Phytochemical Constituents with Antimicrobial and Antioxidant Activities from Xylia xylocarpa (Roxb.) Taub. Sawdust Extracts

Abstract

Xylia xylocarpa (Roxb.) Taub. sawdust was extracted with chloroform-methanol 1:1 ratio (v/v) and separated to 4 fractions with hexane, dichloromethane, ethyl acetate and 30% methanol. The crude extract and fractions were tested for antimicrobial activity with Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Saccharomyces cerevisiae, Aspergillus niger and wood rot fungi, Gloeophyllum sepiarium. The results showed that the concentrations at 50, 100 and 200 mg/mL of crude extract inhibited all tested microorganisms by paper disc diffusion assay. The greatest crude extract inhibition zone was found in B. subtilis. with diameters of 17.5±0.28 mm, 20.1±0.42 mm and 25.0±0.40 mm, respectively. Among the four fractions, methanol fraction inhibited B. subtilis, E. coli and S. aureus the highest, followed by ethyl acetate, dichloromethane and hexane fractions. The antioxidant activity of crude extract and fractions were evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazal radical) radical scavenging assay coupled on line to LC-MS/MS for simultaneous activity testing and structure elucidation of active compounds. The results indicate that the antioxidant compounds are in a group of tannins, gallic acid, afzelechin and catechin polymer form. Isolation of these compounds from crude extract and fractions of X. xylocarpa (Roxb.) Taub. sawdust is reported for the first time here. These results show potential for adding value to this plant’s waste material from the wood industry, for various applications.