Abstract:

The accuracy of three spectrophotometric assays for the determination of flavonoids in hops
(Humulus lupulus L.) using respectively AlCl3, Al(NO3)3 and sodium borohydride/chloranil (SBC) was evaluated by
comparison with the reference data (relatively more accurate) from HPLC analysis. The results showed that the total content
of flavonoids in hops was (12.73 ± 0.26) mg/g by HPLC, compared to (13.66 ± 0.45) mg/g, (43.53 ± 1.16) mg/g, and
(70.25 ± 1.42) mg/g with a relative deviation of 7.3%, 241.9% and 451.8%, respectively, as spectrophotometrically assayed
using AlCl3, Al(NO3)3 and SBC. Therefore, the AlCl3-based assay is proposed to be more suitable for the determination of
flavonoids in hops with smaller errors.

Key words: Humulus lupulus L., total flavonoids, colorimetric methods, high performance liquid chromatography (HPLC), xanthohumol (XN)