AGARWOOD ESSENTIAL OIL QUALITY AND ANTIOXIDANT PROPERTIES OF AQUILARIA MALACCENSIS AND AQUILARIA SINENSIS

Abstract

Agarwood is produced by reacting to physical damage, chemical injection, and microbial and entomological activity on Aquilaria spp. (Thymelaeceae). Agarwood oil is popular as one of the most precious and most expensive oils being traded. As a precious oil, the quality of the oil is an essential issue. The quality of A. malaccensis and A. sinensis oils were analysed using electronic nose, gas chromatography (GC), and gas chromatography/mass spectrometry (GC/MS). The electronic nose signals categorised both oils into the Agarwood Pure Oil Cluster with 100% accuracy via FRIM’s Agarwood Identification System (AIS) database. Chemical analyses of A. malaccensis oil revealed the presence of 4-phenyl-2-butanone (3.27%), β-agarofuran (4.51%), and kusunol (11.30%) as the major compounds. Valerianol (15.78%) was the most abundant compound identified in A. sinensis, followed by β-agarofuran, and γ-eudesmol with a percentage of 7.45 and 6.75, respectively. Unfortunately, the detection of monoethylhexyl phthalate (5.24%) showed that the A. sinensis oil was contaminated with a plasticiser. Simultaneously, as part of our bioprospecting study, exploring the potential of selected Aquilaria spp. oils as antioxidant alternatives were conducted. The total phenolic content of A. malaccensis and A. sinensis was 10.8 and 8.5 mg GAE/g, respectively. A. sinensis essential oil exhibited higher scavenging DPPH radical activity with IC50 value of 8.46 mg/mL compared to A. malaccensis with IC₅₀ value of 11.49 mg/mL. The ferric-reducing power activity of A. malaccensis showed absorbance slightly higher than A. sinensis at 0.165 and 0.104, respectively. The β-carotene/linoleic acid bleaching assay revealed an IC₅₀ of 6.25 mg/mL for A. sinensis and an IC₅₀ value of 3.66 mg/mL for A. malaccensis. A. malaccensis oil revealed higher antioxidant activities in TPC, FRAP, and β-carotene/linoleic acid bleaching assays compared to A. sinensis oil. This study suggests that pure A. malaccensis oil may potentially act an as antioxidant agent in product development.