Effect of indigenous extraction solvents on the phytochemical, GC-MS profile and antioxidant activities of<i> Ocimum gratissimum</i> extracts

Abstract

This study compared the effects of Ethanol and indigenous extractants (Aqueous, 2% NaCl solution, and 40% v/v Lime juice) on the bioactive properties of Ocimum gratissimum extract. Phytochemical, GC-MS, and antioxidant analysis of the Ethanol (EtOHE), Aqueous (AqE), NaCl solution (NaClE), and Lime juice (LjE) extracts were carried out. All the extracts contained saponins, tannins, flavonoids, phenols, steroids, and alkaloids, with Ethanol and Aqueous extracts showing higher concentrations of these compounds compared with NaCl and Lime juice extracts (p < 0.05). GC-MS characterization identified twenty-one bioactive compounds in the Ethanol extract, while only fifteen compounds were found in the Aqueous, NaCl, and Lime juice extracts, respectively. The Ethanol extract had higher Total Antioxidant Capacity (TAC) (26.08 ± 0.76 μg/ml) compared with Aqueous (7.79 ± 0.61 μg/ml), NaCl (7.82 ± 0.81 μg/ml), and Lime juice (3.49 ± 0.48 μg/ml) extracts (p < 0.05). The Aqueous extract had the strongest Ferric reducing antioxidant power, with a lower IC50 value of 117.37 μg/ml, compared with NaCl (228.94 μg/ml) and Lime juice (166.84 μg/ml) extracts, while Ethanol extracts had the lowest IC50 value (60.39 μg/ml) for ABTS radicals compared with NaCl (66.75 μg/ml) and Lime juice (78.52 μg/ml) extracts. In conclusion, all the extracts exhibited potential medicinal and antioxidant properties; however, the bioactive and antioxidant properties of the extracts demonstrate a dependence on the extraction methods and solvents. It is therefore important to always ascertain which extraction solvent and method is appropriate for the preparation of safe medicinal herbs.