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1. Novel selective inhibitors of macropinocytosis-dependent growth in pancreatic ductal carcinoma

Author

Silvia Brambillasca, Maria Rosaria Cera, Adrian Andronache, Sumit Kumar Dey, Giovanni Fagá, Daniele Fancelli, Emanuela Frittoli, Maurizio Pasi, Michela Robusto, Mario Varasi, Giorgio Scita, and Ciro Mercurio

Subjects
Macropinocytosis, Pancreatic ductal adenocarcinoma (PDAC), Drug screening, Drug repurposing, FDA-approved drugs, Therapeutics. Pharmacology, RM1-950
Abstract

Macropinocytosis is a cellular process that enables cells to engulf extracellular material, such as nutrients, growth factors, and even whole cells. It is involved in several physiological functions as well as pathological conditions. In cancer cells, macropinocytosis plays a crucial role in promoting tumor growth and survival under nutrient-limited conditions. In particular KRAS mutations have been identified as main drivers of macropinocytosis in pancreatic, breast, and non-small cell lung cancers. We performed a high-content screening to identify inhibitors of macropinocytosis in pancreatic ductal adenocarcinoma (PDAC)-derived cells, aiming to prevent nutrient scavenging of PDAC tumors. The screening campaign was conducted in a well-known pancreatic KRAS-mutated cell line (MIAPaCa-2) cultured under nutrient deprivation and using FITC-dextran to precisely quantify macropinocytosis. We assembled a collection of 3584 small molecules, including drugs approved by the Food and Drug Administration (FDA), drug-like molecules against molecular targets, kinase-targeted compounds, and molecules designed to hamper protein-protein interactions. We identified 28 molecules that inhibited macropinocytosis, with potency ranging from 0.4 to 29.9 μM (EC50). A few of them interfered with other endocytic pathways, while 11 compounds did not and were therefore considered specific “bona fide” macropinocytosis inhibitors and further characterized. Four compounds (Ivermectin, Tyrphostin A9, LY2090314, and Pyrvinium Pamoate) selectively hampered nutrient scavenging in KRAS-mutated cancer cells. Their ability to impair albumin-dependent proliferation was replicated both in different 2D cell culture systems and 3D organotypic models.These findings provide a new set of compounds specifically targeting macropinocytosis, which could have therapeutic applications in cancer and infectious diseases.

Published
2024
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2. A planar polarized MYO6-DOCK7-RAC1 axis promotes tissue fluidification in mammary epithelia

Author

Luca Menin, Janine Weber, Stefano Villa, Emanuele Martini, Elena Maspero, Carlos A. Niño, Valeria Cancila, Alessandro Poli, Paolo Maiuri, Andrea Palamidessi, Emanuela Frittoli, Fabrizio Bianchi, Claudio Tripodo, Kylie J. Walters, Fabio Giavazzi, Giorgio Scita, and Simona Polo

Subjects
CP: Cell biology, Biology (General), QH301-705.5
Abstract

Summary: Tissue fluidification and collective motility are pivotal in regulating embryonic morphogenesis, wound healing, and tumor metastasis. These processes frequently require that each cell constituent of a tissue coordinates its migration activity and directed motion through the oriented extension of lamellipodium cell protrusions, promoted by RAC1 activity. While the upstream RAC1 regulators in individual migratory cells or leader cells during invasion or wound healing are well characterized, how RAC1 is controlled in follower cells remains unknown. Here, we identify a MYO6-DOCK7 axis essential for spatially restricting RAC1 activity in a planar polarized fashion in model tissue monolayers. The MYO6-DOCK7 axis specifically controls the extension of cryptic lamellipodia required to drive tissue fluidification and cooperative-mode motion in otherwise solid and static carcinoma cell collectives.

