Nanosuspensions as an approach for improved solubility and anti-Ichthyophthirius multifiliis activity of magnolol

Natural products have gained recognition as a valuable resource and have significant implications in the field of aquaculture. Nevertheless, the limited water solubility of drugs, leading to compromised bioavailability, has been a persistent challenge in the realm of pharmaceutical research. Magnolol as a natural product, the low solubility leads to limited activity against Ichthyophthirius multifiliis, which severely limits the application of magnolol. Nanosuspensions are considered to be an important strategy to improve the solubility and bioavailability of insoluble drugs. The purpose of this study is to fabricate nanosuspensions that can effectively improve the solubility and antiparasitic activity of magnolol. Magnolol nanosuspensions (MNs) containg Pluronic F68 as a stabilizer was prepared by the solvent-antisolvent precipitation method. The results of TEM, DSC and FTIR analysis showed that the surfactant attached to the surface of magnolol, and the nanosuspensions process significantly reduced the crystallinity and improved the solubility and dissolution rate of magnolol. The Central Composite Design was adopted to investigate the effects of independent variables viz. amount of temperature (A), the ratio of pluronic F68 to magnolol (w/w) (B), and churning time (C) on particle size (Y), obtaining optimum nanosuspensions with a size of 32.03 nm. Compared with free magnolol, the release rate of magnolol in 119 nm and 35 nm MNs was significantly improved, and the release rate of magnolol was increased from 28.13% to 58.45% and 85.70% within 60 min. Further, the antiparasitic activity of MNs was measured. The results showed the reduction in drug particle size leads to an enhancement in the insecticidal activity of magnolol. Altogether, this study proposes a promising strategy to enhance activity by increasing the solubility of natural products.