The Dew Of The Sea Against Microbes
Rosmarinus Officinalis

Author: Alessia Beux
Date: 08/07/2014


Alessia Beux
Cristina Di Tommaso


Rosmarinus Officinalis, also known as Rosemary, is a shrub of the family of Lamiaceae, originating from Europe, Asia and Africa. Today it is naturally found in the Mediterranean area, in coastal areas, in the hinterland and also in the area of pre-alpine lakes and in the Po Valley. The name "rosemary" derives from the Latin words “ros” which means “dew” and “marinus” which stands for "sea". Rosmarinus Officinalis virtues were discovered in the Middle Age, and since then it has been widely used for culinary and medicinal purposes worldwide.
Rosmarinus Officinalis can be used as a food flavoring, as an ornamental plant but is also known medicinally for its powerful antibacterial, antimutagenic properties and as a chemopreventive agent.

Rosmarinus Officinalis Essential Oil

Rosmarinus Officinalis essential oil was obtained via steam distillation and thirty-seven components were identified in the oil: the main ones being 1,8-cineole, camphor, alfa-pinene, beta-pinene and camphene. Beta-caryophyllene, borneol, alfa-terpeneol, myrcene, limonene and bornyl acetate are others components.
1,8 cineole ( = eucalyptol = 1,8 epoxi-paramentano) is a oxide bicyclic monoterpene with a penetrating odour almost camphorated.
Camphor is a waxy, flammable, white or transparent solid with a strong aromatic odor. It is a terpenoid with the chemical formula C10H16O.
Camphene is a bicyclic monoterpene. It is nearly insoluble in water, but very soluble in common organic solvents. It volatilizes at room temperature and has a pungent smell.
Pinene is a bicyclic monoterpene. There are two structural isomers that can be found in nature: alfa-pinene and beta-pinene.

1,8-Cineole, Camphor and Camphene Structures

Terpenes, also known as isoprenoids, are a large class of organic compounds, produced by a variety of plants. The difference between terpenes and terpenoids is that terpenes are hydrocarbons, whereas terpenoids contain additional functional group. Terpens are derived biosyntetically from units of isoprene (C5H8). The isoprene units may be linked together "head to tail" to form linear chains or they may be arranged to form rings.
The main components of Rosmarinus Officinalis are monoterpenes: they consist of two isoprene units and have the molecular formula C10H16.

Rosmarinus Officinalis As An Antimicrobial Agent

In the last few years, due to the misuse of antibiotics and an increasing incidence of immunodeficiency-related disease, the development of microbial drug resistance has became more and more of a pressing problem. Recently, phytochemicals with antimicrobial potential have been extensively explored to identify components for possible medical applications.

The antimicrobial properties of essential oils are strictly connected with their chemical composition. The usefulness of essential oils as effective antimicrobial agents can be evaluated only by analyzing their individual components. However it is really difficult to attribute the biological activities of a total essential oil to one or a few active principles, because an essential oil always contains a mixture of different chemical compounds. In addition to the major compounds, also minor compounds may make a significant contribution to the oil activity. Rosmarinus Officinalis essential oil antibacterial activities are the cooperative result of its components. The Potential of Use Basil and Rosemary Essential Oils as Effective Antibacterial Agents, 2013

Alfa-Pinene and Beta-Pinene Structures

Alfa and beta pinene exist as optical isomers that do not overlap with each other’s mirror images and they differ only in their interaction with polarized light. These compounds may exhibit differences in toxicity and biological activity. Both structural isomers have enantiomers known in nature as (−) alfa-pinene (more common in Europe), (+) alfa-pinene (more common in North America), (−) beta-pinene and (+) beta-pinene.

