Argan: Phytochemical profiling and evaluation of the antioxidant, hypoglycemic, and antibacterial properties of its fruit pulp extracts

Abstract

Herein, we isolated three triterpenoid saponins from the methanol extract of the fruit pulp of argan. The structures of the identified compounds were determined using comprehensive NMR spectroscopy analyses (1H, 13C NMR, COSY, TOCSY, ROESY, and HSQC), combined with mass spectroscopy. Gas chromatography (GC) was utilized to determine the monosaccharide contents after the samples underwent methanolysis and their glycoside configuration was proved via their trimethylsilyl derivatives. Furthermore, the methanol extract of the fruit pulp and its n-butanol fraction were evaluated for their antioxidant properties via DPPH, ABTS, and FRAP assays, antidiabetic activity using α-amylase and α-glucosidase inhibition activities, and antibacterial properties utilizing microdilution and antibiofilm assays. Compared to the crude methanol extract, our results showed that the n-butanol fraction exhibited more potent antioxidant activity and antibacterial potential against Staphylococcus aureus, Escherichia coli, Salmonella typhi, Enterococcus faecalis, and Pseudomonas aeruginosa (MIC = 12.5–50 mg/mL); while no effect on the bacterial biofilm was observed. The methanol extract was more effective in inhibiting α-glucosidase (EC50 = 0.15 mg/mL), however, the n-butanol fraction elicited strong α-amylase inhibition (EC50 = 0.49 mg/mL). These findings suggest that the fruit pulp of argan could serve as a potential source of phytochemicals suitable for the treatment of diabetes and its related complications.

Keywords

• Argan
• Pulp
• Triterpenoid saponins
• Antioxidant activity
• Antidiabetic activity
• Antibacterial activity