Red Mold Dioscorea Has a Greater Antihypertensive Effect than Traditional Red Mold Rice in Spontaneously Hypertensive Rats

The aim of this study is to investigate the antihypertensive effects of red mold rice (RMR) and red mold dioscorea (RMD) by low-dose oral administration to spontaneously hypertensive rats (SHRs). A single oral dose of 1-fold RMD (150 mg/kg) significantly (p < 0.05) decreased systolic blood pressure (SBP) and diastolic blood pressure (DBP) after 8 h of administration, but RMR showed no significant effect. During the chronic oral administration of 1-fold RMR (150 mg/kg), 0.5-fold RMD, 1-fold RMD, and 5-fold RMD to SHRs for 8 weeks, the increase of blood pressure was slowed significantly. The results indicated that only a 0.5-fold dose of RMD was able to significantly decrease both SBP and DBP. A 1-fold RMD showed a greater antihypertensive effect than 1-fold RMR, and both RMR and RMD can improve the vascular elastin structure remodeling. In comparison to RMR, RMD contained a higher amount of γ-aminobutyric acid (GABA) and anti-inflammatory yellow pigments (monascin and ankaflavin). Moreover, RMD also exhibited higher angiotensin-I-converting enzyme (ACE) inhibitory activity than RMR. These results suggest that RMD has greater antihypertensive bioavailability.