Antioxidant activity-guided phytochemical investigation of Artemisia gmelinii Webb. ex Stechm.: Isolation and spectroscopic challenges of 3,5- O-dicaffeoyl (epi?) quinic acid and its ethyl ester

• Published in: Journal of pharmaceutical and biomedical analysis 2012-02, Vol.59, p.83-89
• Main Authors: Könczöl, Árpád, Béni, Zoltán, Sipos, Márta Meszlényi, Rill, Attila, Háda, Viktor, Hohmann, Judit, Máthé, Imre, Szántay, Csaba, Keserű, György Miklós, Balogh, György Tibor
• Format: Article
• Language: English
• Subjects: Analysis; Analytical, structural and metabolic biochemistry; Antioxidant; antioxidants; Artemisia; Artemisia - chemistry; Artemisia gmelinii; Biological and medical sciences; Biphenyl Compounds - chemistry; caffeic acid; chlorogenic acid; Chlorogenic Acid - analogs & derivatives; Chlorogenic Acid - isolation & purification; Chlorogenic Acid - pharmacology; Chromatography, High Pressure Liquid; Dicaffeoylquinic acid (DCQA); DPPH-HPLC assay; Epimer; Free Radical Scavengers - isolation & purification; Free Radical Scavengers - pharmacology; Free Radicals - chemistry; Fundamental and applied biological sciences. Psychology; General pharmacology; high performance liquid chromatography; Magnetic Resonance Spectroscopy; Medical sciences; Models, Molecular; Pharmacology. Drug treatments; Picrates - chemistry; Plant Components, Aerial - chemistry; Plant Extracts - chemistry; quinic acid; scopoletin; screening; Spectrometry, Mass, Electrospray Ionization; spectroscopy; Structure-Activity Relationship
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/j.jpba.2011.10.012

Although Artemisia gmelinii Webb. ex Stechm. has long been used in south and south-east Asia to treat many kinds of inflammatory diseases, up until now its bioactivity-coupled phytochemical characterization has not been reported. We identified one fraction of the methanolic extract of A. gmelinii as a hit in our antioxidant screening (DPPH) campaign. In order to identify the active radical scavenger components of the extract, a DPPH-HPLC spiking assay was carried out. Out of six detected known compounds caffeic acid ( 1) and scopoletin ( 4) had already been identified in the plant, but four of them, namely chlorogenic acid ( 2), 4- O-caffeoylquinic acid ( 3), luteolin-7- O-glucoside ( 5), and apigenin-7- O-glucoside ( 6) are first described here. Moreover, the two most active compounds of the mixture, 3,5- O-dicaffeoylquinic acid ( 7) and its ethyl ester derivative ( 8) were isolated with preparative HPLC. The spectroscopic identification of 7 and 8 presented a surprising challenge due to literature ambiguities. These questions are discussed in detail.