The current intensification in agricultural pressure has resulted in the addition of excessive amounts of nutrients. While hydroponic systems have become an agricultural tool to reduce this nutrient addition, the produced nutrient-rich drainage solution, which has a negative effect in water bodies, is still a barrier that needs to be overcome. A promising alternative for nutrient recovery is the cultivation of microalgae, which require a significant quantity of nutrients for their growth. Furthermore, their biostimulant properties enhance the circularity and sustainability approach. This study evaluates microalgae growth with a hydroponic drainage solution and the use of the resulting biomass as a source for biostimulant. Three microalgae strains were tested (Desmodesmus sp., Chlorella vulgaris, and Scenedesmus obliquus) and grown at laboratory scale (0.5 and 2 L) with drainage wastewater taken from hydroponic tomato crops. Measures of OD₇₅₀ and OD₆₈₀ revealed Desmodesmus sp. as the strain with the best performance, achieving 1.4 and 1.8, respectively, in the 0.5 L assay and 1.08 and 1.3 in the 2 L assay. These results were confirmed in another assay that compared Desmodesmus sp. growth in drainage wastewater and in control media. Then, Desmodesmus sp. was tested at industrial scale. Results show the columnar PBR reached 1.8 g·L⁻¹ compared to 1.1 g·L⁻¹ achieved with raceways. Finally, the resulting biomass was tested in a biocatalysis process for biostimulant production, suggesting an innovative system to use microalgae biomass cultured in wastewater as a valuable product such as biostimulant.

In recent decades, the worldwide production of microalgae has been carried out on an industrial scale. In recent years, the market for natural products has grown because of changes in consumer preferences for more natural products. The objective of this study was to demonstrate the hepatoprotective capacity of fucoxanthin extract obtained from an industrial culture of the microalgae Phaeodactylum tricornutum (Culture Collection of Alga and Protists in Scotland). The microalga was grown in an artificial and natural seawater mixture (1:9), using Walne’s culture medium in columns and raceway photobioreactors (RWP) inside a greenhouse. The carotenoid content in the tested systems continued to increase from day 5 of the culture, when the stationary phase was reached. The final biomass powder contained 4.9 mg (2.59%) of pure fucoxanthin. The possible hepatoprotective activity of fucoxanthin was then studied in the HepG2 cell line for 24 h in culture, and compared with the cytotoxicity of methotrexate (MTX). In conclusion, the active ingredient showed hepatoprotective activity against MTX in the human hepatocyte cell line HEPG-2 at a concentration of 0.25 mg/mL. The current results also suggest that it has beneficial properties for liver health and is a suitable ingredient for all types of nutraceutical products.

Phycocyanin, a phycobiliprotein derived from the cyanobacterium Limnospira (Arthrospira) platensis (commonly known as Spirulina), is recognized for its antioxidant, immunomodulatory, and bioactive properties. This research aims to develop a new cosmetic ingredient based on phycocyanin incorporated into a high-lipid matrix, such as shea butter. A comprehensive characterization of the cytotoxicity and anti-inflammatory activity of this new bioactive phycocyanin–protein complex in human THP-1 monocytic cells was performed. For this purpose, cytocompatibility was evaluated using MTT assays at concentrations ranging from 10 to 0.0006% v/v. Anti-inflammatory activity was measured under LPS-induced inflammatory stress by measuring IL-6 and IL-8 secretion using ELISA in PMA-differentiated THP-1 cells treated with non-cytotoxic concentrations (0.04, 0.02, and 0.01% v/v). A crucial finding was the absence of anti-inflammatory activity at 0.01% v/v, indicating a minimum effective concentration threshold and, consequently, effective doses. The results of this research indicate that the phycocyanin and shea butter ingredients demonstrate strong cytocompatibility at relevant cosmetic doses and significant anti-inflammatory activity, supporting their suitability for formulations targeting skin sensitivity, erythema reduction, and post-inflammatory recovery.