Published
2023
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3. Sustained Secretion of the Antimicrobial Peptide S100A7 Is Dependent on the Downregulation of Caspase-8

Author

Tanay Bhatt, Aishwarya Bhosale, Bhavya Bajantri, Mruthyunjaya Swamy Mathapathi, Abrar Rizvi, Giorgio Scita, Amitabha Majumdar, and Colin Jamora

Subjects
Biology (General), QH301-705.5
Abstract

Summary: Antimicrobial peptides (AMPs) are the body’s natural innate immune defense against a spectrum of pathogens and can also modulate cell proliferation, chemotaxis, angiogenesis, wound healing, and immune cell activity. Harnessing these diverse functions for prophylactic use is contingent upon understanding the regulatory mechanisms governing their unconventional secretion from cells. Analysis of the secretion of S100A7 (Psoriasin), an abundant AMP stored in differentiated keratinocytes of the skin, has revealed an unexpected biphasic secretory response to bacterial exposure. The core components regulating S100A7 secretion are NFκB/p38MAPK, caspase-1, and interleukin (IL)-1α. The initial activation of this core machinery is mediated by Toll-like receptor signaling, whereas the chronic response is mediated by Caspase-8 downregulation. Interestingly, there is a concomitant downregulation of Caspase-8 in inflammatory skin diseases wherein S100A7 is constitutively released. These results highlight the potential of targeting these components to control the release of AMPs from the skin in both homeostatic and disease conditions. : The global explosion of antibiotic-resistant microorganisms has spurred interest in alternative strategies to combat these “superbugs.” Antimicrobial peptides (AMPs) have emerged as a promising solution. Bhatt et al. show downregulation of epidermal caspase-8 can mediate sustained release of AMPs from the skin and provide an effective defense against infection. keywords: caspase, antimicrobial peptides, skin, TLR, IL-1, NFkB, psoriasis, antibiotic resistance

Published
2019
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4. Bidirectional Crosstalk between Actin Dynamics and Endocytosis

Author

Giorgio Scita and Pier Paolo Di Fiore

Subjects
biology, Profilin, Endocytic cycle, biology.protein, Arp2/3 complex, Actin remodeling, macromolecular substances, Receptor-mediated endocytosis, MDia1, Actin-binding protein, biological phenomena, cell phenomena, and immunity, Microfilament, Cell biology
Abstract

Publisher Summary This chapter covers the cell biology evidence establishing the significance of actin dynamics for the correct execution of endocytosis and emphasizes the molecular connections between the endocytic and actin machineries. It also describes results showing how endocytosis itself controls various forms of actin dynamics, especially those required for the spatial restriction of signaling events. The minimal requirement to support cycles of actin polymerization and depolymerization have been identified through in vitro reconstitution experiments. These experiments showed that five different types of purified proteins are sufficient to generate forces for motility, including de novo actin nucleators and their regulators (Arp2/3 complex and N-WASP), actin severing/depolymerizing factors, barbed end cappers, and an ATP-actin monomeric binding protein (profilin). In mammalian cells, critical components of the actin dynamics machinery such as the Arp2/3 complex, N-WASP, and the capping protein Eps8 are also transiently recruited to clathrin-positive endocytic sites, and their ablation impairs clathrin mediated endocytosis to various extents. Rab5 is a master regulator of endocytosis and endosomal dynamics. Rab5, however, is also involved in the control of actin dynamics. This dual function is underscored by a complex system of regulation, in which several activators of Rab5 (including the GEFs RIN1, Rabex-5, and Alsin) are also involved in the control of actin dynamics. RIN1 is an effector of Ras and binding to Ras enhances the Rab5 specific GEF activity of RIN1 that mediates EGFR mediated Rab5 activation via Ras in vivo. A more direct way of achieving Rab5 activation by surface receptors is through Rabex-5 that possesses two ubiquitin binding domains, which bind ubiquitinated proteins including EGFR.

