| Summary: | 博士 === 高雄醫學大學 === 藥學研究所 === 90 === The effects of lignans, epi-yangambin, epi-magnolin, epi-aschantin, deoxypodophyllotoxin and yatein, isolated from the trunk bark of Hernandia nymphaeifolia (Presl) Kubitzki on Ca2+ mobilization were investigated. The increase of intracellular free Ca2+ levels ([Ca2+]i) in Madin-Darby canine kidney (MDCK) cells and the inhibition of Ca2+ movement induced by Ca2+-mobilizing agents were observed in human neutrophils. These agents also altered reactive oxygen species (ROS) generation, Ca2+ signaling pathways and estrogenic compounds-induced Ca2+ signaling on human neutrophils in multiple manners.
The lignans (50-100 mM) inhibited the release of [Ca2+]i release induced by platelet-activating factor (PAF) (10 mM), leukotriene B4 (LTB4) (0.2 mM), and thapsigargin (1 mM) at different extents, but not altered the basal [Ca2+]i. All of these five lignans (50-100 mM) inhibited 39-89 % of PAF-induced Ca2+ influx; whereas only epi-aschantin inhibited 54-79% of LTB4 and thapsigargin-induced Ca2+ influx.
These five lignans (50-100 mM) blocked the Ca2+ releases induced by 10 mM of 17b-estradiol and 5 mM tamoxifen, but not by 25 mM clomiphene. The supressing of Ca2+ influx also observed by 17b-estradiol in all the tested- lignans (50-100 mM). However, 100 mM of epi-aschantin was able to reduce tamoxifen-induced Ca2+ influx.
These lignans induced the increases of [Ca2+]i in a dose-dependent manner ranging from 10 to 100 mM in MDCK cells. [Ca2+]i triggering Ca2+ influx by these five lignans. La3+ (50 mM) abolished the Ca2+ signals by 100 mM of epi-aschantin, epi-magnolin, epi-yangambin, and 20 mM of deoxypodophyllotoxin. However, 50 mM of yatein only inhibited this response by 60%. All five lignans (50-100 mM) inhibited 42-65% of thapsigargin-induced capacitative Ca2+ entry, and inhibited 23-61% of thapsigargin-induced intracellular Ca2+ release. Epi-yangambin (100 mM), epi-magnolin (100 mM), and epi-aschantin (100 mM) inhibited 8-38% of 10 mM ATP-induced Ca2+ release. Trypan blue exclusion revealed that incubation with deoxypodophyllotoxin or yatein (but not the other lignans) decreased cell viability in a concentration-dependent manner.
All five lignans (25-200 mM) suppressed the ROS generation by 20 mM of N-formyl-methionyl-leucyl-phenylalanine (fMLP) and 1 mM of phorbol myristate acetate (PMA), but not by 0.1 mM of arachidonic acid. The lignans (50-100 mM) inhibited 0.1 mM of arachidonic acid-induced Ca2+ release , but not by 20 mM of fMLP-induced Ca2+ release. These lignans also inhibited fMLP- and arachidonic acid-induced Ca2+ influx.
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