The extensive application of herbicides in crop cultivation has indisputably led to the emergence of weed populations characterized by multiple herbicide resistance (MHR). This phenomenon is associated with the enhanced metabolism and detoxifying ability of endogenous enzymes, such as phi class glutathione transferases (GSTFs). In the present work, a library of mutant GSTFs was created by in vitro directed evolution via DNA shuffling. Selected gstf genes from the weeds Alopecurus myosuroides and Lolium rigidum, and the cereal crops Triticum durum and Hordeum vulgare were recombined to forge a library of novel chimeric GSTFs. The library was activity screened and the best-performing enzyme variants were purified and characterized. The work allowed the identification of enzyme variants that exhibit an eight-fold improvement in their catalytic efficiency, higher thermal stability (8.3 °C) and three-times higher inhibition sensitivity towards the herbicide butachlor. The crystal structures of the best-performing enzyme variants were determined by X-ray crystallography. Structural analysis allowed the identification of specific structural elements that are responsible for k_cat regulation, thermal stability and inhibition potency. These improved novel enzymes hold the potential for utilization in biocatalysis and green biotechnology applications. The results of the present work contribute significantly to our knowledge of the structure and function of phi class plant GSTs and shed light on their involvement in the mechanisms of MHR.

Microalgae are a valuable source of enzymes and active ingredients due to their biochemical variability, health-beneficial properties, lower production cost and viability on an industrial scale. In addition, the growing demand for sustainable products constitutes microalgae as a viable resource for the development of a range of innovative products. In the present work, the proteolytic activity of Arthrospira platensis lysate was assessed and characterized using kinetics analysis and zymography employing different substrates, pH values and divalent ions. The results suggest the presence of two main proteolytic enzymes in the lysate. In addition, a rapid and easy purification protocol of the proteolytic activity, under mild conditions, was developed using a polyethyleneglycol (PEG)/phosphate aqueous two-phase system (ATPS). The proteolytic activity of A. platensis lysate was used to develop a hydrogel formulation as an enzyme-based cosmeceutical, with potential application as a topical exfoliating agent. The incorporation of the A. platensis extract in the developed hydrogel formulation significantly improved its operational stability over time, which is a significant advantage in enzyme-based product development.

In the present study, selected cosmeceutical properties of aqueous extracts from the microalgae strain Trachydiscus minutus were assessed and compared with those obtained using three widely used Chlorella strains (C. vulgaris, C. sorokiniana, and C. minutissima). Among all extracts, T. minutus extracts showed the highest total antioxidant capacity (TAC) and inhibitory potency towards elastase, suggesting potential activity in controlling skin aging. Furthermore, the cytotoxicity, anti-inflammatory activity and UVA protection of T. minutus extract were evaluated employing normal human dermal fibroblasts (NHDF) and human keratinocyte HaCaT cells. The results showed that the T. minutus extract was able to significantly inhibit the transcription of selected marker genes involved in inflammation [interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor alpha (TNFα)]. In addition, treatment of NHDF and HaCaT cells with T. minutus extract ameliorate the UVA-induced cell damage by decreasing the accumulation of reactive oxygen species (ROS). Extracts from T. minutus were formulated into a skin care cream and an aqueous gel. Both formulas exhibited excellent compatibility and stability. Comprehensively, all these results suggest that T. minutus extract displays promising cosmeceutical properties by providing antioxidant, anti-aging, and anti-inflammatory activities, and therefore has potential for cosmeceutical use.