Radical scavenging and antimicrobial activity of horsetail (Equisetum arvense L.) extracts

A reversed-phase high performance liquid chromatography (RP-HPLC) separation on C₈ column and quantitative method were developed to analyse hydroxyl derivatives of benzoic and cinnamic acid and flavonoids in horsetail ( Equisetum arvense L.) extracts. Total phenolic content of n -butanol, ethyl acetate and water extracts, determined by the Folin-Ciocalteu method, was 96.4, 26.4 and 15.4 mg g⁻¹ of dry extracts, respectively. The antioxidative activity of horsetail extracts was tested by measuring their ability to scavenge stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) and reactive hydroxyl radicals by electron spin resonance spectroscopy. The results demonstrated that the free radical scavenging activity (versus both DPPH and hydroxyl radicals) depended on the type and concentration of applied extracts; the highest DPPH (EC₅₀ = 0.65 mg mL⁻¹) and hydroxyl radical scavenging activities (EC₅₀ = 0.74 mg mL⁻¹) were obtained in the case of n -butanol extract. The radical scavenging activity of extracts significantly correlated with total phenolic content. The antimicrobial tests showed that ethyl acetate and n -butanol extracts inhibited the growth of tested bacteria.     

Natural preservative ingredient from marine alga Ulva lactuca L.

The contents of total chlorophyll (T-Chl), carotenoids and phenolics compounds were quantified in the biomasses of Ulva lactuca grown either in normal or artificial sea water under indoor conditions. The antioxidant and antibacterial activities of U. lactuca crude organic extracts ( Ulva- COEs) were determined. Thirty-four compounds in Ulva- COEs were characterised by thin layer chromatography and high-performance liquid chromatography. The major compounds were chlorophyll a (Chl a ) (15.60–30.90%) and b (Chl b ) (12.20–14.89%) , 9-cis β-carotene (13.12–14.47%), α-carotene (11.44–11.47%) and all-trans β-carotene (6.16–29.70%, of total carotenoids).The Ulva- COEs exhibited remarkable antioxidant activity, with an IC₅₀ (concentration which causes a 50% of DPPH radical scavenging activity) values ranged from 16.5 and 18.7 μg mL⁻¹, which could be compared with the synthetic antioxidants: α-tocopherol (14.4 μg mL⁻¹), butylated hydroxyanisol (13.1 μg mL⁻¹) and butylated hydroxyltoluene (13.1 μg mL⁻¹). Also, Ulva- COEs exhibited great potential antibacterial activities against six bacterial strains, with minimal inhibitory concentration values ranged from 0.40 to 0.35 mg mL⁻¹.     

Anti-elastase and anti-hyaluronidase of phenolic substance from Areca catechu as a new anti-ageing agent

Synopsis We have previously screened 150 medicinal plants for the inhibition of elastase and found significant inhibitory effects of the extracts of Areca catechu L. on the ageing and inflammation of skin tissues . To isolate and identify the compounds having biological activity, they were further purified by each fraction of solvents, silica gel column chromatography, preparative TLC and reversed-phase HPLC. The peak in HPLC, which coincided with the inhibitory activity against elastase, was identified as a phenolic substance by using various colorimetric methods, UV and IR. IC₅₀ values of this phenolic substance were 26.9 μg mL⁻¹ for porcine pancreatic elastase (PPE) and 60.8 μg mL⁻¹ for human neutrophil elastase (HNE). This phenolic substance showed more potent activity than that of reference compounds, oleanolic acid (76.5 μg mL⁻¹ for PPE, 219.2 μg mL⁻¹ for HNE) and ursolic acid (31.0 μg mL⁻¹ for PPE, 118.6 μg mL⁻¹ for HNE). According to the Lineweaver–Burk plots, the inhibition against both PPE and HNE by this phenolic substance was competitive inhibition with the substrate. The phenolic substance from A. catechu effectively inhibited hyaluronidase activity (IC₅₀ : 210 μg mL⁻¹ ).
These results suggest that the phenolic substance purified from A. catechu has an anti-ageing effect by protecting connective tissue proteins.     

