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Purpose: Ferulic acid (FA) is a natural compound which is used to treat insomnia. However, its use is limited because of its poor oral bioavailability caused by extremely rapid elimination. The current study aimed to develop a self-microemulsifying drug delivery system (SMEDDS) to improve the oral delivery of FA and to enhance its hypnotic efficacy. Methods: FA-SMEDDS was prepared, and its morphology and storage stability were characterized. The formulation was also subjected to pharmacokinetic and tissue distribution studies in rats. The hypnotic efficacy of FA-SMEDDS was evaluated in p-chlorophenylalanine-induced insomnia mice. Results: FA-loaded SMEDDS exhibited a small droplet size (15.24 nm) and good stability. Oral administration of FA-SMEDDS yielded relative bioavailability of 185.96%. In the kidney, SMEDDS decreased the distribution percentage of FA from 76.1% to 59.4% and significantly reduced its metabolic conversion, indicating a reduction in renal elimination. Interestingly, FA-SMEDDS showed a higher distribution in the brain and enhanced serotonin levels in the brain, which extended the sleep time by 2-fold in insomnia mice. Conclusion: This is the first study to show that FA-loaded SMEDDS decreased renal elimination, enhanced oral bioavailability, increased brain distribution, and improved hypnotic efficacy. Thus, we have demonstrated that SMEDDS is a promising carrier which can be employed to improve the oral delivery of FA and facilitate product development for the therapy of insomnia.

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a b s t r a c tLectins are used extensively as research tools to detect and target specific oligosaccharide sequences. Ricinus communis agglutinin I (RCA 120 ) recognizes non-reducing terminal b-D-galactose (Galb) and its specificities of interactions with neutral and sialylated oligosaccharides have been well documented. Here we use carbohydrate arrays of sulfated Galb-containing oligosaccharide probes, prepared from marine-derived galactans, to investigate their interactions with RCA 120 . Our results showed that RCA 120 binding to Galb1-4 was enhanced by 2-O-or 6-O-sulfation but abolished by 4-O-sulfation. The results were corroborated with competition experiments. Erythrina cristagalli lectin is also a Galb-binding protein but it cannot accommodate any sulfation on Galb.