1. Academic Validation
  2. Carnosic Acid and Carnosol, Two Major Antioxidants of Rosemary, Act through Different Mechanisms

Carnosic Acid and Carnosol, Two Major Antioxidants of Rosemary, Act through Different Mechanisms

  • Plant Physiol. 2017 Nov;175(3):1381-1394. doi: 10.1104/pp.17.01183.
Margot Loussouarn 1 2 Anja Krieger-Liszkay 3 Ljubica Svilar 4 Antoine Bily 2 Simona Birtić 2 Michel Havaux 5
Affiliations

Affiliations

  • 1 Commissariat à l'Energie Atomique et aux Energies Alternatives Cadarache, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7265 Biologie Végétale et Microbiologie Environnementales, Aix Marseille Université, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France.
  • 2 Naturex, BP 81218, F-84911 Avignon cedex 9, France.
  • 3 Institut de Biologie Intégrative de la Cellule, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives Saclay, Institut de Biologie et de Technologie de Saclay, Université Paris-Sud, 91191 Gif-sur-Yvette, France.
  • 4 Criblage Biologique Marseille, Laboratoire Nutrition, Obésité et Risque Thrombotique, Aix-Marseille Université, Institut National de la Recherche Agronomique, Institut National de la Santé et de la Recherche Médicale, 13005 Marseille, France.
  • 5 Commissariat à l'Energie Atomique et aux Energies Alternatives Cadarache, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7265 Biologie Végétale et Microbiologie Environnementales, Aix Marseille Université, Laboratoire d'Ecophysiologie Moléculaire des Plantes, F-13108 Saint-Paul-lez-Durance, France michel.havaux@cea.fr.
Abstract

Carnosic acid, a phenolic diterpene specific to the Lamiaceae family, is highly abundant in rosemary (Rosmarinus officinalis). Despite numerous industrial and medicinal/pharmaceutical applications of its antioxidative features, this compound in planta and its antioxidant mechanism have received little attention, except a few studies of rosemary Plants under natural conditions. In vitro analyses, using high-performance liquid chromatography-ultraviolet and luminescence imaging, revealed that carnosic acid and its major oxidized derivative, carnosol, protect lipids from oxidation. Both compounds preserved linolenic acid and monogalactosyldiacylglycerol from singlet oxygen and from hydroxyl radical. When applied exogenously, they were both able to protect thylakoid membranes prepared from Arabidopsis (Arabidopsis thaliana) leaves against lipid peroxidation. Different levels of carnosic acid and carnosol in two contrasting rosemary varieties correlated with tolerance to lipid peroxidation. Upon Reactive Oxygen Species (ROS) oxidation of lipids, carnosic acid was consumed and oxidized into various derivatives, including into carnosol, while carnosol resisted, suggesting that carnosic acid is a chemical quencher of ROS. The antioxidative function of carnosol relies on another mechanism, occurring directly in the lipid oxidation process. Under oxidative conditions that did not involve ROS generation, carnosol inhibited lipid peroxidation, contrary to carnosic acid. Using spin probes and electron paramagnetic resonance detection, we confirmed that carnosic acid, rather than carnosol, is a ROS quencher. Various oxidized derivatives of carnosic acid were detected in rosemary leaves in low LIGHT, indicating chronic oxidation of this compound, and accumulated in Plants exposed to stress conditions, in parallel with a loss of carnosic acid, confirming that chemical quenching of ROS by carnosic acid takes place in planta.

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