Phyllobilins

Modified Atmosphere Packaging (MAP) for Seaweed Conservation: Impact on Physicochemical Characteristics and Microbiological Activity

Conventional conservation techniques such as drying, salting or freezing do not allow for preserving the original characteristics of seaweeds. The present work aims to study the impact of minimal processing, in particular "Modified Atmosphere Packaging" (MAP), on the physicochemical characteristics and food safety of two seaweed species, "laver" (Porphyra umbilicalis) and "sea-lettuce" (Ulva lactuca), stored at 6 °C for 15 days. Different parameters were evaluated using analytical methods, namely the composition of headspace gases, color, texture, microorganisms, and volatile organic compounds (VOCs). The main findings of this study were that the MAP treatment was able to inhibit the respiration rate of minimally processed seaweeds, also preserving their color and texture. There was a remarkable reduction in the microbial load for P. umbilicalis treated under modified and vacuum atmospheres, and U. lactuca exhibited relatively steady values with no notable differences between the treatments and the control. Therefore, during the 15-day study period, both seaweeds met the requirements for food safety. GC-TOF-MS allowed to conclude that both MAP and vacuum treatments were more efficient in maintaining the odor characteristics of U. lactuca compared to P. umbilicalis with no significant differences throughout the storage days. Metabolic responses to diverse sources of abiotic stress seemed to account for most of the changes observed.

High production of flavonols and anthocyanins in Eruca sativa (Mill) Thell plants at high artificial LED light intensities

Eruca sativa (arugula) is a food crop containing valuable bioactive flavonoids. Plants growing with monochrome light-emitting diodes (LED) and "binary" light sources, including red/blue (RB), were tested using HPLC-DAD-ESI-MS/MS. Most artificial lighting options with a high intensity of 1000 μmol m^-2s^-1 (except for warm white light) resulted in an almost 20-fold increase in flavonol productivity. Monochromatic sources had no advantage over white light in terms of increasing anthocyanin productivity. However, RB light increased the anthocyanin content and productivity of E. sativa plants by more than ten times compared to white light. Plant growth on monochromatic and binary sources at high intensities was comparable to that on white light. Measurement of the content of chlorophyll and its degradation product, phyllobilins, showed that plants are not under stressful conditions. Overall, our data show that a significant increase in flavonoid content can be achieved without a loss of arugula plant biomass.

Metabolomics of Chlorophylls and Carotenoids: Analytical Methods and Metabolome-Based Studies

Chlorophylls and carotenoids are two families of antioxidants present in daily ingested foods, whose recognition as added-value ingredients runs in parallel with the increasing number of demonstrated functional properties. Both groups include a complex and vast number of compounds, and extraction and analysis methods evolved recently to a modern protocol. New methodologies are more potent, precise, and accurate, but their application requires a better understanding of the technical and biological context. Therefore, the present review compiles the basic knowledge and recent advances of the metabolomics of chlorophylls and carotenoids, including the interrelation with the primary metabolism. The study includes material preparation and extraction protocols, the instrumental techniques for the acquisition of spectroscopic and spectrometric properties, the workflows and software tools for data pre-processing and analysis, and the application of mass spectrometry to pigment metabolomics. In addition, the review encompasses a critical description of studies where metabolomics analyses of chlorophylls and carotenoids were developed as an approach to analyzing the effects of biotic and abiotic stressors on living organisms.

The Role of Porphyrinoid Photosensitizers for Skin Wound Healing

Microorganisms, usually bacteria and fungi, grow and spread in skin wounds, causing infections. These infections trigger the immune system and cause inflammation and tissue damage within the skin or wound, slowing down the healing process. The use of photodynamic therapy (PDT) to eradicate microorganisms has been regarded as a promising alternative to anti-infective therapies, such as those based on antibiotics, and more recently, is being considered for skin wound-healing, namely for infected wounds. Among the several molecules exploited as photosensitizers (PS), porphyrinoids exhibit suitable features for achieving those goals efficiently. The capability that these macrocycles display to generate reactive oxygen species (ROS) gives a significant contribution to the regenerative process. ROS are responsible for avoiding the development of infections by inactivating microorganisms such as bacteria but also by promoting cell proliferation through the activation of stem cells which regulates inflammatory factors and collagen remodeling. The PS can act solo or combined with several materials, such as polymers, hydrogels, nanotubes, or metal-organic frameworks (MOF), keeping both the microbial photoinactivation and healing/regenerative processes' effectiveness. This review highlights the developments on the combination of PDT approach and skin wound healing using natural and synthetic porphyrinoids, such as porphyrins, chlorins and phthalocyanines, as PS, as well as the prodrug 5-aminolevulinic acid (5-ALA), the natural precursor of protoporphyrin-IX (PP-IX).

Profile of Chlorophyll Catabolites in Senescent Leaves of Epipremnun aureum Includes a Catabolite Esterified with Hydroxytyrosol 1-O-Glucoside

Despite the fact that chlorophyll degradation is a physiological phenomenon occurring daily in all photosynthetic tissues, chlorophyll catabolites are not fully identified. Three new forms (1, 3, and 4) of linear chlorophyll catabolites (phyllobilins) have been characterized in senescent leaves of Epipremnun aureum with spectroscopic data. Compound 1 is a hypermodified blue fluorescent chlorophyll catabolite (hmFCC) esterified with the potent antioxidant hydroxytyrosol. The sequestration of this phenol by a chlorophyll catabolite could explain the physiological meaning of the persistence of hmFCCs in some senescent plants. Compound 3, a yellow chlorophyll catabolite (YCC) originated from the oxidation at C-15 of 1. YCCs have been identified previously and are exclusively formed in the plant vacuole from the final nonfluorescent chlorophyll catabolites (NCCs). The presence of 3 in leaves implies a new reaction in chlorophyll catabolism, as the characterization of 3 implies that YCCs can be also be oxidized in the cytosol from FCCs. Finally, phyllobilin 4 represents a new type of YCC characterized by an inflexible bicyclo glucosyl moiety linked through an intramolecular esterification of the propionic acid residue with the C-3 hydroxy group. The corresponding NCC precursor was recently identified and now the characterization of 4 shows that even this rigid structure can be further oxidized. Undoubtedly, the characterization of phyllobilins is essential to completely comprehend chlorophyll degradation.