The preservative efficacy of Licorice and Rosemary combination in cream formula

Abstract

Based on our previous results, which proved that each of G. glabra and R. officinalis extracts potentiate the antibacterial effect of the other aganist MRSA when combined together at their sub-MIC. We thought to investigate the capacity of Glycyrrhiza glabra(Licorice) and Rosmarinus officinalis (Rosemary) extracts to act as preservatives for topical formulations, which in our knowledge is the first to be used together. Two Oil/Water(O/W )cream were formulated : using methyl paraben, a common used preservative (MP) and the combination between Licorice and Rosemary (LR) as preservatives, were tested for their Primary skin irritation on Laboratory experimental animals which proved that they were devoid of any primary skin irritation, erythema, or edema even after 48 h of application, and by challenging them with microbial indicators: Bacterial; (Escherichia Coli 25922, Pseudomonas aeruginosa 27853 and Staphylococcus aureus 29737), Yeast; (Candida albicans10231), and fungi; (Aspergillus niger 1015), revealed that the concentration of each test microorganisms decreased during the test period.