Emulsification of chemical and enzymatic hydrolysates of β‐lactoglobulin: characterization of the peptides adsorbed at the interface

Bovine β‐Lactoglobulin (BLG) was cleaved by BNPS‐skatole (2‐(2′‐nitrophenylsulfenyl)‐3‐methyl‐3′‐bromoindolenine( trypsin, or pepsin in 40% ethanol before emulsification with hexadecane in order to characterize the peptides active at the interfaces. The total digests and the different phases obtained after emulsification were analyzed by RP‐HPLC to separate the peptides according to their gradual order on a hydrophilicity‐to‐hydrophobicity scale. In each case, hydrophobic peptides were recovered in the creamed phase and characterized by mass spectrometry and sequencing. After tryptic hydrolysis, short peptides were identified at the interfacial layer as fragments S₂₁–L₃₂, V₄₁–L₅₇, V₄₁–K₆₀, and W₆₁–K₇₀linked to L₁₄₉–I₁₆₂ by a C₆₆–C₁₆₀bond. It indicates that the hydrophilic/hydrophobic distribution of the amino acids in the sequence of the fragments is more relevant to adsorption than the length of the peptide. BNPS‐skatole and peptic hydrolysis produced larger hydrophobic peptides which were also recovered in the creamed phase of the emulsion and characterized.     

Chemical Profiling Using Uplc Q‐Tof/Ms and Antioxidant Activities of Fortunella Fruits

The fruits of Fortunella Swingle are widely consumed as fresh fruits and traditional medicine in China. China is the origin center and has the largest cultivated area of the genus Fortunella. In this study, the chemical compositions of ethanol extracts of the major Fortunella cultivated types including Fortunella japonica Swingle, Fortunella margarita Swingle, Fortunella crassifolia Swingle 1 (Lanshang) and Fortunella crassifolia Swingle 2 (Liuyang) were determined using ultra performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry (UPLC Q‐TOF/MS) method, and their antioxidant activities were evaluated. 12 compounds were identified and 5 compounds were tentatively characterized. The results showed that the chemical compositions of the ethanol extracts of 4 Fortunella cultivated types were largely the same. 3′, 5′‐di‐C‐glucopyranosylphloretin was the predominant flavonoid in Fortunella fruits, and Fortunella margarita Swingle had higher contents of flavonoids than other species. In addition, the data demonstrated high antioxidant activities of Fortunella fruits. The developed method could be available to rapidly analyze the chemical compounds in Fortunella fruits and its products. This study will provide information for further quality assessment and utilization of Fortunella resources.     

Antimicrobial and antioxidant activities of different propolis samples from north‐western Algeria

The aim of this study was the investigation of antimicrobial and antioxidant activities of different ethanolic extracts of propolis (EEP) collected from north‐western Algeria. Total polyphenols and flavonoids contents of extracts were measured. The UV absorption spectrum showed and confirmed their polyphenols constituents. All EEPs exerted antibacterial activity against Gram‐positive bacteria, but no effect on Gram‐negative bacteria. The minimum inhibitory concentration (MIC) of EEPs ranged from 0.01% to 2.6% v/v. The antioxidant activity was measured using ferric‐reducing power (FRAP), 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) free radical‐scavenging and ESR methods. Propolis TIA‐2 and MOH‐MAS samples showed the highest antioxidative capacity, after 35 min, while TIA‐1, NED‐TL and SFS‐SBA samples showed the highest antioxidative potential of measured EEPs, after 3 min. TIA‐2 sample showed the highest antibacterial, antioxidant activity and highest DPPH free radical‐scavenging activity as well as the highest polyphenols and flavonoids content, compared with other propolis samples.     

