-, g-, HP-a-, HP-b-, HP-g-CD 50 mM, water and ethanol/water (1:1 v/v). Total phenolic compounds, procyanidins, flavanols, favonols and antioxidant capacity were measured. The final extraction of total phenolic compounds and antioxidant capacity obtained by using cyclodextrins were higher than those obtained by using water, but lower than those obtained by using ethanol/water. Microwave extraction extracted 75% more of total phenolics than ultrasound. Moreover, CDs had a selective effect on phenolics extraction. Extraction of flavanols and flavonols with CDs were similar to those obtained by using etanol/water. Type of CDs had also a great effect on favonols extraction. In conclusion, CDs could be used as an alternative to organic solvents for the extraction of specific phenolic compounds from pomace.

This work analysed the effect of spontaneous fermentation of sage leaves on the release and extraction of flavonoid and phenolic compounds. Chemical profiling based on thin-layer chromatography was used to compare different extracts from two sage species, common sage (Salvia officinalis) and white sage (Salvia apiana). Non-fermented Salvia apiana extracts are richer in antioxidants, phenolics, and terpenoids. Fermentation significantly enhances extraction of total phenolics, flavonoids, and antioxidants only from Salvia officinalis leaves, while it does not affect extraction from Salvia apiana leaves. In each 20 µL of extract, extraction of polyphenolics increases from 6.55 to 21.01 µg gallic acid equivalents (GAE), anti-oxidants from 0.68 to 2.12 µg GAE, and flavonoid content from 48.01 to 65.33 µg RE (rutin equivalents). Higher antioxidant activity in fermented Salvia apiana ethyl acetate extracts is associated with an increased concentration of phenolics and phenolic terpenoids. However, in Salvia officinalis, the higher antioxidant activity of fermented extract is a result of the release and improved extraction of flavonoids, as there is no increase in the extraction of phenolics. Lactic acid produced via fermentation and proline from Salvia officinalis leaves forms a natural deep eutectic solvent (NADES), which significantly increases the solubility of flavonoids.

Red Wine Phenolic Compounds Reduce Plasma Lipids and Apolipoprotein B and Prevent Early Aortic Atherosclerosis in Hypercholesterolemic Golden Syrian Hamsters (Mesocricetus auratus)

Natural molecules from food have been used to manage sickle cell crises. As a genetic blood disorder, treatment is complex and expensive. This study was carried out to establish the phenolic compounds profile of black bean seeds (Phaseolus vulgarus. L) commonly used by some families in the Western Region of Cameroon to manage sickle cell disease and to evaluate their in vitro antisickling, membrane stability and antioxidant properties. Free, bound and total phenolic contents were estimated to be 0.1±0; 0.108±0 and 0.212±0 mg EAG/g of sample respectively. Free phenolic compounds contain ferulic acid (0.013 μg/g), while bound phenolic compounds contain gallic acid (2.13 μg/g) and ferulic acid (0.037 μg/g). Free phenolic compounds had the higher rates of inhibition (82.26±2%), reversibility (69.86±3%) of sickling and the best effect on membrane stability of erythrocytes. Phenolic extracts from black bean seeds also showed a high global antioxidant activity with free phenolic compounds (28.42± 0 mgFeII/100g). Total phenolic compounds showed a better activity on DPPH radical with a IC50 of 2.42±1µg/µL while free phenolic compounds showed a better activity on scavenging hydroxyl radical with a IC50 of 1.5±0.5µg/µL. These results may justify the use of black bean seeds by sickle cell patients from Cameroon.

