Cardiovascular effects of danshen extract and its magnesium tanshinoate B enriched form

Abstract

The Chinese medicine, danshen, is the dried root and rhizome of Salvia miltiorrhiza Bunge (Labiatae) and has been used as a health supplement to protect against the development of hypertension and myocardial infarction. One of its major active water-soluble components is magnesium tanshinoate B (MTB). The present study examines and compares the cardiovascular effects of the water-soluble extract of danshen (SME) and its MTB enriched form containing 70% of MTB (MTB70) in anaesthetized rats. Rats were subjected to intravenous infusion of saline and phenylephrine to produce a basal state of normal and elevated blood pressure, respectively. Different doses of SME, MTB70 or its vehicle were then injected intravenously in rats and their effects on blood pressure were monitored. Our results indicate that both SME and MTB70 transiently reduce blood pressure in a dose-dependent manner. Independent of the initial blood pressure state, SME caused a smaller reduction in blood pressure than MTB70. While the effect of SME was similar in rats infused with saline or phenylephrine, MTB70 reduced blood pressure to a greater extent in rats infused with phenylephrine compared to those infused with saline. From these findings, it appears that MTB is one of the major components responsible for the cardiovascular effects of danshen, and its beneficial cardiovascular effect is enhanced in conditions with elevated blood pressure. In view of the highly variable content of danshen extract, standardization of danshen preparation is essential to ensure consistent pharmacological actions. Therefore, our data suggests that the amount of MTB might be employed as a standard reference for the preparation of danshen as a therapeutic agent, especially in the treatment of cardiovascular disorders.