Antioxidant and antimicrobial potentials of Serbian red wines produced from international Vitis vinifera grape varieties

BACKGROUND: Antioxidant and antimicrobial potentials of Serbian red wines produced from different international Vitis vinifera grape varieties and their correlation with contents of phenolic compounds were studied by spectrophotometric and chromatographic methods. The antioxidant activity of red wines was estimated through their ability to scavenge 2,2′‐diphenyl‐1‐picrylhydrazyl free radical (DPPH^?). The red wines, gallic acid, (+)‐catechin and quercetin were screened in vitro for antimicrobial activity against Gram‐positive and Gram‐negative strains using microdilution and disc diffusion techniques. RESULTS: Excellent correlations between the contents of quercetin‐3‐glucoside (R² = 0.9463) and quercetin (R² = 0.9337) and DPPH^?‐scavenging ability of the red wines were found. Serbian red wines exhibited significant activity against Staphylococcus aureus, Listeria inocua, Micrococcus flavus, Sarcina lutea, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Shigella sonnei strains, which was in correlation with their phenolic composition and antioxidant activity. The compounds gallic acid, quercetin and (+)‐catechin showed high activity against B. subtilis, S. aureus, S. lutea and M. flavus Gram‐positive and S. enteritidis and P. aeruginosa Gram‐negative strains. CONCLUSION: The results show that quercetin‐3‐glucoside and quercetin concentrations can be used as markers for the determination of antioxidant and antimicrobial potentials of red wines. Copyright © 2012 Society of Chemical Industry     

Antioxidant Properties and Phenolic Composition of Greek Propolis Extracts

This study was undertaken to determine the total phenols, total flavonoids, and major phenolic compounds in the polar (methanol, 80% methanol, and aqueous) extracts of propolis collected from the Greek mainland (West Macedonia) and the Greek island, Rhodes. The antioxidant properties of the propolis extracts were also evaluated by using free 2,2^′-diphenyl-1-picrylhydrazyl radical scavenging assay and ferric reducing antioxidant power assay. The results showed that propolis from West Macedonia was found to be the strongest radical scavenger and ferric reducing agent (mean IC₅₀ 0.179 and 0.009 mg/ml, respectively). Methanol (mean IC₅₀ 0.181 mg/ml) and 80% methanol extracts (mean IC₅₀ 0.138 mg/ml) of propolis from West Macedonia showed higher radical scavenging activity than the synthetic antioxidant butylated hydroxytoluene (mean IC₅₀ 0.207 mg/ml), while exhibiting similar levels of reducing activity (IC₅₀ 0.0099 mg/ml and 0.0085 mg/ml, respectively) with flavonol quercetin (mean IC₅₀ 0.0101 mg/ml). In addition, analysis by high performance liquid chromatography showed that West Macedonia propolis, contained the highest amount of phenolic compounds: phenolic acids (caffeic acid, caffeic acid phenethylester, ferulic acid, p-coumaric acid) and flavonoids (quercetin, galangin, luteolin, apigenin). Caffeic acid (0.639–4.172 mg/g propolis) and galangin (1.317–8.551 mg/g propolis) were found to be the predominant phenolic compounds in these propolis extracts.     

Effect of thermal sterilization on ferulic, coumaric and cinnamic acids: dimerization and antioxidant activity

BACKGROUND: Some phenolic compounds, such as ferulic acid and p‐coumaric acid, exist in the form of free acids, in fruits, rice, corn and other grains. Thermal treatment (121 °C at 15–17 psi) for different times on ferulic, p‐coumaric and cinnamic acids as well as equimolar mixtures of these acids was investigated. RESULTS: Ferulic and p‐coumaric acids underwent decarboxylation, yielding dimeric products formed through their corresponding radical intermediates, while cinnamic acid was recovered unreacted. High‐performance liquid chromatography analysis showed no cross‐dimerization when equimolar mixtures of pairs of hydroxycinnamic acids were treated under the same conditions. Dimers were characterized as (E)‐4′,4″‐(but‐1‐ene‐1,3‐diyl)bis(2′‐methoxyphenol)) (dimer of 4‐vinylguaiacol) and (E)‐4,4′‐(but‐1‐ene‐1,3‐diyl)diphenol) (dimer of 4‐vinylphenol) by nuclear magnetic resonance and mass spectrometry. CONCLUSION: Sterilization by thermal processing produced dimers of ferulic and coumaric acid. The antioxidant activity of these dimers was greater than that of the respective hydroxycinnamic acids. These results may be relevant for fruits and grains that contain hydroxycinnamic acids and undergo sterilization processes such as canning. Copyright © 2012 Society of Chemical Industry     

