Biologically active compounds from Lamiaceae family: Central nervous system effects

Lamiaceae, also known as the mint family, is a family of plants comprising about 245 genera and 7886 species distributed all over the world. Plants of this family are widely used in folk medicine, cosmetics, spices, and as a flavoring agents in food. With the exception of the coldest polar regions, Lamiaceae species are distributed almost throughout the world, particularly in tropical and temperate areas, including the Mediterranean region and in tropical upland savannas. The Lamiaceae family is known for a wealth of species possessing medicinal properties with a strong history of use since early times and is well known for high essential oil content, for their richness with polyphenolic compounds and terpenoids. All of these classes of compounds are of great interest due to their biological activities. A number of studies conducted on different species of Lamiaceae family and their effects on memory, anxiety, depression, and sleep disorders have been reported. For example, Rosmarinus officinalis has long been known as the herb of remembrance and was proved to boost memory, reduce anxiety and depression, and improve sleep quality. Different salvia species are used to enhance memory, as a sedative and for the treatment of headaches. Evidence for the use of other Lamiaceae species on the central nervous system (CNS), such as Dracocephalum moldavica. Clerodendrum formicarum, Nepeta clarkei has also been reported. Thymol and menthol are examples of the essential oils identified in species from Lamiaceae. It has been reported that thymol and menthol both act as positive modulators on GABAA receptors (the primary inhibitory neurotransmitter in the mammalian CNS acting through a number of pharmacologically and structurally different receptor subtypes). Thymol was reported to have a GABAergic activity and acts as a positive allosteric modulator with a mechanism of action similar to other depressants, such as diazepam. This review aims to survey the current literature on the effect of Lamiaceae family and its use in the treatment of CNS disorders to provide sufficient baseline information that would improve the knowledge and the application of this family as safe therapeutic alternatives.