Acid Free Radical Research Articles

Effect of pH on the Radical Quenching Capacity of Tea Infusions Using the ABTS•+ Assay

Aims: The aims of this study were to assess the impact of pH on the free radical quenching activity of tea infusions using a modified 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay and three antioxidant compounds as reference.Study Design: In-vitro method.Place and Duration of Study: Faculty of Life and Health Science, School of Biomedical Sciences, Ulster University, UK. From Sept 2014 and May 2016.Methodology: Free radical quenching capacity of tea (Earl grey, black tea, Ceylon tea, & green tea) infusions were investigated using persulfate activated ABTS with acetate buffer (pH 4.5) or phosphate buffer saline (pH 7.0) as solvent. Tests were performed using 96-well microplates, 20 µl of sample and 280 µl of ABTS reagent, and calibrated using ascorbic acid, trolox or gallic acid as reference antioxidants.Results: Gallic acid free radical quenching was pH dependent and unsuitable as reference. The free radical quenching capacity of trolox and ascorbic acid was not significantly different at pH 4.5 and pH 7.0. The radical quenching capacity of tea infusions expressed as Trolox Equivalent Antioxidant Capacity (TEAC) or Ascorbic Acid Antioxidant Capacity (AAEAC) was grater by 50-300% at pH 7 compared to pH 4.5.Conclusion: The modified ABTS assay is suitable for examining the influence of pH on free radical quenching ability of tea samples. Gallic acid was not a suitable reference compound. The radical quenching capacity of tea infusions increases with rising pH.

PRELIMINARY PHYTOCHEMICAL SCREENING AND IN VITRO ANTIOXIDANT ACTIVITY OF ETHIOPIAN INDIGENOUS MEDICINAL PLANTS, OCIMUM LAMIIFOLIUM HOCHST. EX BENTH AND OCIMUM BASILICUM L.

Antioxidants are the chemical substances which prevent the free radicals damage in the body. Numerous researches are going globally focussed on investigating natural antioxidants of plants origins. The aims of the present study were to evaluate preliminary phytochemical investigation and in vitro antioxidant activities of Ethiopian indigenous medicinal plants, Ocimum lamiifolium Hochst. ex Benth and Ocimum basilicum L. Aqueous, benzene and hexane crude leaves extracts of O. lamiifolium and O. basilicum were subjected to qualitative phytochemical screening using standard procedures. In addition, we investigated the antioxidant potential of crude aqueous leaves extract of O. lamiifolium and O. basilicum using tests involving inhibition of superoxide anions, DPPH, H2O2, NO and ABTS. Preliminary phytochemical investigation for benzene, hexane and aqueous extracts found alkaloids, sterols, carbohydrate and glycosides, tannins and flavonoids. The fraction inhibition of lipid peroxide at the first stage of oxidation illustrated antioxidant activity of O. lamiifolium and O. basilicum as 90% and 88% compared to those of gallic acid (97%) and BHT (84%) respectively. Also, the aqueous leaves extract of O. lamiifolium and O. basilicum exhibited significant DPPH free radical scavenging activity, nitric acid free radical scavenging activity assay, superoxide anion scavenging activity, ABTS scavenging activity and hydrogen peroxide free radical scavenging assay. Our findings provide confirmation that the aqueous leaves extract of O. lamiifolium and O. basilicum are potential source of natural antioxidants, and this warranted its uses in traditional medicine systems.

Investigation of the antioxidant activity of electrosynthesized polyaniline/reduced graphene oxide nanocomposite in a binary electrolyte system on ABTS and DPPH free radicals

Abstract This study investigated the effect of supporting electrolytes with different molar ratios of inorganic (KCl) and organic salt (pTSA) on antioxidant activity of polyaniline/reduced graphene oxide (PAni/r-GO) nanocomposite electrosynthesized on composite 2B graphite pencil in 1 M H3PO4 to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) free radicals. The synthesis of PAni/r-GO nanocomposite was accomplished by cyclic voltammetry. The FT-IR and the electrochemical impedance spectroscopy (EIS) confirmed that the presence of KCl in the medium increased the degree of conductivity of polyaniline. In addition to this, the charge transfer resistance (Rct) value of synthesized composite in the presence of KCl is much smaller than that synthesized in the presence of pTSA; besides, the UV–vis spectra demonstrated the antioxidant activity of composite through reaction with free radicals in methanol solution. This indicated that both DPPH and ABTS eliminate increase in the presence of PAni/r-GO nanocomposite electrosynthesized with pTSA. Thus, scavenging of DPPH and ABTS radicals becomes more efficient when the amount of pTSA supporting electrolyte in the synthesis of PAni/r-GO nanocomposite is increased.

