Inhibitory capacity of extracts and main constituents of hop flowers

Abstract

Background Hops (Humulus lupulus Linn.) produce flowers that are used on an industrial scale to impart sensory properties to beer and have some pharmacologic properties already published in the literature. Gout, type 2 diabetes and Alzheimer’s are diseases the appearance/aggravation of which is related to the action of enzymes such as xanthine oxidase, α-glucosidase and acetylcholinesterase, respectively, which are associated with oxidative stress. Our hypothesis is that the extracts and chemical constituents isolated from the flowers of hops act as enzyme inhibitors and scavenge free radicals. Hexane and methanol extracts were obtained from flowers of different cultivars produced in Brazil and from commercial pellets, with the contents of bitter acids and xanthohumol determined by high-performance liquid chromatography (HPLC), after QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction and were evaluated for their pharmacologic properties. Results The extracts and analytical standards showed a significant capacity against oxidative stress in all evaluated methods (DPPH·, ABTS·+, HO·). Xanthohumol and extracts with a high concentration of this compound demonstrated a strong capacity to inhibit the xanthine oxidase and significantly reduce the formation of uric acid. The results with the α-glucosidase revealed promising pharmacologic action for all samples, even more effective than the commercial drug (acarbose). The acetylcholinesterase inhibition assays were effective for hexane extracts and ICE-4, with values obtained close to the eserine. Conclusion It can be concluded with the results obtained that extracts and patterns of hop flowers showed promising potential to combat oxidative stress and complementary treatment of gout, type 2 diabetes and Alzheimer’s disease.