Comparative Antimicrobial Activity and Bioactive Constituents of Oils from Rhizomes of Zingiber Officinale Roscoe Obtained by Different Extraction Methods.

Abstract:

Ginger, known for its rich array of bioactive compounds, holds significant therapeutic potential due to its diverse medicinal properties. This study investigated the antimicrobial activity and bioactive principles present in ginger rhizome oils obtained using three different extraction methods viz: liquid-liquid extraction, cold maceration, and soxhlet extarction. The oils’ bioactive principles were identified by Gas Chromatography Mass Spectrometry (GC-MS) while their antimicrobial activity was determined by agar well diffusion technique. The GC-MS analysis revealed the presence of thirty compounds in each of the oils from liquid-liquid extraction and cold maceration, and fifty four compounds in the soxhlet-extracted oil. The most predominant compound in both liquid-liquid (31.13 %) and cold maceration (16.99 %) oils was oleic acid whereas the Soxhlet-extracted oil contained predominantly linoleic acid methyl ester (9.27 %). Some bioactive compounds identified in these oils include δ-elemene, isoborneol, α-Bisabolol oxide, steric acid, undecanone, palmitic acid, α-copaene, zingiberene, aromadendrene, farnesol, 2-methyleicsane and farnesene which possess antioxidant, antibacterial, antifungal, antiviral, anti-inflammatory, anti-ulcer, anti-cancer, hypolipidemic, mosquito repellant, antimicrobial, and antidiabetic activities. Additionally, the oils exhibited promising antimicrobial potential against the test organisms with Staphylococcus aureus showing the least susceptibility to all the samples. Staphylococcus aureus and Candida albicans were completely resistant to the oil obtained by Soxhlet extraction at all tested concentrations. Meanwhile, Klebsiella pneumoniae (20 mm), Proteus vulgaris (18 mm), and Pseudomonas aeruginosa (17 mm), were most susceptible to the oil obtained by liquid-liquid extraction, cold maceration and soxhlet extraction, respectively. The study highlighted the significance of extraction methods on the chemical composition and antimicrobial activity of ginger rhizome oils, underscoring the importance of choosing appropriate extraction technique to optimize the oils' therapeutic properties for specific medicinal applications.