Combinative effect of sardine peptides and quercetin alleviates hypertension through inhibition of angiotensin I converting enzyme activity and inflammation

•Combination of SP and QC inhibits ACE activity in vitro better than SP or QC alone.•The combination lowers SBP, heart, left ventricular and kidney indices in vivo.•The combination also reduces the level of NO, IL-6 and TNF-αin vitro.•The combination alleviates hypertension via ACE activity and inflammation inhibition.

Hypertension had relation to angiotensin I converting enzyme (ACE) activity and inflammation. In our previous research, sardine peptides (SP) with ACE inhibitory activity were prepared. However, the combinative effect of SP and quercetin (QC) on hypertension alleviation was still unknown. In the present study, the antihypertensive effect of SP and QC was discovered and the optimal proportion of SP and QC (v/v = 8:2, with 20.00 mg/mL of SP and 12.99 μg/mL of QC for their original concentrations) was screened on ACE activity inhibition in vitro. And the in vivo experiment supported it by indicating that the mixture reduced the systolic blood pressure, heart, left ventricular and kidney weight and their corresponding indices, serum ACE activity, angiotensin-II (ANG-II) and tumor necrosis factor-α (TNF-α) (in high dose) concentration in SHR rats. Besides, the mixture also lowers NO, TNF-α andinterleukin-6 (IL-6) concentration significantly in vitro. Hence, the combinative effect of SP and QC in optimal proportion had stronger inhibition on ACE activity than SP or QC alone, and could alleviate hypertension through inhibition of ACE activity and inflammation.

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