The influence of organ,season and drying method on chemical composition and antioxidant and antimicrobial activities of Juniperus phoenicea L. essential oils

BACKGROUND: Juniperus phoenicea is an important medicinal plant. In the present study, essential oils (18 samples) from leaves and berries of Juniperus phoenicea L. (Cupressaceae), obtained by various drying methods and in different collection months, were analysed by gas chromatography–mass spectrometry and also evaluated for in vitro antimicrobial and antioxidant activities. Correlations were studied between antimicrobial activity and the chemical composition of essential oils. RESULTS: Sixty‐seven compounds were identified in essential oils, representing 97.7–100%. Essential oils were dominated by monoterpenes and sesquiterpenes, which presented 35.0–93.3% and 6.7–62.0%, respectively, depending of organ, season and drying method. Antimicrobial tests showed that essential oils strongly inhibited the growth of Gram‐positive microorganisms and Mucor ramamnianus, but was inactive against Gram‐negative strains. Antioxidant activity was tested using the ABTS radical‐scavenging assay. Most samples showed good activity (the best IC₅₀ = 41.7 ± 1.5 mg L^?1). CONCLUSIONS: It could be concluded that drying of leaves of J. phoenicea in the sun and berries in oven‐drying was more suitable and was recommended for obtaining higher essential oil yield, but for a higher percentage of some special components such as α‐pinene and δ‐3‐carene shade‐drying was more suitable. Copyright © 2009 Society of Chemical Industry     

Bioactive xanthones from the roots of Hypericum perforatum (common St John's wort)

BACKGROUND: Extracts of Hypericum perforatum L. (common St John's wort; Hypericaceae) are sold as phytopharmaceuticals and herbal supplements to treat mild to moderate depression and as food additives. Extensively cultivated in Europe, plants can be infected by anthracnose (Colletotrichum gloeosporioides), a virulent fungal pathogen that causes tissue necrosis and dramatically decreases crop value. Such infections triggered the production of new secondary metabolites, specifically xanthones, in cell culture experiments. RESULTS: Bioassay‐guided fractionation of H. perforatum root extracts, testing for growth inhibition of plant pathogenic fungi from the genera Colletotrichum, Botrytis, Fusarium and Phomopsis, was performed. In vitro anti‐inflammatory activity through inhibition of COX‐1, COX‐2 and 5‐LOX‐catalyzed LTB₄ formation was also evaluated. Extracts were analyzed by various chromatographic means and structure elucidation was performed using data from nuclear magnetic resonance and mass spectrometry. CONCLUSION: Researchers have previously described constituents from the aerial parts of this species, but few reports describe secondary metabolites found in underground parts, of particular interest because the lower stem and upper root are often sites of fungal infection. This work resulted in the isolation of three xanthones: 1,6‐dihydroxy‐5‐methoxy‐4′,5′‐dihydro‐4′,4′,5′‐trimethylfurano‐(2′,3′:3,4)‐xanthone; 4,6‐dihydroxy‐2,3‐dimethoxyxanthone; and cis‐kielcorin, one of which possessed novel bioactivity against species of Phomopsis and inhibited 5‐LOX‐mediated LTB₄ formation. Copyright © 2010 Society of Chemical Industry     

Antioxidant and antimicrobial properties of Thai propolis extracted using ethanol aqueous solution

The potential of using propolis collected from Thailand as a natural antioxidant and antimicrobial agent for food applications was investigated. The propolis extract was prepared by using different ethanol aqueous solutions, including 30%, 40%, 50% and 70%. Total phenolic content (TPC), phenolic compound and antioxidant activity of the propolis were determined using Folin–Ciocalteau method, high performance liquid chromatography (HPLC) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity, respectively. The antimicrobial ability was tested against Staphylococcus aureus (TISTR 118), Salmonella enteritidis (DMST 17368), Escherichia coli (TISTR 780) and Pseudomonas aeruginosa (ATCC 27853) using disc diffusion technique. The major phenolic compounds found in Thai propolis were rutin, quercetin and naringin. The TPC and DPPH radical scavenging activity increased with increasing ethanol concentration in the solvent. Propolis extract showed antimicrobial activity, in terms of inhibitory zone for S. aureus and limited growth underneath paper discs, against all tested bacteria.     

