Abstract

DESIGN, BOX-BEHNKEN RESPONSE-SURFACE OPTIMIZATION, AND IN-SILICO TARGET VALIDATION OF MYRICETIN-LOADED LIPOSOMES FOR ENHANCED ANTIBACTERIAL DELIVERY

Naina Sharma*, Prateek Gupta, Nilesh Jain

ABSTRACT

The progressive depletion of effective conventional antibiotics has prompted intense interest in plant-derived polyphenols as non-traditional antimicrobial candidates. Myricetin (3, 3',4', 5, 5', 7-hexahydroxyflavone) exhibits multi-target antibacterial properties; however, its clinical development is constrained by very low aqueous solubility (~16.6 μg/mL), physiological instability, and low bioavailability (<10%). In the present investigation, a myricetin-loaded liposomal delivery system was engineered using the thin-film hydration method and systematically modeled through a 3-factor, 3-level Box-Behnken Response Surface Design (BBD). Soya phosphatidylcholine (X1: 100–200 mg), cholesterol (X2: 20–60 mg), and probe sonication time (X3: 3–9 min) were evaluated as independent variables against vesicle size (Y1), polydispersity index (Y2), and entrapment efficiency (Y3). The formulation was optimized to achieve sub-200 nm vesicle size, narrow polydispersity (PDI < 0.3), and high drug encapsulation(>80%). To establish the molecular basis of myricetin's antibacterial action, in-silico molecular docking against the 24 kDa ATPase domain of Escherichia coli DNA gyrase B (PDB ID: 1KZN) was performed using AutoDock Vina. The docking protocol was validated by re-docking the crystallographic inhibitor clorobiocin, which yielded a heavy-atom root- mean-square deviation (RMSD) of 0.41 Å. Myricetin exhibited a strong binding affinity of -8.22 kcal/mol, closely matching the reference aminocoumarin clorobiocin (-9.15 kcal/mol) and comparable to quercetin (-8.27 kcal/mol). Contact analysis confirmed direct hydrogen bonding with key catalytic residues Asp73 (1.98 Å), Arg76 (2.12 Å), and Thr165 (2.45 Å), alongside hydrophobic contacts with Ile78, Val167, and Val43. ADMET profiling demonstrated that while myricetin's lipophilicity supports lipid bilayer partitioning (LogP = 1.69), its high polar surface area (151.6 Ų) and hydrogen-bond donor count (HBD = 6) impose strict transport barriers that liposomal encapsulation effectively resolves. This study establishes a validated formulation design and mechanistic computational foundation for the development of liposomal myricetin as a nanotherapeutic platform to combat resistant bacterial infections.

Keywords: Myricetin, Liposomes, Box-Behnken Design, Thin-Film Hydration, DNA Gyrase B, AutoDock Vina, Molecular Docking, ADMET, Antibacterial Nanomedicine.