An evaluation of extracts of five traditional medicinal plants from Iran on the inhibition of mushroom tyrosinase activity and scavenging of free radicals

This study aimed to evaluate the free radical scavenging and inhibition properties of five medicinal plants, including Quercus infectoria Olive., Terminalia chebula Retz. , Lavendula stoechas L., Mentha longifolia L., Rheum palmatum L., toward the activity of mushroom tyrosinase using l -tyrosine and l -3,4-dihydroxyphenylalanine ( l -DOPA) as the substrate. The methanol extracts of Q. infectoria and T. chebula showed strong radical scavenging effect in 2,2'-dipheny l -1-picrylhydrazyl (DPPH) assay (IC₅₀ = 15.3 and 82.2 μg mL⁻¹ respectively). These plants also showed inhibitory effects against the activity of mushroom tyrosinase in hydroxylation of l -tyrosine (85.9% and 82.2% inhibition, respectively). These two plants also inhibited the oxidation of l -DOPA similar to kojic acid as positive control (IC₅₀ = 102.8 and 192.6 μg mL⁻¹ respectively). In general Q. infectoria and T. chebula significantly inhibited tyrosinase activity and DPPH radical. Both activities were concentration-dependant but not in linear manner. It is needed to study the cytotoxicity of these plant extracts in pigment cell culture before further evaluation and moving to in vivo conditions.     

Antioxidant and toxicity tests of roasted noni (Morinda citrifolia) leaf infusion

The antioxidant properties and toxicity profile of roasted noni ( Morinda citrifolia L . ) leaf infusion were evaluated. The 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging activity was greater than green tea infusion (81.6 ± 0.9% vs. 57.5 ± 1.8%, P  < 0.001). The mean quercetin and kaempferol contents of roasted noni leaf infusion, as prepared by the consumer, were 0.24 ± 0.01 and 0.14 ± 0.01 μg mL⁻¹, respectively. Tannic acid content was 10 ± 1 μg mL⁻¹. The infusion was non-mutagenic in the reverse mutation test in Salmonella typhimurium and did not induce primary DNA damage in E. coli PQ37. Further, no significant primary DNA damage was induced by 5,15-dimethylmorindol, which was the only detectable anthraquinone in noni leaves. The infusion was not cytotoxic in the 24 h brine shrimp toxicity test (LC₅₀ > 1 mg mL⁻¹), nor was there any evidence of acute oral toxicity from the freeze–dried infusion in Sprague–Dawley rats (LD₅₀ > 2000 mg kg⁻¹ b.w.).     

Studying the anti-tyrosinase effect of Arbutus andrachne L. extracts

Arbutus andrachne L. is widely distributed in Jordan. Tyrosinase is the key enzyme in the biosynthesis of melanin. This preliminary study was carried out to assess the possible anti-tyrosinase activity of A. andrachne extracts. Arbutin, hydroquinone and kojic acid were selected as inhibitor standards. Five different extracts (chloroform, butanol, ethanol, methanol and water) were prepared from A. andrachne stems and their activities were compared with the selected tyrosinase inhibitors. IC₅₀ was measured for both, standard and plant extracts. Among the different extracts, the methanolic extract exhibited the highest anttyrosinase activity with an IC₅₀ value (1 mg mL⁻¹). Furthermore, 9 mg A. andrachne methanolic extract showed 97.49% inhibition of tyrosinase activity. Arbutin, hydroquinone, β-sitosterol and ursolic acid were identified in the different extracts of A. andrachne by thin layer chromatography (TLC) and isolated by preparative TLC from the methanolic and chloroform stem extracts, respectively.     

Efficacy of extract and essential oil of Lantana indica Roxb. against food contaminating moulds and aflatoxin B1 production

The study investigates the antifungal and antiaflatoxigenic efficacy of Lantana indica against Aspergillus flavus , a key storage fungus. The leaf essential oil of L. indica was found more active than leaf extracts. The oil absolutely inhibited the growth of A. flavus at 1.5 mg mL⁻¹ while ethanolic and chloroform extracts of leaf show MIC at 7.5 and 10.0 mg mL⁻¹ concentrations respectively. The oil also showed pronounced antiaflatoxigenic efficacy and completely inhibited the aflatoxin B₁ production at 0.75 mg mL⁻¹. The ethanolic and chloroformic extracts inhibited the aflatoxin B₁ production at 5.0 and 7.5 mg mL⁻¹, respectively while other extracts exhibited poor efficacy. The L. indica essential oil exhibited broad fungitoxic spectrum against twelve different storage moulds. The present findings may recommend the L. indica essential oil and its bioactive leaf extracts as natural preservative would of immense significance in view of the environmental and toxicological implications by indiscriminate use of synthetic pesticides .     

