Study On Chemical Components And Purification Of Xanthohumol Of Hops (Humulus Lupulus L.)

The hop plant (Humulus lupulus L., Cannabinaceae) is a dioecious twining perennial. The inflorescences (hops or hop cones) are used in the breweries to give beer its characteristics such as flavor and aroma and also as herbs. On abroad, it has been used to aid digestion and as a mild sedative to treat insomnia. Chinese pharmacopoeia recorded that alcoholic extracts of hops have been used clinically in treating numerous forms of leprosy, pulmonary tuberculosis and acute bacterial dysentery. This paper aimed on the comprehensive utilization of hops. Biochemical constituents of hops were studied, especially for the polyphenols, flavonoids and volatile compounds. The main results were as follows:(1) The compounds of hops were tested qualitatively by the methods from Chinese herb chemistry. Results showed that hops contained many bioactivity compounds such as flavonoids, polyphenols, amino acids, polypetide, organic acids, saponins, anthraquinones and alkaloids.(2) Aroma and bitter hops were analyzed for the contents of water extracts, water soluble sugars, water soluble proteins, total amino acids, total polyphenols, total flavonoids , total proteins, total ashes and α -acids, β -acids . The results were as follows: the content of active constituents were higher in aroma hops than in bitter hops except for resins ( α -acids and β -acids); there were high content of water soluble active constituents such as water soluble sugars, flavanoids , ashes and amino acids both in aroma hops and bitter hops . Therefore, hops is a multifunctional resource that can be exploited and utilized in nutrition, health-protection and medicine.(3) Extraction of polyphenols from hops was optimized from extracting solvents and other extracting conditions. The results indicated that the mixture of acetone and water was the best solvent. The results of fractional factorial design experiment showed thatfactors such as acetone concentration, extracting temperature, material and solvent ratio, extracting time had significant effect on the extracting rate. Acetone concentration and extracting temperature were the most significant for extracting rate compared with the other factors. The optimal condition described as that acetone concentration was 62% and extracting temperature was 47 by the steepest accent experiment and the central composite design. Under the optimized condition, the extracting effect of polyphenols from hops was 47.44mg-g~-1.(4) extracting process of flavonoids with organic solvents from hops were optimized. Based on the single factors such as ethanol concentration, material and solvent ratio, extracting temperature and extracting time, orthogonal test was performed and the best combination was conformed for the four factors. Among them, ethanol concentration and extracting temperature had significant effect. Central composite design was further carried out aimed at ethanol concentration and extracting temperature by the central composite design. The results indicated that the optimal conditions were as follows: ethanol concentration was 43% , extracting temperature was 61 , material and solvent ratio was 1 : 25 and extracting time was 90min.Under the optimized condition, the maximal extracting effect of flavonoids from hops was 76.5 mg g~-1.(5) Steam distillation followed by solvent extraction (SDE), direct solvent extraction (DSE) and supercritical fluid (CO2) extraction( SFE) were used for sample preparation in volatile compound analysis in hops (qingdao flower variety). The extracts obtained from three methods were then analyzed by gas chromatography-mass spectrometry (GC - MS). Mass spectra or authentic compounds were used to identify around 70 components in various volatile fractions. 29 chemical constituents were identified in SDE, 29 chemical constituents in DSE, 29 chemical constituents in SFE. Among the volatile compounds obtained from three preparation techniques, there were 8 Compounds in common. Thechemical composition of hop volatiles were hydrocarbon components including aliphatic hydrocarbons and terpenes and oxygenated components such as alcohols, aldehydes, ketones, epoxides and esters. Caryophyllene was the primary component in volatile compounds by SDE methods.(6) Supercritical CO2 (SC- CO2) extraction of effective constituents from hops was tested based on the yield of total solids. The optimal condition described as that extraction temperature was 45 °C and extraction pressure was 20MPa. Under the optimized condition, the yield of total solids was 17.5%. The content of a -acids were 47% and the P -acids were 32% in the total solids.(7) Extraction of flavonoids from waste hops (SC-CO2 extracted hops) using supercritical fluids (ethanol was added as modifier) was investigated. Various temperatures, pressures and concentrations of ethanol and the ratio(w/w) of solvent to material were tested in this study. The results of the single factor and orthogonal experiments showed that at 50 °C, 25MPa, the ratio of solvent to material (50%), ethanol concentration 80% exhibited the maximum extraction yield of flavonoids (8.2 mg.g"1). The results of HPLC-MS analysis of the extracts indicated that some kinds of flavonoids were obtained including Xanthohumol, which was the principal prenylflavonoid in hops.(8) Flavonoids extracted by organic solvent and supercritical fluids were compared based on TLC, HPLC methods. Results showed organic solvent could extract flavanones, flavonol glycosides and prenylflavonoids (xanthohumol was the primary flavonoid ) while supercritical fluids extracted xanthohumol and other prenylflavonoids. The content of xanthohumol in supercritical fluids extracts was 5-6 fold higher than that in organic solvent extracts.(9) The results of HPLC-MS analysis of the supercritical fluids extracts indicated that Isoxanthohumol, Xanthohumol , Dehydrocycloxanthohumol and other two unknown...