Distribution and Antioxidant Activities of Free,Conjugated, and Insoluble-Bound Phenolics from Seven Species of the Genus Camellia

Free phenolic (FP), conjugated phenolic (CP), and insoluble-bound phenolic (IBP) acids were extracted from the seeds of seven species of oil-tea camellia and their antioxidant activities were evaluated. The results indicated that Camellia vietnamensis has the highest total phenolic content (TPC) (31.84 ± 0.11 g of gallic acid equivalent [GAE] kg⁻¹) and that Camellia polyodontia has the lowest TPC (12.34 ± 0.22 g GAE kg⁻¹) in the kernel. The average TPC among the species is similar in both the kernels and in the shells, and the content order of the three forms of phenolic compounds is FP > IBP > CP. HPLC-MS analysis showed the presence of 9–11 phenolic compounds in the FP, CP, or IBP extracts of the seven species of oil-tea camellia seed. Among the phenolics identified, ferulic acid, catechin, and epicatechin were the major contributors of antioxidant activity. Hierarchical cluster analysis conducted based on the phenolic properties showed that C. vietnamensis and Camellia semiserrata belong to the group characterized by high antioxidant capacities (FRAP, ferric-ion-reducing antioxidant power; ABTS assay), and Camellia chekiangoleosa and Camellia oleifera are arranged in a group with moderate phenolic properties. The other species constitute the third cluster with low phenolic content and antioxidant activity. The study demonstrated that oil-tea camellia seed contains significant amounts of phenolic acids. In addition, extracts from various parts of the seed could be interesting novel sources of natural antioxidants.     

Antioxidant activity of macambo (Theobroma bicolor L.) extracts

Macambo is an edible fruit species from the Amazon Region with a high content of lipids (33%). Macambo samples were obtained from the Amazon Region, dried at 60 °C, milled (32 mesh sieve) and submitted to sequential extraction using ether, ethanol and water as solvents. The antioxidant activity of the ether, ethanol and aqueous extracts was 47%, 68% and 67%, respectively, and the antioxidant activity of the control butylated hydroxytoluene (BHT) was 64%. Three phenolic fractions were obtained with tetrahydrofuran: free phenolic acids, soluble and insoluble phenolic esters. The antioxidant activity of these fractions was 83%, 85% and 93% respectively, and the antioxidant activity of the control BHT was 64%. The phenolic acids were identified on the basis of relative retention times as compared with standards. The fractions obtained showed the presence of the following phenolic acids: salicylic, trans‐cinnamic, sinapinic, chlorogenic, protocatechinic, gallic, quinic, and p‐hydroxibenzoic acid. The presence of phenolic compounds in macambo fruit extracts may be responsible for its rather high antioxidant activity and the results obtained suggest that macambo extracts could be used as food antioxidants. Further studies are in progress to analyze the use of its extracts and phenolic fractions in edible oil shelf life.     

Encapsulation of Unsaponifiable Matter of Rice Bran Oil Bychitosan and Lepidium perfoliatum Seed Gum: Characterization and Antioxidant Activity

The unsaponifiable matter (USM) of Tarom and Fajr rice bran oil were encapsulated with chitosan (CS) and Lepidium perfoliatum seed gum (LPSG) and physicochemical and structural properties, the total phenolic content and the antioxidant activity of particles were assessed. The results indicated that particles had a mean size of 145.5–232.7 nm with a narrow size distribution. Besides, theencapsulation efficiency of encapsulated powdersranged from 74.36 to 83.09%.Scanning electron microscopy (SEM) images showed the formation of the spherical-shaped and aggregated particles. Differential scanning calorimetry (DSC) thermograms and Fourier transform infrared spectroscopy analyses confirmed the successful encapsulation of USM. The encapsulated powdersshowed higher total phenolic content than free USM, while presenting desirable antioxidant activity. In addition, the samples coated by LPSG presented better physicochemical properties than those coated by CS. Finally, our results suggested that encapsulated powders could have a promising application in food systems.     

