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This review compares and contrasts the role of carotenoids across the taxa of life—with a focus on the xanthophyll zeaxanthin (and its structural isomer lutein) in plants and humans. Xanthophylls’ multiple protective roles are summarized, with attention to the similarities and differences in the roles of zeaxanthin and lutein in plants versus animals, as well as the role of meso-zeaxanthin in humans. Detail is provided on the unique control of zeaxanthin function in photosynthesis, that results in its limited availability in leafy vegetables and the human diet. The question of an optimal dietary antioxidant supply is evaluated in the context of the dual roles of both oxidants and antioxidants, in all vital functions of living organisms, and the profound impact of individual and environmental context.

Marine algae have received great attention as natural photoprotective agents due to their unique and exclusive bioactive substances which have been acquired as an adaptation to the extreme marine environment combine with a range of physical parameters. These photoprotective substances include mycosporine-like amino acids (MAAs), sulfated polysaccharides, carotenoids, and polyphenols. Marine algal photoprotective substances exhibit a wide range of biological activities such as ultraviolet (UV) absorbing, antioxidant, matrix-metalloproteinase inhibitors, anti-aging, and immunomodulatory activities. Hence, such unique bioactive substances derived from marine algae have been regarded as having potential for use in skin care, cosmetics, and pharmaceutical products. In this context, this contribution aims at revealing bioactive substances found in marine algae, outlines their photoprotective potential, and provides an overview of developments of blue biotechnology to obtain photoprotective substances and their prospective applications.

A radioresistant bacterium identified as Kocuria sp.TMM 11 was isolated from Thal desert. Kocuria sp.TMM11 demonstrated resistance (57.3% survival rate) to an ultraviolet B radiations dose of 4.1 × 10 3  J/m 2 , 61.5% survival rate to hydrogen peroxide (60 mM) and 57.1% survivability to mitomycin C (6 μg/mL). An orange carotenoid pigment from strain TMM 11 was extracted using solvent mixture of methanol, ethyl acetate and acetone (7:5:3), subsequently purified using C18 cartridge column. The purified fraction was analyzed by liquid chromatography mass spectrometry and compounds identified were rhodovibrin, phytoene, 4'-Hydroxy-4,4'-diaponeurosporene-4-oic acid and 3,4,3',4'-Tetrahydrospirilloxanthin. The purified fraction with mixture of carotenoid compounds, was evaluated for its antioxidant activity, total flavonoids, phenolic content and radio protective potential. These assessments were conducted in relation to its ability to prevent protein and lipids oxidation, as well as DNA strand breaks in vitro. The fraction showed strong antioxidant activity, as indicated by its ability to scavenge super oxides, with an IC50 value of 50.8 μg/mL. Additionally, it displayed 75.76% iron chelation activity. The purified fraction strongly inhibited oxidative damage to proteins and lipids, comparable to the activity of standard ascorbic acid. The total phenolic and flavonoid contents in extract were measured 11.6 and 9.8 μg in terms of gallic acid and quercetin equivalents per milligram of dried mass. Hence, it is concluded that the carotenoid mixture from Kocuria sp.TMM 11 not only inhibited DNA strands from UV mediated photo damages but also protected lipid and protein peroxidation and therefore could be a good candidate in radio protective drugs and as sunscreen. Graphical Abstract

The growing demand to fulfill the needs of present-day medicine in terms of novel effective molecules has lead to reexamining some of the old and known bacterial secondary metabolites. Bacterial prodigiosins (prodiginines) have a long history of being re markable multipurpose compounds, best examined for their anticancer and antimalarial activities. Production of prodigiosin in the most common producer strain Serratia marcescens has been described in great detail. However, few reports have discussed the ecophysiological roles of these molecules in the producing strains, as well as their antibiotic and UV-protective properties. This review describes recent advances in the production process, biosynthesis, properties, and applications of bacterial prodigiosins. Special emphasis is put on undecylprodigiosin which has generally been a less studied member of the prodigiosin family. In addition, it has been suggested that proteins involved in undecylprodigiosin synthesis, RedG and RedH, could be a useful addition to the biocatalytic toolbox being able to mediate regio- and stereoselective oxidative cyclization. Judging by the number of recent references (216 for the 2007–2013 period), it has become clear that undecylprodigiosin and other bacterial prodigiosins still hold surprises in terms of valuable properties and applicative potential to medical and other industrial fields and that they still deserve continuing research curiosity.

