Development and evaluation of an antiseptic nasal spray based on aqueous extract of Ocimum gratissimum L.: Formulation, phytochemical characterization and antimicrobial activity

Introduction: Upper respiratory tract infections (URTIs) are common and frequently treated with antibiotics, contributing to the emergence of bacterial resistance. Medicinal plant extracts represent a promising natural alternative. Ocimum gratissimum, rich in bioactive secondary metabolites, has noteworthy antiseptic potential.

Methods: Leaves of O. gratissimum were extracted by aqueous infusion and phytochemically characterized. Antimicrobial activity was evaluated in vitro against Staphylococcus aureus using broth microdilution with resazurin to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Nine nasal spray formulations were developed, physicochemically evaluated, and subjected to microbiological quality control according to the European Pharmacopoeia.

Results: The extraction yield was 33.33%. Phytochemical screening revealed the presence of polyphenols, flavonoids, saponins, alkaloids, sterols, terpenes, and cardiotonic glycosides. Total flavonoid and polyphenol contents were 1413 ± 0.836 mg QE/g dry extract and 202.098 ± 0.691 mg GAE/g dry extract, respectively. The extract exhibited bacteriostatic activity against S. aureus (MIC = 0.048 mg/mL; MBC = 0.195 mg/mL; MBC/MIC ≥ 4). The final formulation showed a pH compatible with the nasal mucosa, consistent spray volume per actuation, and compliance with microbiological standards.

Conclusion: The formulated nasal spray containing aqueous extract of O. gratissimum is stable, safe, and demonstrates promising in vitro antimicrobial activity. Further tolerance and clinical efficacy studies are required before therapeutic application.