Identification of phenolic compounds and antioxidant activity of guava dehydrated by different drying methods

Abstract

The influence of different drying techniques on guava was investigated, including phenolic components and antioxidant activities. Through drying processes, total phenolic content (TPC) increased and formation of small molecular phenolic acids (multi-methoxy benzoic acid and sinapic acid) was promoted. UPLC-ESI-QTOF-MS determination showed flavanol compounds, hydrolyzable tannins, ellagic acid conjugates and cinnamic acid derivatives were four predominant phenolics of guava. Drying treatments caused degradation of catechin and its derivatives. Contrarily, drying treatments contributed to higher contents of procyanidin trimers. Moreover, thermal drying treatments led to degradation of macromolecular tannins and formation of smaller molecular tannins and ellagic acid conjugates, while simultaneously reduced the stabilities of most intrinsic ellagic acid conjugates. Furthermore, drying processes increased the yield of cinnamic acid dihexose, probably generating from lignin or phenolics–carbohydrate complex. Freeze drying and hot air drying showed better performance on retention of TPC and enhancement of antioxidant activity (AA).     

Unexploited Thapsia garganica,Orlaya maritima,and Retama raetam Seeds: Potential Sources of Unsaturated Fatty Acid and Natural Antioxidants

Total lipid contents, fatty acid compositions, phenolic profiles and antioxidants activities of seeds from Thapsia garganica, Orlaya maritima, and Retama raetam were investigated. The oil values were more than 26 %, except seeds of R. raetam (ca. 3 %). Unsaturated fatty acids accounted for the majority of the fatty acids (more than 75 %). Oleic and linoleic acid were the predominant fatty acids. Total phenolic compounds (24–104 mg GAE g^?1 DR), total flavonoids (4–102 mg QE g^?1g DR), total tannins (28–85 mg GAE g^?1 DR) and condensed tannins (0.62–131 mg CE g^?1 DR) were also determined. The antioxidant activities using different assays were evaluated. The predominant detected classes were the phenolic acids (42–85 %) and the flavonoids (11–48 %). The major phenolic acids were caffeic, trans‐4‐hydroxy‐3‐methoxycinnamic, p‐coumaric, and gallic acid. The predominant flavonoids were quercetin, luteolin, naringin, apigenin, and kaempferol. This study brings attention to the medicinal importance of these species as a source of oil and antioxidant molecules.     

Chemo‐enzymatic synthesis of lipophilic ferulates and their evaluation for antioxidant and antimicrobial activities

An efficient chemo‐enzymatic synthesis of ferulic acid‐based structured lipids mimicking triacylglycerol with a pendant phenolic moiety was carried out for the first time. Initially, ferulic acid was reduced to coniferyl alcohol, followed by its esterification with fatty acids. The key step in the synthesis was dihydroxylation of the olefinic side chain of coniferyl ester, which was eventually esterified with fatty acids to generate phenolic structured lipids. Two such compounds of varying fatty acid chain lengths were synthesized in good yield. Structural confirmation of both compounds is based on IR, ¹H and ¹³C NMR, and MS techniques. The synthesized compounds were tested for in vitro antioxidant and antimicrobial activities. Both compounds exhibited moderate to good antioxidant activity. The phenolic structured lipid with only shorter‐chain fatty acids showed antibacterial activity. Both compounds did not show any antifungal activity.     

Conjugation with Phospholipids as a Modification Increasing Anticancer Activity of Phenolic Acids in Metastatic Melanoma—In Vitro and In Silico Studies

Phenolic acids possess many beneficial biological activities, including antioxidant and anti-inflammatory properties. Unfortunately, their low bioavailability restricts their potential medical uses, as it limits the concentration of phenolic acids achievable in the organism. The conjugation with phospholipids constitutes one of the most effective strategies to enhance compounds bioavailability in biological systems. In the present study, the conjugates of anisic (ANISA) and veratric acid (VA) with phosphatidylcholine (PC) were investigated. Since both ANISA and VA are inhibitors of tyrosinase, a melanocyte enzyme, the expression of which increases during tumorigenesis, anticancer potential of the conjugates was tested in several metastatic melanoma cell lines. The conjugates proved to be antiproliferative, apoptosis-inducing and cell-cycle-affecting agents, selective for cancerous cells and not affecting normal fibroblasts. The conjugates substituted by ANISA and VA, respectively, at both the sn-1 and sn-2 positions of PC, appeared the most promising, since they were effective against the vast majority of metastatic melanoma cell lines. Additionally, the conjugation of phenolic acids to PC increased their antioxidant activity. Molecular modeling was employed for the first time to estimate the features of the investigated conjugates relevant to their anticancer properties and membrane permeation. Again, the conjugates substituted by phenolic acid at both the sn-1 and sn-2 positions of PC seemed to be presumably most bioavailable.     

