Gas Chromatography-Mass Spectrometry Characterization and Bioactivity Study of Oudneya africana Leaves Essential Oil: Antidiabetic, Antimicrobial, and Photoprotective Activities.

This study investigated the chemical composition and biological activity of essential oil (EO) extracted from the leaves of Oudneya africana from Ouargla, using gas chromatography-flame ionization detector/mass spectrometry. A total of 35 compounds were identified, representing 87.45% of the oil composition, with hexacosane (34.94%), 2-pentadecanone-6,10,14-trimethyl (4.86%), and hexadecanoic acid methyl ester (3.45%) as major components. The EO demonstrated significant antimicrobial resistance against Gram-positive and Gram-negative bacteria, notably inhibiting Staphylococcus aureus and Escherichia coli growth (inhibition zones: 30.5 ± 1 mm (34.44%) and 28.5 ± 1 mm (32.22%), respectively), while showing minimal effect on Pseudomonas aeruginosa, it's also exhibited strong antifungal activity against Aspergillus niger at minimum concentration of 25 mg/mL. Additionally, the EO displayed dose-dependent anti-diabetic potential through alpha-amylase inhibition, with a half-maximal inhibitory concentration value of 341.12 ± 1.14 µg/mL. However, its sun protection factor (SPF) was relatively low 8.96 ± 0.06. This is the first report on the α-amylase, antifungal, and SPF properties of O. africana EO, highlighting its potential as a source of natural compounds for medical application.