Antimicrobial potency evaluation of free and immobilized l-asparaginase using chitosan nanoparticles

Abstract

Infectious diseases pose one of the major health challenges across the globe. Though some antimicrobial drugs are available commercially, they developed resistance. l-asparaginase is a renowned name in chemotherapeutics. However, we have conducted in silico and in vitro study to decipher the potency of this enzyme isolated from Purpureocilliumlilacinum as an anti-microbial agent in both free and immobilized form. The in vitro anti-microbial property of l-asparaginase was examined against a wide range of gram-negative and gram-positive bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhimurium, Proteus vulgaris, Staphylococcus aureus, and Listeria monocytogenes). The antimicrobial property of the enzyme further enhances when l-asparaginase was encapsulated inside the chitosan nanoparticle that itself possesses antimicrobial activity. Chitosan-based biopolymeric nanoparticles were synthesized using sodium tripolyphosphate (TPP) (particle size = 38 nm) and green tea extract (particle size = 35 nm) through the ionic gelation method. The minimum inhibitory concentration (MIC)of l-asparaginase and chitosan nanoparticle against P. vulgaris is 21.06 mg/mL and 64 mg/mL respectively. However, upon encapsulation, the MIC drastically reduces to 5.26 mg/mL. A similar trend was observed against other tested microbes. The thermal and pH stability of the l-asparaginase was also increased on immobilization. The enzyme was found to be stable in the pH range 7.5–10 and temperature up to 60 °C. A drug release study was also carried out that suggested a biphasic drug release. The entrapment efficiency and loading capacity of the synthesized nanoparticle were 72% and 53% respectively. The present study explores another significant application of this enzyme as an antimicrobial agent and motivates it to explore its role as antibiotherapy. It was also found that enzyme nano-carrier has better therapeutic potential as compared to free enzyme.