Antibacterial and radical scavenging activity of fatty acids from Paullinia pinnata L.

Twelve fatty acids identified from the methanol extract of Paullinia pinnata L. root extract by the use of Gas Chromatography coupled with mass spectrophotometer were screened for antibacterial activity against both Gram positive and Gram negative bacteria as well as three resistant strains of Staphylococcus aureus SA1199B, XU212 and RN4220 resistant to norfloxacin, tetracycline and erythromycin respectively. Using the 96-well microtitre plate method, azelaic acid (a dicarboxylic acid), showed the highest activity against all organisms tested with minimum inhibitory concentration range of 32-256 μg/ml while palmitic, oleic, eicosanoic and stearic acids also showed weak to moderate activity against Staph. aureus, B. subtilis, E. coli and P. aeruginosa. However, docosanoic, tetradecanoic and eicosenoic acids had no activity against all organisms tested. The results also indicated that while the crude methanol extract possess potent antioxidant activity by bleaching DPPH radical (IC ₅₀ of 3.8μg/ml), the fatty acids did not show any significant radical scavenging action.