Microencapsulation of Monascus Red Pigment Using Saccharomyces cerevisiae Ghosts: Process Optimization and Characterization

Abstract

Monascus red pigment (MRP) is a highly pigmented microbial secondary metabolite having a therapeutic potential, which can be further enhanced through incorporation into various drug carriers. In this study, MRP produced by Monascus purpureus ATCC16436 was microencapsulated using Saccharomyces cerevisiae ( S . cerevisiae ) ghosts (ScGs) as a biocarrier, resulting in an innovative bioformulation that integrates the properties of both components. Morphological analysis using light, electron, and confocal microscopy confirmed successful evacuation of S . cerevisiae cells, generating ScGs with a well-preserved three-dimensional structure. The ghosts showed a relatively large internal volume (~ 26 µm 3 ) surrounded by intact, negatively charged cell walls with distinct pores that facilitated the discharge of intracellular contents. Optimization of the microencapsulation process using a Box–Behnken experimental design (BBD) and response surface methodology (RSM) considering temperature, MRP concentration, shaking speed, and incubation time as independent variables, yielded an optimal formulation with a loading efficiency of 61.4 ± 2.3% at 25 °C, 300 mg/mL MRP, 125 rpm shaking rate, and 90 min incubation time. Digital, light, electron, and differential interference contrast (DIC) confocal microscopy confirmed dense MRP encapsulation, with uniform distribution of the pigment throughout the ScGs. The microencapsulated MRP demonstrated a biphasic sustained release profile in PBS (pH 7.4) containing 1.6% Tween 80. In terms of bioactivity, microencapsulation enhanced MRP cytotoxicity against the A549 lung cancer cell line (IC20 > 40, 10 and 3 µg/mL for ScGs, MRP and MRP-ScGs, respectively), consistent with increased cellular uptake observed via confocal microscopy. The MRP-ScGs represent a promising bio-microcapsule platform for biomedical applications, offering structural stability and enhanced therapeutic potential. Additionally, in silico bioinformatic analysis predicted multiple molecular targets associated with vital cellular functions, further supporting their potential in targeted drug delivery.

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