Phenolics,Aroma Profile,and In Vitro Antioxidant Activity of Italian Dessert Passito Wine from Saracena (Italy)

A traditional sweet dessert wine from Saracena (Italy), made with nonmacerated local white grapes (Guarnaccia, Malvasia and Moscato), was analyzed for phenolics and aroma profile and antioxidant activities. The most abundant classes of phenols identified by high‐performance liquid chromatography were hydroxybenzoic acids and flavan‐3‐ols, where gallic acid showed the highest content (376.5 mg/L). The analysis by solid phase microextraction‐gas chromatography‐mass spectrometry revealed the presence of superior alcohols (from iso‐butanol and iso‐amyl alcohol up to 2‐phenylethanol) and their ethyl esters, terpenes (such as linalool), furfuryl compounds, and free fatty acids (up to palmitic acid) as the key odorants of this wine. The antioxidant activity, evaluated by different in vitro assays 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid (ABTS), and β‐carotene bleaching test), showed that passito wine had a radical scavenging activity (IC₅₀ value of 0.03 v/v against DPPH·) and inhibited linoleic acid oxidation with an IC₅₀ value of 0.4 v/v after 30 min of incubation.     

Correlation between Antimicrobial,Antioxidant Activity,and Polyphenols of Alkalized/Nonalkalized Cocoa Powders

Many factors can influence antioxidative and antimicrobial characteristics of plant materials. The quality of cocoa as functional food ingredient is influenced through its processing. The main aim of this study was to test if there is difference in polyphenol content, antioxidant capacity, and antimicrobial activity between nonalkalized and alkalized cocoa powders. To estimate polyphenol and flavonoid content in cocoa samples the spectrophotometric microassays were used. Flavan‐3ols were determined with reversed‐phase high‐performance liquid chromatography (RP‐HPLC). Antimicrobial activity against 3 Gram positive bacteria, 4 Gram negative bacteria and 1 strain of yeast was determined using broth microdilution method. Total polyphenol content was 1.8 times lower in alkalized cocoa samples than in natural ones. Epicatechin/catechin ratio was changed due to the process of alkalization in favor of catechin (2.21 in natural and 1.45 in alkalized cocoa powders). Combined results of 3 antioxidative tests (DPPH, FRAP, ABTS) were used for calculation of RACI (Relative Antioxidant Capacity Index) and GAS (Global Antioxidant Score) values that were consistently higher in natural than in alkalized cocoa extracts. Obtained results have shown significant correlations between these values and phenolic content (0.929 ≤ r ≤ 0.957, P < 0.01). Antimicrobial activity varied from 5.0 to 25.0 mg/ml (MICs), while Candida albicans was the most sensitive tested microorganism. Cocoa powders subjected to alkalization had significantly reduced content of total and specific phenolic compounds and reduced antioxidant capacity (P < 0.05), but their antimicrobial activity was equal for Gram‐positive bacteria or even significantly enhanced for Gram‐negative bacteria.     

Enhancing the antioxidant activity of immature calamondin by heat treatment

The purpose of this study was to investigate the enhancing effect of heat treatment (110 and 130 °C for 0.5, 1.0, 1.5 and 2.0 h, and 150 °C for 1.5 h) on antioxidant activity and phenolic compounds of immature calamondin (Citrus mitis Blanco). The results indicated that heat treatment could enhance the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) scavenging potency, oxygen radical absorbance capacity (ORAC) and total phenolic content. However, the major flavonoid, 3′,5′‐di‐C‐β‐glucopyranosylphloretin (DGPP), decreased drastically after being heated at ≥130 °C over 1.5 h. The increasing ratio of absorbance at UV₄₂₀ nm coincided with the change of the antioxidant activity. Therefore, it was concluded that the browning products resulted in the increase of the antioxidant activity of immature calamondin heated at ≥130 °C over 1.5 h, while the increase of antioxidant activity at 110 and 130 °C ≤ 1.0 h heating was due to increased phenolic content.     

