Phytochemicals and Antibacterial Activity of Zingiber zerumbet Growing in Negeri Sembilan, Malaysia

Abstract

The present study is aimed at analysing the chemical composition of essential oil and screening the phytochemicals in crude extracts from the rhizomes of Zingiber zerumbet (L.) Roscoe ex Sm. (Zingiberaceae) as well as determining their antibacterial activity. The essential oil was extracted from the fresh rhizomes using the hydrodistillation method and analysed by gas chromatography-mass spectrometry (GC-MS). The phytochemicals from the dried rhizomes were extracted by sequential maceration technique using n-hexane, ethyl acetate, and methanol, while phytochemical screening was carried out using standard chemical tests. Antibacterial activity was screened using the disc diffusion method. A total of 31 components (94.5%) were detected in the rhizome oil with zerumbone (28.4%), terpinen-4-ol (16.5%) and α-humulene (11.1%) as the main components. Phytochemical screening of the extracts obtained from the dried rhizomes disclosed the existence of steroids, terpenes, quinones, flavonoids, phenols, alkaloids, tannins, coumarins and glycosides. The rhizome oil showed potent antibacterial activity towards Salmonella typhi and Escherichia coli with inhibition zone diameters of 20.66 and 16.66 mm, respectively. Among the extracts, the methanol extract demonstrated high inhibitory activity against Bacillus cereus (14.00 mm), Staphylococcus aureus (9.00 mm), and Salmonella typhi (10.66 mm), while the ethyl acetate extract gave the biggest inhibition zone on E. coli (10.33 mm). The findings from this study indicate that Z. zerumbet might be one of a promising source of natural chemicals that can act as antibacterial agents.