The in vitro inhibitory activity of crude EtOH/H2O extracts from the leaves and stems of Rosmarinus officinalis L. was evaluated against the following microorganisms responsible for initiating dental caries: Streptococcus mutans, S. salivarius, S. sobrinus, S. mitis, S. sanguinis, and Enterococcus faecalis. Minimum inhibitory concentrations (MIC) were determined with the broth microdilution method. The bioassay-guided fractionation of the leaf extract, which displayed the higher antibacterial activity than the stem extract, led to the identification of carnosic acid (2) and carnosol (3) as the major compounds in the fraction displaying the highest activity, as identified by HPLC analysis. Rosmarinic acid (1), detected in another fraction, did not display any activity against the selected microorganisms. HPLC Analysis revealed the presence of low amounts of ursolic acid (4) and oleanolic acid (5) in the obtained fractions. The results suggest that the antimicrobial activity of the extract from the leaves of R. officinalis may be ascribed mainly to the action of 2 and 3.

The essential oil of Rosmarinus offi cinalis L. (rosemary) was obtained by hydro-distillation and analysed by gas chromatography-mass spectrometry. Sixty-two constituents were identifi ed, representing 98.06% of the total oil content. Oxygenated monoterpenes were the predominant components. The rosemary oil was characterized as having prominent (> 5%) contents of camphor (18.9%), verbenone (11.3%), α-pinene (9.6%), β-myrcene (8.6%), 1,8-cineole (8.0%), and β-caryophyllene (5.1%). The antimicrobial activity of the oil as well as of its major constituents was tested against the following microorganisms: Streptococcus mutans, Streptococcus mitis, Streptococcus sanguinis, Streptococcus salivarius, Streptococcus sobrinus, and Enterococcus faecalis, which are potentially responsible for the formation of dental caries in humans. The microdilution method was used for determination of the minimum inhibitory concentration (MIC) during evaluation of the antibacterial activity. The essential oil displayed low activity against the selected microorganisms. In the present study, the pure major compounds were more active than the essential oil. Among all the microorganisms tested, the pathogen S. mitis was the most susceptible and E. faecalis was the most resistant to the evaluated samples. This is the fi rst report on antimicrobial activity of the major components of rosemary oil against oral pathogens.

The results suggest that the analgesic effects of the acetyl derivative of RA operate via a peripheral-mediated mechanism. The acetyl ester derivative of RA is potentially applicable as a new lead compound for the management of pain and inflammation.

The hydroalcoholic extract of the leaves of Rosmarinus officinalis (HE), a species of medicinal value, and its constituent rosmarinic acid (RA) were evaluated for hepatoprotective in the acetaminophen-induced liver damage model. Groups of Wistar albino rats (n=6) were pre-administered with HE (100, 250 and 500 mg/kg, p.o.) and RA (10, 25 and 50 mg/kg, p.o.) prior to a single dose of acetaminophen (APAP, 600 mg/kg body weight; p.o). The hepatoprotective activity of HE extract was observed through histopathological analysis and reduction of the level of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). These observations were comparable to the normal group prior to APAP administration. Group that was treated with APAP alone exhibited high levels of transaminases and ALP. The obtained results from the present study suggested that HE may prevent APAP-induced hepatic injuries. RA did not displayed significant hepatoprotective activity against APAP-induced liver damage.

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