Antioxidant activity of mojabanchromanol, a novel chromene, isolated from brown alga Sargassum siliquastrum

Silica gel chromatography HPLC, El-Mass, and NMR analyses were performed in order to determine the structure obtained from the separation and refinement of the main components of an ethanol extraction of Sargassum siliquastrum, which indicated its antioxidant activity An ethanol extraction of Sargassum siliquastrum demonstrated the strongest antioxidant activities of ethyl acetate when isolated by silica gel chromatography This amounts to 84.9 +/- 1.2% of its 0.5 mg ml(-1) concentration. The thiobarbituric acid reactive substances (TBARS) measurements from 3 isolations of an HPLC separation of ethyl acetate showed that the antioxidant activity of peak 2 was the most dominant at 84.08% in a 0.5 mg ml(-1) concentration. Peak 2 was verified as a type of chromene through El-Mass and NMR analysis. Its metal sealing characteristic was low while its characteristic of TBARS and DPPH erasure indicated similar or higher levels of metal sealing characteristic. The NMR spectroscopic data was used to elucidate the structure of this new compound, which showed strong antioxidant activity in the assay.

Dibutyryl cyclic AMP and forskolin inhibit phosphatidylinositol hydrolysis, Ca2+ influx and contraction in vascular smooth muscle

Dibutyryl cyclic AMP and forskolin inhibited the contraction induced by norepinephrine (NE) more strongly than the high K(+)-induced contraction in isolated rat aorta. These inhibitors inhibited the 45Ca2+ influx stimulated by NE but not that by high K+, and they inhibited NE-induced inositol monophosphate accumulation. These results suggest that cAMP inhibits NE-induced contraction, at least partly, by inhibiting the alpha-adrenoceptor-mediated signal transduction and high K(+)-induced contraction by decreasing Ca2+ sensitivity but not Ca2+ influx.