Extraction and identification of natural antioxidant from Sideritis euboea (mountain tea).
The dried aerial parts of the mountain tea Sideritis euboea were extracted using n-hexane, methanol, diethyl ether, ethyl acetate, and n-butanol. The residues were tested for their antioxidant activity on sunflower oil at 50 degrees C under UV light. The oxidation of the sunflower oil was measured using PV, absorbance E(1%)1 cm, and malondialdehyde by high-performance liquid chromatography (HPLC). The butanol extract showed the highest antioxidant activity and was further fractionated by silica and cellulose column chromatography and finally by HPLC. The activity of the final fraction on a range of vegetable oils was compared to that of common used antioxidants (BHT, alpha-tocopherol) using DPPH*, the Rancimat method, and the Schaal oven test. At a level of 400 ppm, the extracted kaempherol showed the highest antioxidant activity among all antioxidants tested. The final fraction was identified (using UV, 1H NMR, 13C NMR, mass spectroscopy, and melting point) as 3,5,7,4'-tetrahydroxy flavone (kaempherol).
Tsaknis
John
J
Department of Food Technology, Technological Educational Institution of Athens, Ag. Spyridonos str., Egaleo, 12210 Athens, Greece.
Lalas
Stavros
S
D000975:Antioxidants / Q000032:analysis* / Q000302:isolation & purification / Q000494:pharmacology; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D044949:Kaempferols / Q000032:analysis / Q000302:isolation & purification / Q000494:pharmacology; D008315:Malondialdehyde / Q000032:analysis; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry; D031365:Sideritis / Q000737:chemistry*; D000074242:Sunflower Oil
D000975:Antioxidants; D044949:Kaempferols; D010936:Plant Extracts; D010938:Plant Oils; D000074242:Sunflower Oil; D008315:Malondialdehyde; C006552:kaempferol