Standardized Herbal Lozenges Containing Schefflera leucantha Extract: A Novel Approach for Respiratory Health Support

Objectives Schefflera leucantha leaves have traditionally been used to relieve respiratory symptoms. This study aimed to develop and evaluate a stable herbal lozenge containing S. leucantha extract, emphasizing physicochemical properties, standardization of bioactive markers, and cytotoxicity assessment to ensure safety and quality. Methods Four solvent systems were explored to extract phytoconstituents from S. leucantha leaves. The aqueous extract (M1), obtained by decoction, was selected based on extraction yield, moisture content, and phytochemical profile. M1 was standardized for betulinic acid using validated HPLC-DAD and evaluated for antioxidant, anti-inflammatory, and antimicrobial activities. Safety assessments included cytotoxicity, heavy metal, and microbial contamination tests. Lozenges formulated with M1 were examined for pharmacopoeial quality and stability over six heating–cooling cycles. Results M1 exhibited the highest extraction yield (31.29 ± 0.87%), lowest moisture content (0.03 ± 0.01%), and highest betulinic acid content. It demonstrated strong antioxidant and anti-inflammatory activities (IC 50 = 1.41 ± 0.02 mg/ml) and mild antimicrobial activity against Staphylococcus aureus , while remaining non-cytotoxic. Lozenges met USP 41–NF 36 standards for hardness, friability, and content uniformity, with >98% betulinic acid release within 30 min and maintained stability (98.3 ± 1.8% to 98.2 ± 2.0%) after testing. Conclusion The aqueous extract of S. leucantha leaves was rich in betulinic acid and phenolic compounds, showing antioxidant, anti-inflammatory, and antimicrobial effects without cytotoxicity, as confirmed by the MTT assay. Compressed lozenges containing the extract, Aerosil ® 200, magnesium stearate, and peppermint powder showed rapid betulinic acid release within 30 min, remained non-cytotoxic, and met microbial and heavy metal safety standards. All quality parameters before and after stability testing complied with USP 41–NF 36 requirements. These findings support the potential of S. leucantha lozenges as a safe, stable, and effective natural product for respiratory health.