Topical antimicrobial formulations using medicinal plant-derived essential oils targeting methicillin resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) causes a variety of healthcare-associated and community-acquired infections. Due to limited availability of effective antimicrobials for treating MRSA infections, there is a growing need to explore alternative therapeutic approaches. Here, the antimicrobial activities of 19 oils, popularly used for their medicinal properties, were tested against MRSA USA300. Oils obtained from cinnamon, clove, tangerine, and coriander showed the most promising activities, demonstrating bactericidal, anti-adhesive and anti-biofilm activities, and synergistic properties with common antibiotics. Given that clove and cinnamon oils showed the best activities, they were incorporated into topical formulations. Not only did the formulations with oils maintain antimicrobial and anti-adhesive activities, but their anti-biofilm property was potentiated. Tests on Galleria mellonella larvae suggested that the formulation is non-toxic. The formulations proposed here are a great alternative for the decolonisation of surfaces containing MRSA and can help circumventing antimicrobial resistance, a growing threat in the hospital environment.

In vitro anticariogenic and antibiofilm activities of toothpastes formulated with essential oils.

OBJECTIVE: This study aimed to assess the antibacterial and antibiofilm effects of essential oils and herbal toothpastes against bacteria associated with oral diseases. METHODS: The minimum inhibitory concentration (MIC) and antibiofilm activity of 13 essential oils against Staphylococcus aureus, Streptococcus mutans, Lactobacillus lactis, and Enterococcus faecalis. were determined. Toothpastes were formulated with different concentrations of the most active essential oils, alone and in combination, and evaluated for antibacterial and antibiofilm activities. RESULTS: Clove, oregano, thyme, and cinnamon essential oils were effective in inhibiting all bacterial strains. The antibacterial activity of cinnamon essential oil was similar to that of the control (0.12 % chlorhexidine gluconate mouthwash). Cinnamon essential oil was a strong inhibitor of S. mutans growth. The antibiofilm activity of clove, oregano, thyme, and cinnamon essential oils at 1, 2, and 4 × MIC against S. mutans did not differ from that of the control. In the hole-plate diffusion assay, 17 out of the 18 tested toothpastes produced an inhibition halo at least half as large as that of the control. Toothpastes containing clove, clove and oregano, or clove, oregano, thyme, and cinnamon essential oils were able to completely disrupt S. mutans biofilms, not differing from the control. Thyme essential oil was found to act synergistically with chlorhexidine against S. mutans. CONCLUSIONS: The results indicate that clove, oregano, thyme, and cinnamon essential oils may be added to fluoride-free toothpastes to enhance inhibitory effects against bacteria associated with cavities and periodontal disease. Thyme essential oil may increase the efficiency of chlorhexidine-containing dentifrices.

Use of chiral auxiliaries in the asymmetric synthesis of biologically active compounds: A review.

This review article describes the use of some of the most popular chiral auxiliaries in the asymmetric synthesis of biologically active compounds. Chiral auxiliaries derived from naturally occurring compounds, such as amino acids, carbohydrates, and terpenes, are considered essential tools for the construction of highly complex molecules. We highlight the auxiliaries of Evans, Corey, Yamada, Enders, Oppolzer, and Kunz, which led to remarkable progress in asymmetric synthesis in the last decades and continue to bring advances until the present day.