Phenolic composition and antioxidant properties of some traditionally used medicinal plants affected by the extraction time and hydrolysis.

Polyphenolic phytochemicals in traditionally used medicinal plants act as powerful antioxidants, which aroused an increasing interest in their application in functional food development. 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. 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. 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). 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.

Komes D ，Belščak-Cvitanović A ，Horžić D ，Rusak G ，Likić S ，Berendika M ... -  《-》

Enrichment of antioxidant compounds from lemon balm (Melissa officinalis) by pressurized liquid extraction and enzyme-assisted extraction.

In this work enzyme-assisted extraction (EAE) and pressurized liquid extraction (PLE) are applied for extraction of natural compounds from lemon balm (Melissa officinalis). Cellulase, endo-β-1,4 xylanase and pectinase were studied in order to degrade cell wall of lemon balm leaves and to release phenolic compounds. On the other hand, in order to compare the performance obtained with EAE, PLE using water and ethanol was employed maintaining 150°C as extraction temperature. The obtained extracts were characterized in terms of antioxidant capacity by using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging and trolox equivalent antioxidant capacity (TEAC) in vitro assays, whereas the Folin-Ciocalteu procedure was employed to estimate the total phenols content. On the other hand, extracts were chemically characterized by liquid chromatography tandem mass spectrometry (LC-MS/MS). The results showed that EAE enhanced the total phenolic content and the antioxidant capacity compared to a non-enzymatic control. PLE extracts presented higher amount of phenols and antioxidant capacity than enzyme-assisted extracts, reaching the highest values on water extracts (193.18mggallicacid/gextract and EC50=6.81μg/mL). Among the bioactive phenolic compounds identified in lemon balm, rosmarinic acid was the main component, although other important compounds were also identified, such as caffeic acid derivatives (salvianolic acids, lithospermic acid) and rosmarinic acid derivatives (rosmarinic acid hexoside, sagerinic acid, sulfated rosmarinic acid). The present study confirms that EAE and PLE can be considered alternative methods for the extraction of natural compounds with biological activity from natural sources.

Miron TL ，Herrero M ，Ibáñez E 《-》

Correlations between phenolic content and antioxidant properties in twenty-four plant species of traditional ethnoveterinary use in the Mediterranean area.

Piluzza G ，Bullitta S 《-》

Effect of extraction solvents on the biomolecules and antioxidant properties of Scorzonera undulata (Asteraceae): Application of factorial design optimization phenolic extraction.

Athmouni K ，Belghith T ，Bellassouad K ，Feki AE ，Ayadi H ... -  《-》

Antioxidant properties and principal phenolic phytochemicals of Indian medicinal plants from Asclepiadoideae and Periplocoideae.

Surveswaran S ，Cai YZ ，Xing J ，Corke H ，Sun M ... -  《-》