Botanical Name / Family
Salvia officinalis, Salvia lavandulaefolia (family Labiatae or Lamiaceae)
Plant Part Used
The leaves contain up to 2.5% essential oil, which contains thujone, cineol and camphor, as well as humulene, pinene, camphene, limonene, carnosol and rosmarinicacid. In addition, the leaves contain catechin-type tannins, diterpene bitter principles, triterpenes, steroids, flavones, and flavonoid glycosides, together with polysaccharides. Sage is a rich source of beta-carotene, vitamins C and B-complex. Pharmacopoeial grade sage leaf must contain not less than 1.5% thujone-rich volatile oil.
Sage has been used since ancient times as an antiseptic, astringent and to reduce sweating. The name ‘Salvia’ derives from the Latin salvere (to be saved). Sage oil is used as a culinary spice and as a fragrance in soaps and perfumes. The fragrance is said to suppress the odour offish.
Sage: Main Actions
Sage is reported to have antimicrobial activity attributed to the thujone, thymol and eugenol content of the volatile oil, as well as its rosmarinic acid content. The phenolic acids, salvins and monomethyl ethers have also been attributed with antimicrobial activity. Overall, activity has been reported in vitro against Staphylococcus aureus, Escherichia coli, Salmonella spp., Shigella sonnei, Klebsiella ozanae, Bacillus subtilis and various fungi including Candida albicans. Phenolic extracts have also shown antibacterial activity against Enterococcus. Sage had some in vitro antimicrobial effects on saliva samples from periodontally healthy and diseased subjects, although it had less activity than clove or propolis. Sage essential oil has been shown to have effective inhibitory activity against microorganisms, such as Klebsiella spp., Enterobacter spp., E. coli, Proteus mirabilis and Morganella morganii, isolated from urinary tract infection. There are also reports that sage may also be fungistatic and virustatic.
Sage extracts have been shown to have strong anti-oxidant activity, with labiatic acid and carnosic acid reported to be the active compounds. According to in vivo studies with animal models, ingestion of sage infusion improves the liver’s antioxidant status and protects against azathioprine-induced toxicity. However, sage essential oil did not show protective effects against toxicity from an oxidative compound in isolated rat hepatocytes.
The high tannin content of sage supports its reported astringent activity.
Sage oil has antispasmodic effects in laboratory animals and this is likely due to the irritating effects of the volatile oil. There is some evidence that sage oil may also exert a centrally mediated antisecretory action.
Rosmarinic acid, which is a component of sage essential oil, produces an anxiolytic-like effect without exerting locomotor alterations or DNA damage in the brain tissue of rats. According to in vitro tests, compounds in the methanolic extract have an affinity for human brain benzodiazepine receptors.
Sage: Other Actions
In vitro and in vivo studies suggest that sage essential oil and some individual monoterpenoid constituents inhibit acetylcholinesterase activity, as well as exert antioxidant, anti-inflammatory and oestrogenic effects. The water soluble polysaccharide complex from sage has demonstrated immunomodulatory activity and the terpenoid fractions have shown antimutagenic properties in vivo.
Sage extract has been found to also significantly decrease serum glucose in diabetic rats without affecting insulin release, suggesting a possible role in diabetes. It has been suggested that extracts of sage containing carnosic acid may act as a new class of lipid absorption inhibitor. A methanolic extract of sage has also shown significant inhibitory effect on serum triglyceride elevation in olive oil-loaded mice, and inhibitory activity against pancreatic lipase, mainly because of the carnosic acid content. Carnosic acid was also found to reduce the weight gain and accumulation of epididymal fat in high-fat-diet fed mice after 14 days.