Murta Leaves (Ugni molinae Turcz) as a Source of Antioxidant Polyphenols

• Published in: Journal of agricultural and food chemistry 2006-01, Vol.54 (1), p.59-64
• Main Authors: Rubilar, Mónica, Pinelo, Manuel, Ihl, Mónica, Scheuermann, Erik, Sineiro, Jorge, Nuñez, María José
• Format: Article
• Language: English
• Subjects: antioxidant activity; antioxidants; Antioxidants - analysis; antiradical power; Biological and medical sciences; Biphenyl Compounds; Chromatography, High Pressure Liquid; Flavonoids - analysis; Food industries; free radical scavengers; free radicals; Fundamental and applied biological sciences. Psychology; high performance liquid chromatography; leaves; Mass Spectrometry; medicinal plants; Myrtaceae - chemistry; Myrtales; phenolic compounds; Phenols - analysis; Picrates; Plant Leaves - chemistry; Polyphenols; Solvents; Thiobarbituric Acid Reactive Substances; Ugni molinae
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf051571j

Extracts from Murta leaves are used by Chilean natives for their benefits on health and cosmetic properties, which are mainly due to the presence of polyphenolic compounds. Extraction of such compounds is strongly influenced by several variables, the effects of which are studied in this work; the antioxidant power of the resulting extracts was measured by two different methods [2,2-diphenyl-1-picrylhydrazyl (DPPH) and thiobarbituric acid reactive substances (TBARS)]. On the whole, maximum values of polyphenolic yields and antiradical power (DPPH method) were attained at 50 °C (from 25 to 50 °C) and a solvent-to-solid ratio (v/w) of 15:1 (15:1−25:1). The solvents assayed were ethanol, methanol, and water. The highest polyphenolic yield values (2.6% expressed as gallic acid) were reached with methanol, whereas maximum EC50 was attained by the ethanol extract (0.121 mol gallic acid/mol DPPH). Contact time was shown to have only a slight influence in alcoholic extraction, while in water a remarkable effect of increasing contact times (30−90 min)was observed. Just water was the solvent that offered the best result when the antioxidant power was measured by the TBARS method. High-performance liquid chromatography−mass spectrometry analysis revealed the presence of polyphenols, basically flavonols and flavanols, sometimes glycosilated; myricetin and quercetin glycosides were detected in all extracts, whereas epicatechin was present in alcoholic extracts and gallic acid was only present in water. Keywords: Murta (Ugni molinae Turcz.); polyphenols; DPPH; TBARS; HPLC-MS