Pioglitazone significantly prevented decreased rate of neural differentiation of mouse embryonic stem cells which was reduced by Pex11β knock-down

Peroxisomes constitute special cellular organelles which display a variety of metabolic functions including fatty acid oxidation and free radical elimination. Abundance of these flexible organelles varies in response to different environmental stimuli. It has been demonstrated that PEX11β, a peroxisomal membrane elongation factor, is involved in the regulation of size, shape and number of peroxisomes. To investigate the role of PEX11β in neural differentiation of mouse embryonic stem cells (mESCs), we generated a stably transduced mESCs line that derives the expression of a short hairpin RNA against Pex11β gene following doxycycline (Dox) induction. Knock-down of Pex11β, during neural differentiation, significantly reduced the expression of neural progenitor cells and mature neuronal markers (p<0.05) indicating that decreased expression of PEX11β suppresses neuronal maturation. Additionally, mRNA levels of other peroxisome-related genes such as PMP70, Pex11α, Catalase, Pex19 and Pex5 were also significantly reduced by Pex11β knock-down (p<0.05). Interestingly, pretreatment of transduced mESCs with peroxisome proliferator-activated receptor γ agonist (pioglitazone (Pio)) ameliorated the inhibitory effects of Pex11β knock down on neural differentiation. Pio also significantly (p<0.05) increased the expression of neural progenitor and mature neuronal markers besides the expression of peroxisomal genes in transduced mESC. Results elucidated the importance of Pex11β expression in neural differentiation of mESCs, thereby highlighting the essential role of peroxisomes in mammalian neural differentiation. The observation that Pio recovered peroxisomal function and improved neural differentiation of Pex11β knocked-down mESCs, proposes a potential new pharmacological implication of Pio for neurogenesis in patients with peroxisomal defects.

약재 추출물을 첨가한 과립의 품질 특성 및 항산화 효과

The aim of this study was to investigate the quality characteristics and antioxidant activities of herbal medicine extract granules for the comparison of commercial powder products such as adlay tea powder and roasted grain powder. The antioxidant activities of samples were estimated using reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging activities, and total polyphenolic contents. Herbal extract granules contained 126.44±7.26 mg/100 g of total polyphenolic contents. Interestingly, the highest antioxidant activity was found in 5.5% herbal extract granules, which showed DPPH and ABTS free radical scavenging activities of 71.82% and 85.28%, respectively, at 100 mg/mL and reducing power of O.D 1.25. These results suggested that addition of herbal medicine extract had beneficial effects on the functionality of granules without any affecting on its sensory characteristics.

약재 추출물을 첨가한 노인용 기능성 양갱의 품질 특성 및 항산화 효과

The purpose of this study was to investigate antioxidant activity of yanggaeng containing herbal medicine extracts (YH) by employing various in vitro antioxidant assays for 1,1-diphenyl-2-picrylhydrazyl free radical scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radical scavenging, and reducing power. We also investigated moisture content, pH, texture profile, and sugar content, and evaluated the sensory characteristics of developed yanggaengs. Moisture content of YH was 41.54%. Sugar contents increased while pH decreased as content of herbal medicine extracts increased. Lightness was not significantly different between YH and control. However, herbal medicine extracts enhanced the redness of yanggaeng. Texture profile analysis showed that gumminess and chewiness of yang- gaeng added with herbal medicine extracts decreased compared to control. Herbal medicine extracts enhanced yang- gaeng's antioxidant activity, reducing power, and scavenging ability. Herbal medicine extracts enhanced antioxidant properties of yanggaeng and made it easier to swallow.

