Pluronic F127 Micelles Co-encapsulating a Brachydin-Enriched Fraction and Curcumin: A Self-assembled Platform for Light-assisted Antileishmanial Activity

Abstract

This study developed an associative Pluronic F127-based formulation co-loaded with a brachydin-enriched fraction and curcumin (FBC) for preliminary light-assisted antileishmanial evaluation. The formulation showed high apparent active-material recovery after centrifugation and filtration, as estimated by HPLC-PDA. DLS analysis indicated a polydisperse colloidal profile, with an apparent mean hydrodynamic diameter of approximately 406.5 nm and a number-weighted smaller population centered at approximately 12.1 nm. FTIR data were consistent with formulation-related changes in the vibrational environment of the hydrophobic active materials, while AFM and SEM provided complementary morphological information on deposited or dried samples. Together, these data support an interpretative F127-based self-assembly model, without establishing a fully uniform colloidal population or a definitively resolved internal micellar architecture. In vitro cytotoxicity assays using GM07492A human lung fibroblasts indicated low basal cytotoxicity under dark conditions, whereas light exposure produced concentration-dependent viability reductions at higher formulation concentrations. Antileishmanial assays against Leishmania amazonensis promastigotes revealed a marked light-associated response, mainly in formulations containing the brachydin-enriched fraction. FB showed the highest potency under light exposure, with a formulation-based IC50 of 18.63 μg mL–1, whereas FBC showed an IC50 decrease from 72.74 to 34.33 μg mL–1. Thus, although FBC was not more potent than FB, it combined light-associated antileishmanial activity, high apparent active-material recovery, and favorable macroscopic formulation behavior. Because FB and FBC contain a brachydin-enriched fraction rather than purified individual brachydins, the biological responses should be interpreted as preliminary formulation-level effects. Further studies involving direct reactive oxygen species measurements, intracellular amastigote assays, formal selectivity analysis, fraction standardization, and long-term colloidal stability evaluation are still required before therapeutic efficacy can be inferred.