The leaves and sprigs of Rosemary (Rosmarinus officinalis), have been widely used in food preparation and preservation and also for many medicinal purposes, almost as far back as human history began. As a popular plant that is easy to use and often readily accessible, its reputation as a meat preserver and an alleged hair restorer, are fairly well known in herbal folklore.
As with other long-esteemed herbaceous plants, rosemary’s diverse medicinal capabilities and their relevance to the needs of a modern-day world are being increasingly validated by modern research. Rosemary is now known to have some powerful pharmacological actions, including antioxidant, hepatoprotective, anti-cancer, antimicrobial and potential antidepressant activities(1).
Further possible medicinal uses for this well-known plant have now emerged, following results from recent research.
Preservative actions have long been assigned to rosemary, and scientific evidence supporting an antimicrobial application is very encouraging(2,3). An ethanolic rosemary extract was recently reported to have promising antibacterial activity against different pathogenic bacteria, with particularly good activity against Klebsiella pneumoniae(4). The essential oil of rosemary also exhibits powerful bactericidal (bacteria killing) and anti-biofilm activity against Staphylococcus aureusand Staphylococcus epidermidis(5), common causes of infections such as UTI’s and those from medical devices such as catheters.
Another study by veterinarian researchers recently, found that rosemary essential oil improved the motility of sperm collected from roosters, during its storage at 4 degrees C. These benefits were particularly seen when low concentrations of 8.7 and 87 ug/ml of rosemary essential oil were used. This suggests potential uses in animal fertilisation, and in human fertility clinics and procedures(6). With declining rates of sperm counts and motility, anything that gives sperm a greater chance of successfully fertilising an egg, can only be a good thing. As such it is conceivable that humans (or prehumans) may become exposed to this remarkable herb even before conception itself in the future!
Rosemary also has a reputation for helping prevent cancer, and application of rosemary or its phenolic acid constituents carnosol and ursolic acid were first shown to inhibit skin cancer formation in 1994(7). Such actions have since been extended to other forms of cancer cells, including most recently the growth of human colon adenocarcinoma(8), and three other gastrointestinal cancer cell lines(9).
Benefits on heart health are also associated traditionally with regular ingestion of this herb, and recent studies on rodents have provided some support for this. Pre-treatment with an aqueous rosemary extract protected mice against cardiotoxicity and hepatotoxicity(10). Supplementation of the diet of rats with 0.02% rosemary for three months improved diastolic function, and reduced the degree of hypertrophy after a heart attack (myocardial infarction). These effects were associated with improved energy metabolism and decreased oxidative stress(11). Rosmarinic acid has also shown a cardioprotective effect against myocardial infarction and arrhythmia in rats(12).
Collectively, these recent studies supportfurther investigations into the potential use of rosemary as adjuvant therapy with other cardiac drugs in those at risk of a heart attack, or to be taken immediately following such life-threatening cardiac events.
Finally, rosemary is also used in traditional medicine to alleviate rheumatic and abdominal pain. In a rat model of painful diabetic neuropathy, rosemary extract improved hyperglycemia, hyperalgesia and motor deficit(13). Triterpene constituents of an ethanolic extract also reduce abdominal pain in mice(14). These findings suggest rosemary may have analgesic and neuroprotective effects in painful diabetic neuropathy as well as abdominal pain in humans. Rosmarinic acid is likely to contribute to these effects, as other recent studies found it effective in a rat model of neuropathic pain(15-17). Analgesic properties have also previously been reported for rosemary essential oil (18).
Rosmarinic acid is a highly valued phenolic compound found not only in Rosemary, but also in many other well-known plants in the Lamiaceaeand Boraginaceaefamilies, such as Sage, Lemon balm, and Perilla (Perilla frutescens). Potentially beneficial pharmacological properties of this natural compound include anticancer, anti-angiogenic, anti-inflammatory, antioxidant, and antimicrobial activities(19,20). This has lead to increasing demands for it from the pharmaceutical industry. As a result, methods to chemically synthesise rosmarinic acid or produce it by biotechnological methods, are now being actively explored(19).
Beyond rosmarinic acid, however, the cumulative research into the diverse pharmacological actions of the reliable rosemary, show that other phenolic acids, triterpenoids, essential oil and other constituents, also seem to make powerful contributions to its many potential medicinal uses.
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