증자처리에 의한 갈대 식용가능 부위(어린순과 뿌리)의 이화학적 특성

This study was performed for the comparison of the general components, minerals, amino acids, organic acids, free sugars, ascorbic acid, polyphenol content and DPPH free radical scavenging activity of steamed-treated reed (sprout and root) to those of raw reed. Moisture content of sprout and root of reed after steaming treatment decreased from 81.28% and 81.64% to 70.18% and 65.50%, respectively. Crude ash content was the highest in raw sprout and steam-treated root. Crude lipid content of raw sprout and root were almost similar. In addition, crude lipid content of steam-treated sprout was greater than that of root. Nitrogen free extract content of root was 2 times as high as that of sprout. Total free sugar contents of raw sprout and root increased from 1,311.39 mg% and 4,130.98 mg% to 1,157.79 mg% and 3,750.90 mg%, respectively, after steam treatment. Furthermore, the organic acid contents of sprout and root of reed after steam treatment were less than those of raw sprout and root. Calcium and potassium contents were the highest among others in both steam-treated and raw reed. Amino acid content of sprout was higher than that of root in both before and after steam treatment. Among the amino acids, serine content was the best presented in both before and after steam treated reed. Vitamin C content of steam-treated sprout and root of reed decreased from 61.74 mg% and 6.57 mg% to 4.54 mg% and 80.79 mg%, respectively. Total polyphenol content of sprout was greater than that of root in raw and steam-treated reed. DPPH free radical scavenging activity of ethanol extraction of root was greater than those of other extracts of root.

Antidiabetic and antioxidant activities of Nypa fruticans Wurmb. vinegar sample from Malaysia.

To study the antidiabetic and antioxidant activities of nipa palm vinegar (NPV) used in traditional Malay medicine for treating diabetes. NPV was extracted using liquid-liquid extraction method and the obtained samples were subjected to antidiabetic studies using normal and streptozotocin-induced diabetic rat models whereas antidoxidant activities were investigated via invitro antioxidant tests namely 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azinobis-3-ethylbenzothiozoline-6-sulfonic acid free radicals scavenging activities and the reducing power assay. Single administration of NPV and its extracts were not effective in both normal and diabetic rats. In intraperitoneal glucose tolerance test, NPV and its aqueous extract showed significant blood glucose lowering effect. In the sub-acute study, compared with the diabetic control, aqueous extract of NPV showed the most notable blood glucose lowering effect (56.6%) and a significant improvement in serum insulin levels (79.8%, P<0.05). To assess NPV's antioxidant activity, three invitro antioxidant tests were employed: 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azinobis-3-ethylbenzothiozoline-6-sulfonic acid free radical-scavenging assays, and the reducing power assay. Ethyl acetate extract had the greatest antioxidant potential and content of phenolic and flavonoid compounds. A linear positive correlation between the antioxidant parameters was observed. Chemical profiling analysis of aqueous extract of NPV revealed the presence of acetic acid (35.25%), the main active constituent which significantly contributed to the observed antidiabetic activity. Aqueous extract of NPV possesses antihyperglycaemic activities comparable to the metformin, while the ethyl acetate extract precipitated significant antioxidant effects attributable to its high phenolic content. These findings suggest that antioxidant compounds of NPV do not contribute much towards the overall observed antidiabetic effect.

Hawthorn ethanolic extracts with triterpenoids and flavonoids exert hepatoprotective effects and suppress the hypercholesterolemia-induced oxidative stress in rats.

The current study was aimed to determine the bioactive constituents and biological effects of the Crataegus monogyna ethanolic extracts from bark, leaves and berries on hypercholesterolemia. Oleanolic acid, ursolic acid, quercetin and lupeol concentrations were quantified by HPLC. Total phenol content and radical scavenging activity of extracts were also measured. The hypocholesterolemic, antioxidant, and hepatoprotective effects of the extracts were examined in hypercholesterolemic rats and compared with orlistat. The highest phenol content, oleanolic acid, quercetin and lupeol levels and free radical scavenging potency were found in the bark extract, and the highest ursolic acid level was found in the berries extract. Orlistat and extracts significantly (P<0.05) lowered the hypercholesterolemia-increased serum level of hepatic enzymes and lipid peroxidation level. Hawthorn's extracts protected from hepatic thiol depletion and improved the lipid profile and hepatic damages. Data suggested that hawthorn's extracts are able to protect from hypercholesterolemia-induced oxidative stress and hepatic injuries. Moreover, the hypocholesterolemic effect of extracts was found comparable to orlistat.