Primary Metabolites and Polyphenols in Rapeseed (Brassica napus L.) Cultivars in China

Defatted meals of 10 rapeseed (Brassica napus L.) varieties were investigated for their total phenolic, phenolic acid (free, esterified, and insoluble-bound forms), and tannin contents. The antioxidant capacities (AC) of methanol extracts from samples were assessed using the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH•), Folin–Ciocalteu method and ferric reducing antioxidant power (FRAP), and β-carotene–linoleic acid tests. In the fraction of free phenolic acids, sinapic, caffeic, ferulic, syringic, gallic, and p-coumaric acids were identified. In the fraction of esterified phenolic acids, sinapine, sinapoyl glucoside, and disinapoyl gentiobiose were identified. After basic hydrolysis, sinapic, ferulic, cinnamic, and 4-hydroxybenzoic acids were identified, and sinapic acid (SA) constituted 98.3% to 99.6% of the total esterified phenolic acids. Eleven components (sinapic, protocatechuic, p-coumaric, syringic, vanillic, gallic, caffeic, ferulic, salicylic, cinnamic, and 4-hydroxybenzoic acids) in the fraction of insoluble-bound phenolic acids were identified. The AC of the samples correlated with the total phenolic content. Overall, the total phenolics showed a better correlation with AC than the individual phenolic compounds. Moreover, SA, sinapoyl glucoside, and disinapoyl gentiobiose showed a highly significant and strong positive correlation with the AC of rapeseed meals, and the derivatives of cinnamic acid showed a higher correlation with AC than the derivatives of benzoic acid. The change in the canolol content in rapeseeds under microwave irradiation is discussed. The correlation of the canolol formed with SA and its derivatives is discussed.     

Antioxidant and Biological Activities of Novel Structured Monoacylglycerol Derivatives with Phenolic Acids

Novel structured monoacylglycerol (MAG)-based phenolic lipids are synthesized from11-bromoundecanoic acid, phenolic acids, and solketal. Selected phenolic acids namely 4-hydroxy benzoic, vanillic, syringic, cinnamic, p-coumaric, sinapic, 4-fluorocinnamic, 4-hydroxyphenyl acetic acid, 3-(4-hydroxyphenyl) propanoic and dihydrocaffeic acids are employed for the synthesis of ten novel MAG-based phenolic lipids. The synthesized phenolic lipids are characterized by FT-IR, NMR, and mass spectra analysis. All the compounds are evaluated for antioxidant, antimicrobial, and cytotoxic activities. MAG derivative 8g of sinapic acid exhibits excellent antioxidant activity in both DPPH assay and inhibition of lipid oxidation assay. MAG derivative 8f bearing p-coumaric acid shows good antimicrobial activity against both Gram-positive and Gram-negative bacterial strains with a minimum inhibitory concentration (MIC) value of 6.25 µm mL⁻¹. All the synthesized compounds are found to exhibit cytotoxicity against B16, DU145, and CHO cell lines, while sinapic and p-coumaric acid derivatives exhibit better activities compared to other derivatives.     

Phenolic Acids and Antioxidant Capacity of Distillers Dried Grains with Solubles (DDGS) as Compared with Corn

Three sets of ground corn and the corresponding distillers dried grains with solubles (DDGS) were collected from three commercial plants and analyzed for individual phenolic acids and antioxidant capacity. This study was undertaken to investigate the influence of processing on phenolic acids content and antioxidant capacity of corn and the corresponding processed DDGS samples. The five phenolic acids identified in corn and DDGS were vanillic, caffeic, p-coumaric, ferulic, and sinapic acids. Ferulic and p-coumaric acids accounted for about 80% of the total identified and quantified phenolic acids. The phenolic acids profile of DDGS was comparable to that of corn. The content of total phenolic acids per gram basis, in DDGS was 3.40 fold higher and antioxidant capacity was 2.58 fold more than that of corn. These observations suggest that there was little degradation in individual phenolic acids content during dry grind processing. Furthermore, significant variation in measured individual and total phenolic acids, and antioxidant capacity among processing plants existed for both corn and DDGS. Results from this study will be valuable to bioethanol manufacturers and the feed industry.     

