Water stress as a resource for the production of nutraceuticals with strong antioxidant and wound healing properties

Certain stress conditions, such as water stress, can lead plants to produce higher quantities of bioactive molecules. It is particularly interesting to evaluate the effects of such natural extracts obtained from plants subjected to water stress compared to extracts from non-stressed plants. However, the use of these metabolites in therapy may be limited due to their poor absorption and low bioavailability. The use of nanosystems for the delivery of nutraceuticals can be a resource to address this issue. In this work, the characterization of these extracts and a comparison of their composition were carried out. Formulations for the delivery of these extracts were developed and characterized from a technological perspective. Subsequently, biological tests were conducted to assess cytotoxicity, oxidative stress, and wound healing activity. The study was further investigated using in vitro, in vivo, and ex vivo models. In the first work, the antioxidant properties of a tomato peel extract grown under water stress conditions were evaluated and compared with the properties of the same tomato peel extract obtained from plants grown under normal conditions. These were tested using cellular models of human umbilical vein endothelial cells (HUVECs), demonstrating the validity of this particular type of stress in obtaining nutraceutical products with a pronounced antioxidant power. Subsequently, extracts from olive leaves subjected to water stress or not were tested and compared. These extracts proved effective in reducing oxidative stress and containing the production of ROS in cellular models of human umbilical vein endothelial cells (HUVECs). The same antioxidant effects due to pre-treatment with olive leaf extract were highlighted by nebulizing the extracts on an in vitro model of human distal lung epithelial cells NCI-H441. Furthermore, these effects were made more evident by complexing the olive leaf extract with thiolated hydroxypropyl-β-cyclodextrin and subsequently cross-linked. The olive leaf extract was used to form a spray patch of hyaluronic acid and chitosan microparticles due to its antimicrobial action. The encapsulation regulates the release of olive leaf extract from these microparticulate systems. These systems were tested in an in vitro cellular model called scratch test, using a murine fibroblast cell line BALB/3T3 CLONE A31. The results achieved highlighted the ability of these systems to accelerate wound healing in the cellular system used. Moreover, the following study was aimed formulate an eye drop, based on the capability of olive leaf extract to contribute to the wound healing process in an in vitro cellular model known as the scratch test, utilizing human corneal cells (HCE-T). Moreover, this effect was enhanced when the extract was complexed with a polymer synthesized based on quaternized chitosan and methyl-β-cyclodextrin. Acute toxicity tests were performed in an in vivo model using male albino New Zealand rabbits. In conclusion, the cultivation of native plants of the Mediterranean area through water stress, in the meaning of the lack of water administration, represents a resource for the production of nutraceuticals with high antioxidant abilities. The develop of these through the use of innovative pharmaceutical forms enhances their potential use even further.