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To study the synthesis and determination for enantiomeric purity of 6-fluoro-L-3, 4-dihydroxyphenylalanine (6-fluoro-L-DOPA, 6-FDOPA).2-(2-Fluoro-4, 5-dimethoxybenzyl)-N-(diphenylmethylene) glycine tert-butyl ester (8), a new compound, was synthesized from the starting material nitroveratraldehyde via the nucleophilic displacement, reductive iodination, and chiral catalytic phase-transfer alkylation, and 6-FDOPA was prepared from hydrolysis of 8. The enantiomeric purity of 6-FDOPA was determined by HPLC method using a chiral mobil phase and reversed-phase C18 column.The total time of synthesis was less than 90 min, the overall chemical yield from potassium fluoride was about 33%, and the enantiomeric purity was above 95%.Large scale production of 6-FDOPA and automatic synthesis of 6-[18F]fluoro-L-DOPA with excellent chemical and entiomeric purity are available. The practical technique was provided for the radiochemical synthesis and entiomeric purity of 6-[18F]fluoro-L-DOPA.

Cyclovirobuxine-D (CVB-D) was shown to produce significant and dose-dependent protective effects against atrial fibrillation induced by CaCl2-Ach in mice. On atrial fibrillation induced by aconitine, ouabain or adrenaline in isolated guinea pig atria, the effects of CVB-D were similar to those of amiodarone. CVB-D 0.3-100 mumol.L-1 was shown to depress the automaticity of the isolated guinea pig right atria. In isolated left atria, CVB-D 0.3 mumol.L-1 was found to inhibit the abnormal automaticity elicited by adrenaline, to prolong the duration of action potential and effective refractory period and to reduce excitability. At high concentration (30 mumol.L-1), CVB-D was also found to decrease the maximal velocity of depolarization (Vmax) and to elongate the conduction time of initiation. Amiodarone 0.3-30 mumol.L-1 was shown to closely resemble CVB-D in electrophysiology without effect on Vmax.

Bolus injection(i.v.) of l-stepholidine(l-SPD, 3 mg.kg-1) caused hypotension in anaesthetized rats. The blood pressure reduction was sustained for 46.3 +/- 14.1 min. In in vitro experiments, l-SPD induced a concentration dependent relaxation of rat mesenteric, cerebral, renal and coronary resistance arteries preconstricted with 125 mmol.L-1 KCl. l-SPD was least potent with cerebral resistance arteries with the -Log EC50 value being 4.25 +/- 0.22. The relaxation of l-SPD on mesenteric resistance arteries was the most potent with the -Log EC50 value being 4.76 +/- 0.15. The larger influence of l-SPD (100 mumol.L-1) on the contraction induced by KCl in mesenteric than in cerebral arteries was in line with the above results. It is indicated that l-SPD has a direct relaxation on visceral resistance arteries with some degree of selectivity and the relaxation would decrease total peripheral resistance and thus constitute an important cause of its hypotensive action.