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Polyphenol oxidase

Yoshihiro Uesawa, Naotaka Tsuji
Edible portions of bananas contain high levels of polyphenol oxidase, which catalyzes reactions in the melanin formation pathway. Tyrosine, a physiological substrate of polyphenol oxidase, has an analogous structure to acetaminophen. We investigated whether banana extract causes structural changes in acetaminophen and a decrease in its potency. Acetaminophen concentration in banana extract was measured under different conditions to characterize incompatibility. Reaction products in solution were identified using liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS)...
2018: PloS One
Anthony W Watson, Arjan Scheepens, David O Kennedy, Janine M Cooney, Tania M Trower, Crystal F Haskell-Ramsay
Emerging evidence from human intervention trials indicates health benefits of consuming blackcurrant fruit, including improvements to cognitive performance, modulation of blood flow, regulation of blood glucose and inhibition of enzymes underpinning normal cognitive function. Of particular relevance is our previous demonstration of monoamine oxidase (MAO)-A and B inhibition after the consumption of a New Zealand "Blackadder" blackcurrant juice in humans. The current study uses a double-blind, placebo-controlled, randomised cross- over design to assess the pharmacodynamics of the effects on platelet MAO-B inhibition and associated substrates, plasma prolactin levels and blood glucose levels after consumption of a single serve of "Blackadder" blackcurrant juice standardised to 500 mg polyphenols...
October 5, 2018: Nutritional Neuroscience
Hettiarachchige Dona Sachindra Melshandi Perera, Jayanetti Koralalage Ramani Radhika Samarasekera, Shiroma Mangalika Handunnetti, Ovitigala Vithanage Don Sisira Jagathpriya Weerasena, Hasitha Dhananjaya Weeratunga, Almas Jabeen, Muhammad Iqbal Choudhary
BACKGROUND: The extracts of the ten selected Sri Lankan medicinal plants have been traditionally used in the treatment of inflammatory mediated diseases. The extracts were investigated for anti-inflammatory and anti-oxidant potential in vitro to identify bio-active extracts for further chemical characterization. METHODS: In vitro anti-inflammatory activities of total ethanol extracts were investigated measuring the inhibitory activities of four pro-inflammatory enzymes, arachidonate-5- lipoxygenase (A5-LOX), hyaluronidase (HYL), xanthine oxidase (XO) and inducible nitric oxide (iNO) synthase...
October 3, 2018: BMC Complementary and Alternative Medicine
Efstratios Nikolaivits, Maria Dimarogona, Ioanna Karagiannaki, Angelina Chalima, Ayelet Fishman, Evangelos Topakas
Polyphenol oxidases (PPOs) have been mostly associated with the undesirable post-harvest browning in fruits and vegetables and with implications in human melanogenesis. Nonetheless, they are considered useful biocatalysts in the food, pharmaceutical and cosmetic industries. The aim of the present work was to characterize a novel PPO and explore its potential as a bioremediation agent. A gene encoding an extracellular tyrosinase-like enzyme was amplified from the genome of Thermothelomyces thermophila and expressed in Pichia pastoris The recombinant enzyme ( Tt PPO) was purified and biochemically characterized...
September 28, 2018: Applied and Environmental Microbiology
Marziyeh Sarmadi, Naser Karimi, Javier Palazón, Alireza Ghassempour, Mohammad Hossein Mirjalili
The combined use of elicitors can be an effective way to increase the production of secondary metabolites (SMs) in plant cell, tissue and organ cultures. This study investigated the effects of a salicylic acid (SA) pretreatment and different glucose levels on the growth, biochemical traits and taxane production in a Taxus baccata callus culture. For this purpose, after a pretreatment with SA (5 μM), three-month-old calli were cultured on B5 medium fortified with different concentrations of glucose (0, 0...
September 11, 2018: Plant Physiology and Biochemistry: PPB
Gavirangappa Hithamani, Harshini Medappa, Arugakeerthy Chakkaravarthi, Kulathooran Ramalakshmi, Karumanchi Srisaila Mallikarjuna Srinivasa Raghavarao
Enzymatic browning is a major factor affecting the quality of sugarcane juice, mainly due to the activities of polyphenol oxidase (PPO) and peroxidase (POD). Effect of bentonite (0-1%, w/v) on the activities of these enzymes, when employed alone and also in combination with acidulants, was determined. Bentonite alone could reduce the activities of PPO and POD enzymes to 160 and 24.2 u/mL, respectively. The PPO and POD activity was completely inhibited below pH 4.1 when ascorbic acid was used alone or in combination with bentonite...
October 2018: Journal of Food Science and Technology
Tingtiao Pan, Da-Wen Sun, Jitendra Paliwal, Hongbin Pu, Qing-Yi Wei
Rapid and accurate measurement of polyphenol oxidase (PPO) activity is important in the food industry as PPOs play a vital role in catalyzing enzymatic reactions. In this study, the possibility of using surface-enhanced Raman scattering (SERS) approach based on the reduction in SERS intensity of catechol in reaction medium for accurate determination of PPO activity in fruit and vegetables was investigated. Within a certain catechol concentration, when a purified PPO solution was analyzed, the reduction in SERS intensity (ΔI) was linear to PPO activity (Ec) in a wide range of 500-50000 U/L, and a linear regression equation of logΔI/Δt = 0...