Published
2010

5. Endocytosis and Cytoskeleton

Author

Pier Paolo Di Fiore and Giorgio Scita

Subjects
media_common.quotation_subject, Endocytic cycle, Receptor-mediated endocytosis, Biology, Endocytosis, Actin cytoskeleton, Cell biology, Nocodazole, chemistry.chemical_compound, chemistry, Microtubule, Internalization, Cytoskeleton, media_common
Abstract

This chapter describes the various emerging evidence supporting the involvement of actin dynamics in endocytosis. It also briefly discusses the possible roles for microtubules during the initial and later phases of the endocytic process and describes the known molecular circuitries that link and integrate endocytosis and actin dynamics. Endocytosis of membrane receptors is governed by a complex structural machinery, which is in turn controlled by various accessory regulatory proteins. Links between endocytosis and the actin cytoskeleton have been revealed by a number of studies in yeast A variety of the so-called "end" or "dim" mutations, isolated in screening for endocytic defects. Various activators of Arp2/3, including Las17/Beelp, Abpl, and the type I myosin Myo3/5p have been reported to affect endocytosis to various extents. The role of microtubules in the endocytic process has been established mainly with the use of microtubule depolymerizing drugs, such as nocodazole. In cells kept in suspension, but not in cells grown on substrates, nocodazole was reported to reduce by 40% the initial rate of transferrin receptor internalization. This suggests that the overall structural organization of a cell might affect microtubule organization and dynamics, leading to alterations in membrane plasticity, and consequently affecting the ability of a receptor to be recruited to the invaginating clathrin-coated pit.

