title: Antioxidative properties and ability of phenolic compounds of Myrtus communis leaves to counteract in vitro LDL and phospholipid aqueous dispersion oxidation.
abstract: Antioxidant activities of Myrtus communis leaf phenolic compounds (McPCs) were investigated on 2,2'-9-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS(+) •) and oxygen radical absorbance capacity (ORAC) tests or on oxidation of biological models, human low-density lipoprotein (LDL) and phospholipid aqueous dispersion (L-α-phosphatidylcholine stabilized by bile salts). Two extraction techniques, microwave-assisted (MAE) and conventional (CE), were used to isolate McPCs, producing similar results of phenolic compound content. ABTS(+) • assay showed clearly that myrtle extracts exhibited a stronger scavenging effect than butylated hydroxyanisole and α-tocopherol, with a slight advantage for myrtle CE extract. In ORAC assay, the both McPC extracts were similarly less effective than the pure compounds as caffeic acid and myricitrin (myricetin 3-O-rhamnoside) but stronger than butylated hydroxytoluene. Moreover, myrtle CE and MAE extracts, and myricitrin were able to inhibit similarly the production of conjugated dienes and to prolong the lag phase (Tlag) during Cu(2+)-induced LDL oxidation with a dose-response effect. The cryo-electron microscopy observations on studied phospholipid dispersion stabilized by bile salts (BS) revealed the presence of bilayer vesicles and micelles. In 2,2'-azobis (2-amidinopropane) hydrochloride-induced phospholipid/BS oxidation, myrtle CE and MAE extracts gave similar effects to α-tocopherol and caffeic acid but myricitrin showed a higher protective effect than myrtle extracts. We showed also that no synergic or additive effect between α-tocopherol and myrtle extracts or caffeic acid in α-tocopherol-enriched phospholipid/BS dispersion, but myricitrin showed an additive effect and thus promoted the total antioxidant activity. These data showed that myrtle extract could be used as potential natural antioxidants, food stabilizers, or natural health products.
  
  
  CONCLUSIONS
  We show that microwave-assisted extraction could be an alternative method for plant phenolic compound recovery allowing important gain in time extraction.We report inhibition of low-density lipoprotein oxidation in vitro initiated by Cu(2+) ions. We report that myrtle extract may be a source of natural antioxidants to counteract phospholipid peroxidation as well as α-tocopherol.
authors: Faculty of Nature and Life Sciences, 3BS Laboratory A. Mira Univ, Bejaia, 06000, Algeria; UMR 204 NUTRIPASS, - Univ., Inst. of Clinical Research - -641, Av. Doyen Gaston Giraud, 34093 Montpellier Cedex 5, France.
authors: Sofiane
authors: S
authors: Dairi
authors: Khodir
authors: K
authors: Madani
authors: Manar
authors: M
authors: Aoun
authors: Joséphine Lai Kee
authors: JL
authors: Him
authors: Patrick
authors: P
authors: Bron
authors: Céline
authors: C
authors: Lauret
authors: Jean-Paul
authors: JP
authors: Cristol
authors: Marie-Annette
authors: MA
authors: Carbonneau
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D006801:Humans; D008077:Lipoproteins, LDL / Q000737:chemistry*; D031651:Myrtus / Q000737:chemistry*; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D008077:Lipoproteins, LDL; D010636:Phenols; D010743:Phospholipids; D010936:Plant Extracts
keywords: AAPH-mediated phospholipid dispersion oxidation; ABTS+• test; Myrtus communis; ORAC test; low-density lipoprotein Cu2+-mediated oxidation