研究了牡丹花水提物对肾素-血管紧张素系统中两种关键酶肾素和血管紧张素转化酶（ACE）的抑制作用，选取典型的牡丹花色品种，并与芍药进行比较，考察了样品水提物的肾素和ACE抑制活性及抗氧化能力，并分析酚类及黄酮类物质的含量与其功能活性的相关性。结果表明，红色系的牡丹和芍药花水提物具有优良的肾素和ACE抑制活性，而白色系的牡丹花水提物抑制肾素和ACE活性的能力则很弱。其中活性最高的样品水提物抑制肾素的IC50值为0.08 mg/mL，抑制ACE的IC50值为0.23 mg/mL；此外，红色系的牡丹和芍药花水提物的ABTS自由基清除能力为115.89~121.75 mg TE/g DW，DPPH自由基清除能力为192.67~200.46 mg TE/g DW，铁离子还原能力为119.86~208.94 mg TE/g DW，总酚含量为99.29~122.45 mg GAE/g DW，白色牡丹花水提物的抗氧化能力及总酚含量均远低于红色系样品水提物。相关性分析表明，不同样品水提物的肾素和ACE抑制活性及DPPH、ABTS自由基清除能力和铁离子还原能力与总酚含量显著正相关（p<0.01），相关系数分别为0.99、0.91、0.99、0.99和0.98。本研究指出深色系的牡丹花水提物倾向于表现出更强的肾素和ACE抑制活性，其中酚类化合物是潜在的重要活性物质，这可为探讨新型血压调控因子及实现不同品系牡丹花的高值化利用提供更丰富的基础理论支撑。

The inhibitory effects of aqueous tree peony (Paeonia suffruticosa Andr.) extracts on renin and angiotensin converting enzyme (ACE), two key enzymes in the renin-angiotensin system, were investigated in this research. Tree peony samples with typical colors were selected and compared with herbaceous peony (Paeonia lactiflora Pall.) samples on the renin- and ACE-inhibitory activities and antioxidant activities of aqueous sample extracts were determined. The correlations between the contents of total phenolics or flavonoids and the functionalities were also analyzed. Results showed that the aqueous extracts of red tree peony and herbaceous peony exhibited excellent renin- and ACE-inhibitory activities, while the aqueous extract of white tree peony exhibited very weak inhibitory effects on renin and ACE activities. The IC50 value of the extract with the highest inhibitory activity was 0.08 mg/mL for renin and 0.23 mg/mL for ACE. In addition, the aqueous extracts of red tree peony and herbaceous peony had ABTS free radical scavenging capacities in the range of 115.89~121.75 mg TE/g DW, DPPH radical scavenging capacities in the range of 192.67~200.46 mg TE/g DW, iron ion reduction capacities in the range of 119.86~208.94 mg TE/g DW, and total phenolic content in the range of 99.29~122.45 mg GAE/g DW. However, the antioxidant capacity and total phenolic content of the white tree peony extracts were much lower than those of the red ones. Correlation analysis revealed that the renin-/ACE-inhibitory activities, DPPH/ABTS free radical scavenging capacities, and iron reduction ability of the different aqueous extracts were significantly positively correlated with their total phenolic contents (p<0.01), with the correlation coefficients being 0.99, 0.91, 0.99, 0.99 and 0.98, respectively. This research indicated that the aqueous extracts of the dark colored tree peony tended to show stronger renin-and ACE-inhibitoryactivities, with phenolic compounds as potentially important active substances. These results would provide more fundamental theoretical support for exploring novel blood pressure-regulating agents and fulfilling the high-value utilization of various tree peony flowers.

天津市自然科学基金项目（16JCYBJC23200）