Catechin Reduces Blood Pressure in Spontaneously Hypertensive Rats through Modulation of Arachidonic Acid Metabolism

Inhibition of soluble epoxide hydrolase by natural isothiocyanates

GOAL

The long-term goal of our research is to develop safe and effective soluble epoxide hydrolase (sEH) inhibitors. The objective of this study is to evaluate the potency and selectivity of six natural isothiocyanates (ITCs) as sEH inhibitors.

METHODS

Molecular docking was used to model likely interactions between the ligands and receptors. The sEH inhibitory activity was tested using a validated fluorescence-based assay and PHOME as a substrate. To evaluate their selectivity as sEH inhibitors, the inhibitory potential of the ITCs was determined on microsomal epoxide hydrolase (mEH) and cytochrome P450 (CYP) enzymes in human liver microsomes. Probe substrates such as styrene oxide (mEH substrate) and established substrates for CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4 were used in this study. The metabolites of these substrates were analyzed using validated LC-MS/MS and HPLC-UV assays.

RESULTS

Molecular Docking revealed significant differences in binding site preference among the ITCs in silico and pointed to important interactions between the ligands and the catalytic residues of the sEH enzyme. In vitro, the ITCs showed varying degrees of sEH inhibition, but sulforaphane (SFN) and phenyl isothiocyanate (PITC) were the most potent inhibitors with IC50 values of 3.65 and 7.5 μM, respectively. mEH was not significantly inhibited by any of the ITCs. Erucin and iberin were the only ITCs that did not inhibit the activity of any of the tested CYP enzymes.

CONCLUSION

Our results demonstrate that natural ITCs have the potential to offer safe, selective, and potent sEH inhibition.

The Hypotensive and Vasodilatory Effects Observed in Rats Exposed to Chiranthodendron pentadactylon Larreat Flowers Can Be Attributed to Cyanidin 3-O-Glucoside

Chiranthodendron pentadactylon Larreat is a tree native to southeastern Mexico and Guatemala. Its flower is used in Mexican folk medicine to treat a variety of diseases, including conditions of blood pressure. However, scientific information on its usefulness in this pathology is lacking. The present study evaluates the effect of a methanolic extract (ME) from the flower and its active constituents on heart rate (HR) and mean arterial pressure (MAP) in anesthetized rats (MAPHR). The study also analyzed the effects on rat-isolated aortic rings (RIAR) and the rat mesenteric arterial bed (MABR). Active fractions were chromatographed, which led to the isolation of cyanidin 3-O-glucoside (C3G) identified through HPLC. The Chiranthodendron pentadactylon flowers produced hypotensive and vasorelaxant effects associated with C3G. The vasorelaxant effect is a mechanism underlying the synthesis and release of nitric oxide (NO). Neither cholinergic receptors nor prostaglandins are involved. ME and C3G cause cardiovascular depression in anesthetized rats via cholinergic and prostanoid mechanisms. Our research expands the scientific understanding of the flowers on the rat cardiovascular system. This amplifies the appreciation of the flower's ethnomedicine employed to control blood pressure. However, researchers need to conduct toxicity studies to determine the safety of this plant.

Inhibitory effects of the anthocyanins from Lycium ruthenicum Murray on angiotensin-I-converting enzyme: in vitro and molecular docking studies

BACKGROUND

Lycium ruthenicum Murray (LRM), a perennial shrub plant belonging to the Solanaceae family, is rich in anthocyanins, which have anti-inflammatory, antioxidant, lipid-lowering, intestinal flora regulating, and other pharmacological qualities. This study was primarily aimed to investigate the inhibitory effect of different anthocyanin purities from LRM on angiotensin-I-converting enzyme (ACE) activity in vitro. Moreover, the inhibitory mechanism was further analyzed by molecular docking technology.

RESULTS

Two main anthocyanin isomers were identified by ultra-performance liquid chromatography-tandem mass spectrometry and proton/carbon-13 nuclear magnetic resonance, namely petunidin-3-O-[rhamnopyranosyl-(trans-p-coumaroyl)]-5-O-(β-d-glucopyranoside) (trans-Pt3R5G) and petunidin-3-O-[rhamnopyranosyl-(cis-p-coumaroyl)]-5-O-(β-d-glucopyranoside) (cis-Pt3R5G), with a molar ratio of 9:1. Three purification grades of Pt3R5G all showed excellent inhibitory effects on ACE, with the half maximal inhibitory concentration (IC50 ) values being 0.562, 0.421, and 0.106 mg·mL-1 . Increasing the purity may reduce the IC50 within a certain concentration range. An enzymatic kinetic experiment showed that the inhibitory effect of Pt3R5G on ACE was reversible and non-competitive: Pt3R5G and substrate were not in competition for the active sites of ACE. Molecular docking technology further revealed the possible mechanism was that Pt3R5G and ACE amino acid residues were interacting by hydrogen bonds to exert the inhibitory effect.

CONCLUSION

The results indicated that Pt3R5G from LRM was highly effective at inhibiting ACE activity in vitro, with the hydrogen bonds of Pt3R5G and ACE amino acid residues exerting the inhibition. As a potential plant-based ACE inhibitor, Pt3R5G can be used as a functional ingredient for antihypertensive effects. © 2023 Society of Chemical Industry.

Natural Products; from the Laboratory to Clinical Practice

It has been such a great honor to serve as the Guest Editor for this Special Issue, “Exploration on Pharmacokinetics and Pharmacodynamics of Natural Molecules: Current Status and Future Perspectives” [...]