Key Findings:
A significant reduction in diastolic and lesser decline in the systolic pressure was reported following a dosage of 10 mg/kg of SDG. These results confirm earlier work by the same investigator. The mechanism of effect appears to be due to an inhibition of the angiotensin-converting enzyme which is involved in the regulation of blood pressure. Enhanced ACE activity results in increases in blood pressure by vasoconstriction. Research is supporting a role of phytoestrogens such as SDG as ACE inhibitors. Flaxseed SDG may offer a natural treatment for hypertension.
ABSTRACT:
Secoisolariciresionol diglucoside (SDG) is a plant lignan isolated from flaxseed and is phytoestrogen. SDG is a potent and long-acting hypotensive agent. Plant phytoestrogens have inhibitory effects on angiotensin-converting enzyme (ACE). The hypotensive effects of SDG, a phytoestrogen, may be mediated through inhibition of ACE. The objective of this study was to investigate if SDG-induced hypotension is mediated through inhibition of ACE. The Sprague Dawley male rats were anesthetized and trachea was cannulated. The right jugular vein was cannulated to administer the drug and the carotid artery was cannulated to record arterial pressures using PIOEZ-1 miniature model transducer (Becton, Dickinson and Company, Franklin Lakes, NJ) and Beckman dynograph (Beckman Instruments, Inc., Schiller Park, IL). The effects of angiotensin I (0.2 µg/kg, intravenously [IV]) in the absence and presence of SDG (10 mg/kg, IV), and SDG alone on systolic, diastolic, and mean arterial pressures were measured before and after 15, 30, and 60 minutes of drug administration. SDG decreased the systolic, diastolic, and mean arterial pressure by 37, 47, and 43%, respectively, at 15 minutes and 18.8, 21.2, and 20.3%, respectively, at 60 minutes. Angiotensin I increased the arterial pressure. SDG decreased angiotensin I-induced rise in the systolic, diastolic, and mean arterial pressures by 60, 58, and 51%, respectively, at 15 minutes and 48, 46, and 30%, respectively, at 60 minutes. The data suggest that SDG reduced the angiotensin I-induced rise in the arterial pressures and hence SDG is a potent ACE inhibitor. (Authors Abstract)