Bellis perennis is an interesting daisy not for its ornamental usage but also for its bioactive compounds, particularly phenolics, and related biological effects that explain traditional application for many disorders. The objective of this study was the optimization of phenolic compounds extraction from B. perennis flower with microwave-assisted extraction (MAE) using response surface methodology (RSM) and assessing optimal extract for bioactive contents and in vitro biological properties. The optimization of phenolic extraction was performed by studying four parameters (solvent concentration, time, microwave power, and solvent to solid ratio). Furthermore, the optimal extract was analyzed for flavonoid content, antioxidant capacity, anti-inflammatory activity, and FTIR analysis. Data fitting to the secondary polynomial model revealed that optimal conditions allowing the best phenolic extraction regarding solvent concentration, time, microwave power, and solvent to solid ratio were 56%, 83s, 200 W, and 68 mL/g, respectively. The phenolic yield obtained using this optimal combination was 135.67 mg GAE/g dw. The obtained optimal extract demonstrated an interesting flavonoids content (27.68 mg EQ/g dw) and expressed a good antioxidant activity measured with DPPH free radical scavenging activity (46.4mg GAE/g dw), ABTS free radical scavenging activity (59.6mg TE/g dw), reducing power (288.0mg GAE/g dw), iron chelating activity (32.7mg EDTAE/g dw), and anti-inflammatory activity (7.9mg IbuE/g dw). FTIR analysis revealed the presence of characteristic functional groups of phenolic compounds in the studied extract. This investigation allowed the development of a validated mathematic model for phenolic compounds extraction from B. perennis flower using MAE and optimal extract expressed good bioactive contents with the best antioxidant properties.

The antioxidant activity and bioactive compounds of different blackberry fruit genotypes from the major Brazilian producer region (three cultivars and four selections) were evaluated and compared to the Cherokee cultivar. Phenolic and anthocyanic extracts were obtained and evaluated for each fruit genotype. The phenolic extracts of selections 02/96 and 07/001 presented higher antioxidant activity than those of cultivars in most assays. This activity was partially correlated to the higher amount of total phenolics in these samples. Thus, the phenolic compounds are probably the major responsible for the antioxidant activity in the diphenyl-2-picrylhydrazyl radical scavenging assay (DPPH), ferric reducing antioxidant power (FRAP) assay and thiobarbituric acid reactive substances (TBARS) assay. Quercetin seems to be responsible for the antioxidant activity of blackberry phenolic extracts in the β-carotene bleaching assay. Concerning anthocyanic extracts, the selection 02/96 and Cherokee cultivar from harvest 2007 had higher antioxidant activity than the other genotypes in most assays. Anthocyanins appear to be the major responsible for the antioxidant activity of anthocyanic extracts in the DPPH and FRAP assays, although ascorbic acid also contributed to the DPPH antioxidant activity. Selection 02/96 appears to have higher antioxidant activity than the commercial cultivars cultivated in the southern Brazil and appears to be promising for nutritional and health purposes.

The emergence of bacterial strains resistant to different antibiotics has prompted the search for new sources of antimicrobial compounds. Studies have shown that jambolan [Syzygium cumini (L.) Skeels], a tropical fruit from the Mirtaceae family, contains a great variety of phytochemical compounds with high antioxidant and antimicrobial activity. This study aimed to determine the centesimal composition and physicochemical characteristics of the pulp and seed of S. cumini (L.) Skeels, as well as the content of total phenolic compounds and the antioxidant, antibacterial, antibiofilm and anti-quorum sensing (QS) activities of the phenolic extracts obtained from the pulp and the seeds of this fruit. The in vitro antibacterial and anti-QS activities of active films incorporating phenolic extracts were also evaluated. Additionally, we performed molecular docking of phenolic compounds present in jambolan with the CviR QS regulator of Chromobacterium violaceum. The composition and physicochemical characteristics of the samples presented similar values to those found for the species. However, the seed phenolic extract had a higher content of phenolic compounds and antioxidant activity than the pulp. Both phenolic extracts presented antibacterial activity against Aeromonas hydrophila, C. violaceum, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica serovar Typhimurium, Serratia marcescens, Listeria monocytogenes, and Staphylococcus aureus. The seed phenolic extract was particularly inhibitory against S. aureus. The pulp phenolic extract inhibited swarming motility and biofilm formation of A. hydrophila, E. coli, and S. marcescens in sub-MIC concentrations. The pulp and seed phenolic extracts inhibited violacein production in C. violaceum. Films incorporating both phenolic extracts inhibited the growth of bacteria, particularly Pseudomonas fluorescens, L. monocytogenes, and S. aureus, as well as QS in C. violaceum. Molecular docking showed that a variety of compounds found in pulp and seed extracts of jambolan, particularly chlorogenic acid and dihydroquercetin, potentially bind CviR protein and may interfere with QS. Our results indicate that pulp and seed of jambolan are good sources of antibacterial, antibiofilm, and anti-QS compounds that can be used in the development of natural preservatives and for application in antibacterial active films.