Physicochemical properties and in vitro antioxidant activities of pyroligneous acid prepared from brushwood biomass waste of Mangosteen, Durian, Rambutan, and Langsat

Physicochemical characteristics and in vitro antioxidant activities of four pyroligneous acids carbonized from the wastes of wood species including Mangosteen (Garcinia mangostana Linn.), Durian (Durio zibethinus L.), Rambutan (Nephelium lappaceum L.), and Langsat (Lansium domesticum Serr.) were assessed. Appearing as transparent liquors with pH 3.9-4.2, the pyroligneous acid samples under test possessed acetic acid (23.22-25.46%) as the dominant component. The total soluble tar, total acid, and water content were 0.15-0.28wt%, 99-192mg KOH/g and 84.5-93.5wt%, respectively. Phenolic compounds namely: 2,6-dimethoxyphenol (6.88-9.69%), phenol (2.97-5.88%), 4-methylsyringol (3.10-3.56%), guaiacol (2.36-3.55%), and 2-methoxy-4-methylphenol (1.08-1.28%) were found. All had in vitro antioxidant activities especially mangosteen pyroligneous acid, which showed activity roughly similar to BHT (P>0.05) against anti-lipid peroxidation. Nitric oxide scavenging capacities of all pyroligneous acids were significantly higher than BHT (P<0.05). Our results suggest that pyroligneous acids from the four types of branch waste could be used as sources of beneficial natural antioxidants, possibly as food or feed additives to protect against lipid peroxidation, and potentially also in veterinary medicine in anti-inflammatory products.