Analysis of Phenolic Compounds and Antioxidant Abilities of Extracts from Germinating Vitis californica Seeds Submitted to Cold Stress Conditions and Recovery after the Stress

The material for this study consisted of stratified seeds of Vitis californica submitted to germination under optimum conditions (+25 °C) or under chill stress (+10 °C), also followed by recovery. It has been determined that the germinating seeds contain considerable amounts of tannins, catechins as well as phenolic acids such as gallic, p-coumaric, caffeic and ferulic acids. Gallic acid appeared in the highest amount in the germinating seeds (from 42.40–204.00 µg/g of fresh weight (FW)), followed by caffeic acid (from 6.62–20.13 µg/g FW), p-coumaric acid (from 2.59–5.41 µg/g FW), and ferulic acid (from 0.56–0.92 µg/g FW). The phenolic acids occurred mostly in the ester form. Under chill stress, the germinating seeds were determined to contain an elevated total amount of phenolics, as well as raised levels of condensed tannins, catechins, gallic acid, and gafeic acid. The levels of p-coumoric and ferulic acids were found to have decreased. In extracts isolated from a sample exposed to low temperature, increased antioxidant activity and reduction potential were also demonstrated. Tissue of the germinating seeds which underwent post-stress recovery was found to have less total phenolics.     

Improvement of quality and antioxidant properties of dried mulberry leaves with combined far-infrared radiation and air convection in Thai tea process

Combined far-infrared radiation with hot-air convection (FIR-HA) drying was used for improving colour and antioxidant properties of mulberry leaf tea. Antioxidant properties and phenolic compounds of FIR-HA dried mulberry tea were determined and compared with the commercial product and with fresh leaves. We found that a smaller decrease in L and b values of the FIR-HA dried tea than those of commercial tea was observed. FIR-HA tea was found to have similar colour to fresh leaf while the commercial tea had darker colour. A significant decrease in total phenolic acid content (TPC) and total flavonoid content (TFC) was found in hot-air (HA) dried commercial tea compared to fresh leaves, while TPC in FIR-HA dried tea was significantly increased. Similar results were found in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activities. However, the results were different for ferric reducing antioxidant power (FRAP). Both teas had lower FRAP values compared to fresh leaves. Eleven phenolic compounds were identified in fresh leaf and in mulberry tea, namely p-coumaric acid, benzoic acid, (+)-catechin, chlorogenic acid, vanillic acid, syringic acid, sinapic acid, protocatechuic acid, ferulic acid, gallic acid and caffeic acid. The total content of phenolic compounds (TPCC) increased in FIR-HA dried samples compared to those of HA dried tea, except for chlorogenic and syringic acids, which were found in greater amounts in HA dried commercial tea. Our results have demonstrated that FIR-HA should be considered as a suitable drying method for mulberry tea with respect to preserving its antioxidant properties and phenolic compounds.     

Bacterial Cellulose Membrane Containing Epilobium angustifolium L. Extract as a Promising Material for the Topical Delivery of Antioxidants to the Skin

Bacterial cellulose membranes (BCs) are becoming useful as a drug delivery system to the skin. However, there are very few reports on their application of plant substances to the skin. Komagataeibacter xylinus was used for the production of bacterial cellulose (BC). The BC containing 5% and 10% ethanolic extract of Epilobium angustifolium (FEE) (BC-5%FEE and BC-10%FEE, respectively) were prepared. Their mechanical, structural, and antioxidant properties, as well as phenolic acid content, were evaluated. The bioavailability of BC-FESs using mouse L929 fibroblasts as model cells was tested. Moreover, In Vitro penetration through the pigskin of the selected phenolic acids contained in FEE and their accumulation in the skin after topical application of BC-FEEs was examined. The BC-FEEs were characterized by antioxidant activity. The BC-5% FEE showed relatively low toxicity to healthy mouse fibroblasts. Gallic acid (GA), chlorogenic acid (ChA), 3,4-dihydroxybenzoic acid (3,4-DHB), 4-hydroxybenzoic acid (4-HB), 3-hydroxybenzoic acid (3-HB), and caffeic acid (CA) found in FEE were also identified in the membranes. After topical application of the membranes to the pigskin penetration of some phenolic acid and other antioxidants through the skin as well as their accumulation in the skin was observed. The bacterial cellulose membrane loaded by plant extract may be an interesting solution for topical antioxidant delivery to the skin.     

