Labiateae species in Mediterranean environment: unrivaled sources of secondary metabolites

Marco Landi [Department of Agriculture, Food and Environment, University of Pisa];
Lucia Guidi [Interdepartmental Research Center “Nutraceuticals and Food for Health”, University of Pisa]

The Mediterranean basin represents a harsh environment for plant species to inhabit due to the occurrence of many environmental constrains including high level of solar radiation, temperature, drought, and salinity. In many instances these factors occur simultaneously. Seasonal or even daily variation of climatic conditions can also seriously threaten plant survival. Under this combination of environmental cues, plants have evolved a wide range of secondary metabolites to contrast/counteract the detrimental effects of these factors on plant’s physiological processes. Besides their adaptative meaning in plants, these compounds can also be useful for human applications such as: antibiotics, antimycotic, animal nutrition, cosmetics, food additives, biorepellents and many others. In the last few years there has been a substantial increment in the use of aromatic herbs and their essential oils, hence increasing the prospective for a profitable cultivation of these species. The growing interest for aromatic species is mainly attributable to the increasing body of scientific evidence, which confirms the potentiality of their metabolites, and supports the empiric uses that in the past was made by folk medicine. Despite most of the herbs are still collected from the wild, especially in developing countries, many reports suggest that most of them can be successfully cultivated as powerful biofarm species. Aromatic species are particularly attractive because they require low agronomical inputs and are grown under sub-optimal environmental conditions, since most secondary metabolites are usually synthetized in response to stress factors. The knowledge of the factors leading to maximize and standardize the production of desired compounds is of crucial importance. Indeed, albeit the progresses that have been made on the chemical synthesis of organic compounds, for some of them the extraction from plant tissues is actually cheaper than their chemical synthesis, and for other secondary metabolites the extraction from plants is the only way to obtain the moiety, being impossible (or still unknown) their chemical synthesis. This article reviews the literature on the effect of environmental as well as agronomical practice that can affect the biosynthesis of secondary metabolites in Labiateae members. This family is one of the most representatives in Mediterranean area, encompassing many herbs including lavender, mint, oregano, rosemary, sage, summer savory, sweet basil, and sweet marjorana. The review also includes the potentiality of extracts, essential oils and other secondary metabolites isolated from the aforementioned Labiateae species. Further work is necessary to identify the best agronomical techniques and the pedo-climatic conditions that could increase the yield of nutraceutical compounds, especially in this family of plant that represents an urivaled source of secondary metabolites.

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