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.).     

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.     

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.     

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.     

Optimising the free radical scavenging activity of shrimp protein hydrolysate produced with alcalase using response surface methodology

Response surface methodology (RSM) was used to optimise the hydrolysis parameters of Acetes chinensis by Alcalase 2.4L in order to obtain a hydrolysate with potent radical scavenging activity. The parameters were temperature, pH and enzyme concentration/substrate concentration (E/S) ratio with degree of hydrolysis (DH) being the response. The results showed that the optimum condition was: temperature at 57 °C, pH at 8.0, E/S ratio at 2.6AU 100 g⁻¹ shrimp, hydrolysis time 3 h. The DH was 26.32%, the hydroxyl radical scavenging activity was up to 88.12% and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was 35.61%. The gel column filtration chromatography by a Sephadex G-25 column yielded five fractions. The molecular weight of the most potent free radical scavenging activity fraction ranged from 915 to 207 Da, its IC₅₀ for hydroxyl radical was 0.03 mg mL⁻¹, and IC₅₀ for DPPH radical was 8.86 mg mL⁻¹.     

Selenium content in selected products of animal origin and estimation of the degree of cover daily Se requirement in Poland

The aim of the study was to determine Se concentration in selected products of animal origin (dairy products, pork, beef, chicken, giblets, fish, eggs) and to estimate the degree to which these products cover daily Se requirement in humans. Selenium concentrations were determined using the spectrofluorometric method. Mean Se concentration in the milk, yoghurt, kefir, and probiotic drinks was 0.020 μg mL⁻¹, 0.010 μg mL⁻¹, 0.012 μg mL⁻¹ and 0.012 μg mL⁻¹, respectively. Selenium concentration in cheese ranged 0.022–0.088 μg g⁻¹ wet weight. The average selenium content of meat ranged from 0.064 (beef) to 0.094 (chicken) μg g⁻¹ w.w. The mean Se content of giblets (liver: 0.307–0.401 μg g⁻¹ w.w.) was significantly ( P  < 0.05) higher than in meat. The concentration of Se depends on fish species and in our study it ranged from 0.136 ± 0.023 (flounder) to 0.282 ± 0.024 μg g⁻¹ w.w. (mackerel). The results obtained show that the analysed food provides 22.8% of the daily selenium requirement. Considering that animal products account for 40–45% of the diet daily selenium intake averages 33–37 μg.     

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.     

Rapid and sensitive determination of formaldehyde in some beverages and foods by flow-injection fluorimetric analysis

A simple and sensitive flow-injection (FI) method for rapid determination of formaldehyde in beverage and food products has been developed. Adopting stop-flow technique, the proposed method distinctly improved the sensitivity of FI fluorimetric method for the determination of formaldehyde based on Hantzsch reaction with cyclohexane-1,3-dione. The fluorescent intensity was proportional to formaldehyde concentrations ranging 0.1 ng mL⁻¹ to 1.000 μg mL⁻¹, and the detection limit ( S / N  = 3) was 0.04 ng mL⁻¹ of formaldehyde. The relative standard deviations ( n  = 11) for determination of 0.100 and 0.005 μg mL⁻¹ of formaldehyde were 1.3% and 2.1%, respectively. The analytical frequency was 18 samples per hour. This method was applied directly for the determination of formaldehyde in diluted beverages and extraction solutions of foods, and the results obtained correlated well with those obtained by the standard method in which a sample pretreatment of steam distillation was required.     

Arbutin determination in medicinal plants and creams

A simple flow injection (FI) manifold with spectrophotometric detection was fabricated and tested for arbutin determination. It is based on the measurement of a red-coloured product at 514 nm formed by the complexation reaction between arbutin and 4-aminoantipyrine (4-AP) in the presence of hexacyanoferrate (III) in an alkaline medium. On injecting 300 μL standard solutions at various concentrations of arbutin into the FI system under optimum conditions, a linear calibration graph over the range of 1.0–30.0 μg mL⁻¹ arbutin was established. It is expressed by the regression equation y  = 0.2188 ± 0.0036 x  + 0.1019 ± 0.0366 ( r ²   = 0.9990, n  = 5). The detection limit (3σ) and the limit of quantitation (10σ) were 0.04 μg mL⁻¹ and 0.13 μg mL⁻¹, respectively. The RSD of intraday and interday precisions were found to be 1.2–1.4% and 1.7–2.7%, respectively. The method was successfully applied in the determination of arbutin in four selected fruits and three commercial whitening cream extracts with the mean recoveries of the added arbutin over the range of 96.2–99.0%. No interference effects from some common excipients used in commercial whitening creams were observed. The method is simple, rapid, selective, accurate, reproducible and relatively inexpensive.     