Diversity and bioactive potential of endophytic fungi from Nothapodytes foetida, Hypericum mysorense and Hypericum japonicum collected from Western Ghats of India

Endophytic fungi are major contributors to fungal diversity and an important component of plant microbiota. Plants growing in biodiversity hotspots and having ethnobotanical utility are often explored for the presence of endophytic fungi with bioactive potential. Western Ghat mountains of India are one of the ten famous biodiversity hotspots in the world. Hence, in the present study, we investigated the diversity of endophytic fungi associated with tissues of Nothapodytes foetida (a tree), Hypericum mysorense (a shrub) and Hypericum japonicum (a herb) collected from forests of Western Ghats with emphasis on diversity of endophytic fungi harbored in different tissues of three plants and their antimicrobial and free radical scavenging activities. A total of 298 isolates belonging to 31 genera were isolated along with dark septate and sterile fungi. All isolates belonged to Dothidiomycetes, Eurotiomycetes and Sordariomycetes of the phylum Ascomycota. Most frequent colonizers were Penicillium, Aspergillus, Fusarium, Gliocladium, Cladosporium, Trichoderma, Colletotrichum, and Pestalotiopsis. Endophytes showed neither any host preference nor any dominance of a single species. Ethyl acetate extracts of 39 endophytic fungi exhibited antimicrobial activity against one or more pathogens, of which the activity of Bionectria ochroleuca NOTL33, Chaetomium globosum HYML55, Alternaria brassicae HYMS01, Aspergillus sp. HYML56 was prominent against most of the pathogens tested. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radicals were effectively quenched by the ethyl acetate extracts of 28 isolates and 34 isolates, respectively. This study is the first of its kind in H. mysorense and H. japonicum, and not only describes the endophytic diversity of these plants but also emphasizes the bioactive potential of endophytic isolates for future use in agricultural, pharmaceutical and industrial applications.

Antioxidant properties of naturally brown-colored cotton fibers

Naturally brown-colored cotton (NBCC) fibers have been reported as having excellent antibacterial properties. In this study, the antioxidant properties of NBCC fibers were investigated . The results demonstrate that the antioxidant capacity of NBCC is significantly higher than that of white cotton. An NBCC variety with a darker color has a much higher capacity in which the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging activities are 6.9 and 6.1 times those of white cotton, respectively. The antioxidant properties of NBCC were durable after scouring and laundering. The phenolic pigment composition in the fibers was found to contribute to their antioxidant properties. The results presented have furthered the understanding of the polyfunctional properties of NBCC fibers and their pigment components.

A new cyclolignan glycoside from the tubers of Pinellia ternata

A new 2,7′-type cyclolignan glycoside, cyclolignanyingoside A (1), together with six known compounds (2–7) were isolated from the tubers of Pinellia ternata (Thunb.) Breit. The structure of 1 was elucidated on the basis of chemical and spectral analysis, including 1D, 2D NMR analyses, HR-ESI-MS, and CD spectrometry. The cytotoxic, antioxidant and tyrosinase-inhibiting activities of all the isolates were determined. However, all the isolates exhibited no activity on the selected cell lines (Hep-3B, Bcap-37, and MCF-7). In addition, compounds 1–3 and 7 exhibited strong 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) free radical scavenging activity, and compounds 2 and 4 showed a moderate mushroom tyrsinase inhibitory activity.

