title: Phenolic composition and antioxidant properties of some traditionally used medicinal plants affected by the extraction time and hydrolysis.
abstract: BACKGROUND
  Polyphenolic phytochemicals in traditionally used medicinal plants act as powerful antioxidants, which aroused an increasing interest in their application in functional food development.
  
  
  OBJECTIVE
  The effect of extraction time (5 and 15 min) and hydrolysis on the qualitative and quantitative content of phenolic compounds and antioxidant capacity of six traditionally used medicinal plants (Melissa officinalis L., Thymus serpyllum L., Lavandula officinalis Miller, Rubus fruticosus L., Urtica dioica L., and Olea europea L.) were investigated.
  
  
  METHODS
  The content of total phenols, flavonoids, flavan-3-ols and tannins was determined using UV/Vis spectrophotometric methods, while individual phenolic acids, flavones and flavonols were separated and detected using HPLC analysis. Also, to obtain relevant data on the antioxidant capacity, two different assays, (2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging and ferric reducing/antioxidant power (FRAP) assays were used.
  
  
  RESULTS
  The extraction efficiency of phenolics, as well as the antioxidant capacity of plant extracts, was affected by both prolonged extraction and hydrolysis. The overall highest content of phenolic compounds was determined in hydrolyzed extract of blackberry leaves (2160 mg GAE/L), followed by the non-hydrolyzed extract of lemon balm obtained after 15 min of extraction (929.33 mg GAE/L). The above extracts also exhibited the highest antioxidant capacity, while extracts of olive leaves were characterized with the lowest content of phenolic compounds, as well as the lowest antioxidant capacity. The highest content of rosmarinic acid, as the most abundant phenolic compound, was determined in non-hydrolyzed extract of lemon balm, obtained after 15 min of extraction. Although the hydrolysis provided the highest content of polyphenolic compounds, longer extraction time (15 min) was more efficient to extract these bioactives than shorter extraction duration (5 min).
  
  
  CONCLUSIONS
  The distribution of detected phenolic compounds showed a wide variability with regard to their botanical origin. Examined medicinal plants showed to be a valuable supplement to a daily intake of bioactive compounds.
authors.affiliation: Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia. dkomes@pbf.hr
authors.forename: Draženka
authors.initials: D
authors.lastname: Komes
authors.forename: Ana
authors.initials: A
authors.lastname: Belščak-Cvitanović
authors.forename: Dunja
authors.initials: D
authors.lastname: Horžić
authors.forename: Gordana
authors.initials: G
authors.lastname: Rusak
authors.forename: Saša
authors.initials: S
authors.lastname: Likić
authors.forename: Marija
authors.initials: M
authors.lastname: Berendika
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D017523:Croatia; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification; D006868:Hydrolysis; D019686:Lamiaceae / Q000737:chemistry; D029592:Oleaceae / Q000737:chemistry; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification*; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification*; D010946:Plants, Medicinal / Q000737:chemistry*; D025341:Principal Component Analysis; D013634:Tannins / Q000737:chemistry / Q000302:isolation & purification; D013997:Time Factors; D026982:Urtica dioica / Q000737:chemistry
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D013634:Tannins