Nicotine Detoxification of Rutin, Quercitrin, and Chlorogenic Acid Isolated from Houttuynia cordata by Reducing Reactive Oxygen Species and Inducing Conversion from Nicotine to Cotinine

摘要

The hypothesis of the present study is that methanol extract of Houttuynia cordata Thunb (MEH) and its targeted bioactive components including rutin, quercitrin, and chlorogenic acid can be effective in reducing reactive oxygen species (ROS) caused by nicotine and promoting nicotine to cotinine in HepG2 cell. Oxygen radical absorbance capacity (ORAC) of bioactive components and MEH was measured to assess free radical scavenging capacity. ROS inhibition ability of bioactive components and MEH was measured by 2',7'-dichlorodihydrofluorescein diacetate assay. The conversion rate of nicotine to cotinine by bioactive components and MEH was determined by the direct barbiturate assay method. ORAC value confirmed that MEH and its bioactive components provided an antioxidant capacity ranging from 126 to 138 mu Mtrolox equivalents/100 g. Compared to nicotine only, pretreatment of MEH, rutin, and quercitrin was revealed to effectively inhibit ROS production in HepG2 cell by up to 9, 7.4, and 14%, respectively. Nicotine conversion to cotinine after 120 min incubation was 1.7 and 1.4 times higher in rutin and chlorogenic acid pretreatment than the control, respectively. H. cordata and its targeted bioactive components could be a valuable natural ingredient for inhibiting ROS formation by nicotine as well as enhancing the rate of nicotine to cotinine turnover