Evaluation of antioxidant activity of medicinal plants containing polyphenol compounds. Comparison of two extraction systems.

Abstract

This study investigates the influence of extraction system on the extractability of polyphenol compounds and antioxidant activity of various medicinal plants. Oxygen radical absorbance capacity (ORAC) and total polyphenol content of 25 Bulgarian medicinal plants subjected to water or 80 % acetone extractions were investigated and compared. The type of extragent significantly influenced the efficiency of the polyphenol extraction and the antioxidant activity. In all cases ORAC results and total polyphenol content were higher for acetone extraction than for water extraction. The acetone extract of peppermint had the highest ORAC value - 2917 micromol Trolox equivalent (TE)/g dry weight (DW) and polyphenol content - 20216 mg/100 g DW. For water extraction thyme exhibited the highest ORAC antioxidant activity - 1434 micromol TE/g DW. There was a significant linear correlation between the concentration of total polyphenols and ORAC in the investigated medicinal plants. It can be concluded that the solvent used affects significantly the polyphenol content and the antioxidant activity of the extract and therefore it is recommended to use more than one extraction system for better assessment of the antioxidant activity of natural products. Several of the investigated herbs contain substantial amounts of free radical scavengers and can serve as a potential source of natural antioxidants for medicinal and commercial uses.

Effects of in vitro digestion on the composition of flavonoids and antioxidant activities of the lotus leaf at different growth stages

“…It is possible that after the protein is hydrolysed by pepsin or trypsin, the polyphenols that are covalently or noncovalently bound to the protein may be released. However, the amount of polyphenols does not represent a potential synergistic or antagonistic effect among the compounds in the sample, depending on their structure and interaction (Kratchanova et al ., ). This study found that the antioxidant activity of phenolic compounds may decrease after interacting with protein.…”

Diffusion of polyphenols from alginate, alginate/chitosan, and alginate/inulin particles

“…Thyme aqueous extract was prepared by standard method of aqueous extraction as follows (Komes et al, ; Kratchanova, Denev, Ciz, Lojek, & Mihailov, ): 10 g of dried thyme (Institute of Medicinal Plants Research Dr Josif Pancic, Serbia) was extracted with distilled water (200 mL) at 80–100°C. It was constantly stirred under heating for a period of 30 min.…”

“…Thyme aqueous extract was prepared by standard method of aqueous extraction as follows (Komes et al, 2010;Kratchanova, Denev, Ciz, Lojek, & Mihailov, 2010)…”

Effect of flavonoids content on antioxidant activity of commercial cosmetic plant extracts

“…The extract of Centella asiatica possesses confirmed antioxidant, cognitiveenhancing, antiepileptic, antinociceptive and anti-inflammatory properties [28,29]. Free radical scavenging activity of Melilotus officinalis was confirmed in ORAC (Oxygen radical absorbance capacity) [30]. In turn Hippophae rhamnoides has the ability to scavenge peroxyl radicals and to protect against UV radiation.…”