Hyphenated LC-ABTS•+ and LC-DAD-HRMS for simultaneous analysis and identification of antioxidant compounds in Astragalus emarginatus Labill. extracts.
J Pharm Anal 2021;
12:253-262. [PMID:
35582407 PMCID:
PMC9091927 DOI:
10.1016/j.jpha.2021.09.008]
[Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/30/2021] [Accepted: 09/15/2021] [Indexed: 01/20/2023] Open
Abstract
The compounds in leaf and stem extracts of Astragalus emarginatus Labill. (AEL), a plant species used in traditional Lebanese medicine, were investigated for antioxidant properties. First, the activity of various extracts was assessed using the Trolox equivalent antioxidant capacity, oxygen radical absorption capacity, and 2,2-diphenyl-1-picryl-hydrazyl-hydrate assays. The extract obtained using 30% ethanol showed the greatest activity. The antioxidant compounds in this extract were screened using a hyphenated high-performance liquid chromatography-2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) radical (ABTS·+) system before being separated by ultra-high-performance liquid chromatography and identified using high-resolution mass spectrometry and ultra-violet-visible diode array detection. Approximately 40 compounds were identified. Hydroxycinnamates (caffeic, ferulic, and p-coumaric acid derivatives) and flavonoids (quercetin, luteolin, apigenin, and isorhamnetin derivatives) were the two main categories of the identified compounds. The active compounds were identified as caffeic acid derivatives and quercetin glycosides. In addition, the catechol moiety was shown to be key to antioxidant activity. This study showed that AEL is a source of natural antioxidants, which may explain its medicinal use.
Antioxidant activity of 30% ethanol extract from Astragalus emarginatus Labill was shown by an on-line HPLC-ABTS •+ assay.
Caffeic acid derivatives and quercetin glycosides were responsible for antioxidant activity.
Approximately forty compounds were tentatively identified using UHPLC-DAD-HRMS.
Structure-activity investigations showed that the catechol moiety is central to the detected antioxidant activity.
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