Inhibition of Staphylococcus aureus by rosmarinic acid and carnosic acid, two main polyphenols isolated from rosemary

MARÍA V. BARNI; VICTORIA REPETTO; ADRIÁN A. VOJNOV; SILVIA MORENO

Rosario, Argentina

Congreso; V CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL; 2008

SAMIGE

Rosmarinus officinalis L, belongs to the Lamiaceae family, is a rich source of phenolic phytochemicals with antioxidant and antimicrobial potential. This plant produces phenolics which are an important sub-group of secondary metabolites with diverse functional and medicinal potential. Lamiaceae plants have long been used in traditional medicine and have potential for control of pathogenic bacteria. Earlier, we reported the antioxidant and antimicrobial properties of non-volatile compounds of rosemary and our results showed that carnosic acid and rosmarinic acid may be the main bioactive antimicrobial compounds present in rosemary (Free Radical Research, 40 (2) 223-231, 2006). Here, we study the anti-S. aureus activity of  osmarinic acid and carnosic acid by the broth dilution method. S. aureus, a Gram-positive organism, is a  uman pathogen of significant importance. It is responsible for numerous infections and syndromes ranging  n severity from skin and soft tissue infections to endocarditis and septic arthritis. As is the case for many  ther infectious diseases, S. aureus can develop resistance to antibiotics and it is one of major causes of  reatment failure. The prevalence of resistant isolates, their virulence and increasing resistance indicates  he need for alternative therapy to treat these infections with effective antibacterial agents with new modes  f action. The objective of this research was to evaluate the efficiency of carnosic acid and rosmarinic acid  lone and in combination with other compounds to inhibit this human pathogen. Comparison using pure  orms of other phenolic compounds found in a range of herbs species belonging to Lamiaceae as gallic  cid  nd cafeic acid were also evaluated. In addition, combinatory assays with common antibiotics were  erformed. The final objective is to explore the potential for managing S. aureus infection in conjunction with  urrent treatment options. Results showed that the anti-S. aureus activity of all compounds improved with  ncreased dosage. Bactericide as well as bacteriostatic actions of the phenolic compounds was observed.   Different mode of action for rosmarinic acid and carnosic acid are suggested. The antibacterial activities of these natural products make them interesting as antibacterial agents with potential new targets. Supported by PICT 2005- N° 35401.