The first and committed step in proline synthesis from glutamate is catalyzed by δ¹‐pyrroline‐5‐carboxylate synthetase (P5CS). Two P5CS genes have been found in most angiosperms, one constitutively expressed to satisfy proline demand for protein synthesis, the other stress‐induced. Despite the number of papers to investigate regulation at the transcriptional level, to date, the properties of the enzymes have been subjected to limited study. The isolation of Arabidopsis thaliana P5CS isoenzymes was achieved through heterologous expression and affinity purification. The two proteins were characterized with respect to kinetic and biochemical properties. AtP5CS2 showed K_M values in the micro‐ to millimolar range, and its activity was inhibited by NADP⁺, ADP and proline, and by glutamine and arginine at high levels. Mg²⁺ ions were required for activity, which was further stimulated by K⁺ and other cations. AtP5CS1 displayed positive cooperativity with glutamate and was almost insensitive to inhibition by proline. In the presence of physiological, nonsaturating concentrations of glutamate, proline was slightly stimulatory, and glutamine strongly increased the catalytic rate. Data suggest that the activity of AtP5CS isoenzymes is differentially regulated by a complex array of factors including the concentrations of proline, glutamate, glutamine, monovalent cations and pyridine dinucleotides.

Black garlic, a product obtained from fresh garlic (Allium sativum L.) under specific temperature and humidity conditions, has garnered significant scientific attention due to its enhanced organoleptic qualities and superior health-promoting properties compared to the fresh product. The Maillard reaction, alongside other chemical transformations, converts pungent organosulfur compounds like allicin into stable, highly bioactive compounds such as S-allyl-l-cysteine and S-allylmercaptocysteine, while also increasing the levels of polyphenols and other potent antioxidants. This review provides a comprehensive overview of black garlic, detailing the impact of its unique ripening process on its chemical composition, encompassing changes in sugars, proteins, amino acids, lipids, vitamins, minerals, and organic acids. We explore how variations in temperature and humidity during production influence the final product quality attributes and bioactive compound profiles. Furthermore, we extensively discuss the diverse biological activities of black garlic and its key constituents, including significant antioxidant, anti-inflammatory, anticancer, immunostimulatory, antiallergic, hepatoprotective, antidiabetic, and antiobesity effects. By synthesizing current research, this review highlights black garlic potential as a functional food and a source of therapeutic agents, while also emphasizing the need for standardized production methods to ensure consistent quality and maximize its health benefits.

The enzyme that, in Saccharomyces cerevisiae, catalyzes the last step in both proline synthesis and arginine catabolism, δ¹-pyrroline-5-carboxylate (P5C) reductase, was purified to near homogeneity and characterized thoroughly. Retention patterns upon gel permeation chromatography were consistent with a homodecameric composition of the holomer. High lability of the purified preparations and stabilization by reducing compounds suggested susceptibility to reactive-oxygen-species-mediated damage. Both NADH and NADPH were used as the electron donor, the latter resulting in a 3-fold higher V_max. However, a higher affinity toward NADH was evident, and the NADPH-dependent activity was inhibited by NAD⁺, proline, arginine, and a variety of anions. With proline and arginine, the inhibition was of the competitive type with respect to the specific substrate, and of the uncompetitive- or mixed-type with respect to NADPH, respectively. The results suggest that, contrary to the enzyme from higher plants, yeast P5C reductase may preferentially use NADH in vivo. An in silico analysis was also performed to investigate the structural basis of such enzyme features. Superposition of the protein model with the experimental structure of P5C reductase from Medicago truncatula allowed us to hypothesize on the possible allosteric sites for arginine and anion binding, and the cysteine pairs that may be involved in disulfide formation.

Black garlic peels (BGPs) are a largely underutilized by-product despite representing an untapped source of bioactive compounds. This study presents a sustainable upcycling protocol for black garlic peels, evaluating natural deep eutectic solvents (NaDES) to develop multifunctional extracts for green cosmetics. Following the screening of four eutectic mixtures, the choline chloride–lactic acid (ChCl:LA) system demonstrated the highest extraction efficiency. The optimized extract yielded a remarkable total phenolic content (5216.61 µg GAE/mL) and strong antioxidant capacity, confirmed by DPPH and FRAP assays, associated with recovering both free and bound phenolic fractions. Subsequent HPLC profiling characterized the extract, and the comparative analysis explicitly demonstrated that antimicrobial activity is entirely driven by and identical to the pure eutectic solvent vehicle rather than the extracted garlic biomass, with broad-spectrum efficacy against C. albicans, P. aeruginosa, and S. aureus. To evaluate its cosmeceutical potential, the extract was incorporated into emulsions (5%, 10%, 15% w/w) with inorganic or organic UV filters. Although the direct Sun Protection Factor (SPF) and the UVA Protection Factor (UVA-PF) did not show enhancing results, a photochemiluminescence (PCL) analysis revealed a synergistic behaviour with organic filters, successfully boosting the formulation’s biological antioxidant shield. This pioneering work highlights BGP’s upcycling potential, proposing NaDES extracts as highly promising multifunctional, antioxidant, and antimicrobial ingredients for next-generation cosmeceuticals.

The analysis of volatile organic compounds emitted by cell cultures provides a non-invasive method for monitoring metabolic and oxidative stress states. However, detection is challenged by low volatile organic compound concentrations and high sample humidity. This study introduces an integrated system combining a MEMS-based pre-concentrator with an array of n-type Metal-Oxide chemiresistive gas sensors to analyze emissions from the K562 leukemia cell line. The main goal is to distinguish cellular volatile organic compound signals from those of the culture medium. To achieve this, the pre-concentrator is used with different temperature-programmed desorption protocols to enhance signal intensity and improve discrimination performance.