AbstractThe composition of methylated fatty acids from wood, bark, and leaves of Brachychiton diversifolius was analyzed for the first time using gas chromatography (GC). The results indicated that the major methyl ester of fatty acids found in wood, bark, and leaves were: myristic acid (8.32%), palmitic acid (15.66%), and palmitic acid (9.95%), respectively. In accordance to the biological effects of fatty acid fraction, they were moderately effective against Bacillus subtilis and Sarcina lutea, but they did not show any effect against the growth of Staphylococcus aureus and Pectobacterium carotovorum at a concentration of 2000 μg/mL. The maximum percentages of inhibition of fungal mycelial growth against Penicillium selerotigenum (60.35%), Paecilomyces variotii (70.80%), and Aspergillus niger (70.50%) were shown by the fatty acids from leaves, bark, and bark, respectively. The total antioxidant activity (TAA %) of fatty acids from wood, bark, and leaves, were 40±3.13%, 80±5.14%, and 60±4.50%, respectively. In accordance to the results, the different parts of B. diversifolius could provide important components, such as fatty acids with antimicrobial and antioxidant activities for future studies or uses.