Phytocompounds of Curcuma longa extract are more effective against bacterial biofilm than pure curcumin only: An in-vitro and in-silico analysis

Abstract

Bioactive compounds are the group of secondary metabolites of plants that have a potent impact on antimicrobial and antibiofilm agents. Although Curcuma longa (turmeric) is well known for its antimicrobial activity, the question arises if curcumin, the primary bioactive compound is only responsible for it or the synergistic and simultaneous contribution of more than one bioactive compound are responsible for this antibiofilm efficacy. The research work aims to determine the efficacy of the extract Curcuma longa has a higher potential of antimicrobial and antibiofilm activity than the purchased curcumin and standard antibiotic. Present work was initiated with GC-MS analysis of the ethanolic extract of Curcuma longa (turmeric) and showed that in addition to curcumin, methyl palmitate de-hydro zingerone had a higher percent of availability within the extract. The in-silico studies also showed that when targeted upon Gram-positive biofilm-forming protein of Staphylococcus aureus (3TIP), curcumin alone had a binding constant value of -6.33 Kcal/mol but showed a value of -17.811 Kcal/mol when acted in association with Dehydrozingerone. Similarly, the binding constant's value changed from -6.07 Kcal/mol to - 23.844 Kcal/mol, when Gram-negative biofilm-forming protein (3ZYB) of Pseudomonas aeruginosa was acted upon by curcumin only and in association with methyl palmitate, respectively. Lower minimum inhibitory concentration (MIC) and higher effectivity in reducing the bacterial quorum sensing (QS) activity of the turmeric extract than pure Curcumin indicated the higher antimicrobial and antibiofilm efficiency of the extract, respectively. This indicated clearly that the synergistic action of all the bioactive compounds imparts the antibiofilm activity of turmeric. The result was further confirmed by the scanning electron microscopic (SEM) studies, fluorescent microscopic studies, and FTIR analysis of EPS as well.