Novel action of lignans isolated from Hernandia nymphaeifolia on Ca2+ signaling in human neutrophils
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The effects of five lignans (epi-aschantin, epi-magnolin, epi-yangambin, deoxypodophyllotoxin, yatein) isolated from Hernandia nymphaeifolia (Presl.) Kubitzki (Hernandiaceae) on intracellular Ca2+ levels ([Ca2+]i) in human neutrophils were investigated by using fura-2 as a fluorescent probe. In both Ca2+-containing and Ca2+-free media, the lignans (50–100 µM) did not alter basal [Ca2+]i but inhibited the [Ca2+]i increase induced by platelet activating factor (PAF, 10 µM), leukotriene B4 (LTB4, 0.2 µM), and thapsigargin (1 µM) to different extents. In Ca2+-free medium, after depleting stores of Ca2+ with PAF, LTB4 or thapsigargin, addition of 3 mM Ca2+ induced Ca2+ influx. Each of the lignans (50–100 µM) caused 39–89% inhibition of PAF-induced Ca2+ influx; whereas only epi-aschantin was able to inhibit LTB4- and thapsigargin-induced Ca2+ influx by 54–79%. Together, the results suggest that in human neutrophils, these lignans did not alter basal [Ca2+]i but inhibited Ca2+ movement induced by Ca2+ mobilizing agents.
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