Phytochemical and Antimicrobial Evaluation of the Essential Oil of Croatian Salvia brachyodon Vandas

This study was designed to evaluate the phytochemical profile and the antimicrobial potential of the essential oil of Salvia brachyodon Vandas growing wild in Croatia. The emergence of multidrug resistant bacteria has become a serious threat to public health that has prompted research to the discovery and development of new active agents capable of partly or completely suppressing bacterial growth. Recently, a class of biological active compounds that has been attracting increased attention in drug discovery is the plant based derivatives. Many plants produce special biomolecules to protect themselves according to a stress or infection caused by microorganisms. Plants produce a broad assortment of secondary metabolites, including tannins, terpenoids, alkaloids, polyphenols and favonoids, which have been found in vitro to have antimicrobial properties against both Gram- positive and Gram- negative bacteria. Essential oils (EOs) are secondary metabolites, and are important for plant defense mechanism hence, they have various medicinal properties including antimicrobial activity. Natural products isolated from Salvia spp. have long been used in traditional medicine to treat several microbial afflictions, but considering the high number of species of this genus, the antimicrobial properties of all of them is not well known. Short tooth sage (S. brachyodon Vandas), an endemic species that grows in the south east areas of the Adriatic coast in Croatia, Bosnia and Herzegovina, and Montenegro. It is a perennial plant that grows up to 70-80 cm in height and flowers from July to September. The phytochemical components of the essential oil were identified by gas chromatography-mass spectrometry (GC-MS) analysis. The antimicrobial activity was assessed against a panel of representative Gram-positive and Gram-negative bacteria as well as fungi. The antimicrobial activities of the oil against pathogenic microorganisms were determined by using agar disc diffusion and broth microdilution methods. From the thirty-eight identified constituents representing 95.7% of the oil, 1,8-cineole (16.7%), β-pinene (19.7%) and α-pinene (7.6%), were the major components. The levels of oxygenated monoterpenes such as camphor (5.6%), borneol (4.2%), myrtenol (2.4 %) and terpinen-4-ol were significant. Other important compounds were sesquiterpenes hydrocarbons β-caryophyllene (6.6%), α-humulene (4.9%), viridiflorol (3.0%), spathulenol (2.9%) and aromadendrene. Preliminary antimicrobial screening revealed that the oil exhibited a very interesting antimicrobial profile. The oil exhibited moderate in vitro antibacterial activity after it was tested against twenty pathogenic bacteria and fungal strains, but high antimicrobial activity observed against medically important pathogens such as E. coli O157:H7, Listeria monocytogenes and Candida albicans. Results presented here may suggest that the essential oil of S. brachyodon possess antimicrobial properties, and is, therefore, a potential source of antimicrobial ingredient in food and pharmaceutical industry. The obtained results are preliminary and a further research is needed in order to obtain information regarding the practical effectiveness of essential oil to prevent the growth of foodborne and spoilage microbes under specific application conditions.