Amifostine has been the only small molecule radio-protector approved by FDA for decades; however, the serious adverse effects limit its clinical use. To address the toxicity issues and maintain the good potency, a series of modified small polycysteine peptides had been prepared. Among them, compound 5 exhibited the highest radio-protective efficacy, the same as amifostine, but much better safety profile. To confirm the correlation between the radiation-protective efficacy and the DNA binding capability, each of the enantiomers of the polycysteine peptides had been prepared. As a result, the l -configuration compounds had obviously higher efficacy than the corresponding d -configuration enantiomers; among them, compound 5 showed the highest DNA binding capability and radiation-protective efficacy. To our knowledge, this is the first study that has proved their correlations using direct comparison. Further exploration of the mechanism revealed that the ionizing radiation (IR) triggered ferroptosis inhibition by compound 5 could be one of the pathways for the protection effect, which was different from amifostine. In summary, the preliminary result showed that compound 5 , a polycysteine as a new type of radio-protector, had been developed with good efficacy and safety profile. Further study of the compound for potential use is ongoing.

Ultraviolet light (UV) is an inducer of reactive oxygen species (ROS) as well as 6-4-photoproducts and cyclobutane pyrimidine dimers (CPD) in the skin, which further cause damage to the skin cells. Irradiation of cultured human melanocytes with UVB stimulated ROS production, which was reduced in cells treated with melatonin or its metabolites: 6-hydroxymelatonin (6-OHM), N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), N -acetylserotonin (NAS), and 5-methoxytryptamine (5-MT). Melatonin and its derivatives also stimulated the expression of NRF2 (nuclear factor erythroid 2 [NF-E2]-related factor 2) and its target enzymes and proteins that play an important role in cell protection from different damaging factors including UVB. Silencing of NRF2 using siRNA diminished the protective effects of melatonin, while the membrane melatonin receptors (MT1 or MT2) did not change the activities of either melatonin or its derivatives. Melatonin and its metabolites enhanced the DNA repair in melanocytes exposed to UVB and stimulated expression of p53 phosphorylated at Ser-15. In conclusion, melatonin and its metabolites protect melanocytes from UVB-induced DNA damage and oxidative stress through activation of NRF2-dependent pathways; these actions are independent of an effect on the classic membrane melatonin receptors. Thus, melatonin and its derivatives can serve as excellent protectors of melanocytes against UVB-induced pathology.

