Sesquiterpenes from Indonesian of Curcuma aeruginosa rhizome and its antibacterial activities

Curcuma aeruginosa, a member of the Zingiberaceae family, is an indigenous plant of Southeast Asia and the Indian subcontinent. Previous researches reported that compounds in this plant have antibacterial activities. However, a study on bioactive compounds contained in C. aeruginosa rhizomes as an antibacterial activity is still limited. Phytochemical study on C. aeruginosa rhizomes from Tropical Biopharmaca Research Centre Indonesian had yielded four sesquiterpenes, identified as curcumenol, curcumenone, and mixture of two compounds, i.e., 1(10), 4(5)-diepoxygermacrone, and isoaromadendrene epoxide. These compounds were elucidated using one-dimensional nuclear magnetic resonance (NMR) (1H and 13C) and two-dimensional - NMR spectroscopy (heteronuclear single quantum coherence and heteronuclear multiple bond correlation) followed by mass spectrometry. Preliminary antibacterial assay of MeOH extract demonstrated moderate activity toward Salmonella typhi and Escherichia coli, in contrast, it was inactive toward Bacillus cereus and Staphylococcus aureus. Curcumenol exhibited moderate activity on S. typhi and showed weak activity toward E. coli, in contrast, it was inactive toward both B. cereus and S. aureus. On the other hand, curcumenone and mixture of two compounds were inactive toward all bacteria. It can be suggested that curcumenol had a contribution to an antibacterial activity toward gram-negative bacteria, i.e., S. typhi and E. coli, while the others had antagonist effect of antibacterial activity compared with C. aeruginosa rhizomes extract.