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1. Structure and hypotensive activity relationships of tetrandrine (TD), an alkaloid isolated from the Chinese herb Radix stephaniae tetrandrae and its derivatives were investigated in conscious stroke-prone spontaneously hypertensive rats (SHRSP). 2. Derivatives substituted at the 7-O position with various types of alkyl group produced varying degrees of hypotensive effect. 3. While the demethylated derivative, fangchinoline (FC), and its acetylated compound had no effect on blood pressure, 7-O-methyl FC (TD), and 7-O-ethyl and 7-O-isopropyl FC at oral doses of 25 and 50 mg/kg produced a gradual and sustained hypotensive effect without any significant effects on heart rate and plasma renin concentration. 4. Substitution at the 7-O position with longer side chains such as n-propyl, n-butyl and n-pentyl groups reduced both the degree and duration of hypotensive activity. 5. Substitution of N-methyl groups at the 2 and 2' positions with quaternary ammonium or N-oxide attenuated the hypotensive activity. 6. The results of this study suggest a possibility that 7-O-ethyl and 7-O-isopropyl derivatives as well as TD can be considered as potential antihypertensive drugs because of the gradual onset and long duration of their hypotensive action in SHRSP.

1. Effects of oral administration of synthetic tetrandrine (TD) derivatives (20 mg/kg per day) for 9 weeks on blood pressure, heart rate, plasma renin concentration (PRC) and vascular reactivities to pressor substances were studied in spontaneously hypertensive (SHR) rats. 2. 7-O-Ethyl fangchinolin (7-O-EFC) and 7-O-isopropyl fangchinolin (7-O-IFC) produced a significant and sustained reduction in blood pressure from the first week of administration. 7-O-EFC reduced heart rate when determined under restraint conditions, but not under unanesthetized, freely moving conditions. 3. TD derivatives produced no effect on PRC. 4. Pressor response to phenylephrine was reduced significantly whereas the response to angiotensin II was enhanced after prolonged administration of 7-O-EFC and 7-O-IFC. 5. These results demonstrate that TD derivatives are potential antihypertensive drugs, and that attenuation of the pressor response to phenylephrine may contribute at least in part to its antihypertensive effect.

The type and fineness of a filler significantly affect the performance of an asphalt mixture. There is a lack of specific research on the effects of filler fineness and dust from aggregates on the properties of epoxy asphalt (EA) mixtures. The effects of aggregate dust and mineral powder on the properties of an EA mixture were evaluated. These filler were tested to determine their fineness, specific surface area and mineral composition. The effects of these fillers on the EA mastic sample and mixture were evaluated. The morphology of the EA mastic samples was analyzed using scanning electron microscopy (SEM). The effects of the fillers on the Marshall stability, tensile strength and fatigue performance of the EA mixture were evaluated. The dust from the aggregates exhibited an even particle size distribution, and its average particle size was approximately 20% of that of the mineral powder. The SEM microanalysis showed that the EA mastic sample containing relatively fine dust formed a tight and dense interfacial bonding structure with the aggregate. The EA mixture sample containing filler composed of dust from aggregate had a significantly higher strength and longer fatigue life than that of the EA sample containing filler composed of mineral powder.