Chemical composition and antioxidant and radical‐scavenging activities of Periploca laevigata root bark extracts

BACKGROUND: The root powder of Periploca laevigata is used for preparing soft drinks and as an aromatic in Tunisia. The infusion or decoction of its root bark has widespread use in folk medicine. The plant is used to treat digestive disorders and hypertensive effects as well as other health problems. RESULTS: The antioxidant activities of extracts of P. laevigata root bark obtained with solvents of different polarity were investigated using assays of 1,1‐diphenyl‐2‐picrylhydrazyl radical‐scavenging activity, ferric‐reducing capacity, β‐carotene‐bleaching ability, hydroxyl radical‐scavenging activity and lipid peroxidation inhibition. The methanol extract, with the highest amount of total phenolics and flavonoids, showed the highest antioxidant activities in all assays, followed by the water extract. Gas chromatography/mass spectrometry was used to determine the composition of the water and methanol extracts. Thirty‐four compounds were identified in the methanol extract, with proflavine (516.2 g kg^?1 dry matter (DM)) and 4‐methoxysalicylaldehyde (198.3 g kg^?1 DM) being the most abundant. Sixteen compounds were identified in the water extract, of which 4‐hydroxy‐3‐methoxyphenethylene glycol (351.2 g kg^?1 DM) was the main component. CONCLUSION: As far as is known, this is the first report on the chemical composition and biological activities of phenolic extracts from P. laevigata. The results of the study indicate that the root bark of this plant might be a good candidate for further investigation in developing new antioxidants. Copyright © 2009 Society of Chemical Industry     

Rapid Identification and Comparison of Compounds with Antioxidant Activity in Coreopsis tinctoria Herbal Tea by High‐Performance Thin‐Layer Chromatography Coupled with DPPH Bioautography and Densitometry

A simple and efficient method based on high‐performance thin‐layer chromatography coupled with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) bioautography (HPTLC‐DPPH) was established for the screening and comparison of antioxidants in different parts of Coreopsis tinctoria herbal tea from different origins and other related herbal tea materials, which used Chrysanthemum morifolium cv. “Gongju” and “Hangju” in this study. Scanning densitometry after DPPH derivatization was applied for the determination of antioxidant capacities of isolated compounds in each sample. It is considered that ethanol extracts of C. tinctoria had stronger antioxidant activity and more characteristic bands than those of 2 compared samples, C. morifolium cv. “Gongju” and “Hangju.” Chemometric analysis results showed that the combination of hierarchical clustering analysis and principal component analysis based on determined antioxidant capacities could be used for the discrimination of different parts of C. tinctoria and C. morifolium. Results showed that 7 compounds made up the major contributions of antioxidant activity in C. tinctoria, including okanin, isookanin, marein, flavanomarein, 5,7,3′,5′‐tetrahydroxyflavanone‐7‐O‐glucoside, 3,5‐dicaffeoylquinic acid, and chlorogenic acid. Therefore, 7 compounds were identified as major antioxidant biomarkers for quality control of C. tinctoria. Results demonstrated that the established method could be applied for the identification of C. tinctoria, and were beneficial for the bioactivity‐based quality control of C. tinctoria.     

Growth inhibition of foodborne pathogens by co‐microencapsulation of lactobacilli cell free and propolis extracts

