Bioactivity of plant extracts against Burkholderia pseudomallei

Background: Burkholderia pseudomallei are causative agents of melioidosis, a disease found mostly in South- East Asia and Northern Australia. Recent reports of a reduced susceptibility of B. pseudomallei to antibiotics, especially ceftazidime, have indicated need for further research into new antimicrobial substances from plants.

Objectives: We tested antimicrobial activity of 10 plant extracts; Barringtonia acutangula (L.) Gaertn., Cleome gynandra Linn., Luffa acutangula (Linn.) Roxb., Limnophila geoffrayi Bonati, Centella asiatica (L.) Urban, Piper sarmentosum Roxb., Tamarindus indica, Cyperus rotundus Linn., Cassia fistula Linn., and Allium sativum Linn.

Materials and Methods: Crude extracts were tested for their antimicrobial activity by the standard disc diffusion assay and micro-dilution assay. Methanol, ethyl acetate, ethanol, hexane, and water were used as solvents for extraction.

Results: The methanolic extract of B. acutangula (L.) Gaertn. showed the best antimicrobial results against B. pseudomallei with an inhibition zone of 18 mm and minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of 4 mg/ml. The chemical structure of crude methanolic extracts of B. acutangula (L.) Gaertn. was primarily elucidated by nuclear magnetic resonance spectroscopy (NMR). The results showed that the chemical constituent was in the group of steroids.

Conclusions: It is concluded that Barringtonia acutangula (L.) Gaertn. may play an active part in the inhibition of the growth of B. pseudomallei.