DPPH free-radical scavenging ability, total phenolic content, and chemical composition analysis of forty-five kinds of essential oils

Forty-five kinds of commonly used essential oils were employed to investigate the DPPH (1,1-diphenyl2-picrylhydrazyl) radical scavenging ability and total phenolic content of major chemical compositions. The free-radical scavenging ability and total phenolic content of cinnamon leaf and clove bud essential oils are the best among these essential oils. One-half milliliter of cinnamon leaf and clove bud essential oils (10 mg mL EtOH) are shown to be 96.74% and 96.12% of the DPPH (2.5ml, 1.52 × 10^-4 M) free-radical scavenging ability, respectively. Their EC50 (effective concentrations) are 53 and 36 (μg mL^-1). One milligram per milliliter of cinnamon leaf, clove bud, and thyme red essential oils were shown to be 420, 480, and 270 (mg g^-1 of GAE) of total phenolic content, respectively. Eugenol in cinnamon leaf and clove bud essential oils (82.87% and 82.32%, respectively) were analyzed by GC-MS. It is clear that the amounts of the phenol compounds in essential oils and the DPPH free-radical scavenging ability are in direct proportion.     

2种蛋白酶酶解曲拉干酪素条件优化及抗氧化性比较

以曲拉干酪素为原料、水解度为指标,在酶解时间、酶解温度、pH值、曲拉干酪素质量浓度、酶添加量单因素试验基础上,采用响应面试验对碱性蛋白酶和胰蛋白酶酶解工艺条件进行优化,并对2 种酶解液的1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、超氧阴离子自由基、羟自由基清除率,Fe2＋、Cu2＋螯合能力和还原力等抗氧化性指标进行比较。结果表明,碱性蛋白酶和胰蛋白酶分别在酶解时间3.8、2.5 h,酶解温度49.8、47.8 ℃,曲拉干酪素质量浓度60、35 g/L,pH 8.5、7.5,酶添加量140、2 900 U/g时水解度最大,为24.25%和13.57%。碱性蛋白酶解液超氧阴离子自由基清除率、Fe2＋螯合能力显著低于胰蛋白酶解液（P＜0.01）;羟自由基清除能力高于胰蛋白酶解液（P＞0.05）;2 种蛋白酶酶解液在酶解液质量浓度1～5 mg/mL时,Cu2＋螯合能力、DPPH自由基清除率和还原力随质量浓度均呈上升趋势,Cu2＋螯合能力低于Fe2＋螯合能力（P＞0.05）,DPPH自由基清除率和还原力二者差异显著（P＜0.01）。2 种蛋白酶对酶解物抗氧化性指标影响不同,碱性蛋白酶酶解物抗氧化性相对较优。     

Comparative Flavonoids Contents of Selected Herbs and Associations of Their Radical Scavenging Activity with Antiproliferative Actions in V79-4 Cells

ABSTRACT:  To elucidate the health benefit of herbal teas on the cytotoxicity induced by H₂O₂ in V79-4 cells, herbal extracts and its flavonoids were tested using lactate dehydrogenase release and determining intracellular reactive oxygen species generation and antioxidant activity with superoxide radical scavenging assay. Significant decrease in cell viability was observed on V79-4 cells treated with H₂O₂ (1 mM), while herbal extracts and its flavonoids including catechin and epigallocatechin gallate prevented the LDH release from H₂O₂ cytotoxicity. Total catechin contents of green tea (65.6 mg/g of dry matter) were significantly higher than other herbal teas (35.8 to 1.2 mg/g of DM). The relative concentration of the 4 major tea catechins ranked EGCG > EGC > EC > C. Green tea exhibited the lowest IC₅₀ values (2 g fresh herb/100 mL) of superoxide radical scavenging activity among the tested herbal tea, which indicates powerful antioxidant activity in O₂^·− radicals scavenging, followed by black tea, dandelion, hawthorn, rose hip, chamomile.     

Screening of cereal varieties for antioxidant and radical scavenging properties applying various spectroscopic and thermoanalytical methods

Twenty varieties of four representative cereals, and sixteen varieties of six pseudocereals were investigated by different assays and analyses, covering the quantitative analysis of antioxidants, radical scavenging capacity (RSC) as well as total antioxidant capacity of cereals. The inter-variety variability in antioxidant capacity was determined by four independent methods for evaluation of antioxidant activity including 2,2'-azinobis-(3-ethylbenzthiazoline)-6-sulphonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrasyl (DPPH) tests, electron paramagnetic resonance (EPR)/spin-trapping assay and differential thermal analysis (DTA). The antioxidant capacity of studied samples determined in ABTS test ranged from 0.70 to 7.33 mg Trolox g⁻¹, in DPPH test from 1.31 to 54.79 mg Trolox g⁻¹and RSC values from EPR/spin-trapping assay varied from 0.27 to 13.52 mg Trolox g⁻¹ dry matter. The best antioxidant capacity was found for buckwheat ( Fagopyrum esculentum Moench), barley ( Hordeum vulgare L.) and Japanese millet ( Echinochloa frumentacea L.), where also the highest contents of total phenolics and exceptional thermal stability were observed.     

