The effect of water de ficit stress on the composition of phenolic compounds in medicinal plants

Secondary metabolites play an important role in the adaptation of plants to the environment and in their recovering process to stress conditions. Among the different types of stress, the scarcity of water resources is considered a negative factor because it is responsible for productivity losses of several crops. However, plants grown under drought conditions generally produce higher concentrations of active substances that protect them against free radicals and reactive oxygen species and prevent damage to the photosynthetic process. In addition to plant protection, secondary metabolites, such as phenolic compounds, have great applicability in human health, acting as a healing, antimicrobial, anti-inflammatory and antitumor agent. The aim of this paper is to present a systematic review on the influence of water stress on the production of phenolic compounds in plants of medicinal interest. For this, a search was performed in three international databases (PubMed, Scopus and Web of Science) using keywords related to water stress and phenolic compounds. A total of 343 publications were obtained, which after the screening and eligibility process comprised 34 articles published between 1994 and 2019, showing that the widely accepted idea that there is a general increase in phenolic compounds in response to water scarcity is misguided. In opposition to this idea, this complex system differs for each plant species. In addition, due the large number of papers that have been conducted in greenhouses, further studies concerning tree species under different ecophysiological conditions are necessary. (C) 2020 SAAB. Published by Elsevier B.V. All rights reserved.