반응표면분석법을 이용한 차가버섯(Inonotus obliquus)의 생리활성물질 최적 추출조건 탐색

본 연구에서는 차가버섯(Inonotus obliquus)의 유효성분과 항산화능이 최대가 되는 추출물의 제조를 위하여 반응표면분석법을 이용하여 최적 추출조건을 탐색하였다. 추출 수율, 총 폴리페놀 함량, 항산화능(ABTS 자유 라디칼 소거능, ORAC), <TEX>${\beta}$</TEX>-1,3-glucan 함량의 총 다섯 가지 반응변수에서 유의적인 이차 회귀식을 얻었고, 반응표면그래프와 등고선도를 통하여 최적 추출조건을 예측하였다. 각 반응변수에 따른 최적 추출조건은 추출 수율에서 50% (v/v), <TEX>$88.7^{\circ}C$</TEX>, 14.5 h, 총 폴리페놀 함량에서 9.2%, <TEX>$92.7^{\circ}C$</TEX>, 14.5 h, ABTS free radical scavanging activity에서 50.8%, <TEX>$92.7^{\circ}C$</TEX>, 14.5 h, ORAC에서 9.2%, <TEX>$92.7^{\circ}C$</TEX>, 1.5 h, <TEX>${\beta}$</TEX>-1,3-glucan 함량에서 90.8%, <TEX>$92.7^{\circ}C$</TEX>, 1.5 h으로 예측되었다. 각 반응변수의 예측 최대추출조건에서 실제 실험을 실행하여 예측 값과 비교해본 결과, 상대오차는 0.4-12.5%였다. 각 반응 변수에서 유의적인 이차 회귀식을 얻었으며, 예측 값과 실험 값의 오차가 크지 않아 반응표면모델이 최적 추출조건을 예측하는데 적합하다고 판단하였으며, 다섯 가지 반응 변수를 통합하는 최적 추출조건은 81.4%, <TEX>$92.7^{\circ}C$</TEX>, 14.5 h으로 예측하였다. 본 연구는 주로 열수추출물의 형태로 유통되는 차가버섯 추출물의 품질 개선을 위하여 에탄올 용매를 포함한 최적 추출조건을 설정하였고, 구체적인 추출 수율과 생리활성물질 함량 및 항산화능이 최대가 되는 추출조건을 제시하였다. This study determined the optimum extraction conditions based on five response variables (yield, total phenolics, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavanging activity, oxygen radical absorbance capacity (ORAC), and <TEX>${\beta}$</TEX>-1,3-glucan content) in chaga mushroom (Inonotus obliquus) using the response surface methodology, where three independent variables (ethanol concentration, extraction temperature, and extraction time) were optimized using a central composite design. The optimum ethanol concentration, extraction temperature, and extraction time were 50% (w/w), <TEX>$88.7^{\circ}C$</TEX>, and 14.5 h; 9.2%, <TEX>$92.7^{\circ}C$</TEX>, and 14.5 h; 50.8%, <TEX>$92.7^{\circ}C$</TEX>, and 14.5 h; 9.2%, <TEX>$92.7^{\circ}C$</TEX>, and 1.5 h; and 90.8%, <TEX>$92.7^{\circ}C$</TEX>, and 1.5 h for yield, total phenolics, ABTS, ORAC, and <TEX>${\beta}$</TEX>-1,3-glucan content, respectively. The predicted values of the response variables were compared with those of the extracts under the optimal extraction conditions to verify the models. The optimum extraction condition for the five response variables was predicted to be 81.4% ethanol at <TEX>$92.7^{\circ}C$</TEX> for 14.5 h.

A new polyphenol, 1, 3-di-O-caffeoyl-5-O-(1-methoxyl-2-O-caffeoyl-4-maloyl)-quinic acid, isolated from cultured cells of Saussurea involucrata

The present study was designed to isolate the polyphenol constituents of cultured cells of Saussurea involucrata. The polyphenol type constituents were isolated using chromatography methods, and then characterized by spectral analysis. 1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl)-hydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radical scavenging were assayed using Vitamin C as the positive control. One new polyphenol 18, 1, 3-di-O-caffeoyl-5-O-(1-methoxyl-2-O-caffeoyl-4-maloyl)-quinic acid, together with 17 known compounds, was isolated and characterized. In conclusion, Compound 18 was a new caffeoyl maloyl quinic acid type polyphenol and showed desired vitro anti-oxidant activity. Compounds 1–5, 9, 10, 14, 15, and 17 were isolated from cultured cells of Saussurea involucrata for the first time.

