The aluminum chloride method was employed to estimate the flavonoid contents of EOs. The standard or EOs (100 μL) were mixed with 20 μL of (10%, w/v) aluminum chloride, 20 μL (1 mol L−1 ) sodium acetate, 300 μL methanol, and 560 μL distilled water in Eppendorf tubes, followed by incubation at room temperature for 30 min in the dark. The absorbance of the reaction mixture was measured at 415 nm. Quercetin was used as a reference standard and the results were expressed as μg quercetin equivalent mg−1 dry extract (n = 3) (Orhan et al., 2011).