Comparison of chemical constituents and antibacterial activities and antioxidant activities of the essential oil from leaves and fruits of Bridelia retusa (L.) A. Juss

The essential oils from the leaves and fruits of Bridelia retusa (L.) A.Juss. were isolated by hydrodistillation. The essential oils were obtained in 0.0013% yield as a pale yellow liquid and 0.0026% yield as a violet-light brown liquid for the leaf oil and fruit oil respectively. The composition of each essential oil was analysed by means of GC-(FID) and GC-MS. Eleven constituents accounting for 48.77% of total leaves oil were identified. The most abundant compound was phytol (33.4%), followed by phthalic acid (5.2%), 6, 13-dimethoxy-2, 3, 9, 10-tetramethylpentacene-1, 4, 8, 11-tetrone (3.4%), heptacosane (2.3%) and nonacosane (1.2%). Sixteen constituents accounting for 51.8% of total fruits oil were identified. The major components were dibutyl sebacate (25.6%), phytol isomer (4.8%), diacetin (4.3%), tricosane (3.9%), isophytol (2.7%), erucylamide (2.5%), phthalic acid (1.9%), hexadecanoic acid (1.5%) and eicosane (1.2%). The essential oils exhibited strong antioxidant activities with the IC50 values of 1.12±0.0010 mg/mL and 1.79±0.0005 mg/mL for the leaf and fruit essential oils respectively, by using the ABTS radical cation scavenging assay. The antibacterial activity of the essential oils was performed by using the standard disc diffusion method. The results revealed that the leaf and fruit essential oils of B. retusa were active against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa with the minimum inhibitory concentrations (MICs) between 20-50 mg/mL.