Isolation and Characterisation of Akuammine from the Seed of Parinari curatellifolia and its Molecular Dynamics in Angiotensin -1- Converting Enzyme Inhibition

Abstract

Over the years, isolated compounds from medicinal plants have been lead candidates in drug discovery and they are useful therapeutic aid to patients. This work isolated a compound from the seed of Parinari curatellifolia and investigated its inhibitory potential and mechanism on angiotensin-1-converting enzyme (ACE1). The methanolic extract of the seed was subjected to chromatographic techniques and yielded a white, crystalline solid. Structural elucidation of the compound was carried out using NMR and MS spectroscopic techniques. The use of N-(3-[2-furyl-acryloyl]-Phe-Gly-Gly) (FAPGG) as an enzyme substrate and the Michealis-Menten method in this study showed how sensitive and fast ACE1 could be inhibited. Inhibition mechanism was explored using the Lineweaver-Burk model, and IC₅₀ was determined using Cheng-Prusoff empirical analysis. Molecular interaction with ACE1 was investigated computationally. NMR and MS spectroscopy showed the compound to be Akuammine, with 26 protons, 22 carbons, 2 nitrogen, and 4 oxygen atoms and chlorinated molecular ion peak at m/z 417.1593. Akuammine exhibited an IC₅₀ of 8.5 µM and displayed mixed type inhibition. Molecular dynamics simulations indicated strong interaction at the allosteric site of ACE1, primarily through hydrophobic interactions. Akuammine demonstrated an ability as a template for antihypertensive agent. This ability may contribute to the ethno botanical uses of Parinari curatellifolia seed.