Angiotensin I-converting enzyme inhibitory activity of Acetes chinensis peptic hydrolysate and its antihypertensive effect in spontaneously hypertensive rats

Peptic hydrolysate with angiotensin I-converting enzyme (ACE) inhibitory activity was prepared from Acetes chinensis . The 3 kDa ultrafiltration filtrates (UF-IV) of the desalted hydrolysate exerted a potent ACE inhibitory activity with IC50 being 0.67 mg mL⁻¹. The fractions with molecular weight located between 611 and 240 Da achieved a total percentage of 63.6% in the UF-IV, with a mean peptide length of about 5.6–2.1. Gastrointestinal digestions were simulated on the hydrolysate and UF-IV and addressed their effect on the ACE inhibitory activity. The ACE inhibitory activity of the UF-IV could survive or be maintained in active form by simulated gastrointestinal digestion. Furthermore, the UF-IV exerted potent antihypertensive effect after oral administrations were given to spontaneously hypertensive rats (SHR) at a dose of 900 mg kg⁻¹ body weight. In conclusion, the UF-IV could serve as useful antihypertensive peptides in the prevention and treatment of hypertension and other associated disorders.     

Storage stability of a stimulant coconut water–acerola fruit juice beverage

The objective of this work was to study the stability of a beverage formulated with acerola fruit juice and green coconut water with added caffeine. The beverage was prepared with 25% acerola pulp, 75% green coconut water and sugar up to 12°Brix, and caffeine (125 mg L⁻¹), heat processed at 90 °C for 30 s and packed in 250-mL glass bottles. Chemical, physicochemical, microbiological and sensory analyses of the beverage were performed just after processing and during 6 months of storage at room temperature (27 °C). The vitamin C content decreased significantly throughout storage, from 399.5 to 189.6 mg 100 mL⁻¹, although it has remained relatively high. The anthocyanins initially present (0.025 mg 100 mL⁻¹) were completely lost during the storage at a mean rate of 4 μg 100 mL⁻¹ month⁻¹. The product was microbiologically stable during storage. Colour changes were also observed with absorbance at 420 nm, with average values ranging from 0.19 to 0.24. However, according to the sensory analyses the product was acceptable during the 6 months of storage, presenting sensory scores (colour, taste and global acceptance) from 6.5 to 5.5, which suggests its potential for market.     

Comparison of hot air-drying and freeze-drying on the physicochemical properties and antioxidant activities of pumpkin (Cucurbita moschata Duch.) flours

Freeze-drying and hot air-drying were applied in the preparation of pumpkin flours to investigate the effects of drying methods on the antioxidant activities and physicochemical properties. The antioxidant activities of methanol extracts from pumpkin flours were studied in terms of total antioxidant activity, reducing power, free radical scavenging, superoxide anion radical scavenging and metal chelating activities. Hot air-dried pumpkin flour showed stronger antioxidant activities than freeze-dried flour. The percentage inhibition of peroxidation in linoleic acid system by 15 mg mL⁻¹ extracts from hot air-dried and freeze-dried pumpkin flours was found to be 92.4% and 86.1% after 120 h of incubation, respectively. Hot air-dried pumpkin flour exhibited higher reducing power, free radical scavenging and metal chelating activities than freeze-dried flour. This study also indicated that freeze-drying significantly reduced the browning and preserved the redness of pumpkin flours. Hot air-drying reduced the oil absorption capacity, water absorption and porosity of pumpkin flours, while it markedly increased the water solubility and bulk density.     

A modified colorimetric method for the estimation of β-cyclodextrin using phenolphthalein

The binding equilibrium between β-cyclodextrin and phenolphthalein has been used to develop a method for the estimation of β-cyclodextrin in solution. From logarithmic plots of amounts of β-cyclodextrin against absorbance at 554 nm, a relation log X  = (log A  − log Y )/ B was found, which gave an estimate of β-cyclodextrin in the concentration range 0.0045 mg mL⁻¹ (3.96 μm) to 4.7 mg mL⁻¹ (4.14 mm), where X =  intercept and B  = slope. This method was found to be highly reproducible and reliable.     