Published
2003

6. Contributors

Author

John M. Abrams, John P. Adelman, Joseph L. Alcorn, Dario R. Alessi, Emil Alexov, Simon Alford, Kari Alitalo, James P. Allison, Steven C. Almo, Christelle Alory, Aymen Al-Shamkhani, Sally A. Amundson, Carl W. Anderson, Jannik N. Andersen, Peter Angel, Ettore Appella, William J. Arendshorst, Steve Arkinstall, Anjon Audhya, Joseph Avruch, Gary D. Bader, Cinzia Bagala, William E. Balch, Jesus Balsinde, Utpal Banerjee, David Barford, Dafna Bar-Sagi, Perry F. Bartlett, Philippe I.H. Bastiaens, Chiara Battelli, Linnea M. Baudhuin, Andrew J. Beavil, Rebecca L. Beavil, Joseph A. Beavo, Elsa Bello-Reuss, Stephen Bellum, Juan Carlos Izpisúa Belmonte, Craig B. Bennett, Jeffrey L. Benovic, Michael J. Berridge, Penny J. Beuning, Rashna Bhandari, Ananya Bhattacharya, Martin Biel, Vincent A. Bielinski, Hana Bilak, Lutz Birnbaumer, Geoff Birrell, Gail A. Bishop, Trillium Blackmer, Perry J. Blackshear, Christine Blattner, Mordecai P. Blaustein, Gary M. Bokoch, Lynda F. Bonewald, Marco Bonomi, Michelle A. Booden, Charles Boone, Martin D. Bootman, Johannes L. Bos, Jane M. Bradbury, Ralph A. Bradshaw, Anne R. Bresnick, Lena Brevnova, Ross I. Brinkworth, Michael S. Brown, Steven A. Brown, Anne Brunet, Robert Bucki, Robert D. Burgoyne, Janice E. Buss, Ronald A. Butow, Javier Capdevila, Ernesto Carafoli, Cathrine R. Carlson, Graham Carpenter, Juan J. Carrillo, Patrick J. Casey, William A. Catterall, Richard A. Cerione, Gianni Cesareni, Andrew C. Chan, Geoffrey Chang, Moses V. Chao, Harry Charbonneau, Philip Chen, Alan Cheng, Chris Chiu, Dar-chone Chow, Ted D. Chrisman, Anne Elisabeth Christensen, Jee Y. Chung, Grant C. Churchill, Aaron Ciechanover, Gino Cingolani, Sylvie Claeysen, Jean Closset, Shamshad Cockcroft, Patricia T.W. Cohen, Philip Cohen, Roger J. Colbran, Clay E.S. Comstock, Marco Conti, Jackie D. Corbin, Daniela Corda, Sabine Costagliola, Rick H. Cote, Shaun R. Coughlin, L. Ashley Cowart, Adrienne D. Cox, Mark S. Cragg, José L. Crespo, Claudia Crosio, Christopher Daly, Sami Damak, Mary Dasso, Michael David, Anthony J. Davis, Roger J. Davis, Richard N. Day, Eva Degerman, Warren L. DeLano, Mark L. Dell'Acqua, Emmanuèle Délot, Bruce Demple, Edward A. Dennis, John M. Denu, Anna A. DePaoli-Roach, Channing J. Der, Johan de Rooij, Frederic de Sauvage, Peter N. Devreotes, Valérie Dewaste, Robert B. Dickson, Becky A. Diebold, Pier Paolo Di Fiori, Maria Di Girolamo, Julie Diplexcito, Jack E. Dixon, Robert W. Doms, Daniel J. Donoghue, Russell F. Doolittle, Stein Ove Døskeland, Wolfgang R.G. Dostmann, Matthias K. Dreyer, Guo Guang Du, Keyong Du, Michael R. Duchen, William G. Dunphy, Joanne Durgan, Michael L. Dustin, Peter A. Edwards, Jackson G. Egen, Lee E. Eiden, Elaine A. Elion, Scott Emr, Othmar G. Engelhardt, Christophe Erneux, Peter J. Espenshade, Edward D. Esplin, B. Mark Evers, Joanne L. Eyles, Sheelagh Fame, Marilyn Farquhar, Robert Feil, Gui-Jie Feng, Stanley Fields, James J. Fiordalisi, Richard A. Firtel, Garret A. Fitzgerald, Andrew Flint, Marco Foiani, Barry Marc Forman, Albert J. Fornace, Sharron H. Francis, Günter Fritz, David A. Fruman, Antony Galione, Chris S. Gandhi, David L. Garbers, K. Christopher Garcia, Benjamin Geiger, Larry Gerace, Andrea Gerstner, Amato J. Giaccia, Michele Giannattasio, Vincent Giguère, Christopher K. Glass, Martin J. Glennie, Jennifer L. Glick, Joseph L. Goldstein, Venkatesh Gopal, Myriam Gorospe, Cedric Govaerts, Paul R. Graves, Patrick W. Gray, Irene Graziani, Douglas R. Green, Michael E. Greenberg, Iva Greenwald, Haihua Gu, Nuri Gueven, J. Silvio Gutkind, Jesper Z. Haeggström, Alan