Only the positive enantiomers of pinene have antimicrobial activity against microorganisms especially against Candida Albicans, Cryptococcus Neoformans, Rhizopus oryzae and methicillin-resistant Staphylococcus aureus (MRSA).
Alfa-pinene and beta-pinene can be combined with commercial antimicrobials with an important result. The synergistic effect reduces the MIC, maintaining the antimicrobial activity and decreasing toxicity.
The pinene positive enantiomers inhibit C. Neoformans phospholipase (50%) and esterase (72%) activities thanks to their potent antimicrobial action against this fungus. Biological activities of alfa-pinene and beta-pinene enantiomers, 2012

Terpenoids, as camphor in Rosmarinus Officinalis, thanks to its phenolic group and to an intense electron delocalization, act against microorganisms through the membrane disruption. Investigating the mechanism of action of terpenoids and the effect of interfering substances on a indian medicinal plant extract demonstrating antibacterial activity, 2011

There are some studies whose aim is to demonstrate Rosmarinus Officinalis essential oils activities against multidrug-resistant microorganisms. These studies are based on MIC and MBC. The MIC is defined as the lowest concentration of the essential oil, at which the microorganism being tested does not demonstrate visible growth. The MBC is the lowest concentration without colony growth on the agar plates.
Gram positive bacteria, as Bacillus Subtilis, Staphylococcus Aureus and Staphylococcus Epidermidis, were a little bit more sensitive to Rosemary essential oil than Gram negative bacteria, as Escherichia Coli and Pseudomonas Aeruginosa.
Furthermore it has been shown Rosmarinus Officinalis essential oil demonstrates the strongest antibacterial activities in comparisons to its components: Rosmarinus Officinalis > alfa-pinene > beta-pinene > 1,8 cineole. This shows that all components contribute to the antimicrobial activity.
For example towards Staphylococcus Aureus the concentration of Rosmarinus Officinalis essential oil is 0.0313% (MIC) and 0,0625% (MBC), the concentration of alfa-pinene is 0.0313% (MIC) and 0,125% (MBC), the concentration of beta-pinene is 0,0313% (MIC) and 0,125% (MBC) and the concentration of 1,8 cineole is 1,25% (MIC) and 5% (MBC). Antibacterial Activity and Anticancer Activity of Rosmarinus Officinalis L. Essential Oil Compared to that of Its Main Components, 2012

In addition to the essential oils, also the crude hydroalcoholic extract of Rosmarinus Officinalis and the fractions and the pure compound rosmarinic acid play an important role in the antimicrobial activity. In particular, Rosmarinus Officinalis crude hydroalcoholic extract displayed in vitro activity against Gram positive bacteria, with satisfactory MBC for the clinical isolate Staphylococcus Saprophyticus. The fractions and the pure compound rosmarinic acid gave encouraging results for Gram positive bacteria and acted as bactericide against Staphylococcus Epidermidis as well as Enterococcus Faecalis but did not provide promising results for Gram negative bacteria.
Rosmarinic acid is a caffeic acid ester and it has antioxidant and medicinal properties thanks to its two phenolic rings. Its mechanism of action is not clearly known in spite of scanning electron micrographs that show a damaged cell surface under rosmarinic acid treatment. Rosmarinic acid can be taken orally or topically with a good bioavailability and low toxicity. Evaluation of antibacterial potential of Petroselinum crispum and Rosmarinus Officinalis against bacteria that cause urinary tract infections, 2012 ; Rosmarinic Acid and its methyl ester as antimicrobial components of the hydromethanolic extract of Hyptis atrorubens poit. (Lamiaceae), 2013 ; Orally administered rosmarinic acid is present as the conjugated and/or methylated forms in plasma, and is degraded and metabolized to conjugated forms of caffeic acid, ferulic acid and m-coumaric acid, 2004 ; Percutaneous absorption of rosmarinic acid in the rat, 1989

Rosmarinic Acid Structure

In conclusion, studies try to demonstrate the antimicrobial activity of Rosmarinus Officinalis in clinical strains, obtained from patients with infection of the respiratory tract, abdominal cavity, urinary tract, skin and from hospital equipment. Different organisms react differently to the same extract, as well as fractions and pure compounds. These essential oils and their constituents possess useful properties concerning human health: they do have great value in preventing and treating infectious diseases. Rosmarinus Officinalis essential oils not only have bactericidal activity, but also can inhibit multidrug bacteria strain formation. Their multiple antibacterial, antifungal, antiviral and also anti-inflammatory and antioxidant effects, have made them valuable agents in human treatment and for the prevention of pathological changes. Considering the huge increase in the number of multidrug resistant bacterial strains in health care facilities, essential oils may prove to be effective natural antimicrobial agents. Rosmarinus Officinalis revealed promising results, particularly against Gram-positive bacteria.

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