An investigation of Humulus lupulus L.: Phenolic composition, antioxidant capacity and inhibition properties of clinically important enzymes

Humulus lupulus L., known as hop, is used mostly in brewing industry. It is known that hops have some secondary metabolites having significant biological activities. As far as we know this is the first paper reporting urease, alpha-amylase and acetylcholinesterase inhibition activity of hop extracts. In this study, phenolic composition, antioxidant capacities, and some clinically important enzyme inhibition properties of the methanol extracts were investigated. Total polyphenolic content (TPC), ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity tests were used for antioxidant activity determinations. Inhibition activity of the extracts on three clinically important enzymes of urease, alpha-amylase and acetylcholinesterase was studied. Polyphenolic composition of the extracts was identified by using RP-HPLC-UV in the presence of fourteen phenolic standards. TPC was found 7.12 +/- 0.09 and 6.86 +/- 0.05 mg GAE/g in methanol extract of hop cone and leaf respectively. It was found that methanol extract of hop cones and leaves showed good urease (IC50 0.58 +/- 0.02 and 0.87 +/- 0.02 mg/mL), acetylcholinesterase (IC50 2.13 +/- 0.03 and 4.18 +/- 0.02 mg/mL) and alpha-amylase (IC50 3.92 +/- 0.02 and 6.05 +/- 0.03 mg/mL) inhibitory effect respectively. It can be concluded that methanol extract of H. lupulus may be an alternative for the treatment of peptic ulcer, Alzheimer's disease and diabetes mellitus. (c) 2018 SAAB. Published by Elsevier B.V. All rights reserved.