Development of novel indole-3-aldehyde loaded gastro-resistant spray-dried microparticles for post-biotic small intestine local delivery

Considering the recent evidences on the therapeutic potential of post-biotics, this study was focused on two mains goals: i) to develop an enteric microparticle (MP) formulation for intestinal localized delivery of Indole-3-aldehyde (3-IAld) (a microbial-derived metabolite produced by the host's lactobacilli during the catabolic pathway of tryptophan); ii) to provide support to the employment of spray-drying as innovative one-step manufacturing technique for enteric products. For this purpose, special attention was taken in the knowledge of the influence of equipment setup and feedstock properties on MP enteric behaviour. Eudragit® S100 and L100 and ethyl cellulose were used as wall materials and NaOH and ethanol solutions as solvent systems. 3-IAld loading was maintained at 10% w/w. As postulated, feedstock properties influenced spray-drying regime. In addition, they prevailed over other spray-drying process factors in determining MP enteric behavior. Albeit the high buckling regime that produced crumped particles, gastro-resistance was obtained by spray-drying 2:1 Eudragit® S100:L100 with 30% w/w ethyl cellulose (EC) in ethanol solution. These results support the use of spray-drying as a method for manufacturing gastro-resistant MP. The obtained 3-IAld loaded enteric MP will be useful to investigate novel post-biotic-based treatments in different therapeutic areas.