Isolation and derivatization of bioactive compounds from zingiber zerumbet essential oil with antifungal activity against rice pathogens

This study examined the chemical composition and antifungal properties of essential oil extracted from the rhizomes of wild ginger (Zingiber zerumbet Smith) and evaluated its major constituents against three pathogenic fungi: Bipolaris oryzae, Fusarium moniliforme, and Rhizoctonia solani. The essential oil was obtained via hydrodistillation and was analyzed using Gas Chromatography–Mass Spectrometry (GC–MS) to identify both major and minor components. Key constituents included endo-borneol (15.77%), limonene (11.95%), zerumbone (10.73%), and camphene (11.53%), along with minor compounds such as caryophyllene (1.80%), caryophyllene oxide (3.99%), 4-terpineol (2.01%), and borneol formate (2.14%). Bioactivity-guided isolation led to the identification of three prominent terpenoids: limonene, caryophyllene, and zerumbone. Among them, zerumbone exhibited the strongest antifungal activity and was further derivatized into its alcohol and epoxide forms to investigate structure–activity relationships. The alcohol derivative demonstrated enhanced antifungal efficacy against all tested fungi, comparable to a standard fungicide. These findings underscore the potential of wild ginger essential oil, particularly zerumbone, as a natural fungicide for managing fungal pathogens.