Inhibition of biofilm formation in Serratia marcescens by Andrographolide from Andrographis paniculata

Quorum sensing (QS) is well known for bacterial virulence, antibiotic resistance and biofilm production. Inhibition of quorum sensing can reduce the risk of microbial pathogenicity in all infection. In this present study the compound Andrographolide which is present in Andrographis paniculata leaf extract was assessed for its anti quorum sensing activity against acyl homoserine lactone (AHL)-dependent biofilm formation in Serratia marcescens. The Andrographolide obtained from Andrographis paniculata exhibited a concentration dependent (100 μg/ml) reduction in biofilm production in Serratia marcescens to a level of 90% and compared with the standard Andrographolide (sigma aldrich). Microtiter plate and Light microscopic analysis further confirmed the reduction in the biofilm forming ability of Serratia marcescens when treated with andrographolide. In addition the Andrographolide present in Andrographis paniculata by itself showed no growth inhibitory effect on Serratia marcescens.