Sage (Salvia) is a group of plants belonging to the Lamiaceae or mint family of. The plants are mostly aromatic on account of the presence of a characteristic essential oil. The most commonly known species of sage is perhaps Salvia officinalis which is also known as garden sage, golden sage, broadleaf sage culinary sage or common sage, although there are perhaps as many as 900 species throughout the World. Sage is often taken as a tea or decoction in order to confer medicinal properties to the consumer. The current understanding of sage suggests that extracts of the herb may play a role treating digestive disorders, circulation problems, bronchitis, asthma, coughs, angina, throat infections, skin diseases and angina. In terms of mood disorders, sage has been shown to be effective as an antidepressant, anxiolytic and a memory enhancing agent. The mood elevating effects of sage may be due to the ability of the herb to increase brain levels of the neurotransmitter acetylcholine by inhibiting the enzyme acetylcholinesterase.
The pharmacology of Salvia officinalis (common sage) has been extensively investigated. The essential oil contains a number of chemicals that are mostly terpenes, and these include 1,8‑cineole, camphor, borneol, bornyl acetate, camphene, α‑thujone and β‑thujone, thymol, linalool, α‑caryophyllene and β‑caryophyllene, α‑humulene, α‑pinene and β‑pinene, viridiflorol, pimaradiene, salvianolic acid, rosmarinic acid, carnosolic acid and ursolic acid. Some of these compounds, particularly rosmarinic acid, β‑caryophyllene, thymol and linalool have been investigated for their effects against mood disorders and found to be effective anxiolytic agents. Many of the chemicals in the essential oils have been shown to possess potent free radical scavenging activity. The ability to scavenge free radicals and reduce oxidative stress may be one of the primary mechanisms by which sage exerts its medicinal properties. In particular, evidence suggests that α‑thujone, β‑thujone, bornyl acetate, camphor, menthone, and 1,8‑cineol in the essential oil may have particularly strong radical scavenging activity.
The memory improving effects of sage species are quite well reported. For example, in one study on healthy human subjects sage essential oil extracts caused significant improvements in memory. It was confirmed using rat experiments that the sage essential oil extract cause significant inhibition of the acetylcholinesterase enzyme. This inhibition would raise acetylcholine levels in the brain, and this could improve memory. Postmortems on humans have also provided evidence that sage can inhibit the acetylcholinesterase enzyme in humans. It is likely that the main components of sage that are responsible for this memory enhancing effect may be the terpene compounds in the essential oil. Sage may also have neuroprotective effects due to the presence of high amounts of antioxidant chemicals in the essential and non-essential fractions of herbal extracts. The general improvements in brain function attributed to sage may therefore explain the mood elevating effects, suggesting that sage could be a general brain tonic.
Sage also contains flavonoids and other polyphenolic substances including carnosic acid, rosmarinic acid and particularly caffeic acid. Evidence suggests that most of the polyphenolic substances in sage are derivatives of the phenolic acid caffeic acid. Polyphenols including flavonoids and phenolic acids have strong free radical scavenging activity, which may confer protection from disease. Both rosmarinic acid and carnosic acid may be responsible for a large part of the antioxidant activity of sage. However certain flavonoids and phenolic acids have been shown to have particular beneficial effects against mood disorders. For example, caffeic acid may possess anxiolytic effects. Rosmarinic acid is a derivative of caffeic acid, and it may too possess anxiolytic activity. Ursolic acid is a pentacyclic triterpenoid found in sage that may also have medicinal properties as an anti-inflammatory. As inflammation is associated with oxidative stress and detrimental effects to brain tissue, ursolic acid may also play a role in the mood elevating effects of sage. The flavonoid luteolin‑7‑O‑β‑glucopyranoside is present in sage. Luteolin and its glycosides belong to the flavone group of flavonoids and have been shown to have an affinity for the benzodiazepine receptor in animal studies, suggesting they may exert anxiolytic effects in a similar way to benzodiazepine drugs.
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