Essential Oils of The Leaves of Syzygium hemilamprum (F. Muell.) Craven & Biffin.: Chemical Analysis, Antimicrobial, Mosquito Larvicidal, Molecular Docking, and ADMET Studies.

Abstract

The chemical composition of the essential oil and n-hexane extract from Syzygium hemilamprum leaves was first performed. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the essential oil was predominantly composed of monoterpene hydrocarbons (71.5 %) and oxygenated derivatives (20.2 %), with β-pinene (31.5 %), limonene (19.4 %), α-pinene (12.3 %), and α-terpineol (7.4 %) being the principal constituents. The n-hexane extract contained monoterpene hydrocarbons (42.2 %) and non-terpenic compounds (34.0 %), with β-pinene (32.8 %) and n-hexadecane (10.2 %) as the major components. Antimicrobial and mosquito larvicidal assays demonstrated that both samples exhibited antimicrobial activity against Staphylococcus aureus (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Saccharomyces cerevisiae (yeast), with a minimum inhibitory concentration (MIC) of 128 μg/mL for all tested organisms. Both samples also showed significant mosquito larvicidal activity against Aedes aegypti and Culex quinquefasciatus, with LC50 and LC90 values below 20 μg/mL at 24 and 48 hours post-treatment. Molecular docking studies suggested that limonene and α-terpineol could serve as potent inhibitors of mosquito odorant binding proteins. Additionally, an in silico analysis was performed to evaluate the physicochemical and ADMET (absorption, distribution, metabolism, and toxicity) properties of the major constituents of the essential oil.