Orange Peel Lactiplantibacillus plantarum: Development of A Mucoadhesive Nasal Spray with Antimicrobial and Anti-inflammatory Activity

Abstract

Background/Objectives: Due to the high frequency and severity of upper respiratory bacterial infections, probiotics could offer a new medical approach. We explored the antibacterial and anti-inflammatory properties of the new strain Lactiplantibacillus plantarum BIA and formulated a nasal spray. Methods: L. plantarum BIA was isolated from orange peel and taxonomically identified through 16S rRNA gene sequencing. Its antibacterial activity was tested against Pseudomonas aeruginosa, Streptococcus pyogenes, Bacillus subtilis, Escherichia coli, and Staphylococcus aureus, while anti-inflammatory potential was evaluated by Griess assay. BIA genome was fully sequenced and analyzed to assess its safety. BIA was formulated in a freeze-dried matrix, containing prebiotics and cryoprotectants, to be reconstituted with a polymer solution. Solutions containing two types of hydroxypropyl methylcellulose (HPMC) and hyaluronic acid were evaluated as resuspending media and compared in terms of pH, viscosity, and mucoadhesion ability. The biological activity of BIA formulated as nasal spray was verified together with the stability of the selected formulations. Results: L. plantarum BIA inhibited human pathogens’ growth and showed anti-inflammatory activity and a safe profile. In the best-performing formulation, the probiotic is lyophilized in 10% fructooligosaccharides, 0.1% ascorbic acid, and 0.5% lactose and reconstituted with HPMC high viscosity 1% w/v. This composition ensured the probiotic’s viability for up to six months in its dried form and one week after reconstitution. It also allowed interaction with the nasal mucosa, preserving its antimicrobial and anti-inflammatory activities. Conclusion: The developed nasal spray could become a promising formulation in the field of nasal infectious and inflammatory diseases.