Production of sodium copper chlorophyllin from a green microalga Chlorella minutissima: a value-added co-product for sustainable microalgal refinery

Absolute chlorophyll composition of commercial green food colorants and coloring foodstuff by HPLC-ESI-QTOF-MS/MS: Copper chlorophyllins

Sodium copper chlorophyllins (SCC) are used worldwide to brightly color green foods as authorized food colorants, although their composition is only partially known. This study applied a combination of experimental and in silico techniques to describe the SCC profile in commercial colorant products and coloring foods. Different approaches have allowed identifying five new chlorophyll compounds in the food colorants besides the description of unique product ions able to distinguish among different chlorophyll isomers for the first time. In addition, a detailed isotope cluster analysis has revealed the formation of two new structures of copper chlorophyllins, featuring the copper in peripheral positions instead of the central pocket. Finally, a computational study of thermodynamic parameters and molecular descriptors has determined the factors responsible for the formation of the two main copper chlorophyllins present in the food colorants. This information will sustain alternative processing leading to SCC products with tailored composition.

Chlorophyllin-Containing Copolymers and Their Responsive Properties

Copper-chlorophyllin is a water-soluble derivative of chlorophylls and shows low cytotoxicity and antimutagenic properties in cultured cells. It has multiple applications, including its use as a photosensitizer in photothermal therapy because of its green light-activated photothermal performance. In this work, it was copolymerized with a poly(ethylene glycol) methacrylic monomer to yield random copolymers by free radical polymerization, which showed dual temperature- and pH-dependent phase transitions in aqueous solutions. The cloud points of the copolymer solutions were raised by lowering the pH of the aqueous solutions due to the protonation of the carboxylic groups on the chlorophyllin moieties, which decreased the overall hydrophilicity of the polymers. At low pH values, complete protonation of the carboxylic acid groups of the chlorophyllin moieties led to an irreversible aggregation of the copolymers in water. The incorporation of chlorophyllin in the copolymer improved its stability over its single molecular form.

Metabolic engineering and synthetic biology strategies for producing high-value natural pigments in Microalgae

Microalgae are microorganisms capable of producing bioactive compounds using photosynthesis. Microalgae contain a variety of high value-added natural pigments such as carotenoids, phycobilins, and chlorophylls. These pigments play an important role in many areas such as food, pharmaceuticals, and cosmetics. Natural pigments have a health value that is unmatched by synthetic pigments. However, the current commercial production of natural pigments from microalgae is not able to meet the growing market demand. The use of metabolic engineering and synthetic biological strategies to improve the production performance of microalgal cell factories is essential to promote the large-scale production of high-value pigments from microalgae. This paper reviews the health and economic values, the applications, and the synthesis pathways of microalgal pigments. Overall, this review aims to highlight the latest research progress in metabolic engineering and synthetic biology in constructing engineered strains of microalgae with high-value pigments and the application of CRISPR technology and multi-omics in this context. Finally, we conclude with a discussion on the bottlenecks and challenges of microalgal pigment production and their future development prospects.

Development of Biotechnological Photosensitizers for Photodynamic Therapy: Cancer Research and Treatment-From Benchtop to Clinical Practice

Photodynamic therapy (PDT) is a noninvasive therapeutic approach that has been applied in studies for the treatment of various diseases. In this context, PDT has been suggested as a new therapy or adjuvant therapy to traditional cancer therapy. The mode of action of PDT consists of the generation of singlet oxygen (¹O₂) and reactive oxygen species (ROS) through the administration of a compound called photosensitizer (PS), a light source, and molecular oxygen (³O₂). This combination generates controlled photochemical reactions (photodynamic mechanisms) that produce ROS, such as singlet oxygen (¹O₂), which can induce apoptosis and/or cell death induced by necrosis, degeneration of the tumor vasculature, stimulation of the antitumor immune response, and induction of inflammatory reactions in the illuminated region. However, the traditional compounds used in PDT limit its application. In this context, compounds of biotechnological origin with photosensitizing activity in association with nanotechnology are being used in PDT, aiming at its application in several types of cancer but with less toxicity toward neighboring tissues and better absorption of light for more aggressive types of cancer. In this review, we present studies involving innovatively developed PS that aimed to improve the efficiency of PDT in cancer treatment. Specifically, we focused on the clinical translation and application of PS of natural origin on cancer.