antioxidants Article Evaluation of Polyphenol Content and Antioxidant Capacity of Aqueous Extracts from Eight Medicinal Plants from Reunion Island: Protection against Oxidative Stress in Red Blood Cells and Preadipocytes Eloïse Checkouri 1,2, Franck Reignier 2, Christine Robert-Da Silva 1 and Olivier Meilhac 1,3,* 1 INSERM, UMR 1188 Diabète Aathérothombose Réunion Océan Indien (DéTROI), Université de La Réunion, 97490 Sainte-Clotilde, La Réunion, France;
[email protected] (E.C.);
[email protected] (C.R.-D.S.) 2 Habemus Papam, Food Industry, 97470 Saint-Benoit, La Réunion, France;
[email protected] 3 CHU de La Réunion, CIC 1410, 97410 Saint-Pierre, La Réunion, France * Correspondence:
[email protected]; Tel.: +262-0262-938-811 Received: 18 August 2020; Accepted: 30 September 2020; Published: 7 October 2020 Abstract: Background—Medicinal plants are traditionally used as infusions or decoctions for their antioxidant, anti-inflammatory, hypolipidemic and anti-diabetic properties. Purpose—The aim of the study was to define the polyphenol composition and to assess the antioxidant capacity of eight medicinal plants from Reunion Island referred to in the French Pharmacopeia, namely Aphloia theiformis, Ayapana triplinervis, Dodonaea viscosa, Hubertia ambavilla, Hypericum lanceolatum, Pelargonium x graveolens, Psiloxylon mauritianum and Syzygium cumini. Methods—Polyphenol content was assessed by biochemical assay and liquid chromatography coupled to mass spectrometry. Antioxidant capacity was assessed by measuring DPPH reduction and studying the protective effects of herbal preparation on red blood cells or preadipocytes exposed to oxidative stress. Results—Polyphenol content ranged from 25 to 143 mg gallic acid equivalent (GAE)/L for infusions and 35 to 205 mg GAE/L for decoctions.