Optimisation of the medium composition for production of protease and soybean peptides by Bacillus subtilis SHZ using response surface methodology

Responses surface methodology was employed to enhance the production of protease and soybean peptides by Bacillus subtilis SHZ. For screening of medium composition significantly influencing protease and soybean peptides yield, the two-level Plackett–Burman design was used. Among thirteen variables tested; KH₂PO₄, glucose and defatted soybean flour (DSF) were selected based on their high significant effect on both protease activity and soybean peptides yield. Then, a three-level Box–Behnken design was employed to optimise the medium composition for the production of the protease and soybean peptides in submerged fermentation. Mathematical models were then developed to show the effect of each medium composition and their interactions on the production of protease and soybean peptides. The model estimated that, the maximal protease activity (320 ± 1 U mL⁻¹) could be obtained when the concentrations of glucose, KH₂PO₄, DSF were set at 8–9 g L⁻¹, 2–3 g L⁻¹, 55–65 g L⁻¹, respectively; while a maximal yield of soybean peptides (8.5 ± 0.1 g L⁻¹) could be achieved when the concentrations of glucose, KH₂PO₄, DSF were set at 7–9 g L⁻¹, 3–4 g L⁻¹ and 55–58 g L⁻¹, respectively. These predicted values were also verified by validation experiments.     

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.     

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.     

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 .     

番石榴不同部位乙醇提取物的抗氧化、降血糖及酪氨酸酶抑制活性

目的:比较研究番石榴不同部位(根、茎、叶、果实)乙醇提取物抗氧化、降血糖和抑制酪氨酸酶活性.方法:分别采用ABTS法和DPPH法、pNPG法和DNS法、L-DOPA法评价番石榴不同部位抗氧化活性、降血糖活性和酪氨酸酶抑制活性.结果:番石榴不同部位乙醇提取物均具有一定的体外抗氧化、降血糖和酪氨酸酶抑制活性,并呈现一定的量...     

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.     

Phenolic compound composition and antioxidant activity of fruits of Rubus and Prunus species from Croatia

Two fraction, one containing flavonols, flavan-3-ols, phenolic acids and the other containing anthocyanins, were isolated from Rubus (red raspberry, blackberry) and Prunus (sweet cherry, sour cherry) fruits to study their phenol content by HPLC and antioxidant activity using the DPPH test. Raspberries and blackberries were characterised by catechins and ellagic acid derivatives; sour and sweet cherries by phenolic acids. All fruits had relatively high anthocyanin content. Anthocyanins contributed more to the antioxidant activity of all fruits (∼90%) than flavonols, flavan-3-ols and phenolic acids (∼10%). A biphasic reaction was observed between DPPH^• radicals and phenols, with 'fast' and 'slow' scavenging rates which might be important in the biological activity of these fruits. Sour cherries and blackberries which stand out with the highest total phenol content (1416 and 1040 mg kg⁻¹) had also the strongest antioxidant activity (EC₅₀ = 807 and 672 g of fruit per gram of DPPH) and can be considered as good source of dietary phenols.     

刺玫果水层萃取物活性成分及其体外活性研究

采用紫外分光光度法,测定刺玫果水层萃取物中总黄酮、多酚、原花青素及花青素的含量,探究刺玫果水层萃取物的多种体外活性及其DPPH自由基清除能力的稳定性。结果表明,刺玫果水层萃取物对DPPH自由基、亚硝酸盐清除率的IC₅₀分别为0.005、0.155 mg/mL,对α-葡萄糖苷酶、酪氨酸酶、脲酶抑制率的IC₅₀分别为0.130、5.955、1.568 mg/mL,对牛磺胆酸钠、胆酸钠结合率的IC₅₀分别为2.155、2.216 mg/mL;刺玫果水层萃取物对DPPH自由基的清除率在pH10和温度为100 ℃的条件下明显下降,紫外光照射条件下清除率略微降低,其他条件下较为稳定。研究结果表明,刺玫果水层萃取物具有众多生理活性,为刺玫果的开发利用提供了数据基础。     

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.