From Tradition to Bioactivity: Chemical and Biological Evaluation of a Reformulated Algerian Ancestral Soap Enriched With Lavandula dentata L. Essential Oil.

The growing demand for sustainable and bioactive personal care products has renewed interest in traditional formulations. Saboun Dzair, a traditional Algerian olive oil-based soap widely used in hammam practices, remains poorly investigated for its bioactive properties. Lavandula dentata L. essential oil (LDEO) was extracted by hydrodistillation from plants collected near Mostaganem, Algeria (yield: 0.10%). GC-MS/MS analysis identified linalool (22.28%), linalyl acetate (14.42%), camphor, borneol, and 1,8-cineole as major constituents. The extra virgin olive oil (EVOO) used for superfatting was dominated by oleic acid (60.97%). LDEO was incorporated at 5%, 8%, and 12% (w/w). DPPH antioxidant activity increased in a concentration-dependent manner, from 9.09% inhibition in unenriched soap to 26.67% for 12% LDEO + 5% EVOO, an approximately 2.9-fold enhancement. Antimicrobial assays against six microbial strains showed inhibition zones of 8-10 mm for unenriched soap and up to 24.96 mm for the optimized formulation (12% LDEO + 5% EVOO), with a MIC of 1.85 mg/mL against Staphylococcus aureus. These findings demonstrate that LDEO enrichment enhanced the antioxidant and antimicrobial properties of Saboun Dzair while supporting its potential as a sustainable, bioactive, and culturally relevant natural soap.