Antioxidant Activity of Extracts of Wild Humulus lupulus L.

Abstract

Plants from natural flora (wild-growing) as well as cultural plants demonstrated numerous useful properties that play an important role in human life. They often can be used as medicinal, forage, food, etc. Searching for new sources of valuable capacities of wild plants still is actual. Humulus lupulus L. (hop) is well-known species from the small family Cannabaceae that is used as a bittering agent in the brewing industry and as a medicinal plant. H. lupulus raw is a valuable source of biologically active compounds and demonstrated different biological activities. This study was aimed to determine the antioxidant activity and accumulation of polyphenol compounds in raw wild plants of H. lupulus. Raw (leaves, stems, and female flowers) collected from the natural flora of M.M. Gryshko National Botanical Garden of the NAS of Ukraine. In ethanol extracts of leaves, flowers and stems determined 54.13, 44.69 and 23.76 mg GAE/g (gallic acid equivalent) of polyphenol content (TPC), respectively; 7.24, 4.92, 2.56 mg CAE/g (caffeic acid equivalent) of phenolic acids (TPAC), respectively; 45.48, 29.64 and 18.31 mg QE/g (quercetin equivalent) of flavonoid content (TFC), respectively. Molybdenum reducing power of leaf, flower, and stem extracts was 168.17, 236.45, and 97.57 mg TE/g (Trolox equivalent), respectively; antioxidant activity by DPPH method 8.64, 8.02, and 7.97 mg TE/g, respectively. This study showed that the highest values of polyphenol compounds found in the leaves and the lowest in the stem extracts. The strongest correlation found between TPAC and TFC (r = 0.995), TPC and TPAC (r = 0.978), TPC and TFC (r = 0.952), TFC and DPPH (r = 0.936). This investigation showed the high antioxidant potential of the wild H. lupulus plant that can be used in the further pharmacological study.