Radical scavenging compounds in onion skin

Two major flavonols (F_I and F_II) in onion skin were isolated. According to the ultraviolet–visible absorption spectra, F_I and F_II fractions were thought to be 3,5,7,3′-OH and 3 (5),7,3′,4′-OH of flavonol, respectively. After acid hydrolysis of the two fractions, F_I was found to consist of quercetin and glucose, but F_II only contained quercetin. F_I and F_II were confirmed by fast atom bombardment as quercetin 4′-glucoside and quercetin, respectively. The F_I and F_II fractions exhibited potent radical scavenging activity against DPPH, superoxide anion (O₂·^-) , and hydroxyl (·OH) radicals.     

石斑鱼肉肽的酶法制备工艺及其抗氧化性

以冰鲜石斑鱼肉为原料,采用碱性蛋白酶酶解的方法制备蛋白肽。以水解度和1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除率为评价指标,在单因素试验的基础上,运用正交试验设计优化肽的制备工艺;利用DPPH自由基法、2,2’-联氮双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azinobis（3-ethylbenzothi azoline-6-sulfonic acid）ammonium salt,ABTS）自由基法、羟自由基（·OH）法和铁氰化钾还原法评价酶解物的抗氧化性。结果表明：石斑鱼肉肽的最佳制备条件为：酶解温度55 ℃、酶解pH 9、酶用量5 000 U/g、底物质量浓度8 g/100 mL、酶解时间5 h;石斑鱼肉肽酶解物具有较强的抗氧化性,清除DPPH自由基能力、ABTS+·能力、·OH能力和总还原力均随酶解物质量浓度的增加而增强;酶解物清除DPPH自由基、ABTS+·、·OH的半抑制浓度（IC50）值分别为（1.18±0.26）、（0.89±0.05） mg/mL和（0.35±0.02） mg/mL。     

Simple HPLC Method for Resolution of Curcuminoids with Antioxidant Potential

ABSTRACT:  Development of methodology for qualitative analysis and quantitative separation of individual curcuminoids in curcumin removed turmeric oleoresin (CRTO) and study of antioxidant activity of individual curcuminoids have been achieved in the present study. A simple HPLC protocol was outlined for optimal resolution of curcuminoids (I), (II), and (III) on an Exil-NH₂ column using isocratic elution with a mixture of isopropanol and water. CRTO is shown to be good source for the compounds II and III, as they are in an enriched form. The optimum resolution of the curcumin and its analogs in the present method developed, affords a facile method for estimation of individual curcuminoids in turmeric samples, which is an improvement over the standard AOAC method which estimates only total curcuminoids. The free radical scavenging capacity of pure curcuminoids I, II, and III, as determined by DPPH method at 100 ppm concentration was 88%, 80%, and 68% with IC₅₀ values being 56, 62, and 73 ppm, respectively. Their antioxidant potential could render them useful as important nutraceuticals or functional food ingredients.     

Radical scavenging activity and phenolic compounds in persimmon (Diospyros kaki L. cv. Mopan)

ABSTRACT:  The Mopan persimmon ( Diospyros kaki L. cv. Mopan) is the major cultivar of astringent persimmon in northern China. This study investigates the radical scavenging activity against ABTS and DPPH radical, and the content of total and individual phenolics (catechin, epicatechin, epigallocatechin, chlorogenic acid, caffeic acid, and gallic acid) with apple, grape, and tomato as controls. The radical scavenging activities against ABTS and DPPH radicals of the Mopan persimmon are 23.575 and 22.597 μm trolox eq/g f.w., respectively. These findings suggest that the Mopan persimmon's antioxidant activity is significantly ( P < 0.05) stronger than that of reference materials. The Mopan persimmon showed the highest content of total phenolics among the 4 materials tested. Significant correlations ( R ²= 0.993, P < 0.05, ABTS radical; R ²= 0.980, P < 0.05, DPPH radical) are found between the total phenolics and the radical scavenging activities. The total content of these 6 kinds of phenolics (catechin, epicatechin, epigallocatechin, chlorogenic acid, caffeic acid, and gallic acid) is significantly correlated ( R ²= 0.831, P < 0.05, ABTS radical; R ²= 0.745, P < 0.05, DPPH radical) with the individual radical scavenging activity of the 4 materials, although the total content of the 6 phenolics accounts for no more than 20% of the total phenolics in the Mopan persimmon. Gallic acid exhibits the strongest antioxidant activity in all 6 kinds of phenolics and its content is the largest in the Mopan persimmon, presumably being responsible for its much higher antioxidant activity as compared to apple, grape, and tomato.