Antioxidant Capacities and Total Phenolic Contents Enhancement with Acute Gamma Irradiation in Curcuma alismatifolia (Zingiberaceae) Leaves

The present study was conducted in order to assess the effect of various doses of acute gamma irradiation (0, 10, 15, and 20 Gy) on the improvement of bioactive compounds and their antioxidant properties of Curcuma alismatifolia var. Sweet pink. The high performance liquid chromatography (HPLC) and gas chromatography (GC) analysis uncovered that various types of phenolic, flavonoid compounds, and fatty acids gradually altered in response to radiation doses. On the other hand, antioxidant activities determined by 1,1-Diphenyl-2-picryl-hydrazyl (DPPH), ferric reduction, antioxidant power (FRAP), and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging assay showed a higher irradiation level significantly increased the antioxidant properties. This study revealed an efficient effect of varying levels of gamma radiation, based on the pharmaceutical demand to enhance the accumulation and distribution of bioactive compounds such as phenolic and flavonoid compounds, fatty acids, as well as their antioxidant activities in the leaves of C. alismatifolia var. Sweet pink.     

Renewable antioxidant properties of suspensible chitosan–polypyrrole composites

Conductive polymers have the ability to capture radicals and have become in focus for antioxidant applications of food packaging or biomedical applications. Unfortunately, the conducting polymers such as polypyrrole are difficult to suspense in solution after chemical or electrochemical polymerization. Chitosan, as a natural polymer from chitin, can be dissolved in diluted acetic acid solutions. In the present study, composites suspensible in diluted acetic acid solutions have been produced by the chemical polymerization of pyrrole in chitosan solution using ammonium persulfate (APS) as the oxidant. FTIR and UV–Vis measurements did identify an attachment of polypyrrole to chitosan.In order to optimize the activity and stability of the composites, the ratios of APS: polypyrrole: chitosan were analyzed. The chitosan–polypyrrole composites were formed as membranes (coatings); impedance measurements indicated their conductivity to be in the range of 10^?3–10^?7 S cm^?1. The antioxidant (radical scavenger activity) properties were determined by the di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (DPPH) assay. The radical scavenger activity of the composites was found renewable by means of electrochemical cycling.     

Phenolic Profile and Biological Activities of the Pepino (Solanum muricatum) Fruit and Its Wild Relative S. caripense

The pepino (Solanum muricatum) is an edible and juicy fruit native to the Andean region which is becoming increasingly important. However, little information is available on its phenolic composition and bioactive properties. Four pepino varieties (37-A, El Camino, Puzol, and Valencia) and one accession (E-7) of its close wild relative S. caripense were characterized by HPLC-DAD-MSⁿ/ESI. Twenty-four hydroxycinnamic acid derivatives were detected (5 to 16 compounds per variety or accession), with differences of more than two-fold for their total content among the materials studied. The major phenolics in the pepino varieties were chlorogenic acids and derivatives, while in S. caripense a caffeoyl-synapoyl-quinic acid was the major compound. The in vitro antioxidant capacity (DPPH (2,2-diphenyl-1-picrylhydrazyl hydrate), ORAC (oxygen radical absorbance capacity), and TRC (total reducing capacity) tests) was higher in S. caripense. Pepino and S. caripense extracts were not toxic for RAW 264.7 macrophage cells, and the raw extracts inhibited NO production of the lipopolysaccharide (LPS)-stimulated macrophages by 36% (El Camino) to 67% (37-A). No single variety ranked high simultaneously for hydroxycinnamic acids content, antioxidant activity and biological activity. We suggest the screening of large collections of germplasm or the use of complementary crosses between Puzol (high for hydroxycinnamic acids and biological activity) and S. caripense E-7 (high for antioxidant activity) to select and breed pepino varieties with enhanced properties.     

The Interactions Between Rapeseed Lipoxygenase and Native Polyphenolic Compounds in a Model System

The focus of the present research was to study inhibition of lipoxygenase activity by rapeseed native polyphenols and the interactions between those compounds and the enzyme. The enzyme and polyphenolic compounds (polyphenols, phenolic acids) were extracted from rapeseed (Brassica napus) varieties Aviso and PR45DO3. The total phenolic compounds concentration in tested rapeseed was 1,485–1,691 mg/100 g d.m. (dry matter) and the free phenolic acids content in both rapeseed varieties was about 76 μg/100 g d.m. The isolated proteins showed lipoxygenase activity. Prooxidant properties of phenolic compounds in the presence of lipoxygenase and linoleic acid were observed rather in the case of extracts containing a relatively high concentration of miscellaneous polyphenols. Antioxidant properties were recorded in the case of phenolic acid extracts which contain only 1.4–1.9% of phenolics present in raw phenolic extracts. We propose that the prooxidant effect of phenolic compounds comes from quinone and oxidized polyphenols formation. The observed antioxidant activity of phenolic acid extracts is probably due to their ability to scavenge free radicals formed from linoleic acid. However, reduction of lipoxygenase ferric to ferrous ions, which prevent the activation of the enzyme and inhibited its activity, was also observed.     

