Chemical constituents and toxicity effects of leaves from several agarwood tree species (Aquilaria)

Abstract

While chemical constituents in agarwood produced by Aquilaria sp. are widely recognised for its fragrance and pharmaceutical properties, not much is known about the potential of the leaf or its toxicity effects to human. As an alternate source for income generation, the green leaves are commonly processed into food products such as tea, capitalising on its potential of medicinal properties. This study investigated hydrodistilled and solvent-extracted leaf extracts from three commercially available Aquilaria species: Aquilaria crassna, Aquilaria malaccensis and Aquilaria sinensis, using GC-FID and GC-MS. A total of 115 compounds were obtained from the essential oils, and hexane and methanol extracts. Among the major compounds are hexadecanoic acid and squalene, which possess antifungal and antioxidant properties, respectively. Effects of the essential oil and crude extract were tested against human's peripheral blood mononuclear cells (PBMCs) using MTT assay for cytotoxicity and comet assay for genotoxicity. Only the methanol extract of A. malaccensis had cytotoxic effect (IC50 = 24.5 mg mL-1 and LD50 = 4537 mg kg-1), which can be classified as slightly hazardous (Class III). This extract also caused DNA fragmentation with comet-like appearance (p < 0.05) in PBMCs, implying that it has genotoxic effect as well. The results provided evidence that leaf extracts from certain Aquilaria species could be slightly hazardous to human. Therefore, additional research is needed to ensure its safety for human consumption.