Hall, Michael N. Hall, Otto Haller, Heidi E. Hamm, Yusef A. Hannun, Carl A. Hansen, T. Kendall Harden, D. Grahame Hardie, Kiminori Hasegawa, Phillip T. Hawkins, Timothy A.J. Haystead, Xiao-lin He, Claus W. Heizmann, Carl-Henrik Heldin, Michelle L. Hermiston, Peter Herrlich, Elizabeth A. Hewat, Bertil Hille, Douglas J. Hilton, K.A. Hinchliffe, Steffan N. Ho, Su-Chin Ho, Mark Hochstrasser, Franz Hofmann, Christopher W. Hogue, Wim G.J. Hol, Jocelyn Holash, Robert A. Holmgren, Barry Honig, Bruce S. Hostager, Stevan R. Hubbard, Michael Huber, Tony Hunter, Anna Huttenlocher, Sarah G. Hymowitz, James N. Ihle, Jean-Luc Imler, R.F. Irvine, Ehud Y. Isacoff, Xavier Iturrioz, Lars F. Iversen, Ravi Iyengar, Stephen P. Jackson, Lily Yeh Jan, Fabiola Janiak-Spens, Paul A. Janmey, Peter Gildsig Jansen, Sophie Jarriault, Jonathan A. Javitch, Elwood V. Jensen, Kristen Jepsen, E. Yvonne Jones, Katherine A. Jones, J. Dedrick Jordan, Jomon Joseph, Louis B. Justement, Yariv Kafri, Richard A. Kahn, Shin W. Kang, Arthur Karlin, Heidi R. Kast-Woelbern, Randal J. Kaufman, Andrius Kazlauskas, James H. Keen, Rolf Kemler, Bruce E. Kemp, Mary B. Kennedy, Matthew A. Kennedy, Ushio Kikkawa, Albert H. Kim, Soo-A Kim, Sung-Hou Kim, Youngjoo Kim, Kirst King-Jones, Chris Kintner, Saul Kivimäe, Claude B. Klee, Rüdiger Klein, Thomas Kleppisch, Steven A. Kliewer, Richard A. Klinghoffer, Juergen A. Knoblich, Bostjan Kobe, George Kochs, Monica Kong-Beltran, Rolf König, Albert C. Koong, Murray Korc, Daniel Kornitzer, Anthony A. Kossiakoff, Jun Kotera, M.V. Kovalenko, Tohru Kozasa, Sergei Kozlov, Keith G. Kozminski, Sonja Krugmann, John Kuriyan, Riki Kurokawa, Peter D. Kwong, Wi S. Lai, Elise Lamar, Millard H. Lambert, David G. Lambright, Doron Lancet, Reiko Landry, Wallace Y. Langdon, Lorene K. Langeberg, Paul Lasko, Vaughn Latham, Martin F. Lavin, Kevin A. Lease, Hakon Leffler, Mark A. Lemmon, Ann E. Leonard, Alexander Levitzki, Hong-Jun Liao, Lucy Liaw, Giordano Liberi, Heiko Lickert, Robert C. Liddington, Thomas M. Lincoln, Jürgen U. Linder, Maurine E. Linder, Hui Liu, Zhengchang Liu, Marja K. Lohela, Sarah H. Louie, Deirdre K. Luttrell, Louis M. Luttrell, Karen M. Lyons, S. Lance Macaulay, Michael Maceyka, Thomas Maciag, Fernando Macian, Carol MacKintosh, David H. MacLennan, Nadir A. Mahmood, Craig C. Malbon, Sohail Malik, Orna Man, Carol L. Manahan, Anna Mandinova, Vincent C. Manganiello, James L. Manley, Matthias Mann, Gerald Manning, Ed Manser, Marta Margeta-Mitrovic, Robert F. Margolskee, Julia Marinissen, Roy A. Mariuzza, Mina D. Marmor, G. Steven Martin, Karen H. Martin, Sergio E. Martinez, Michael B. Mathews, Bruce J. Mayer, Mark L. Mayer, Maria R. Mazzoni, Frank McCormick, Clare H. McGowan, Melissa M. McKay, Wallace L. McKeehan, Alison J. McLean, Anthony R. Means, Ruedi Meili, Jingwei Meng, Mark Merchant, Frank Mercurio, Graeme Milligan, Guo-Li Ming, Daniel L. Minor, Nadeem Moghal, Neils Peter H. Møller, Marco Mongillo, Marc Montminy, Randall T. Moon, Richard I. Morimoto, Stephen E. Moss, Helen R. Mott, Carla Mouta, Marco Muda, Marc C. Mumby, Gretchen A. Murphy, Marco Muzi-Falconi, Raghavendra Nagaraj, Stefan R. Nahorski, Angus C. Nairn, Piers Nash, Benjamin G. Neel, Alexandra C. Newton, Yasutomi Nishizuka, Joseph P. Noel, Ellen A.A. Nollen, Irene M.A. Nooren, Rodney O'Connor, Stefan Offermanns, Tsviya Olender, Shao-En Ong, Darerca Owen, Lisa J. Pagliari, Lily Pao, John Papaconstantinou, Leonardo Pardo, Hay-Oak Park, Young Chul Park, Peter J. Parker, J. Thomas Parsons, J.M. Passner, Tony Pawson, Achille Pelliccioli, J. Regino Perez-Polo, Norbert Perrimon, Fabrice