Antinutritive and Oxidative Components as Mechanisms of Induced Resistance in Cotton to Helicoverpa zea

Induced resistance in cotton (Gossypium hirsutum) foliage and squares to herbivory by Helicoverpa zea (Lepidoptera: Noctuidae) is reported in this study. Induced resistance was indicated by decreased larval growth when larvae fed on previously damaged foliage or squares compared to the controls. Herbivory caused a significant decline in host nutritional quality as shown by a reduction in protein and most amino acids in both foliage and squares. Peroxidase, ascorbate oxidase, and diamine oxidase activities increased in both damaged foliage and squares, whereas levels of the nutritional antioxidant, ascorbate, were depressed after larval feeding. Larval feeding also markedly enhanced lipoxygenase activity and lipid peroxides in square tissues. Moreover, feeding damage altered the quantitative levels of phenolic compounds in foliage and squares. These results indicate a significant shift in the oxidative status of cotton plants following herbivory as indicated by increased oxidative enzyme activity, decreased levels of the nutritional antioxidant ascorbate, and increased levels of phenolic prooxidants (i.e., chlorogenic acid) and lipid peroxides.     

Antioxidant effect of mono‐ and dihydroxyphenols in sunflower oil with different levels of naturally present tocopherols

Antioxidant properties of mono‐ and dihydroxyphenolic acids and their alkyl esters were examined, with emphasis on the relationship between their molecular structure and antioxidant activity. Test media with different tocopherol level were used for determining the oxidative stability: original refined sunflower oil (total tocopherols 149.0 mg/kg), partially tocopherol‐stripped sunflower oil (total tocopherols 8.7 mg/kg) and distilled fatty acid methyl esters (FAME) as a tocopherol‐free medium. The chemical reaction of tocopherols with diazomethane tested for the purpose to eliminate their antioxidant activity failed due to the negligible degree of methylation of hydroxyl group in the tocopherol molecule. Caffeic acid and protocatechuic acid (3,4‐dihydroxyphenolic acids) and their alkyl esters were found to be more active antioxidants than monohydroxyphenolic acid (p‐hydroxybenzoic acid), 2,5‐dihydroxyphenolic acid (gentisic acid), 3‐methoxy‐4‐hydroxyphenolic acids (vanillic and ferulic acids) and their corresponding alkyl esters. Naturally present tocopherols in refined sunflower oil proved to have a synergistic effect on gentisic acid but not on its alkyl esters. In contrast, tocopherols showed an antagonistic effect on alkyl esters of caffeic acid, because their protection factors decreased with increasing level of tocopherols in the test medium. Moreover, the antioxidant activity of these alkyl esters decreased with increasing length of their alkyl chain in conformity with the polar paradox hypothesis. Practical applications: Tocopherols as naturally present antioxidants influence considerably the antioxidant activity of other antioxidants added to plant oils used as a test medium. Distilled fatty acid methyl esters prepared from refined sunflower oil may serve as an optimal tocopherol‐free test medium. Some alkyl esters of phenolic acids were evaluated to be applicable as natural more lipophilic antioxidants in comparison with phenolic acids.     

Biological Activities of Toninia candida and Usnea barbata Together with Their Norstictic Acid and Usnic Acid Constituents

The aim of this study was to investigate the chemical composition of acetone extracts of the lichens Toninia candida and Usnea barbata and in vitro antioxidant, antimicrobial, and anticancer activities of these extracts together with some of their major metabolites. The chemical composition of T. candida and U. barbata extracts was determined using HPLC-UV analysis. The major phenolic compounds in these extracts were norstictic acid (T. candida) and usnic acid (U. barbata). Antioxidant activity was evaluated by free radical scavenging, superoxide anion radical scavenging, reducing power and determination of total phenolic compounds. Results of the study proved that norstictic acid had the largest antioxidant activity. The total content of phenols in the extracts was determined as the pyrocatechol equivalent. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration using the broth microdilution method. The most active was usnic acid with minimum inhibitory concentration values ranging from 0.0008 to 0.5 mg/mL. Anticancer activity was tested against FemX (human melanoma) and LS174 (human colon carcinoma) cell lines using the microculture tetrazolium test. Usnic acid was found to have the strongest anticancer activity towards both cell lines with IC₅₀ values of 12.72 and 15.66 μg/mL.