Antioxidant, Antibacterial, Enzyme Inhibitory, and Anticancer Activities and Chemical Composition of Alpinia galanga Flower Essential Oil

Alpinia galanga is widely cultivated for its essential oil (EO), which has been used in cosmetics and perfumes. Previous studies of A. galanga focussed mostly on the rhizome but seldom on the flower. Therefore, this study was designed to identify the chemical composition of A. galanga flower EO and firstly estimate its antioxidant, antibacterial, enzyme inhibitory, and anticancer activities. According to the results of the gas chromatography with flame ionization or mass selective detection (GC-FID/MS) analysis, the most abundant component of the EO was farnesene (64.3%), followed by farnesyl acetate (3.6%), aceteugenol (3.2%), eugenol (3.1%), E-nerolidol (2.9%), decyl acetate (2.4%), octyl acetate (2.0%), sesquirosefuran (1.9%), (E)-beta-farnesene (1.7%), and germacrene D (1.5%). For the bioactivities, the EO exhibited moderate DPPH and ABTS radical scavenging effects with IC50 values of 138.62 +/- 3.07 mu g/mL and 40.48 +/- 0.49 mu g/mL, respectively. Moreover, the EO showed strongto-moderate antibacterial activities with various diameter of inhibition zone (DIZ) (8.79-14.32 mm), minimal inhibitory concentration (MIC) (3.13-6.25 mg/mL), and minimal bactericidal concentration (MBC) (6.25-12.50 mg/mL) values against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Proteus vulgaris. Interestingly, the EO possessed remarkable alpha-glucosidase inhibition (IC50 = 0.16 +/- 0.03 mg/mL), which was equivalent to that of the positive control acarbose (IC50 = 0.15 +/- 0.01 mg/mL) (p > 0.05). It showed moderate tyrosinase inhibition (IC50 = 0.62 +/- 0.09 mg/mL) and weak inhibitory activity on acetylcholinesterase (AChE) (IC50 = 2.49 +/- 0.24 mg/mL) and butyrylcholinesterase (BChE) (IC50 = 10.14 +/- 0.59 mg/mL). Furthermore, the EO exhibited considerable selective cytotoxicity to K562 cells (IC50 = 41.55 +/- 2.28 mu g/mL) and lower cytotoxicity to non-cancerous L929 cells (IC50 = 120.54 +/- 8.37 mu g/mL), and it induced K562 cell apoptosis in a dose-dependent manner. Hence, A. galanga flower EO could be regarded as a bioactive natural product with great application potential in the pharmaceutical field.

Automated summary

This study aimed to identify the chemical composition of the essential oil (EO) from Alpinia galanga flowers and evaluate its antioxidant, antibacterial, enzyme inhibitory, and anticancer activities. The EO was found to contain various components, exhibiting moderate scavenging effects on free radicals and strong antimicrobial properties against multiple bacteria. It also showed inhibitory activity against specific enzymes. Additionally, the EO demonstrated remarkable selective cytotoxicity towards leukemia cells.