G. Petite, Emmanuel Petroulakis, Samuel L. Pfaff, Jacob Piehler, Linda J. Pike, Michael J. Pinkoski, Fiona J. Pixley, Paolo Plevani, Mu-ming Poo, Tullioi Pozzan, Stephen M. Prescott, Igor Prudovsky, James W. Putney, Thomas Radimerski, Elzbieta Radzio-Andzelm, Prahlad T. Ram, Lucia Rameh, Danica Ramljak, Barbara Ranscht, Anjana Rao, Carol J. Raport, Jacqueline D. Reeves, Holger Rehman, Trevor W. Reichman, Eric Reiter, Michael A. Resnick, Michael Reth, Sue Goo Rhee, Joel D. Richter, Rodney L. Rietze, James M. Rini, Jürgen A. Ripperger, Josep Rizo, Janet D. Robishaw, H. Llewelyn Roderick, Robert G. Roeder, Larry R. Rohrschneider, David Ron, Michael G. Rosenfeld, Hans Rosenfeldt, Kent L. Rossman, Christopher B. Roth, Markus G. Rudolph, Anja Ruppelt, Lino Saez, Thomas P. Sakmar, Guy S. Salvesen, Paolo Sassone-Corsi, Charles L. Saxe, Beat W. Schäfer, Ueli Schibler, Christian W. Schindler, Tobias Schmelzle, Sandra L. Schmid, Anja Schmidt, Eric F. Schmidt, Gideon Schreiber, Joachim E. Schultz, Beat Schwaller, Klaus Schwamborn, Thue Schwartz, William F. Schwindinger, Giorgio Scita, John D. Scott, Shaun Scott, Thomas Seebeck, Charles N. Serhan, John B. Shabb, Andrey S. Shaw, Stephen B. Shears, Shirish Shenolikar, Lei Shi, Chanseok Shin, Kazuhiro Shiozaki, Kevan M. Shokat, Trevor J. Shuttleworth, David P. Siderovski, Steven A. Siegelbaum, Adam M. Silverstein, Robert H. Singer, Michael K. Skinner, Jill K. Slack-Davis, Stephen J. Smerdon, Graeme C.M. Smith, Guillaume Smits, Sarah M. Smolik, Jessica E. Smotrys, Emer M. Smyth, Jason T. Snyder, Naoko Sogame, Raffaella Soldi, John Sondek, Nahum Sonenberg, Erica Dutil Sonneberg, Lindsay G. Sparrow, Sarah Spiegel, Stephen R. Sprang, Deepak Srivastava, Robyn L. Stanfield, E. Richard Stanley, Deborah J. Stauber, Christopher Stefan, Lena Stenson-Holst, Len Stephens, Paul W. Sternberg, Paul C. Sternweis, Ruth Steward, John T. Stickney, Andrew W. Stoker, Stephen M. Strittmatter, Beth E. Stronach, Roland K. Strong, Robert M. Stroud, Thomas C. Südhof, Roger K. Sunahara, Brian J. Sutton, Sipeki Szabolcs, Xiao-Bo Tang, Kjetil Taskén, Hisashi Tatebe, Servane Tauszig-Delamasure, Colin W. Taylor, Garry L. Taylor, Laura J. Taylor, Susan S. Taylor, George Thomas, Robert P. Thomas, E. Brad Thompson, Michael J. Thompson, Janet M. Thornton, Carl S. Thummel, Hideaki Togashi, Amy Hin Yan Tong, Nicholas K. Tonks, Peter Tontonoz, M.K. Topham, Knut Martin Torgersen, Hien Tran, Michel L. Tremblay, Ming-Jer Tsai, Sophia Y. Tsai, Susan Tsunoda, Stewart Turley, Darren Tyson, Robert L. Van Etten, Gilbert Vassart, Peter J. Verveer, Virginie Vlaeminck, Abraham M. de Vos, Ty C. Voss, Robert Walczak, Graham C. Walker, John C. Walker, Gernot Walter, Mark R. Walter, Fen Wang, Jean Y.J. Wang, Weiru Wang, Richard J. Ward, Philip Wedegaertner, Christian Wehrle, Arthur Weiss, Jamie L. Weiss, Alan Wells, Claudia Werner, Ann H. West, Marie C. Weston, John K. Westwick, Anders Wetterholm, Morris F. White, Malcolm Whitman, Matt R. Whorton, Christian Wiesmann, Roger L. Williams, William D. Willis, Timothy M. Willson, Ian A. Wilson, Ofer Wiser, Matthew J. Wishart, Alfred Wittinghofer, James R. Woodgett, David K. Worthylake, Jeffrey L. Wrana, Hao Wu, Yijin Xiao, H. Eric Xu, Yan Xu, Zheng Xu, Michael B. Yaffe, Kenneth M. Yamada, Seun-Ah Yang, Wannian Yang, Yosef Yarden, Hong Ye, Weilan Ye, Todd O. Yeates, Helen L. Yin, John D. York, Edgar C. Young, Kenneth W. Young, Matthew A. Young, Michael W. Young, Minmin Yu, Nathan R. Zaccai, Manuela Zaccolo, Eli Zamir, Mark von Zastrow, Chao Zhang, Xuewu Zhang, Zhong-Yin Zhang, Wenhong Zhou, and Roya Zoraghi

