Phytochemicals and Biological Activity Studies of Curcuma aeruginosa Roxb.

Abstract

Curcuma aeruginosa Roxb., also known as temu hitam is one of the species from the Zingiberaceae family. The phytochemicals and bioactivities of this plant species have been studied. Cold maceration technique was used to extract the phytochemicals of the dried rhizomes of C. aeruginosa and n-hexane, dichloromethane, and methanol were used in this technique as solvents. Fractionation and purification on the crude extracts of the species using vacuum liquid chromatography (VLC) and column chromatography (CC) successfully isolated curzerenone (1) and curcumenol (2). Their structures were elucidated using spectroscopic methods such as Infrared (IR), 1H Nuclear Magnetic Resonance (NMR), and Gas Chromatography- Mass Spectrometry (GCMS). The crude extracts and the pure compounds were screened for anti-tyrosinase and anti-acetylcholinesterase activities. Modified dopachrome method with L-DOPA as the substrate and kojic acid as positive control was chosen to screen the anti-tyrosinase activity. Among all the tested samples, the n-hexane crude extract and curcumenol (2) exhibited the highest activities with 88.7% and 87.9% inhibition against the mushroom tyrosinase. For anti-acetylcholinesterase bioassay, a slightly modified Ellman’s method was used with galantamine being used as the positive control and 5,5’-dithiobis-(2-nitrobenzoic acid) (DTNB) or Ellman’s reagent was added before being scanned with microplate reader to determine the anti-acetylcholinesterase activity in the samples. It was found that curzerenone (1) exhibited acetylcholinesterase inhibitory activity with 88.4% inhibition against acetylcholinesterase enzyme when compared to the positive control, which gave 93.1% acetylcholinesterase inhibition. In conclusion, the objectives of this study were successfully achieved and the plant species exhibits anti-tyrosinase and anti-acetylcholinesterase properties.