Identification of compounds with potential angiotensin converting enzyme inhibitory activity in <i>Adansonia digitata</i> L. fruit pulp

The study employed bioassay-guided fractionation to identify novel angiotensin-converting enzyme inhibitory compounds from Adansonia digitata fruit pulp, potentially responsible for its antihypertensive effects. A. digitata Fruit pulp was extracted using the solvents n-hexane, ethylacetate, methanol, and water. The percentage weight, in vitro Angiotensin Converting Enzyme (ACE) inhibitory activities and IC50 values of the extracts were determined. Fractionation and phytocompound identification were performed by thin layer chromatography (TLC), column chromatography techniques, and gas chromatography-mass spectrometry (GC-MS) techniques. The yields obtained from solvent extractions using n-hexane, ethylacetate, methanol, and water were 0.14%, 1.17%, 4.30%, and 21.80%, respectively. The IC50 values of Ramipril®, n-hexane, ethylacetate, methanol, and water extracts were found to be 101.40μg/ml, 116.70μg/ml, 40.53μg/ml, 47.25μg/ml, and 81.05μg/ml, in that order. The most potent ACE inhibitory activity was found in methanol extract of A. digitata Fruit (MEADF), which was chosen for bioassay-guided fractionation. From the assay, two fractions (Fraction I and III), among others, showed low IC50s of 11.77±0.10 μg/ml and 11.96±0.16 μg/ml, respectively, and significant ACE inhibitory activity. The most relatively abundant compounds found in Fractions I and III) were 9, 12, octadecadienoic acid methyl ester (conjugated linoleic acid isomers), cis-Vaccenic acid, 3H-Pyrazol-3-one, 4-benzoyl-2, 4-dihydro-5-methyl-2-phenyl (a pyrazole), and Hexadecanoic acid methyl ester (aromatic acid ester). The study reveals valuable compounds in the methanol extract of Baobab fruit pulp, which could be a promising source for developing antihypertensive foods.