Published
2003

8. [44] Antioxidant radical-scavenging activity of carotenoids and retinoids compared to α-tocopherol

Author

Masahiko Tsuchiya, Lester Packer, Valerian E. Kagan, Giorgio Scita, and Hans-Joachim Freisleben

Subjects
Lipid peroxidation, chemistry.chemical_compound, Antioxidant, Chemistry, Superoxide, medicine.medical_treatment, Radical, Fluorescence spectrometry, medicine, Organic chemistry, Hydroxyl radical, Tocopherol, Hydrogen peroxide
Abstract

Publisher Summary Free radicals are potentially dangerous for the cell, although in vivo they may be generated by metabolism. These radicals can be classified into two groups: (1) oxygen-derived radicals and active oxygen species, including superoxide anion radical, hydroxyl radical, hydrogen peroxide, and singlet molecular oxygen and (2) organic radicals that usually originate in the course of lipid peroxidation. According to the location in which they are generated, oxygen-derived radicals react mainly with components in the aqueous phases, such as extra- and intracellular fluids, while organic radicals interact mainly with constituents of the hydrophobic membranous phase. This chapter investigates the antioxidant activity of carotenoids and retinoids compared to α -tocopherol and its homologs. For the assay in the aqueous phase, a modified method of a phycoerythrin fluorescence-based procedure is used, whereas for the assay in the hydrophobic phase, a new cis-parinaric acid fluorescence-based assay is developed.

Published
1992

9. [16] Stability of β-carotene under different laboratory conditions

Author

Giorgio Scita

Subjects
Metabolic pathway, Antioxidant, Atmospheric oxygen, Stereochemistry, Chemistry, beta-Carotene, medicine.medical_treatment, medicine, Degradation (geology), Food science, Biodegradation, Incubation, Relative stability
Abstract

Publisher Summary This chapter discusses an experimental study, which investigated the factors that can affect the stability of β-carotene (BC) under the common laboratory conditions generally used to evaluate its biological role and to investigate its metabolic pathway. BC remained fairly stable during 48 hours of incubation conditions generally used for cell-free or cell culture model systems. Besides, as great emphasis has been put on the anticarcinogenic properties of BC, independently of a vitamin A-mediated action, it was important to show that, under the condition used, the integrity of the molecule is preserved. BC rapidly degraded by ultraviolet and visible light in the presence of atmospheric oxygen, the degradation rate being lower with a lower air–oxygen exchange. This points to specific laboratory working conditions to preserve BC solutions from degradation. These conditions include the use of a subdued fight environment and the use of a dark container with a small air-surface exchange. The relative stability of BC is confirmed when the degradative factors are strictly controlled and antioxidants are present, suggesting conditions to be used to prolong its storage life.

Published
1992

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