Chemical contents and antibacterial activity of volatile oils from Paederia pilifera

Volatile oils from aerial parts, leaves and flowers of Paederia pilifera were extracted by steam distillation. The volatile constituents and chemical compositions were investigated by gas chromatography-mass spectrometry (GC-MS). A total of 28, 18 and 26 volatile compounds were identified in the oils obtained from the aerial parts, leaves and flowers, respectively. Interestingly, hexadecanoic acid (25) was the highest component, accounting for 56.78% of the volatile oil derived from the aerial parts and 60.37% from the leaves. The most abundant compounds in the volatile oil from flowers were diisooctyl sebacate (42, 27.03%), followed by bis(2-ethylhexyl) phthalate (37, 9.03%) and docosane (34, 6.82%). The volatile oils of Paederia pilifera were evaluated for antibacterial activity and the bioassay results revealed that the oils displayed antibacterial activity against strains of Bacillus cereus B4ac-DSM4384, Staphylococcus aureus TISTR746 and Escherichia coli JM107 with values of MIC ranging from 0.278 to 35.63 mg/mL. The flower oil was found to be the most active agent against Escherichia coli with MIC value of 0.278 mg/mL. The volatile oil obtained from the aerial parts exhibited antimicrobial activity against all three strains of Bacillus cereus, Staphylococcus aureus and Escherichia coli with MIC values of 33.63, 5.11 and 0.531 mg/mL, respectively. The leaf oil possessed antibacterial activity against the strains of Bacillus cereus and Escherichia coli with MIC values of 31.64 and 0.494 mg/mL, respectively and a similar pattern was observed in the flower oil with MIC values of 35.63 and 0.278 mg/mL, respectively.