title: An on-line HPLC system for detection of antioxidant compounds in some plant extracts by comparing three different methods.
abstract: Echinacea (Echinacea purpurea), green tea (Camellia sinensis) and yaylacayi (Thymus praecox OPIZ subsp. grossheimii (Ronniger) Jalas) are herbs used in traditional medicine because of their beneficial health effects. A high performance liquid chromatography (HPLC) post-column method was developed by coupling HPLC with on-line antioxidant assays using diode array (DAD) and ultraviolet (UV) detectors. Thus antioxidant compounds and fifteen phenolic standards were detected in echinacea, green tea and yaylacayi methanol extracts simultaneously. Later on, the developed on-line HPLC coupled system was used to compare three different antioxidant methods, ABTS [2,2'-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)], DPPH (2,2-diphenyl-1-picrylhydrazyl and FRAP (Ferric reducing antioxidant power). Eight compounds with antioxidant activity were identified as gallic acid, protocatechuic aldehyde, p-OH benzoic acid, chlorogenic acid, caffeic acid, vanillin, ferulic acid, and rosmarinic acid. For validation purposes, LOD (limit of detection) (0.36-14.68μg/mL) and LOQ (limit of quantification) (1.35-48.92μg/mL) values were calculated for six standards. The results showed that while the post-column ABTS and FRAP assays were repeatable, sensitive and supportive of each other, the post-column DPPH assay did not provide reliable results. Also due to the base-line noise and drifts in post-column DPPH assay, identification and quantitation of analytes could not be done accurately.
authors.affiliation: Department of Nutrition and Dietetics, Faculty of Health Sciences, Gümüşhane University, 29100 Gümüşhane, Turkey. Electronic address: nsbburnaz@gmail.com.
authors.forename: Nesibe
authors.initials: N
authors.lastname: Arslan Burnaz
authors.affiliation: Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey. Electronic address: mkucuk@ktu.edu.tr.
authors.forename: Murat
authors.initials: M
authors.lastname: Küçük
authors.affiliation: Department of Genetics and Bioengineering, Faculty of Engineering and Natural Sciences, Gümüşhane University, 29100 Gümüşhane, Turkey. Electronic address: ziskefiyeli@gumushane.edu.tr.
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Akar
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D052160:Benzothiazoles / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D028241:Camellia sinensis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004365:Drugs, Chinese Herbal / Q000032:analysis* / Q000494:pharmacology; D020900:Echinacea / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D010636:Phenols / Q000032:analysis* / Q000494:pharmacology; D010851:Picrates / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry; D046930:Thymus Plant / Q000737:chemistry
chemical_list: D000975:Antioxidants; D052160:Benzothiazoles; D001713:Biphenyl Compounds; D004365:Drugs, Chinese Herbal; D005609:Free Radicals; D010636:Phenols; D010851:Picrates; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: Antioxidants; Camellia sinensis; Echinacea purpurea; On-line HPLC-ABTS/DPPH/FRAP; Thymus praecox