Cell free extracts (CFE) obtained from Lactobacillus plantarum FI 8595 and Lactobacillus reuteri ATCC 55730 alone or in combination with propolis ethanolic or water extracts (1%) were microencapsulated with maltodextrin (25%) before the subsequent spray drying process. They were morphologically characterized by scanning electron microscope. Chemical compositions of pure extracts were identified by gas chromatography–mass spectrometry. Antimicrobial activities of pure and microencapsulated extracts against four foodborne pathogens (Staphylococcus aureus ATCC29213, Listeria monocytogenes ATCC19112, Klebsiella pneumoniae ATCC700603 and Salmonella Paratyphi A NCTC13) were determined using agar well diffusion, broth microdilution and time kill assays. CFE from L. reuteri and L. plantarum consisted of acetic acid, pyrrolo[1,2‐a]pyrazine‐1,4‐dione, hexahydro‐3‐(phenylmethyl)‐, 2,3,4‐trihydroxybenzaldehyde and 9‐octadecenoic acid. The results also indicated the presence of two respective major compounds, namely, 2‐methoxy‐4‐vinylphenol (19.03%) and trans‐cinnamic acid (27.67%) in water and ethanolic propolis extracts. Presence of propolis extracts mainly ethanolic extract in microencapsulation led to higher inhibition zones against all foodborne pathogens (p < .05). The co‐microencapsulation of CFE from L. reuteri in combination with ethanolic or water extract of propolis resulted in 2.34‐ and 2.2‐fold higher inhibition zone towards L. monocytogenes. Pure and microencapsulated CFE from L. reuteri resulted in 2.89 and 2.14 log cfu/ml reduction in growth of S. Paratyphi A at 3 hr, respectively. The co‐microencapsulation of CFE from lactobacilli and propolis extracts mainly ethanolic extract could be suggested as a novel antimicrobial on inhibition of food pathogens, as they contain abundant bioactive substances.     

The effect of hopping regime,cultivar and β‐glucosidase activity on monoterpene alcohol concentrations in wort and beer

Previous studies show that the complexity of hop aroma in beer can be partly attributed to the hydrolysis of glycosidically bound monoterpene alcohols extracted from hops during the brewing process to release volatile aglycones. However, fundamental studies that examine the extraction of glycosides during brewing and their subsequent hydrolysis by yeast have not been performed. Furthermore, extraction of other hop‐derived compounds into beer shows a strong dependency on the hop cultivar being used and the point at which it is added. This study focused on the extent of glycoside extraction owing to hopping regime and cultivar, and their hydrolysis by yeast β‐glucosidase activity. Glycoside concentrations of wort made with three different hopping regimes and three cultivars were measured by the difference in volatile aglycone concentrations between samples treated with purified β‐glucosidase and untreated samples. Aglycone concentrations were measured by solid‐phase microextraction gas chromatography–mass spectrometry. Additionally, β‐glucosidase activities for 80 different yeast strains and their effect on aglycone concentration in wort were determined. Results showed that yeast have a wide range of abilities to hydrolyse glycosides with a maximum hydrolysis occurring after 3 days of fermentation regardless of yeast activity. Although it was shown that yeast are capable of glycoside hydrolysis, glycoside concentrations in wort are low and make small contributions to hop aroma. These results help explain the extent to which different brewing yeasts and hopping regimes contribute to hoppy beer aroma through the hydrolysis of non‐volatile hop‐derived compounds. Copyright © 2017 The Institute of Brewing & Distilling     

Jabuticaba (Myrciaria cauliflora) Seeds: Chemical Characterization and Extraction of Antioxidant and Antimicrobial Compounds

This study was aimed to assess the effect of time and temperature on the extraction of antioxidant compounds from jabuticaba seeds (Myrciaria cauliflora cv. Sabará), to optimize the solvent proportion (water, ethyl alcohol, and propanone), and to characterize the extract according to the chemical composition, antioxidant, and antimicrobial properties. Proximal composition, total phenolic content (TPC), antioxidant, and antimicrobial activities were analyzed. The optimized solvent ratio of 60% water and 40% propanone provided a mean TPC of 8.65 g GAE/100 g seeds and the antioxidant activity toward 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) was 82.79% ± 0.50%. Time and temperature parameters did not influence the yield of TPC. The gross seed extract was partially purified and both exhibited a high antioxidant activity and antimicrobial potential toward Gram‐positive and Gram‐negative bacteria. The purified jabuticaba seed lyophilized extract contained a higher (P < 0.05) TPC, o‐diphenols, flavonols, and antioxidant activity measured by the DPPH assay and total reducing capacity as compared to the gross lyophilized extract. Electrospray ionization coupled with tandem mass spectrometry (ESI‐MS/MS) data showed the presence of ellagitannins and ellagic acid in the extracts, which are probably the responsible for the antimicrobial and antioxidant activities.     

