ABSTRACT Cyperus rotundus L. (Suada, Sueda, family: Cyperaceae) is vastly spread in several world's subtropical and tropical regions. It had variable traditional uses and bioactivities. A new flavonol derivative: cyperaflavoside (myricetin 3,3',5'-trimethyl ether 7-O-β-D-glucopyranoside) and five flavonoids: vitexin, orientin, cinaroside, quercetin 3-O-β-D-glucopyranoside, and myrcetin 3-O-β-D-glucopyranoside were separated from the methanolic extract of C. rotundus aerial parts. Their structures were verified based on UV, IR, NMR (1D and 2D), HRESIMS, and comparison with literature. All metabolites were assessed for their 5-lipoxygenase inhibitory potential. All compounds possessed 5-lipoxygenase inhibitory potentials with IC50s 5.1, 4.5, 5.9, 4.0, 3.7, and 2.3 µM, respectively, in comparison to indomethacin (IC50 0.98 µM). These results supported the traditional uses of C. rotundus in treating inflammation and its related symptoms.