Background As we know, radiotherapy plays an irreplaceable role in the clinical management on solid tumors. However, due to the non-specific killing effects of ionizing radiation, normal tissues damages would be almost simultaneous inevitably. Therefore, ideal radioprotective agents with high efficiency and low toxicity are always desirable. In this work, atomically precise Ag 14 clusterzymes were developed, and their applications in radioprotection were studied in vitro and in vivo for the first time. Methods The ultra-small glutathione supported Ag 14 clusterzymes were synthesized by convenient sodium borohydride (NaBH 4 ) reduction of thiolate-Ag (I) complexes and then they were purified by desalting columns. The enzyme-like activity and antioxidant capacity of Ag 14 clusterzymes have been tested by various commercial kits, salicylic acid method and electron spin resonance (ESR). Next, they were incubated with L929 cells to evaluate whether they could increase cell viability after γ-ray irradiation. And then Ag 14 clusterzymes were intravenously injected into C57 mice before 7 Gy whole-body γ-ray irradiation to evaluate the radioprotection effects in vivo. At last, the in vivo toxicities of Ag 14 clusterzymes were evaluated through biodistribution test, hematological details, serum biochemical indexes and histological test in female Balb/c mice with intravenous injection of Ag 14 clusterzymes. Results Our studies suggested atomically precise Ag 14 clusterzymes were potential radioprotectants. Ag 14 clusterzymes exhibited unique superoxide dismutase (SOD)-like activity, strong anti-oxidative abilities, especially on •OH scavenging. The Ag 14 clusterzymes could effectively improve cell viability through eliminating ROS and prevent DNA damages in cells dealt with γ-ray irradiation. In vivo experiments showed that Ag 14 clusterzymes could improve the irradiated mice survival rate by protecting hematological systems and repairing tissue oxidative stress damage generated by γ-ray irradiation. In addition, bio-distribution and toxicological experiments demonstrated that the ultrasmall Ag 14 clusterzymes could be excreted quickly from the body by renal clearance and negligible toxicological responses were observed in mice up to 30 days. Conclusion In summary, atomically precise, ultrasmall and water soluble Ag 14 clusterzymes with SOD-like activity were successfully developed and proved to be effective both in vitro and in vivo for radioprotection. Furthermore, with atomically precise molecular structure, Ag 14 clusterzymes, on aspect of the catalytic and optical properties, may be improved by structure optimization on atom-scale level for other applications in disease diagnosis and treatment. Graphical Abstract

Summary Microbial melanins provide a biocompatible and scalable approach for bioremediation and radioprotection technologies due to their physicochemical properties. Melanotic microorganisms are useful in achieving a sustainable future as they provide a biocompatible and scalable source of melanins for radioprotection and bioremediation technologies.

Polyaromatic hydrocarbons (PAHs) are major and recalcitrant pollutants of the environment and their removal presents a significant problem. Phytoremediation has shown much promise in PAH removal from contaminated soil, but may be inhibited because the plant experiences phytotoxic effects from low-molecular-weight PAHs such as naphthalene. This paper describes the construction of a naphthalene-degrading endophytic strain designated Pseudomonas putida VM1441(pNAH7). This strain was found to be an efficient colonizer of plants, colonizing both the rhizosphere and interior root tissues. The inoculation of plants with P. putida VM1441(pNAH7) resulted in the protection of the host plant from the phytotoxic effects of naphthalene. When inoculated plants were exposed to naphthalene, both seed germination and plant transpiration rates were higher than those of the uninoculated controls. The inoculation of plants with this strain also facilitated higher (40%) naphthalene degradation rates compared with uninoculated plants in artificially contaminated soil.

Ultraviolet B (UVB) radiation severely damages human skin by causing DNA damage, oxidative stress, and collagen degradation. This study explored the photoprotective properties of Asparagus cochinchinensis extracts fermented with endophytic fungus Aspergillus aculeatus TD103. Compared to the unfermented control, TD103-fermented A. cochinchinensis demonstrated stronger radical scavenging and ferric ion reduction abilities in vivo, significantly reduced intracellular reactive oxygen species (ROS) and increased the antioxidant enzymes including heme oxygenase-1 (HO-1), superoxide dismutase (SOD), and catalase (CAT) in UVB-induced HaCaT cells. It also downregulated the expression of the AP-1 and MMP genes, reduced the content of matrix metalloproteinase (MMP-1) and increased type I procollagen amino-terminal propeptide (PINP) levels in UVB-induced HaCaT cells. Non-targeted metabolomics and HPLC quantification revealed that elevated sarsasapogenin content may critically contribute to enhanced photoprotective capacity in Asparagus cochinchinensis . The safety assessment of fungus TD103 revealed that this strain was not drug resistant and did not produce mycotoxins, thereby indicating its safety for application. Eye irritation tests demonstrated the safety profile of the fermented extract, indicating negligible irritant potential. The TD103-mediated fermentation markedly potentiated the photoprotective capacity of A. cochinchinensis , ​providing a viable biotechnological platform for sustainable cosmeceutical development targeting UV-induced skin damage.