September 13, 2018: Journal of Agricultural and Food Chemistry
Gai-Fang Yao, Zeng-Zheng Wei, Ting-Ting Li, Jun Tang, Zhong-Qin Huang, Feng Yang, Yan-Hong Li, Zhuo Han, Fan Hu, Lan-Ying Hu, Kang-Di Hu, Hua Zhang
Ethylene (C2 H4 ) and hydrogen sulfide (H2 S) play important physiological roles in regulating fruit ripening and senescence. The mechanism of H2 S in ethylene-induced tomato fruit ripening and senescence is still unknown. Here, we show that exogenous H2 S reduced the production of superoxide anion (·O2 - ), malondialdehyde (MDA), and H2 O2 in tomato fruit. Further, additional H2 S was found to induce the activities of guaiacol peroxidase, catalase, ascorbate peroxidase, and superoxide dismutase compared with C2 H4 treatment alone, whereas the activities of lipoxygenase, polyphenol oxidase, and phenylalanine ammonia lyase were adversely affected...
September 26, 2018: Journal of Agricultural and Food Chemistry
Ruyi Luo, Jianling Fan, Weijin Wang, Jiafa Luo, Yakov Kuzyakov, Jin-Sheng He, Haiyan Chu, Weixin Ding
Anthropogenic activities have substantially increased soil nutrient availability, which in turn affects ecosystem processes and functions, especially in nutrient-limited ecosystems such as alpine grasslands. Although considerable efforts have been devoted to understanding the responses of plant productivity and community composition to nitrogen (N) and phosphorus (P) enrichment, the nutrient enrichment effects on soil organic carbon (SOC) and microbial functions are not well understood. A four-year field experiment was established to evaluate the influence of continuous N and P enrichment on plant growth and SOC content in an alpine grassland of the Qinghai-Tibetan Plateau...
February 10, 2019: Science of the Total Environment
Lei Yan, Muhammad Riaz, Xiuwen Wu, Chenqing Du, Yalin Liu, Bo Lv, Cuncang Jiang
Aluminum (Al) toxicity is a major factor limiting plant productivity. The objective of the present study was to develop the mechanisms of boron (B) alleviating aluminum toxicity in citrus. The results showed that aluminum toxicity severely hampered root elongation. Interestingly, under aluminum exposure, boron supply improved superoxide dismutase activity while reducing peroxidase, catalase and polyphenol oxidase activities. Likewise, the contents of H2 O2 , lipid peroxidation, protein and proline in roots were markedly decreased by boron application under aluminum exposure...
September 10, 2018: Journal of Environmental Science and Health. Part C, Environmental Carcinogenesis & Ecotoxicology Reviews
Siyu Liu, Ayesha Murtaza, Yan Liu, Wanfeng Hu, Xiaoyun Xu, Siyi Pan
Polyphenol oxidase (PPO) in plants plays an important role in browning reactions and may affect the quality of sweet melon products. In this study, a browning-related protein (BRP) with PPO activity was partially purified from oriental sweet melon ( Cucumis melo var. makuwa Makino) by salt precipitation and column chromatography. The BRP possessed a high degree of identity with several chitinase proteins, particularly defense-related proteins, by MS identification. Pyrogallol was determined as the most appropriate substrate for BRP ( K m = 0...
2018: Frontiers in Chemistry
Dong Chen, Hong Yan Yu, Lu Yi Zou, Yue Teng, Chun Wu Zhu
It is vital to study the effects of elevated atmospheric CO2 concentration on the soil orga-nic carbon (SOC) stability in different soil layers for better understanding the mechanism of SOC transformation under the elevated atmospheric CO2 concentration. The paddy soil in a long-term FACE (Free Air Carbon-dioxide Enrichment) experiment was selected as the research object. Through the SOC physical fractionation and soil mineralization incubation, the effects of elevated atmospheric CO2 concentration on the soil organic carbon (SOC) content, particle organic matter (POM) content, SOC mineralization intensity, and enzyme activities were measured...
August 2018: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Yong Li Ku, Guo Yi Xu, Hua Zhao, Tian Wang Dong, Cui Ling Cao
The continuous cropping obstacles caused by the increase of kiwifruit planting period resulted in imbalance of soil microbial community structure, and decrease of soil enzyme activity and physicochemical indicators, which substantially reduced both the quality and yield of kiwifruit. Under the field conditions, the traditional fertilization of fruit farmers was used as a control (CK) to study the effects of two different microbial fertilizers, JF and KF, which had been verified the growth promotion of kiwifruit aseptic seedlings test, on soil microbial community structure, soil enzyme activities, soil physicochemical characters during different growth periods of kiwifruit (germination period, florescence period, fruit enlargement period, fruit ripening period and next year germination period), as well as fruit quality...