Antioxidant Capacities,Phenolic Contents,and GC/MS Analysis of Rhodiola imbricata Edgew. Root Extracts from Trans‐Himalaya

Our aim was to assess the antioxidant capacities and phenolic constituents of methanol and aqueous extracts of Rhodiola imbricata Edgew. root from Trans‐Himalayan cold desert of Ladakh. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) radical scavenging capacity of the root extracts increased in a dose‐dependent manner (up to 0.1 mg/mL) and root extract concentrations required for 50% inhibition of radical scavenging effect (IC₅₀) were recorded as 0.013 and 0.014 mg/mL (for DPPH) and 0.016 and 0.017 mg/mL (for ABTS) for methanol and aqueous extracts, respectively. The total antioxidant power of the extract was determined by ferric reducing antioxidant power (FRAP) assay. Total polyphenol and phenolic acid content of methanol and aqueous extracts were 112.24, 59.06, 39.02, and 16.95 mg gallic acid equivalent/g of extract, respectively. Total flavonoid and flavonol contents were estimated to be 30.2, 17.67, 20.68, and 7.38 mg quercetin equivalent/g of extract, respectively. In all antioxidant capacity assays, the methanol extract exhibited significantly higher antioxidant capacity than that of aqueous extract due to the presence of significantly higher amount of vital phytoconstitiuents, viz. polyphenol, phenolic acid, and flavonol. GC/MS analysis showed that phytosterols, alkyl halide, phenols, and fatty acid esters were major phytochemical clusters. On the other hand, monoterpenes, fatty acids, tocopherols, aliphatic hydrocarbons, and ethers were found to be present in comparatively less amount in the methanol extract. Hence, our study signifies that this high‐altitude medicinal herb could be used as the natural source of antioxidants and supports its use in traditional system of medicine to ameliorate oxidative stress and high‐altitude maladies.     

Antioxidant activities of different Teucrium montanum L. Extracts

The sequential extraction of Teucrium montanum L. was realised with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, and n‐butanol) and HPLC method was used for identification of phenolic compounds. The total phenolic content of the extracts was determined spectrophotometrically according to the Folin–Ciocalteau procedure and range from 0 to 296 mg g^?1. The antioxidant activity of extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using electron spin resonance (ESR) spectroscopy. Moreover, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (1) sunflower oil (37 °C, 3 h) induced by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and (2) liposomes induced by 2,2′‐azobis(2‐amidino‐propane)dihydrochloride (AAPH) was studied. n‐Butanol extract, because of the highest content of total phenolic compounds (296 mg g^?1) had the best antioxidant activity (100% at 0.16 mg mL^?1 in Fenton reaction system; 90.57% at 5 mg mL^?1 in system I; 100% at 5 mg mL^?1 in system II).     

ANTIFUNGAL,AFLATOXIN INHIBITORY AND FREE RADICAL‐SCAVENGING ACTIVITIES OF SOME MEDICINAL PLANTS EXTRACTS

ABSTRACT

The antifungal, aflatoxin inhibitory and antioxidant activity of methanol–aqueous extract (2:1) of 62 medicinal plants was explored. Based on the antifungal results, the extracts of 25 plants showed more than 50% antifungal activity and were further investigated for their aflatoxin inhibition and antioxidant properties. Methanol–aqueous extracts of Phyllanthus emblica and Terminalia chebula fruits caused 100% inhibition of aflatoxin production by the toxigenic strain of Aspergillus flavus in semisynthetic medium at 1 mg/mL. In addition, P. emblica (IC₅₀ = 4.1 µg/mL) and T. chebula (IC₅₀ = 6.9 µg/mL) fruits extracts exhibited strong antioxidant activity during the 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging assay in comparison with butylated hydroxytoluene (IC₅₀ = 8.1 µg/mL) and butylated hydroxyanisole (IC₅₀ = 6 µg/mL).

PRACTICAL APPLICATIONS

Based on the results of the present study, methanol–aqueous extracts of Phyllanthus emblica and Terminalia chebula, being endowed with strong antifungal, aflatoxin inhibitory and antioxidant activity, may be recommended as plant‐based preservatives for the enhancement of shelf life of food items and their protection from the undesirable harmful effects of molds, aflatoxin and free radical‐mediated damages.