Phenol content and antioxidant activity of green, yellow and black tea leaves

Green, black and yellow tea leaves are rich in phenolic compounds that are known for their antioxidant activity thus beneficial effect on human health. In practice, different methods are used to determine antioxidant activity. The objective of this study was to determine content of phenols, flavonoids and tannins, as well as antioxidant activity of tea leaves. Green, yellow and black tea leaves (intact and pulverised leaves) were used for extraction by methanol or acidified methanol. Spectrophotometric methods were used for determination of selected parameters. Antioxidant activity was determined in extracts and pulverised tea leaves by application of 2,2-diphenyl-1-picrilhydrazyl (DPPH) and 2,2′azinobis-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) free radicals. For determination of antioxidant activity of the pulverised leaves, ‘QUENCHER’ method was used. The method is based on the direct treatment of dry sample with free radicals. Extracts obtained by extraction of pulverised tea leaves with acidified methanol had the highest phenolic content (3.823, 4.226 and 6.829 g/kg for green, black and yellow tea, respectively). In methanol extracts, phenol content decreased in order yellow > green > black tea and, in acidified methanol extracts, yellow > black > green tea, regardless of particle size of tea leaves for extraction. Flavonoid and tannin contents followed the same tendency as phenol content. The highest antioxidant activity had acidified methanol extracts of pulverised tea leaves, regardless of used method (DPPH and ABTS). Results of antioxidant activity obtained with ‘QUENCHER’ method were compared with results of acidified methanol extracts. Green and yellow tea had higher antioxidant activity when ‘QUENCHER’ method was used in contrast to the black tea where higher antioxidant activity was determined in extract. Particle size and extraction solvent had high influence on total phenolic compounds, total flavonoid and tannin content as well as on antioxidant activity. Also, antioxidant activity of samples highly depended on used free radicals and sample preparation prior their application.

Antioxidant and tyrosinase inhibitory effects of neolignan glycosides from Crataegus pinnatifida seeds.

In our efforts to find an inhibitor of melanin formation and develop potential depigmenting agents for skin-protecting cosmetics and medicinal products from natural resources, we focused on the seeds of Crataegus pinnatifida which showed antioxidant and tyrosinase-inhibiting activities. By activity-guided fractionation of an extract of C. pinnatifida seeds, four new neolignan glycosides, pinnatifidaninsides A-D (1-4), along with two known compounds (5-6), were isolated. Their structures were elucidated by spectroscopic analyses, especially 1D, 2D NMR and CD spectra. The antioxidant and tyrosinase-inhibiting activities of all isolates were assayed. Compound 6 showed good activity against 2,2-diphenyl-1-pikrylhydrazyl, while compounds 1, 2, 5, and 6 exhibited strong 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) free radical scavenging activity, being as effective as, or even more effective than the positive control Trolox. Moreover, compounds 5 and 6 displayed a moderate mushroom tyrosinase inhibitory activity.

Methanol Partition Fraction of Ethanol Extract of Discorea nipponica Makino Inhibits Melanogenesis

Purpose: To investigate the inhibitory effect of the methanol fraction of Dioscorea nipponica Makino ethanol extract (DNM) on melanogenesis both in vitro and in vivo.Methods: Cultured mouse B16 melanoma cell and zebra fish were used to evaluate the melanogenesis inhibitory activity of DNM in vitro and in vivo, respectively. In B16 cells, inhibitory effects on intracellular melanogenesis, tyrosinase activity and reactive oxygen species (ROS) were determined after DNM treatment. In zebra fish, both toxic and antimelanogenic ctivities of DNM on developed larvae were evaluated.Results: In B16 cells, the results show that DNM dose-dependently inhibited melanogenesis at non-toxic concentrations. Surprisingly, however, DNM had no effect on intracellular tyrosinase activity or the amount of the enzyme in B16 cells. On the other hand, DNM showed strong antioxidant activities against cell-free 2,2-diphenyl-1-picryl-hydrazl (DPPH) and 2,2’-azino-bis (3-etnylbenzthiazoline-6-sulphaonic acid) (ABTS+) free radical and intracellular ROS in B16 cells. In zebra fish, DNM significantly and dose-dependently inhibited skin melanogenesis of zebra fish larvae at non-toxic concentrations.Conclusion: The findings demonstrate that DNM inhibits melanogenesis in vitro in B16 melanoma cells and in vivo in zebrafish. Furthermore, DNM exhibits potent inhibition of melanogenesis probably as a result of its antioxidant activity in the cells.Keywords: Dioscorea nipponica, Makino, Melanogenesis, Tyrosinase, Antioxidant, Melanoma, Zebra fish

A pulse radiolysis study of the dynamics of ascorbic acid free radicals within a liposomal environment.

