Antibacterial activity of curcumenol from rhizomes of Indonesian Curcuma aeruginosa (Zingiberaceae)

The rhizomes of Curcuma aeruginosa (Zingiberaceae), locally known as Temu Hitam, is usually used as a traditional medicine. The bioactive compounds in this plant were known to have antibacterial activities. However, information regarding bioactive compounds on antibacterial activity contained in C. aeruginosa rhizomes is still limited. In continuing our study on Indonesian medicinal plants, the isolation of bioactive compounds from C. aeruginosa growing in Indonesia had been conducted. Curcumenol had been isolated from the methanol extract of C. aeruginosa rhizomes by using extraction methods and several chromatography techniques, i.e. vacuum liquid, radial, and preparative thin layer chromatography. Furthermore, this compound had been elucidated based on one-dimensional NMR ( ¹ H and ¹³ C) and MS. The preliminary antibacterial assay of methanol extract of C. aeruginosa rhizomes on Salmonella typhi and Escherichia coli showed moderate activity with an inhibition zone of 7 mm (inhibition index of 1.17) and 6 mm (inhibition index of 1.00), in 50 ppm, respectively. Moreover, curcumenol also exhibited moderate activity in 50 ppm with 8 mm of inhibition zone (1.33 of inhibition index) on S. typhi while on E. coli showed weak activity in 50 ppm with 4 mm of inhibition zone (0.67 of inhibition index). However, both the methanol extract of C. aeruginosa rhizomes and curcumenol were inactive on Bacillus cereus and Staphylococcus aureus. It can be suggested that curcumenol played an important contribution to an antibacterial activity toward Gram-negative bacteria (S. typhi and E. coli) in C. aeruginosa rhizomes.