The essential oils found in Curcuma herbs have many uses. Researchers in China determine the composition and therapeutic activity of Curcuma herb essential oils extracted from four Curcuma herb species.
Curcuma herbs have been used in Southeast Asia for thousands of years for their claimed antioxidative, antimicrobial, anti-inflammatory, and cytotoxic effects. the chemical composition of the Curcuma herb essential oils extracted from the four different Curcuma species vary significantly. Therefore, each species will have different therapeutic uses. This study investigates the composition and therapeutic activity of essential oils extracted from the four Curcuma herb species. The purpose of this study is to determine the best use for each herb species.
Lanyue Zhang and her colleagues, from the Institute of Natural Medicine and Green Chemistry, School of Chemical Engineering and Light Industry in Guangdong, China reported their findings in the journal Chemistry and Biodiversity. Through gas chromatography and mass spectroscopy (GC-MS), the essential oils of the four Curcuma herbs species (C. longa, C. phaeocaulis, C. wenyujin, and C. kwangsiensis) were extracted. The essential oil extracts were then further analyzed for their component compounds. Each of these compounds exhibits different therapeutic activities in vitro.
The DPPH radical-scavenging assay was used to test antioxidant activity. The Curcuma essential oil extracted from the C. kwangsiensis species exhibited the best radical-scavenging ability, therefore providing the best antioxidant properties. At a dose of 50mg/kg, all essential oils were more efficacious than the same dose of ibuprofen. Once the doses were increased to 100mg/kg, ibuprofen had superior effects compared with any essential oil. C. kwangsiensis, at a dose of 100mg/kg, exhibited similar anti-inflammatory effects as ibuprofen.
Antimicrobial activity was determined by testing the compound for its ability to inhibit microorganism growth in an overnight incubation. The lowest concentration of compound required inhibiting the growth of bacteria or fungus is known as the minimum inhibitory concentration (MIC). The MIC of each essential oil was used to compare antimicrobial activity. The essential oil of C. phaeocaulis displayed optimum antimicrobial activity against gram-negative and gram-positive bacteria. For fungus, C. wenyujin had the lowest MIC compared with the other oils. The positive controls used in the antimicrobial activity analysis were streptomycin; an antibiotic, and bifonazole; an antifungal. While the Curcuma essential oils did display antimicrobial activity in vitro, the positive controls were far more effective.
Testing the cytotoxic (toxic to cells) activity of the compounds was similar to the antimicrobial testing. The minimum concentration of compound required to inhibit the growth of two cancer cell lines (a prostate cancer and hepatoma cell line) by 50% was used to compare anticancer properties of each essential oil. C. wenyujin and C. phaeocaulis had superior cytotoxic activity against the prostate cancer line compared with the other oils; however, the positive control (paclitaxel, an anticancer drug) was significantly more effective. The essential oil of C. longa displayed the best anticancer properties against the hepatoma cells.
Curcuma herbs are composed of many molecules and each compound has different biological activities. Isolating the essential oils found in the 4 Curcuma herb species and analyzing their therapeutic benefits in vitro has provided a guide to the best use among each of the species.
Written by Jessica Caporuscio, PharmD
Zhang L, Yang Z, Chen D, et al. Variation on composition and bioactivity of essential oils of four common Curcuma herbs. Chem Biodivers. 2017.