The dynamics of free-radical species in a model cellular system are examined by measuring the formation and decay of ascorbate radicals within a liposome with pulse radiolysis techniques. Upon pulse radiolysis of an N2O-saturated aqueous solution containing ascorbate-loaded liposome vesicles, ascorbate radicals are formed by the reaction of OH(·) radicals with ascorbate in unilamellar vesicles exclusively, irrespective of the presence of vesicle lipids. The radicals are found to decay rapidly compared with the decay kinetics in an aqueous solution. The distinct radical reaction kinetics in the vesicles and in bulk solution are characterized, and the kinetic data are analyzed.

Phenolic contents, antioxidant and anticholinesterase potentials of crude extract, subsequent fractions and crude saponins from Polygonum hydropiper L.

BackgroundWe investigated Polygonum hydropiper L. (P. hydropiper) for phenolic contents, antioxidant, anticholinesterase activities, in an attempt to rationalize its use in neurological disorders.MethodsPlant crude extract (Ph.Cr), its subsequent fractions: n-hexane (Ph.Hex), chloroform (Ph.Chf), ethyl acetate (Ph.EtAc), n-Butanol (Ph.Bt), aqueous (Ph.Aq) and saponins (Ph.Sp) were evaluated for 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) free radical scavenging potential. Further, acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities were performed using Ellman's assay. Moreover, total phenolic contents of plant extracts were determined and expressed in mg of gallic acid equivalent per gram of dry sample (mg GAE/g dry weight).ResultsAmong different fractions, Ph.Cr (90.82), Ph.Chf (178.16), Ph.EtAc (203.44) and Ph.Bt (153.61) exhibited high phenolic contents. All fractions showed concentration dependent DPPH scavenging activity, with Ph.EtAc 71.33% (IC50 15 μg/ml), Ph.Bt 71.40% (IC50 3 μg/ml) and Ph.Sp 71.40% (IC50 35 μg/ml) were most potent. The plant extracts exhibited high ABTS scavenging ability i.e. Ph.Bt (91.03%), Ph.EtAc (90.56%), Ph.Sp (90.84%), Ph.Aq (90.56%) with IC50 < 0.01 μg/ml. All fractions showed moderate to high AChE inhibitory activity as; Ph.Cr, 86.87% (IC50 330 μg/ml), Ph.Hex, 87.49% (IC50 35 μg/ml), Ph.Chf, 84.76% (IC50 55 μg/ml), Ph.Sp, 87.58% (IC50 108 μg/ml) and Ph.EtAc 79.95% (IC50 310 μg/ml) at 1 mg/ml). Furthermore the BChE inhibitory activity was most prominent in Ph.Hex 90.30% (IC50 40 μg/ml), Ph.Chf 85.94% (IC50 215 μg/ml), Ph.Aq 87.62% (IC50 3 μg/ml) and Ph.EtAc 81.01% (IC50 395 μg/ml) fractions.ConclusionsIn this study, for the first time, we determined phenolic contents, isolated crude saponins, investigated antioxidant and anticholinestrase potential of P. hydropiper extracts. The results indicate that P. hydropiper is enriched with potent bioactive compounds and warrant further investigation by isolation and structural elucidation to find novel and affordable compounds for the treatment of various neurological disorders.

Synergistic impact of sonication and high hydrostatic pressure on microbial and enzymatic inactivation of apple juice

The combination of innovative, non-thermal technologies for the production of safe and quality fruit juices is a recent trend in food processing. The purpose of this study was to evaluate the effects of combined treatment of ultrasound (US) and high hydrostatic pressure (HHP) on enzymes (polyphenolase, peroxidase and pectinmethylesterase), microorganisms (total plate counts, yeasts and molds) and phenolic compounds (total phenols, flavonoids and flavonols) of apple juice. Moreover, its effects on ascorbic acid, antioxidant capacity and DPPH free radical scavenging activity, color values, pH, soluble solids and titratable acidity were investigated. Fresh apple juice was treated with US (25 kHz and 70% amplitude) at 20 °C for 60 min with subsequent HHP treatment at 250, 350 and 450 MPa for 10 min at room temperature. The results revealed that the combined US-HHP450 treatment caused highest inactivation of enzymes with complete inactivation of total plate counts, yeasts and molds. It also significantly improved the phenolic compounds, ascorbic acid, antioxidant capacity, DPPH free radical scavenging activity and color values. The present results suggest that the combination of US and HHP can act as a potential hurdle to produce safe and high quality apple juice with reduced enzymes and microbial activity and improved nutrition.