Gaharu (agarwood, Aquilaria malaccensis Lamk.) is a valuable tropical rainforest product traded internationally for its distinctive fragrance. It is not only popular as incense and in perfumery, but also favored in traditional medicine due to its sedative, carminative, cardioprotective and analgesic effects. The current study addresses the chemical differences and similarities between gaharu samples of different grades, obtained commercially, using 1H-NMR-based metabolomics. Two classification models: partial least squares-discriminant analysis (PLS-DA) and Random Forests were developed to classify the gaharu samples on the basis of their chemical constituents. The gaharu samples could be reclassified into a ‘high grade’ group (samples A, B and D), characterized by high contents of kusunol, jinkohol, and 10-epi-γ-eudesmol; an ‘intermediate grade’ group (samples C, F and G), dominated by fatty acid and vanillic acid; and a ‘low grade’ group (sample E and H), which had higher contents of aquilarone derivatives and phenylethyl chromones. The results showed that 1H- NMR-based metabolomics can be a potential method to grade the quality of gaharu samples on the basis of their chemical constituents.

Polyphenol oxidase (PPO) from rambutan (Nephelium lappaceum L) peel was extracted and purified by (NH ) SO precipitation, ion-exchange chromatography and gel filtration chromatography. The biochemical 4 2 4characteristics reveal that the PPO from rambutan peel has higher affinity towards catechol (K = 13.7mM and M V = 18,105 U/ml min ) at an optimum pH of 5.9. The enzyme had an optimum temperature of 37°C and was max 1 relatively stable up to 47°C for a period of 60 minutes with almost 77% activity remaining. Among the various PPO inhibitors tested, the most effective inhibitor for the enzyme with 10mM catechol as substrate was ascorbic acid.