August 2018: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Xiaohong Kou, Yulong He, Yunfei Li, Xiuyu Chen, Yanchun Feng, Zhaohui Xue
The color change of the jujube fruit after harvest is used as a quality indicator. The effects of abscisic acid (ABA) and a chitosan/nano-silica/sodium alginate composite film on the color development and qualitative properties of harvested jujube in cold storage were investigated. The results indicate that a composite film could prolong the shelf life of post-harvested winter jujube for approximately 1 month, while the ABA treatment induced ripening and reduced the quality. A significant positive correlation between the a∗/b∗ values, water loss and the malondialdehyde (MDA) content was found for fruits in cold storage...
January 1, 2019: Food Chemistry
Kojiro Takanashi, Yukimi Nakagawa, Shunsuke Aburaya, Kenta Kaminade, Wataru Aoki, Yuka Saida-Munakata, Akifumi Sugiayama, Mitsuyoshi Ueda, Kazufumi Yazaki
Plants produce a large variety of specialized (secondary) metabolites having a wide range of hydrophobicity. Shikonin, a red naphthoquinone pigment, is a highly hydrophobic metabolite produced in the roots of Lithospermum erythrorhizon, a medicinal plant in the family Boraginaceae. The shikonin molecule is formed by the coupling of p-hydroxybenzoic acid and geranyl diphosphate, catalyzed by a membrane-bound geranyltransferase LePGT at the endoplasmic reticulum, followed by cyclization of the geranyl chain and oxidations; the latter half of this biosynthetic pathway, however, has not yet been clarified...
August 30, 2018: Plant & Cell Physiology
Pushpendra Kumar, Shruti Sethi, R R Sharma, Surender Singh, Eldho Varghese
The objective of this study was to monitor overall quality and to extend the shelf life of fresh-cut apple wedges. Fresh-cut apple wedges were treated with anti-browning agents and edible coatings alone as well as in combination and packed in polypropylene trays. Packed apple wedges were stored at 5 ± 2 °C and monitored for physical (colour, physiological loss in weight and firmness), bio-chemical (ascorbic acid, total antioxidant, phenol, polyphenol oxidase and peroxidase enzymes) and microbial quality...
September 2018: Journal of Food Science and Technology
José Dilson Francisco da Silva, Ana Paula Folmer Correa, Carolina Pereira Kechinski, Adriano Brandelli
Buffalo whey was hydrolyzed with Alcalase for different times ti (i = 0, 0.5, 1, 2, 3, 4 or 6 h) and the browning inhibition of minimally processed apples was investigated. The hydrolysis process was followed by determination of the degree of hydrolysis. In order to understand possible modes of action on the enzymatic browning, whey was submitted to the analysis of antioxidant activity (ABTS·+ radical sequestration, Fe2+ chelating activity and reducing power), reactivity with quinones and inhibitory activity on polyphenol oxidases (PPO) extracted from Red Delicious apples...
September 2018: Journal of Food Science and Technology
Shin-Young Park, Tae-Min Kang, Min-Ju Kim, Myo-Jeong Kim
The aim of this study was to investigate the effect of juicer type (blender or LSM household juicer) on the browning reaction of apple juice and evaluate the remaining antioxidant activity in the juice. The blender apple juice showed a darker brown color and 4.5 times higher PPO activity than LSM apple juice. This result suggested that the blender caused severer damage to plastids in cells leading to leakage of PPO into the juice than the LSM juicer. The total polyphenol and flavonoid content of LSM apple juice was approximately 2 times higher than that of blender apple juice because polyphenols and flavonoids can be used as substrates by PPO...
August 25, 2018: Bioscience, Biotechnology, and Biochemistry
Soo-Jung Moon, Han-Woo Kim, Sung-Jong Jeon
A putative laccase-like gene, GPPO, encoding a protein of 17.2 kDa and belonging to the multicopper oxidase family, was cloned and overexpressed in Escherichia coli cells. The purified recombinant protein GPPO is homodecameric protein with a molecular weight of 171.6 kDa. GPPO was not detected the ultraviolet-visible spectroscopy (UV/Vis) spectrum of typical laccases. Co2+ or Cu2+ was essential for substrate oxidation of GPPO, and the enzyme contained 1 mol of Co or Cu per mole of protein. The optimum pH required for the oxidation of 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonate) (ABTS) and 2,6-dimethoxyphenol (DMP) was 4...
November 2018: Enzyme and Microbial Technology
P G Toral, F J Monahan, G Hervás, P Frutos, A P Moloney
Growth in demand for foods with potentially beneficial effects on consumer health has motivated increased interest in developing strategies for improving the nutritional quality of ruminant-derived products. Manipulation of the rumen environment offers the opportunity to modify the lipid composition of milk and meat by changing the availability of fatty acids (FA) for mammary and intramuscular lipid uptake. Dietary supplementation with marine lipids, plant secondary compounds and direct-fed microbials has shown promising results...
August 24, 2018: Animal: An International Journal of Animal Bioscience
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