Mechanistic evaluation of Clerodendrum serratum anti-biofilm potency against Mycobacterium species

Abstract

Biofilm formation in Mycobacterium species significantly contributes to their pathogenicity and resistance to conventional antimicrobial therapies, posing a major challenge in clinical management. Plant-derived phytoconstituents have emerged as promising alternatives due to their diverse biological activities, including anti-biofilm properties. Clerodendrum serratum, a medicinal plant known for antimicrobial potential, offers a rich source of such bioactive compounds. This study aimed to first optimize robust biofilm formation in three Mycobacterium species (M. smegmatis, M. fortuitum, and M. marinum) using specific nutritional supplements, followed by the evaluation of the anti-biofilm efficacy of C. serratum leaf extract against pre-formed mature biofilms. Finally, potential molecular targets and mechanisms of action of key phytoconstituents were investigated through in silico analysis. Enhanced biofilm formation was achieved by supplementing Middlebrook 7H9 broth with KH₂PO₄, (NH₄)₂SO₄, Acicase, and DTT, with KH₂PO₄ showing the most pronounced effect. Disruption of pre-formed biofilms by C. serratum leaf extract was quantified using the crystal violet microtiter plate assay and confirmed via Atomic Force Microscopy (AFM), which revealed significant alterations in biofilm architecture. In silico molecular docking of five major phytoconstituents (Hispidulin, Luteolin, Salvigenin, Pectolinarigenin, and Uncinatone) with critical biofilm-associated targets (FadD32, InhA, and MmpL3) showed strong binding affinities of docking score up to -11.0 kcal/mol, indicating potential mechanisms of biofilm disruption. This study presents the optimization of enhanced biofilm formation in Mycobacterium species and demonstrates the anti-biofilm potential of C. serratum leaf extract. The integrated experimental and computational approach offers new insights into targeting resilient mycobacterial biofilms using plant-based therapeutics.

Keywords: Antimycobacterial activity; Clerodendrum serratum extract; Molecular docking; Mycobacterium biofilm disruption; Mycobacterium biofilm optimization; Phytoconstituents.