Abstract

Objective: To assess the antioxidant activity of aerial parts of Allium roseum var. grandiflorum subvar. typicum Regel. (A. roseum var. grandiflorum subvar. typicum Regel.) for the first time, as well as to isolate the main bioactive compounds. Methods: The chloroformic extract of Allium roseum (A. roseum) and their fractions obtained by subjection to a chromatographic study were tested for their antioxidant activities by using 2, 2-diphenyl-2-picrylhydrazyl and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) assays. An activity-guided purification was conducted to isolate five compounds in pure form where their structures were identified by means of nuclear magnetic resonance analyses, including 1D and 2D nuclear magnetic resonance experiments. Results: The evaluation of the antioxidant activity of chloroformic extract and their fractions from A. roseum var. grandiflorum subvar. typicum Regel. showed interesting results. The active chloroformic extract afforded five isolated compounds where their structures were identified as β-sitosterol (1), chrysoeriol (2), luteolin (3), apigenin (4), and β-sitosterol 3-O-β-D-glucoside (5). All the compounds were isolated for the first time from the A. roseum var. grandiflorum subvar. typicum Regel. The three flavonoids (2–4) exhibited the highest antioxidant activity with IC50 values of 62.28, 21.26 and 513.42 μg/mL, respectively (2, 2-diphenyl- 2-picrylhydrazyl assay) and 218.00, 73.50 and 877.66 μg/mL, respectively [2,2′-azinobis- (3-ethylbenzothiazoline-6-sulfonic acid) assay]. An important value of trolox equivalent antioxidant capacity (2.10 mmol/L) was reported for luteolin (3). Conclusions: These results may suggest that the A. roseum var. grandiflorum subvar. typicum Regel. have great potential as a source of a natural preservative ingredient in beneficial for natural health products.

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