Discovery of new angiotensin converting enzyme (ACE) inhibitors from medicinal plants to treat hypertension using an in vitro assay

Abstract

Background and purpose of the studyAngiotensin converting enzyme (ACE) inhibitors plays a critical role in treating hypertension. The purpose of the present investigation was to evaluate ACE inhibition activity of 50 Iranian medicinal plants using an in vitro assay.MethodsThe ACE activity was evaluated by determining the hydrolysis rate of substrate, hippuryl-L-histidyl-L-leucine (HHL), using reverse phase high performance liquid chromatography (RP-HPLC). Total phenolic content and antioxidant activity were determined by Folin-Ciocalteu colorimetric method and DPPH radical scavenging assay respectively.ResultsSix extracts revealed > 50% ACE inhibition activity at 330 μg/ml concentration. They were Berberis integerrima Bunge. (Berberidaceae) (88.2 ± 1.7%), Crataegus microphylla C. Koch (Rosaceae) (80.9 ± 1.3%), Nymphaea alba L. (Nymphaeaceae) (66.3 ± 1.2%), Onopordon acanthium L. (Asteraceae) (80.2 ± 2.0%), Quercus infectoria G. Olivier. (Fagaceae) (93.9 ± 2.5%) and Rubus sp. (Rosaceae) (51.3 ± 1.0%). Q. infectoria possessed the highest total phenolic content with 7410 ± 101 mg gallic acid/100 g dry plant. Antioxidant activity of Q. infectoria (IC50 value 1.7 ± 0.03 μg/ml) was more than that of BHT (IC50 value of 10.3 ± 0.15 μg/ml) and Trolox (IC50 value of 3.2 ± 0.06 μg/ml) as the positive controls.ConclusionsIn this study, we introduced six medicinal plants with ACE inhibition activity. Despite the high ACE inhibition and antioxidant activity of Q. infectoria, due to its tannin content (tannins interfere in ACE activity), another plant, O. acanthium, which also had high ACE inhibition and antioxidant activity, but contained no tannin, could be utilized in further studies for isolation of active compounds.

Antihypertension Study of Anredera Cordifolia (Ten). V. Steenis Extract and Its Fractions in Rats Through Dexamethasone Induction and Nitric Oxide Release.

“…Phenolic compounds widely distributed and the most secondary metabolite found in plants. It can act as an antioxidant since it can scavenge free radicals [30]. Phenolic compounds included phenolic acid, anthocyanin, and flavonoid [31].…”

Medicinal Plants that can Cause Changes in Blood Pressure and Interactions with Antihypertensive Agents

“…Oligomeric flavonoids, as procyanidins, present in plants such as Crataegus laevigata, exert vasodilatory effect with consequent reduction in blood pressure [25,26]. Crataegus laevigata also has its hypotensive activity justified by the presence of amines in their fresh flowers, as tyramine [20] and by angiotensin converting enzyme inhibition [27].…”

Phytopharmaceutical Potentials of Prosopis Laevigata, Symplocos Cochinchinensis and Nymphaea Alba: A Review

“…Study shows that it possess active compounds which can trigger the receptor response of endometrial and myometrial lining of uterus. It was able to induce a dose-related increase in force of contraction of rat uterus when tested against like antagonists such as salbutamol and atropine [46].…”